Obey kvm.halt_poll_ns in VMs not using KVM_CAP_HALT_POLL on every halt,
rather than just sampling the module parameter when the VM is first
created. This restore the original behavior of kvm.halt_poll_ns for VMs
that have not opted into KVM_CAP_HALT_POLL.
Notably, this change restores the ability for admins to disable or
change the maximum halt-polling time system wide for VMs not using
KVM_CAP_HALT_POLL.
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: acd05785e4 ("kvm: add capability for halt polling")
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20221117001657.1067231-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Avoid re-reading kvm->max_halt_poll_ns multiple times during
halt-polling except when it is explicitly useful, e.g. to check if the
max time changed across a halt. kvm->max_halt_poll_ns can be changed at
any time by userspace via KVM_CAP_HALT_POLL.
This bug is unlikely to cause any serious side-effects. In the worst
case one halt polls for shorter or longer than it should, and then is
fixed up on the next halt. Furthmore, this is still possible since
kvm->max_halt_poll_ns are not synchronized with halts.
Fixes: acd05785e4 ("kvm: add capability for halt polling")
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20221117001657.1067231-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cap vcpu->halt_poll_ns based on the max halt polling time just before
halting, rather than after the last halt. This arguably provides better
accuracy if an admin disables halt polling in between halts, although
the improvement is nominal.
A side-effect of this change is that grow_halt_poll_ns() no longer needs
to access vcpu->kvm->max_halt_poll_ns, which will be useful in a future
commit where the max halt polling time can come from the module parameter
halt_poll_ns instead.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20221117001657.1067231-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In mark_page_dirty_in_slot(), we bail out when no running vcpu exists
and a running vcpu context is strictly required by architecture. It may
cause backwards compatible issue. Currently, saving vgic/its tables is
the only known case where no running vcpu context is expected. We may
have other unknown cases where no running vcpu context exists and it's
reported by the warning message and we bail out without pushing the
dirty information to the backup bitmap. For this, the application is
going to enable the backup bitmap for the unknown cases. However, the
dirty information can't be pushed to the backup bitmap even though the
backup bitmap is enabled for those unknown cases in the application,
until the unknown cases are added to the allowed list of non-running
vcpu context with extra code changes to the host kernel.
In order to make the new application, where the backup bitmap has been
enabled, to work with the unchanged host, we continue to push the dirty
information to the backup bitmap instead of bailing out early. With the
added check on 'memslot->dirty_bitmap' to mark_page_dirty_in_slot(), the
kernel crash is avoided silently by the combined conditions: no running
vcpu context, kvm_arch_allow_write_without_running_vcpu() returns 'true',
and the backup bitmap (KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP) isn't enabled
yet.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221112094322.21911-1-gshan@redhat.com
ARM64 needs to dirty memory outside of a VCPU context when VGIC/ITS is
enabled. It's conflicting with that ring-based dirty page tracking always
requires a running VCPU context.
Introduce a new flavor of dirty ring that requires the use of both VCPU
dirty rings and a dirty bitmap. The expectation is that for non-VCPU
sources of dirty memory (such as the VGIC/ITS on arm64), KVM writes to
the dirty bitmap. Userspace should scan the dirty bitmap before migrating
the VM to the target.
Use an additional capability to advertise this behavior. The newly added
capability (KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP) can't be enabled before
KVM_CAP_DIRTY_LOG_RING_ACQ_REL on ARM64. In this way, the newly added
capability is treated as an extension of KVM_CAP_DIRTY_LOG_RING_ACQ_REL.
Suggested-by: Marc Zyngier <maz@kernel.org>
Suggested-by: Peter Xu <peterx@redhat.com>
Co-developed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110104914.31280-4-gshan@redhat.com
The VCPU isn't expected to be runnable when the dirty ring becomes soft
full, until the dirty pages are harvested and the dirty ring is reset
from userspace. So there is a check in each guest's entrace to see if
the dirty ring is soft full or not. The VCPU is stopped from running if
its dirty ring has been soft full. The similar check will be needed when
the feature is going to be supported on ARM64. As Marc Zyngier suggested,
a new event will avoid pointless overhead to check the size of the dirty
ring ('vcpu->kvm->dirty_ring_size') in each guest's entrance.
Add KVM_REQ_DIRTY_RING_SOFT_FULL. The event is raised when the dirty ring
becomes soft full in kvm_dirty_ring_push(). The event is only cleared in
the check, done in the newly added helper kvm_dirty_ring_check_request().
Since the VCPU is not runnable when the dirty ring becomes soft full, the
KVM_REQ_DIRTY_RING_SOFT_FULL event is always set to prevent the VCPU from
running until the dirty pages are harvested and the dirty ring is reset by
userspace.
kvm_dirty_ring_soft_full() becomes a private function with the newly added
helper kvm_dirty_ring_check_request(). The alignment for the various event
definitions in kvm_host.h is changed to tab character by the way. In order
to avoid using 'container_of()', the argument @ring is replaced by @vcpu
in kvm_dirty_ring_push().
Link: https://lore.kernel.org/kvmarm/87lerkwtm5.wl-maz@kernel.org
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110104914.31280-2-gshan@redhat.com
Add a new "interruptible" flag showing that the caller is willing to be
interrupted by signals during the __gfn_to_pfn_memslot() request. Wire it
up with a FOLL_INTERRUPTIBLE flag that we've just introduced.
This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the
SIGIPI) even during e.g. handling an userfaultfd page fault.
No functional change intended.
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221011195809.557016-4-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new pfn error to show that we've got a pending signal to handle
during hva_to_pfn_slow() procedure (of -EINTR retval).
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221011195809.557016-3-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* Fix the pKVM stage-1 walker erronously using the stage-2 accessor
* Correctly convert vcpu->kvm to a hyp pointer when generating
an exception in a nVHE+MTE configuration
* Check that KVM_CAP_DIRTY_LOG_* are valid before enabling them
* Fix SMPRI_EL1/TPIDR2_EL0 trapping on VHE
* Document the boot requirements for FGT when entering the kernel
at EL1
There are two capabilities related to ring-based dirty page tracking:
KVM_CAP_DIRTY_LOG_RING and KVM_CAP_DIRTY_LOG_RING_ACQ_REL. Both are
supported by x86. However, arm64 supports KVM_CAP_DIRTY_LOG_RING_ACQ_REL
only when the feature is supported on arm64. The userspace doesn't have
to enable the advertised capability, meaning KVM_CAP_DIRTY_LOG_RING can
be enabled on arm64 by userspace and it's wrong.
Fix it by double checking if the capability has been advertised prior to
enabling it. It's rejected to enable the capability if it hasn't been
advertised.
Fixes: 17601bfed9 ("KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option")
Reported-by: Sean Christopherson <seanjc@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221031003621.164306-4-gshan@redhat.com
Although simple_attr_open() fails only with -ENOMEM with current code
base, it would be nicer to return retval of simple_attr_open() directly
in kvm_debugfs_open().
No functional change intended.
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <69d64d93accd1f33691b8a383ae555baee80f943.1665975828.git.houwenlong.hwl@antgroup.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We will introduce the first architecture specific compat vm ioctl in the
next patch. Add all necessary boilerplate to allow architectures to
override compat vm ioctls when necessary.
Signed-off-by: Alexander Graf <graf@amazon.com>
Message-Id: <20221017184541.2658-2-graf@amazon.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Fixes for single-stepping in the presence of an async
exception as well as the preservation of PSTATE.SS
- Better handling of AArch32 ID registers on AArch64-only
systems
- Fixes for the dirty-ring API, allowing it to work on
architectures with relaxed memory ordering
- Advertise the new kvmarm mailing list
- Various minor cleanups and spelling fixes
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Merge tag 'kvmarm-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for v6.1
- Fixes for single-stepping in the presence of an async
exception as well as the preservation of PSTATE.SS
- Better handling of AArch32 ID registers on AArch64-only
systems
- Fixes for the dirty-ring API, allowing it to work on
architectures with relaxed memory ordering
- Advertise the new kvmarm mailing list
- Various minor cleanups and spelling fixes
In order to differenciate between architectures that require no extra
synchronisation when accessing the dirty ring and those who do,
add a new capability (KVM_CAP_DIRTY_LOG_RING_ACQ_REL) that identify
the latter sort. TSO architectures can obviously advertise both, while
relaxed architectures must only advertise the ACQ_REL version.
This requires some configuration symbol rejigging, with HAVE_KVM_DIRTY_RING
being only indirectly selected by two top-level config symbols:
- HAVE_KVM_DIRTY_RING_TSO for strongly ordered architectures (x86)
- HAVE_KVM_DIRTY_RING_ACQ_REL for weakly ordered architectures (arm64)
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20220926145120.27974-3-maz@kernel.org
KVM_REQ_UNHALT is now unnecessary because it is replaced by the return
value of kvm_vcpu_block/kvm_vcpu_halt. Remove it.
No functional change intended.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20220921003201.1441511-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When alloc_cpumask_var_node() fails for a certain cpu, there might be some
allocated cpumasks for percpu cpu_kick_mask. We should free these cpumasks
or memoryleak will occur.
Fixes: baff59ccdc ("KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Link: https://lore.kernel.org/r/20220823063414.59778-1-linmiaohe@huawei.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The variable is initialized but it is only used after its assignment.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Message-Id: <20220819021535.483702-1-kunyu@nfschina.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The variable is initialized but it is only used after its assignment.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Message-Id: <20220819022804.483914-1-kunyu@nfschina.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The motivation of this renaming is to make these variables and related
helper functions less mmu_notifier bound and can also be used for non
mmu_notifier based page invalidation. mmu_invalidate_* was chosen to
better describe the purpose of 'invalidating' a page that those
variables are used for.
- mmu_notifier_seq/range_start/range_end are renamed to
mmu_invalidate_seq/range_start/range_end.
- mmu_notifier_retry{_hva} helper functions are renamed to
mmu_invalidate_retry{_hva}.
- mmu_notifier_count is renamed to mmu_invalidate_in_progress to
avoid confusion with mn_active_invalidate_count.
- While here, also update kvm_inc/dec_notifier_count() to
kvm_mmu_invalidate_begin/end() to match the change for
mmu_notifier_count.
No functional change intended.
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Message-Id: <20220816125322.1110439-3-chao.p.peng@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Invoke kvm_coalesced_mmio_init() from kvm_create_vm() now that allocating
and initializing coalesced MMIO objects is separate from registering any
associated devices. Moving coalesced MMIO cleans up the last oddity
where KVM does VM creation/initialization after kvm_create_vm(), and more
importantly after kvm_arch_post_init_vm() is called and the VM is added
to the global vm_list, i.e. after the VM is fully created as far as KVM
is concerned.
Originally, kvm_coalesced_mmio_init() was called by kvm_create_vm(), but
the original implementation was completely devoid of error handling.
Commit 6ce5a090a9 ("KVM: coalesced_mmio: fix kvm_coalesced_mmio_init()'s
error handling" fixed the various bugs, and in doing so rightly moved the
call to after kvm_create_vm() because kvm_coalesced_mmio_init() also
registered the coalesced MMIO device. Commit 2b3c246a68 ("KVM: Make
coalesced mmio use a device per zone") cleaned up that mess by having
each zone register a separate device, i.e. moved device registration to
its logical home in kvm_vm_ioctl_register_coalesced_mmio(). As a result,
kvm_coalesced_mmio_init() is now a "pure" initialization helper and can
be safely called from kvm_create_vm().
Opportunstically drop the #ifdef, KVM provides stubs for
kvm_coalesced_mmio_{init,free}() when CONFIG_KVM_MMIO=n (s390).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220816053937.2477106-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Unconditionally get a reference to the /dev/kvm module when creating a VM
instead of using try_get_module(), which will fail if the module is in
the process of being forcefully unloaded. The error handling when
try_get_module() fails doesn't properly unwind all that has been done,
e.g. doesn't call kvm_arch_pre_destroy_vm() and doesn't remove the VM
from the global list. Not removing VMs from the global list tends to be
fatal, e.g. leads to use-after-free explosions.
The obvious alternative would be to add proper unwinding, but the
justification for using try_get_module(), "rmmod --wait", is completely
bogus as support for "rmmod --wait", i.e. delete_module() without
O_NONBLOCK, was removed by commit 3f2b9c9cdf ("module: remove rmmod
--wait option.") nearly a decade ago.
It's still possible for try_get_module() to fail due to the module dying
(more like being killed), as the module will be tagged MODULE_STATE_GOING
by "rmmod --force", i.e. delete_module(..., O_TRUNC), but playing nice
with forced unloading is an exercise in futility and gives a falsea sense
of security. Using try_get_module() only prevents acquiring _new_
references, it doesn't magically put the references held by other VMs,
and forced unloading doesn't wait, i.e. "rmmod --force" on KVM is all but
guaranteed to cause spectacular fireworks; the window where KVM will fail
try_get_module() is tiny compared to the window where KVM is building and
running the VM with an elevated module refcount.
Addressing KVM's inability to play nice with "rmmod --force" is firmly
out-of-scope. Forcefully unloading any module taints kernel (for obvious
reasons) _and_ requires the kernel to be built with
CONFIG_MODULE_FORCE_UNLOAD=y, which is off by default and comes with the
amusing disclaimer that it's "mainly for kernel developers and desperate
users". In other words, KVM is free to scoff at bug reports due to using
"rmmod --force" while VMs may be running.
Fixes: 5f6de5cbeb ("KVM: Prevent module exit until all VMs are freed")
Cc: stable@vger.kernel.org
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220816053937.2477106-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Properly unwind VM creation if kvm_create_vm_debugfs() fails. A recent
change to invoke kvm_create_vm_debug() in kvm_create_vm() was led astray
by buggy try_get_module() handling adding by commit 5f6de5cbeb ("KVM:
Prevent module exit until all VMs are freed"). The debugfs error path
effectively inherits the bad error path of try_module_get(), e.g. KVM
leaves the to-be-free VM on vm_list even though KVM appears to do the
right thing by calling module_put() and falling through.
Opportunistically hoist kvm_create_vm_debugfs() above the call to
kvm_arch_post_init_vm() so that the "post-init" arch hook is actually
invoked after the VM is initialized (ignoring kvm_coalesced_mmio_init()
for the moment). x86 is the only non-nop implementation of the post-init
hook, and it doesn't allocate/initialize any objects that are reachable
via debugfs code (spawns a kthread worker for the NX huge page mitigation).
Leave the buggy try_get_module() alone for now, it will be fixed in a
separate commit.
Fixes: b74ed7a68e ("KVM: Actually create debugfs in kvm_create_vm()")
Reported-by: syzbot+744e173caec2e1627ee0@syzkaller.appspotmail.com
Cc: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20220816053937.2477106-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Doing debugfs creation after vm creation leaves things in a
quasi-initialized state for a while. This is further complicated by the
fact that we tear down debugfs from kvm_destroy_vm(). Align debugfs and
stats init/destroy with the vm init/destroy pattern to avoid any
headaches.
Note the fix for a benign mistake in error handling for calls to
kvm_arch_create_vm_debugfs() rolled in. Since all implementations of
the function return 0 unconditionally it isn't actually a bug at
the moment.
Lastly, tear down debugfs/stats data in the kvm_create_vm_debugfs()
error path. Previously it was safe to assume that kvm_destroy_vm() would
take out the garbage, that is no longer the case.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-6-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
At the time the VM fd is used in kvm_create_vm_debugfs(), the fd has
been allocated but not yet installed. It is only really useful as an
identifier in strings for the VM (such as debugfs).
Treat it exactly as such by passing the string name of the fd to
kvm_create_vm_debugfs(), futureproofing against possible misuse of the
VM fd.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-5-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allocate a VM's fd at the very beginning of kvm_dev_ioctl_create_vm() so
that KVM can use the fd value to generate strigns, e.g. for debugfs,
when creating and initializing the VM.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-4-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Initialize stats_id alongside other kvm_vcpu fields to make it more
difficult to unintentionally access stats_id before it's set.
No functional change intended.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-3-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Initialize stats_id alongside other struct kvm fields to make it more
difficult to unintentionally access stats_id before it's set. While at
it, move the format string to the first line of the call and fix the
indentation of the second line.
No functional change intended.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-2-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM/s390, KVM/x86 and common infrastructure changes for 5.20
x86:
* Permit guests to ignore single-bit ECC errors
* Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache
* Intel IPI virtualization
* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS
* PEBS virtualization
* Simplify PMU emulation by just using PERF_TYPE_RAW events
* More accurate event reinjection on SVM (avoid retrying instructions)
* Allow getting/setting the state of the speaker port data bit
* Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent
* "Notify" VM exit (detect microarchitectural hangs) for Intel
* Cleanups for MCE MSR emulation
s390:
* add an interface to provide a hypervisor dump for secure guests
* improve selftests to use TAP interface
* enable interpretive execution of zPCI instructions (for PCI passthrough)
* First part of deferred teardown
* CPU Topology
* PV attestation
* Minor fixes
Generic:
* new selftests API using struct kvm_vcpu instead of a (vm, id) tuple
x86:
* Use try_cmpxchg64 instead of cmpxchg64
* Bugfixes
* Ignore benign host accesses to PMU MSRs when PMU is disabled
* Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior
* x86/MMU: Allow NX huge pages to be disabled on a per-vm basis
* Port eager page splitting to shadow MMU as well
* Enable CMCI capability by default and handle injected UCNA errors
* Expose pid of vcpu threads in debugfs
* x2AVIC support for AMD
* cleanup PIO emulation
* Fixes for LLDT/LTR emulation
* Don't require refcounted "struct page" to create huge SPTEs
x86 cleanups:
* Use separate namespaces for guest PTEs and shadow PTEs bitmasks
* PIO emulation
* Reorganize rmap API, mostly around rmap destruction
* Do not workaround very old KVM bugs for L0 that runs with nesting enabled
* new selftests API for CPUID
The kvm_mmu_topup_memory_cache() always uses GFP_KERNEL_ACCOUNT for
memory allocation which prevents it's use in atomic context. To address
this limitation of kvm_mmu_topup_memory_cache(), we add gfp_custom flag
in struct kvm_mmu_memory_cache. When the gfp_custom flag is set to some
GFP_xyz flags, the kvm_mmu_topup_memory_cache() will use that instead of
GFP_KERNEL_ACCOUNT.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Add a new debugfs file to expose the pid of each vcpu threads. This
is very helpful for userland tools to get the vcpu pids without
worrying about thread naming conventions of the VMM.
Signed-off-by: Vineeth Pillai (Google) <vineeth@bitbyteword.org>
Message-Id: <20220523190327.2658-1-vineeth@bitbyteword.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declarations. This will
be used in a follow-up commit to declare an cache in x86 with a capacity
of 512+ objects without having to increase the capacity of all caches in
KVM.
This change requires each cache now specify its capacity at runtime,
since the cache struct itself no longer has a fixed capacity known at
compile time. To protect against someone accidentally defining a
kvm_mmu_memory_cache struct directly (without the extra storage), this
commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
In order to support different capacities, this commit changes the
objects pointer array to be dynamically allocated the first time the
cache is topped-up.
While here, opportunistically clean up the stack-allocated
kvm_mmu_memory_cache structs in riscv and arm64 to use designated
initializers.
No functional change intended.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-22-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop the unnecessary initialization of the local 'pfn' variable in
hva_to_pfn(). First and foremost, '0' is not an invalid pfn, it's a
perfectly valid pfn on most architectures. I.e. if hva_to_pfn() were to
return an "uninitializd" pfn, it would actually be interpeted as a legal
pfn by most callers.
Second, hva_to_pfn() can't return an uninitialized pfn as hva_to_pfn()
explicitly sets pfn to an error value (or returns an error value directly)
if a helper returns failure, and all helpers set the pfn on success.
The zeroing of 'pfn' was introduced by commit 2fc843117d ("KVM:
reorganize hva_to_pfn"), probably to avoid "uninitialized variable"
warnings on statements that return pfn. However, no compiler seems
to produce them, making the initialization unnecessary.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename and refactor kvm_is_reserved_pfn() to kvm_pfn_to_refcounted_page()
to better reflect what KVM is actually checking, and to eliminate extra
pfn_to_page() lookups. The kvm_release_pfn_*() an kvm_try_get_pfn()
helpers in particular benefit from "refouncted" nomenclature, as it's not
all that obvious why KVM needs to get/put refcounts for some PG_reserved
pages (ZERO_PAGE and ZONE_DEVICE).
Add a comment to call out that the list of exceptions to PG_reserved is
all but guaranteed to be incomplete. The list has mostly been compiled
by people throwing noodles at KVM and finding out they stick a little too
well, e.g. the ZERO_PAGE's refcount overflowed and ZONE_DEVICE pages
didn't get freed.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Operate on a 'struct page' instead of a pfn when checking if a page is a
ZONE_DEVICE page, and rename the helper accordingly. Generally speaking,
KVM doesn't actually care about ZONE_DEVICE memory, i.e. shouldn't do
anything special for ZONE_DEVICE memory. Rather, KVM wants to treat
ZONE_DEVICE memory like regular memory, and the need to identify
ZONE_DEVICE memory only arises as an exception to PG_reserved pages. In
other words, KVM should only ever check for ZONE_DEVICE memory after KVM
has already verified that there is a struct page associated with the pfn.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop helpers to convert a gfn/gpa to a 'struct page' in the context of a
vCPU. KVM doesn't require that guests be backed by 'struct page' memory,
thus any use of helpers that assume 'struct page' is bound to be flawed,
as was the case for the recently removed last user in x86's nested VMX.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop a WARN_ON() if kvm_pfn_to_page() encounters a "reserved" pfn, which
in this context means a struct page that has PG_reserved but is not a/the
ZERO_PAGE and is not a ZONE_DEVICE page. The usage, via gfn_to_page(),
in x86 is safe as gfn_to_page() is used only to retrieve a page from
KVM-controlled memslot, but the usage in PPC and s390 operates on
arbitrary gfns and thus memslots that can be backed by incompatible
memory.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Invert the order of KVM's page/pfn release helpers so that the "inner"
helper operates on a page instead of a pfn. As pointed out by Linus[*],
converting between struct page and a pfn isn't necessarily cheap, and
that's not even counting the overhead of is_error_noslot_pfn() and
kvm_is_reserved_pfn(). Even if the checks were dirt cheap, there's no
reason to convert from a page to a pfn and back to a page, just to mark
the page dirty/accessed or to put a reference to the page.
Opportunistically drop a stale declaration of kvm_set_page_accessed()
from kvm_host.h (there was no implementation).
No functional change intended.
[*] https://lore.kernel.org/all/CAHk-=wifQimj2d6npq-wCi5onYPjzQg4vyO4tFcPJJZr268cRw@mail.gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't set Accessed/Dirty bits for a struct page with PG_reserved set,
i.e. don't set A/D bits for the ZERO_PAGE. The ZERO_PAGE (or pages
depending on the architecture) should obviously never be written, and
similarly there's no point in marking it accessed as the page will never
be swapped out or reclaimed. The comment in page-flags.h is quite clear
that PG_reserved pages should be managed only by their owner, and
strictly following that mandate also simplifies KVM's logic.
Fixes: 7df003c852 ("KVM: fix overflow of zero page refcount with ksm running")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove a check from kvm_release_pfn() to bail if the provided @pfn is
zero. Zero is a perfectly valid pfn on most architectures, and should
not be used to indicate an error or an invalid pfn. The bogus check was
added by commit 917248144d ("x86/kvm: Cache gfn to pfn translation"),
which also did the bad thing of zeroing the pfn and gfn to mark a cache
invalid. Thankfully, that bad behavior was axed by commit 357a18ad23
("KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache").
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make it use the same verb as in kvm_kick_many_cpus().
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220605063417.308311-5-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
s390:
* add an interface to provide a hypervisor dump for secure guests
* improve selftests to show tests
x86:
* Intel IPI virtualization
* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS
* PEBS virtualization
* Simplify PMU emulation by just using PERF_TYPE_RAW events
* More accurate event reinjection on SVM (avoid retrying instructions)
* Allow getting/setting the state of the speaker port data bit
* Rewrite gfn-pfn cache refresh
* Refuse starting the module if VM-Entry/VM-Exit controls are inconsistent
* "Notify" VM exit
On SVM, if preemption happens right after the call to finish_rcuwait
but before call to kvm_arch_vcpu_unblocking on SVM/AVIC, it itself
will re-enable AVIC, and then we will try to re-enable it again
in kvm_arch_vcpu_unblocking which will lead to a warning
in __avic_vcpu_load.
The same problem can happen if the vCPU is preempted right after the call
to kvm_arch_vcpu_blocking but before the call to prepare_to_rcuwait
and in this case, we will end up with AVIC enabled during sleep -
Ooops.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220606180829.102503-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
kvm_arch_vcpu_precreate() targets to handle arch specific VM resource
to be prepared prior to the actual creation of vCPU. For example, x86
platform may need do per-VM allocation based on max_vcpu_ids at the
first vCPU creation. It probably leads to concurrency control on this
allocation as multiple vCPU creation could happen simultaneously. From
the architectual point of view, it's necessary to execute
kvm_arch_vcpu_precreate() under protect of kvm->lock.
Currently only arm64, x86 and s390 have non-nop implementations at the
stage of vCPU pre-creation. Remove the lock acquiring in s390's design
and make sure all architecture can run kvm_arch_vcpu_precreate() safely
under kvm->lock without recrusive lock issue.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Zeng Guang <guang.zeng@intel.com>
Message-Id: <20220419154409.11842-1-guang.zeng@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A KVM device cleanup happens in either of two callbacks:
1) destroy() which is called when the VM is being destroyed;
2) release() which is called when a device fd is closed.
Most KVM devices use 1) but Book3s's interrupt controller KVM devices
(XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during
the machine execution. The error handling in kvm_ioctl_create_device()
assumes destroy() is always defined which leads to NULL dereference as
discovered by Syzkaller.
This adds a checks for destroy!=NULL and adds a missing release().
This is not changing kvm_destroy_devices() as devices with defined
release() should have been removed from the KVM devices list by then.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* ultravisor communication device driver
* fix TEID on terminating storage key ops
RISC-V:
* Added Sv57x4 support for G-stage page table
* Added range based local HFENCE functions
* Added remote HFENCE functions based on VCPU requests
* Added ISA extension registers in ONE_REG interface
* Updated KVM RISC-V maintainers entry to cover selftests support
ARM:
* Add support for the ARMv8.6 WFxT extension
* Guard pages for the EL2 stacks
* Trap and emulate AArch32 ID registers to hide unsupported features
* Ability to select and save/restore the set of hypercalls exposed
to the guest
* Support for PSCI-initiated suspend in collaboration with userspace
* GICv3 register-based LPI invalidation support
* Move host PMU event merging into the vcpu data structure
* GICv3 ITS save/restore fixes
* The usual set of small-scale cleanups and fixes
x86:
* New ioctls to get/set TSC frequency for a whole VM
* Allow userspace to opt out of hypercall patching
* Only do MSR filtering for MSRs accessed by rdmsr/wrmsr
AMD SEV improvements:
* Add KVM_EXIT_SHUTDOWN metadata for SEV-ES
* V_TSC_AUX support
Nested virtualization improvements for AMD:
* Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
nested vGIF)
* Allow AVIC to co-exist with a nested guest running
* Fixes for LBR virtualizations when a nested guest is running,
and nested LBR virtualization support
* PAUSE filtering for nested hypervisors
Guest support:
* Decoupling of vcpu_is_preempted from PV spinlocks
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"S390:
- ultravisor communication device driver
- fix TEID on terminating storage key ops
RISC-V:
- Added Sv57x4 support for G-stage page table
- Added range based local HFENCE functions
- Added remote HFENCE functions based on VCPU requests
- Added ISA extension registers in ONE_REG interface
- Updated KVM RISC-V maintainers entry to cover selftests support
ARM:
- Add support for the ARMv8.6 WFxT extension
- Guard pages for the EL2 stacks
- Trap and emulate AArch32 ID registers to hide unsupported features
- Ability to select and save/restore the set of hypercalls exposed to
the guest
- Support for PSCI-initiated suspend in collaboration with userspace
- GICv3 register-based LPI invalidation support
- Move host PMU event merging into the vcpu data structure
- GICv3 ITS save/restore fixes
- The usual set of small-scale cleanups and fixes
x86:
- New ioctls to get/set TSC frequency for a whole VM
- Allow userspace to opt out of hypercall patching
- Only do MSR filtering for MSRs accessed by rdmsr/wrmsr
AMD SEV improvements:
- Add KVM_EXIT_SHUTDOWN metadata for SEV-ES
- V_TSC_AUX support
Nested virtualization improvements for AMD:
- Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
nested vGIF)
- Allow AVIC to co-exist with a nested guest running
- Fixes for LBR virtualizations when a nested guest is running, and
nested LBR virtualization support
- PAUSE filtering for nested hypervisors
Guest support:
- Decoupling of vcpu_is_preempted from PV spinlocks"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (199 commits)
KVM: x86: Fix the intel_pt PMI handling wrongly considered from guest
KVM: selftests: x86: Sync the new name of the test case to .gitignore
Documentation: kvm: reorder ARM-specific section about KVM_SYSTEM_EVENT_SUSPEND
x86, kvm: use correct GFP flags for preemption disabled
KVM: LAPIC: Drop pending LAPIC timer injection when canceling the timer
x86/kvm: Alloc dummy async #PF token outside of raw spinlock
KVM: x86: avoid calling x86 emulator without a decoded instruction
KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leak
x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave)
s390/uv_uapi: depend on CONFIG_S390
KVM: selftests: x86: Fix test failure on arch lbr capable platforms
KVM: LAPIC: Trace LAPIC timer expiration on every vmentry
KVM: s390: selftest: Test suppression indication on key prot exception
KVM: s390: Don't indicate suppression on dirtying, failing memop
selftests: drivers/s390x: Add uvdevice tests
drivers/s390/char: Add Ultravisor io device
MAINTAINERS: Update KVM RISC-V entry to cover selftests support
RISC-V: KVM: Introduce ISA extension register
RISC-V: KVM: Cleanup stale TLB entries when host CPU changes
RISC-V: KVM: Add remote HFENCE functions based on VCPU requests
...
Rework the gfn=>pfn cache (gpc) refresh logic to address multiple races
between the cache itself, and between the cache and mmu_notifier events.
The existing refresh code attempts to guard against races with the
mmu_notifier by speculatively marking the cache valid, and then marking
it invalid if a mmu_notifier invalidation occurs. That handles the case
where an invalidation occurs between dropping and re-acquiring gpc->lock,
but it doesn't handle the scenario where the cache is refreshed after the
cache was invalidated by the notifier, but before the notifier elevates
mmu_notifier_count. The gpc refresh can't use the "retry" helper as its
invalidation occurs _before_ mmu_notifier_count is elevated and before
mmu_notifier_range_start is set/updated.
CPU0 CPU1
---- ----
gfn_to_pfn_cache_invalidate_start()
|
-> gpc->valid = false;
kvm_gfn_to_pfn_cache_refresh()
|
|-> gpc->valid = true;
hva_to_pfn_retry()
|
-> acquire kvm->mmu_lock
kvm->mmu_notifier_count == 0
mmu_seq == kvm->mmu_notifier_seq
drop kvm->mmu_lock
return pfn 'X'
acquire kvm->mmu_lock
kvm_inc_notifier_count()
drop kvm->mmu_lock()
kernel frees pfn 'X'
kvm_gfn_to_pfn_cache_check()
|
|-> gpc->valid == true
caller accesses freed pfn 'X'
Key off of mn_active_invalidate_count to detect that a pfncache refresh
needs to wait for an in-progress mmu_notifier invalidation. While
mn_active_invalidate_count is not guaranteed to be stable, it is
guaranteed to be elevated prior to an invalidation acquiring gpc->lock,
so either the refresh will see an active invalidation and wait, or the
invalidation will run after the refresh completes.
Speculatively marking the cache valid is itself flawed, as a concurrent
kvm_gfn_to_pfn_cache_check() would see a valid cache with stale pfn/khva
values. The KVM Xen use case explicitly allows/wants multiple users;
even though the caches are allocated per vCPU, __kvm_xen_has_interrupt()
can read a different vCPU (or vCPUs). Address this race by invalidating
the cache prior to dropping gpc->lock (this is made possible by fixing
the above mmu_notifier race).
Complicating all of this is the fact that both the hva=>pfn resolution
and mapping of the kernel address can sleep, i.e. must be done outside
of gpc->lock.
Fix the above races in one fell swoop, trying to fix each individual race
is largely pointless and essentially impossible to test, e.g. closing one
hole just shifts the focus to the other hole.
Fixes: 982ed0de47 ("KVM: Reinstate gfn_to_pfn_cache with invalidation support")
Cc: stable@vger.kernel.org
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429210025.3293691-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Add support for the ARMv8.6 WFxT extension
- Guard pages for the EL2 stacks
- Trap and emulate AArch32 ID registers to hide unsupported features
- Ability to select and save/restore the set of hypercalls exposed
to the guest
- Support for PSCI-initiated suspend in collaboration with userspace
- GICv3 register-based LPI invalidation support
- Move host PMU event merging into the vcpu data structure
- GICv3 ITS save/restore fixes
- The usual set of small-scale cleanups and fixes
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Merge tag 'kvmarm-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for 5.19
- Add support for the ARMv8.6 WFxT extension
- Guard pages for the EL2 stacks
- Trap and emulate AArch32 ID registers to hide unsupported features
- Ability to select and save/restore the set of hypercalls exposed
to the guest
- Support for PSCI-initiated suspend in collaboration with userspace
- GICv3 register-based LPI invalidation support
- Move host PMU event merging into the vcpu data structure
- GICv3 ITS save/restore fixes
- The usual set of small-scale cleanups and fixes
[Due to the conflict, KVM_SYSTEM_EVENT_SEV_TERM is relocated
from 4 to 6. - Paolo]
Fix a goof in kvm_prepare_memory_region() where KVM fails to free the
new memslot's dirty bitmap during a CREATE action if
kvm_arch_prepare_memory_region() fails. The logic is supposed to detect
if the bitmap was allocated and thus needs to be freed, versus if the
bitmap was inherited from the old memslot and thus needs to be kept. If
there is no old memslot, then obviously the bitmap can't have been
inherited
The bug was exposed by commit 86931ff720 ("KVM: x86/mmu: Do not create
SPTEs for GFNs that exceed host.MAXPHYADDR"), which made it trivally easy
for syzkaller to trigger failure during kvm_arch_prepare_memory_region(),
but the bug can be hit other ways too, e.g. due to -ENOMEM when
allocating x86's memslot metadata.
The backtrace from kmemleak:
__vmalloc_node_range+0xb40/0xbd0 mm/vmalloc.c:3195
__vmalloc_node mm/vmalloc.c:3232 [inline]
__vmalloc+0x49/0x50 mm/vmalloc.c:3246
__vmalloc_array mm/util.c:671 [inline]
__vcalloc+0x49/0x70 mm/util.c:694
kvm_alloc_dirty_bitmap virt/kvm/kvm_main.c:1319
kvm_prepare_memory_region virt/kvm/kvm_main.c:1551
kvm_set_memslot+0x1bd/0x690 virt/kvm/kvm_main.c:1782
__kvm_set_memory_region+0x689/0x750 virt/kvm/kvm_main.c:1949
kvm_set_memory_region virt/kvm/kvm_main.c:1962
kvm_vm_ioctl_set_memory_region virt/kvm/kvm_main.c:1974
kvm_vm_ioctl+0x377/0x13a0 virt/kvm/kvm_main.c:4528
vfs_ioctl fs/ioctl.c:51
__do_sys_ioctl fs/ioctl.c:870
__se_sys_ioctl fs/ioctl.c:856
__x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
And the relevant sequence of KVM events:
ioctl(3, KVM_CREATE_VM, 0) = 4
ioctl(4, KVM_SET_USER_MEMORY_REGION, {slot=0,
flags=KVM_MEM_LOG_DIRTY_PAGES,
guest_phys_addr=0x10000000000000,
memory_size=4096,
userspace_addr=0x20fe8000}
) = -1 EINVAL (Invalid argument)
Fixes: 244893fa28 ("KVM: Dynamically allocate "new" memslots from the get-go")
Cc: stable@vger.kernel.org
Reported-by: syzbot+8606b8a9cc97a63f1c87@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220518003842.1341782-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For TDX guests, the maximum number of vcpus needs to be specified when the
TDX guest VM is initialized (creating the TDX data corresponding to TDX
guest) before creating vcpu. It needs to record the maximum number of
vcpus on VM creation (KVM_CREATE_VM) and return error if the number of
vcpus exceeds it
Because there is already max_vcpu member in arm64 struct kvm_arch, move it
to common struct kvm and initialize it to KVM_MAX_VCPUS before
kvm_arch_init_vm() instead of adding it to x86 struct kvm_arch.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Message-Id: <e53234cdee6a92357d06c80c03d77c19cdefb804.1646422845.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fixes for (relatively) old bugs, to be merged in both the -rc and next
development trees:
* Fix potential races when walking host page table
* Fix bad user ABI for KVM_EXIT_SYSTEM_EVENT
* Fix shadow page table leak when KVM runs nested
When KVM_EXIT_SYSTEM_EVENT was introduced, it included a flags
member that at the time was unused. Unfortunately this extensibility
mechanism has several issues:
- x86 is not writing the member, so it would not be possible to use it
on x86 except for new events
- the member is not aligned to 64 bits, so the definition of the
uAPI struct is incorrect for 32- on 64-bit userspace. This is a
problem for RISC-V, which supports CONFIG_KVM_COMPAT, but fortunately
usage of flags was only introduced in 5.18.
Since padding has to be introduced, place a new field in there
that tells if the flags field is valid. To allow further extensibility,
in fact, change flags to an array of 16 values, and store how many
of the values are valid. The availability of the new ndata field
is tied to a system capability; all architectures are changed to
fill in the field.
To avoid breaking compilation of userspace that was using the flags
field, provide a userspace-only union to overlap flags with data[0].
The new field is placed at the same offset for both 32- and 64-bit
userspace.
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Gonda <pgonda@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Message-Id: <20220422103013.34832-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Flush the CPU caches when memory is reclaimed from an SEV guest (where
reclaim also includes it being unmapped from KVM's memslots). Due to lack
of coherency for SEV encrypted memory, failure to flush results in silent
data corruption if userspace is malicious/broken and doesn't ensure SEV
guest memory is properly pinned and unpinned.
Cache coherency is not enforced across the VM boundary in SEV (AMD APM
vol.2 Section 15.34.7). Confidential cachelines, generated by confidential
VM guests have to be explicitly flushed on the host side. If a memory page
containing dirty confidential cachelines was released by VM and reallocated
to another user, the cachelines may corrupt the new user at a later time.
KVM takes a shortcut by assuming all confidential memory remain pinned
until the end of VM lifetime. Therefore, KVM does not flush cache at
mmu_notifier invalidation events. Because of this incorrect assumption and
the lack of cache flushing, malicous userspace can crash the host kernel:
creating a malicious VM and continuously allocates/releases unpinned
confidential memory pages when the VM is running.
Add cache flush operations to mmu_notifier operations to ensure that any
physical memory leaving the guest VM get flushed. In particular, hook
mmu_notifier_invalidate_range_start and mmu_notifier_release events and
flush cache accordingly. The hook after releasing the mmu lock to avoid
contention with other vCPUs.
Cc: stable@vger.kernel.org
Suggested-by: Sean Christpherson <seanjc@google.com>
Reported-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Message-Id: <20220421031407.2516575-4-mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SPDX comments use use /* */ style comments in headers anad
// style comments in .c files. Also fix two spelling mistakes.
Signed-off-by: Tom Rix <trix@redhat.com>
Message-Id: <20220410153840.55506-1-trix@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Initialize debugfs_entry to its semi-magical -ENOENT value when the VM
is created. KVM's teardown when VM creation fails is kludgy and calls
kvm_uevent_notify_change() and kvm_destroy_vm_debugfs() even if KVM never
attempted kvm_create_vm_debugfs(). Because debugfs_entry is zero
initialized, the IS_ERR() checks pass and KVM derefs a NULL pointer.
BUG: kernel NULL pointer dereference, address: 0000000000000018
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 1068b1067 P4D 1068b1067 PUD 1068b0067 PMD 0
Oops: 0000 [#1] SMP
CPU: 0 PID: 871 Comm: repro Not tainted 5.18.0-rc1+ #825
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:__dentry_path+0x7b/0x130
Call Trace:
<TASK>
dentry_path_raw+0x42/0x70
kvm_uevent_notify_change.part.0+0x10c/0x200 [kvm]
kvm_put_kvm+0x63/0x2b0 [kvm]
kvm_dev_ioctl+0x43a/0x920 [kvm]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x31/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xae
</TASK>
Modules linked in: kvm_intel kvm irqbypass
Fixes: a44a4cc1c9 ("KVM: Don't create VM debugfs files outside of the VM directory")
Cc: stable@vger.kernel.org
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@google.com>
Reported-by: syzbot+df6fbbd2ee39f21289ef@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Message-Id: <20220415004622.2207751-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Some PSCI fixes after introducing PSCIv1.1 and SYSTEM_RESET2
- Fix the MMU write-lock not being taken on THP split
- Fix mixed-width VM handling
- Fix potential UAF when debugfs registration fails
- Various selftest updates for all of the above
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Merge tag 'kvmarm-fixes-5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 fixes for 5.18, take #1
- Some PSCI fixes after introducing PSCIv1.1 and SYSTEM_RESET2
- Fix the MMU write-lock not being taken on THP split
- Fix mixed-width VM handling
- Fix potential UAF when debugfs registration fails
- Various selftest updates for all of the above
Unfortunately, there is no guarantee that KVM was able to instantiate a
debugfs directory for a particular VM. To that end, KVM shouldn't even
attempt to create new debugfs files in this case. If the specified
parent dentry is NULL, debugfs_create_file() will instantiate files at
the root of debugfs.
For arm64, it is possible to create the vgic-state file outside of a
VM directory, the file is not cleaned up when a VM is destroyed.
Nonetheless, the corresponding struct kvm is freed when the VM is
destroyed.
Nip the problem in the bud for all possible errant debugfs file
creations by initializing kvm->debugfs_dentry to -ENOENT. In so doing,
debugfs_create_file() will fail instead of creating the file in the root
directory.
Cc: stable@kernel.org
Fixes: 929f45e324 ("kvm: no need to check return value of debugfs_create functions")
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220406235615.1447180-2-oupton@google.com
kvm_vcpu_release() will call kvm_dirty_ring_free(), freeing
ring->dirty_gfns and setting it to NULL. Afterwards, it calls
kvm_arch_vcpu_destroy().
However, if closing the file descriptor races with KVM_RUN in such away
that vcpu->arch.st.preempted == 0, the following call stack leads to a
NULL pointer dereference in kvm_dirty_run_push():
mark_page_dirty_in_slot+0x192/0x270 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3171
kvm_steal_time_set_preempted arch/x86/kvm/x86.c:4600 [inline]
kvm_arch_vcpu_put+0x34e/0x5b0 arch/x86/kvm/x86.c:4618
vcpu_put+0x1b/0x70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:211
vmx_free_vcpu+0xcb/0x130 arch/x86/kvm/vmx/vmx.c:6985
kvm_arch_vcpu_destroy+0x76/0x290 arch/x86/kvm/x86.c:11219
kvm_vcpu_destroy arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 [inline]
The fix is to release the dirty page ring after kvm_arch_vcpu_destroy
has run.
Reported-by: Qiuhao Li <qiuhao@sysec.org>
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Reported-by: Yongkang Jia <kangel@zju.edu.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't actually set a request bit in vcpu->requests when making a request
purely to force a vCPU to exit the guest. Logging a request but not
actually consuming it would cause the vCPU to get stuck in an infinite
loop during KVM_RUN because KVM would see the pending request and bail
from VM-Enter to service the request.
Note, it's currently impossible for KVM to set KVM_REQ_GPC_INVALIDATE as
nothing in KVM is wired up to set guest_uses_pa=true. But, it'd be all
too easy for arch code to introduce use of kvm_gfn_to_pfn_cache_init()
without implementing handling of the request, especially since getting
test coverage of MMU notifier interaction with specific KVM features
usually requires a directed test.
Opportunistically rename gfn_to_pfn_cache_invalidate_start()'s wake_vcpus
to evict_vcpus. The purpose of the request is to get vCPUs out of guest
mode, it's supposed to _avoid_ waking vCPUs that are blocking.
Opportunistically rename KVM_REQ_GPC_INVALIDATE to be more specific as to
what it wants to accomplish, and to genericize the name so that it can
used for similar but unrelated scenarios, should they arise in the future.
Add a comment and documentation to explain why the "no action" request
exists.
Add compile-time assertions to help detect improper usage. Use the inner
assertless helper in the one s390 path that makes requests without a
hardcoded request.
Cc: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220223165302.3205276-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This reverts commit 3d3aab1b97.
Now that the KVM module's lifetime is tied to kvm.users_count, there is
no need to also tie it's lifetime to the lifetime of the VM and vCPU
file descriptors.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220303183328.1499189-3-dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tie the lifetime the KVM module to the lifetime of each VM via
kvm.users_count. This way anything that grabs a reference to the VM via
kvm_get_kvm() cannot accidentally outlive the KVM module.
Prior to this commit, the lifetime of the KVM module was tied to the
lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU
file descriptors by their respective file_operations "owner" field.
This approach is insufficient because references grabbed via
kvm_get_kvm() do not prevent closing any of the aforementioned file
descriptors.
This fixes a long standing theoretical bug in KVM that at least affects
async page faults. kvm_setup_async_pf() grabs a reference via
kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing
prevents the VM file descriptor from being closed and the KVM module
from being unloaded before this callback runs.
Fixes: af585b921e ("KVM: Halt vcpu if page it tries to access is swapped out")
Fixes: 3d3aab1b97 ("KVM: set owner of cpu and vm file operations")
Cc: stable@vger.kernel.org
Suggested-by: Ben Gardon <bgardon@google.com>
[ Based on a patch from Ben implemented for Google's kernel. ]
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220303183328.1499189-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allocations whose size is related to the memslot size can be arbitrarily
large. Do not use kvzalloc/kvcalloc, as those are limited to "not crazy"
sizes that fit in 32 bits.
Cc: stable@vger.kernel.org
Fixes: 7661809d49 ("mm: don't allow oversized kvmalloc() calls")
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the generic kvm_reload_remote_mmus() and open code its
functionality into the two x86 callers. x86 is (obviously) the only
architecture that uses the hook, and is also the only architecture that
uses KVM_REQ_MMU_RELOAD in a way that's consistent with the name. That
will change in a future patch, as x86's usage when zapping a single
shadow page x86 doesn't actually _need_ to reload all vCPUs' MMUs, only
MMUs whose root is being zapped actually need to be reloaded.
s390 also uses KVM_REQ_MMU_RELOAD, but for a slightly different purpose.
Drop the generic code in anticipation of implementing s390 and x86 arch
specific requests, which will allow dropping KVM_REQ_MMU_RELOAD entirely.
Opportunistically reword the x86 TDP MMU comment to avoid making
references to functions (and requests!) when possible, and to remove the
rather ambiguous "this".
No functional change intended.
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220225182248.3812651-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
VM worker kthreads can linger in the VM process's cgroup for sometime
after KVM terminates the VM process.
KVM terminates the worker kthreads by calling kthread_stop() which waits
on the 'exited' completion, triggered by exit_mm(), via mm_release(), in
do_exit() during the kthread's exit. However, these kthreads are
removed from the cgroup using the cgroup_exit() which happens after the
exit_mm(). Therefore, A VM process can terminate in between the
exit_mm() and cgroup_exit() calls, leaving only worker kthreads in the
cgroup.
Moving worker kthreads back to the original cgroup (kthreadd_task's
cgroup) makes sure that the cgroup is empty as soon as the main VM
process is terminated.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220222054848.563321-1-vipinsh@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
I saw the below splatting after the host suspended and resumed.
WARNING: CPU: 0 PID: 2943 at kvm/arch/x86/kvm/../../../virt/kvm/kvm_main.c:5531 kvm_resume+0x2c/0x30 [kvm]
CPU: 0 PID: 2943 Comm: step_after_susp Tainted: G W IOE 5.17.0-rc3+ #4
RIP: 0010:kvm_resume+0x2c/0x30 [kvm]
Call Trace:
<TASK>
syscore_resume+0x90/0x340
suspend_devices_and_enter+0xaee/0xe90
pm_suspend.cold+0x36b/0x3c2
state_store+0x82/0xf0
kernfs_fop_write_iter+0x1b6/0x260
new_sync_write+0x258/0x370
vfs_write+0x33f/0x510
ksys_write+0xc9/0x160
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
lockdep_is_held() can return -1 when lockdep is disabled which triggers
this warning. Let's use lockdep_assert_not_held() which can detect
incorrect calls while holding a lock and it also avoids false negatives
when lockdep is disabled.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1644920142-81249-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The "struct kvm *kvm" parameter of kvm_make_vcpu_request() is not used,
so remove it. No functional change intended.
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220125095909.38122-19-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* Redo incorrect fix for SEV/SMAP erratum
* Windows 11 Hyper-V workaround
Other x86 changes:
* Various x86 cleanups
* Re-enable access_tracking_perf_test
* Fix for #GP handling on SVM
* Fix for CPUID leaf 0Dh in KVM_GET_SUPPORTED_CPUID
* Fix for ICEBP in interrupt shadow
* Avoid false-positive RCU splat
* Enable Enlightened MSR-Bitmap support for real
ARM:
* Correctly update the shadow register on exception injection when
running in nVHE mode
* Correctly use the mm_ops indirection when performing cache invalidation
from the page-table walker
* Restrict the vgic-v3 workaround for SEIS to the two known broken
implementations
Generic code changes:
* Dead code cleanup
There will be another pull request for ARM fixes next week, but
those patches need a bit more soak time.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"Two larger x86 series:
- Redo incorrect fix for SEV/SMAP erratum
- Windows 11 Hyper-V workaround
Other x86 changes:
- Various x86 cleanups
- Re-enable access_tracking_perf_test
- Fix for #GP handling on SVM
- Fix for CPUID leaf 0Dh in KVM_GET_SUPPORTED_CPUID
- Fix for ICEBP in interrupt shadow
- Avoid false-positive RCU splat
- Enable Enlightened MSR-Bitmap support for real
ARM:
- Correctly update the shadow register on exception injection when
running in nVHE mode
- Correctly use the mm_ops indirection when performing cache
invalidation from the page-table walker
- Restrict the vgic-v3 workaround for SEIS to the two known broken
implementations
Generic code changes:
- Dead code cleanup"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (43 commits)
KVM: eventfd: Fix false positive RCU usage warning
KVM: nVMX: Allow VMREAD when Enlightened VMCS is in use
KVM: nVMX: Implement evmcs_field_offset() suitable for handle_vmread()
KVM: nVMX: Rename vmcs_to_field_offset{,_table}
KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER
KVM: nVMX: Also filter MSR_IA32_VMX_TRUE_PINBASED_CTLS when eVMCS
selftests: kvm: check dynamic bits against KVM_X86_XCOMP_GUEST_SUPP
KVM: x86: add system attribute to retrieve full set of supported xsave states
KVM: x86: Add a helper to retrieve userspace address from kvm_device_attr
selftests: kvm: move vm_xsave_req_perm call to amx_test
KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time
KVM: x86: Update vCPU's runtime CPUID on write to MSR_IA32_XSS
KVM: x86: Keep MSR_IA32_XSS unchanged for INIT
KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2}
KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02
KVM: selftests: Don't skip L2's VMCALL in SMM test for SVM guest
KVM: x86: Check .flags in kvm_cpuid_check_equal() too
KVM: x86: Forcibly leave nested virt when SMM state is toggled
KVM: SVM: drop unnecessary code in svm_hv_vmcb_dirty_nested_enlightenments()
KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real
...
Revert a completely broken check on an "invalid" RIP in SVM's workaround
for the DecodeAssists SMAP errata. kvm_vcpu_gfn_to_memslot() obviously
expects a gfn, i.e. operates in the guest physical address space, whereas
RIP is a virtual (not even linear) address. The "fix" worked for the
problematic KVM selftest because the test identity mapped RIP.
Fully revert the hack instead of trying to translate RIP to a GPA, as the
non-SEV case is now handled earlier, and KVM cannot access guest page
tables to translate RIP.
This reverts commit e72436bc3a.
Fixes: e72436bc3a ("KVM: SVM: avoid infinite loop on NPF from bad address")
Reported-by: Liam Merwick <liam.merwick@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Message-Id: <20220120010719.711476-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The async parameter of hva_to_pfn_remapped() is not used, so remove it.
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Message-Id: <20220124020456.156386-1-xianting.tian@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- selftest compilation fix for non-x86
- KVM: avoid warning on s390 in mark_page_dirty
x86:
- fix page write-protection bug and improve comments
- use binary search to lookup the PMU event filter, add test
- enable_pmu module parameter support for Intel CPUs
- switch blocked_vcpu_on_cpu_lock to raw spinlock
- cleanups of blocked vCPU logic
- partially allow KVM_SET_CPUID{,2} after KVM_RUN (5.16 regression)
- various small fixes
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull more kvm updates from Paolo Bonzini:
"Generic:
- selftest compilation fix for non-x86
- KVM: avoid warning on s390 in mark_page_dirty
x86:
- fix page write-protection bug and improve comments
- use binary search to lookup the PMU event filter, add test
- enable_pmu module parameter support for Intel CPUs
- switch blocked_vcpu_on_cpu_lock to raw spinlock
- cleanups of blocked vCPU logic
- partially allow KVM_SET_CPUID{,2} after KVM_RUN (5.16 regression)
- various small fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (46 commits)
docs: kvm: fix WARNINGs from api.rst
selftests: kvm/x86: Fix the warning in lib/x86_64/processor.c
selftests: kvm/x86: Fix the warning in pmu_event_filter_test.c
kvm: selftests: Do not indent with spaces
kvm: selftests: sync uapi/linux/kvm.h with Linux header
selftests: kvm: add amx_test to .gitignore
KVM: SVM: Nullify vcpu_(un)blocking() hooks if AVIC is disabled
KVM: SVM: Move svm_hardware_setup() and its helpers below svm_x86_ops
KVM: SVM: Drop AVIC's intermediate avic_set_running() helper
KVM: VMX: Don't do full kick when handling posted interrupt wakeup
KVM: VMX: Fold fallback path into triggering posted IRQ helper
KVM: VMX: Pass desired vector instead of bool for triggering posted IRQ
KVM: VMX: Don't do full kick when triggering posted interrupt "fails"
KVM: SVM: Skip AVIC and IRTE updates when loading blocking vCPU
KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption
KVM: SVM: Remove unnecessary APICv/AVIC update in vCPU unblocking path
KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs
KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode
KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks
KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers
...
Move the seemingly generic block_vcpu_list from kvm_vcpu to vcpu_vmx, and
rename the list and all associated variables to clarify that it tracks
the set of vCPU that need to be poked on a posted interrupt to the wakeup
vector. The list is not used to track _all_ vCPUs that are blocking, and
the term "blocked" can be misleading as it may refer to a blocking
condition in the host or the guest, where as the PI wakeup case is
specifically for the vCPUs that are actively blocking from within the
guest.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove kvm_vcpu.pre_pcpu as it no longer has any users. No functional
change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Avoid warnings on s390 like
[ 1801.980931] CPU: 12 PID: 117600 Comm: kworker/12:0 Tainted: G E 5.17.0-20220113.rc0.git0.32ce2abb03cf.300.fc35.s390x+next #1
[ 1801.980938] Workqueue: events irqfd_inject [kvm]
[...]
[ 1801.981057] Call Trace:
[ 1801.981060] [<000003ff805f0f5c>] mark_page_dirty_in_slot+0xa4/0xb0 [kvm]
[ 1801.981083] [<000003ff8060e9fe>] adapter_indicators_set+0xde/0x268 [kvm]
[ 1801.981104] [<000003ff80613c24>] set_adapter_int+0x64/0xd8 [kvm]
[ 1801.981124] [<000003ff805fb9aa>] kvm_set_irq+0xc2/0x130 [kvm]
[ 1801.981144] [<000003ff805f8d86>] irqfd_inject+0x76/0xa0 [kvm]
[ 1801.981164] [<0000000175e56906>] process_one_work+0x1fe/0x470
[ 1801.981173] [<0000000175e570a4>] worker_thread+0x64/0x498
[ 1801.981176] [<0000000175e5ef2c>] kthread+0x10c/0x110
[ 1801.981180] [<0000000175de73c8>] __ret_from_fork+0x40/0x58
[ 1801.981185] [<000000017698440a>] ret_from_fork+0xa/0x40
when writing to a guest from an irqfd worker as long as we do not have
the dirty ring.
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reluctantly-acked-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220113122924.740496-1-borntraeger@linux.ibm.com>
Fixes: 2efd61a608 ("KVM: Warn if mark_page_dirty() is called without an active vCPU")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Use common KVM implementation of MMU memory caches
- SBI v0.2 support for Guest
- Initial KVM selftests support
- Fix to avoid spurious virtual interrupts after clearing hideleg CSR
- Update email address for Anup and Atish
ARM:
- Simplification of the 'vcpu first run' by integrating it into
KVM's 'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to
a simpler state and less shared data between EL1 and EL2 in
the nVHE case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be
unmapped from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once
the vcpu xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and
page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
s390:
- fix sigp sense/start/stop/inconsistency
- cleanups
x86:
- Clean up some function prototypes more
- improved gfn_to_pfn_cache with proper invalidation, used by Xen emulation
- add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery
- completely remove potential TOC/TOU races in nested SVM consistency checks
- update some PMCs on emulated instructions
- Intel AMX support (joint work between Thomas and Intel)
- large MMU cleanups
- module parameter to disable PMU virtualization
- cleanup register cache
- first part of halt handling cleanups
- Hyper-V enlightened MSR bitmap support for nested hypervisors
Generic:
- clean up Makefiles
- introduce CONFIG_HAVE_KVM_DIRTY_RING
- optimize memslot lookup using a tree
- optimize vCPU array usage by converting to xarray
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"RISCV:
- Use common KVM implementation of MMU memory caches
- SBI v0.2 support for Guest
- Initial KVM selftests support
- Fix to avoid spurious virtual interrupts after clearing hideleg CSR
- Update email address for Anup and Atish
ARM:
- Simplification of the 'vcpu first run' by integrating it into KVM's
'pid change' flow
- Refactoring of the FP and SVE state tracking, also leading to a
simpler state and less shared data between EL1 and EL2 in the nVHE
case
- Tidy up the header file usage for the nvhe hyp object
- New HYP unsharing mechanism, finally allowing pages to be unmapped
from the Stage-1 EL2 page-tables
- Various pKVM cleanups around refcounting and sharing
- A couple of vgic fixes for bugs that would trigger once the vcpu
xarray rework is merged, but not sooner
- Add minimal support for ARMv8.7's PMU extension
- Rework kvm_pgtable initialisation ahead of the NV work
- New selftest for IRQ injection
- Teach selftests about the lack of default IPA space and page sizes
- Expand sysreg selftest to deal with Pointer Authentication
- The usual bunch of cleanups and doc update
s390:
- fix sigp sense/start/stop/inconsistency
- cleanups
x86:
- Clean up some function prototypes more
- improved gfn_to_pfn_cache with proper invalidation, used by Xen
emulation
- add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery
- completely remove potential TOC/TOU races in nested SVM consistency
checks
- update some PMCs on emulated instructions
- Intel AMX support (joint work between Thomas and Intel)
- large MMU cleanups
- module parameter to disable PMU virtualization
- cleanup register cache
- first part of halt handling cleanups
- Hyper-V enlightened MSR bitmap support for nested hypervisors
Generic:
- clean up Makefiles
- introduce CONFIG_HAVE_KVM_DIRTY_RING
- optimize memslot lookup using a tree
- optimize vCPU array usage by converting to xarray"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (268 commits)
x86/fpu: Fix inline prefix warnings
selftest: kvm: Add amx selftest
selftest: kvm: Move struct kvm_x86_state to header
selftest: kvm: Reorder vcpu_load_state steps for AMX
kvm: x86: Disable interception for IA32_XFD on demand
x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state()
kvm: selftests: Add support for KVM_CAP_XSAVE2
kvm: x86: Add support for getting/setting expanded xstate buffer
x86/fpu: Add uabi_size to guest_fpu
kvm: x86: Add CPUID support for Intel AMX
kvm: x86: Add XCR0 support for Intel AMX
kvm: x86: Disable RDMSR interception of IA32_XFD_ERR
kvm: x86: Emulate IA32_XFD_ERR for guest
kvm: x86: Intercept #NM for saving IA32_XFD_ERR
x86/fpu: Prepare xfd_err in struct fpu_guest
kvm: x86: Add emulation for IA32_XFD
x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation
kvm: x86: Enable dynamic xfeatures at KVM_SET_CPUID2
x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM
x86/fpu: Add guest support to xfd_enable_feature()
...
"Cleanup of the perf/kvm interaction."
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Merge tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Borislav Petkov:
"Cleanup of the perf/kvm interaction."
* tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Drop guest callback (un)register stubs
KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
KVM: arm64: Convert to the generic perf callbacks
KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
KVM: Move x86's perf guest info callbacks to generic KVM
KVM: x86: More precisely identify NMI from guest when handling PMI
KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable
perf/core: Use static_call to optimize perf_guest_info_callbacks
perf: Force architectures to opt-in to guest callbacks
perf: Add wrappers for invoking guest callbacks
perf/core: Rework guest callbacks to prepare for static_call support
perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv
perf: Stop pretending that perf can handle multiple guest callbacks
KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest
KVM: x86: Register perf callbacks after calling vendor's hardware_setup()
perf: Protect perf_guest_cbs with RCU
This can be used in two modes. There is an atomic mode where the cached
mapping is accessed while holding the rwlock, and a mode where the
physical address is used by a vCPU in guest mode.
For the latter case, an invalidation will wake the vCPU with the new
KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any
caches it still needs to access before entering guest mode again.
Only one vCPU can be targeted by the wake requests; it's simple enough
to make it wake all vCPUs or even a mask but I don't see a use case for
that additional complexity right now.
Invalidation happens from the invalidate_range_start MMU notifier, which
needs to be able to sleep in order to wake the vCPU and wait for it.
This means that revalidation potentially needs to "wait" for the MMU
operation to complete and the invalidate_range_end notifier to be
invoked. Like the vCPU when it takes a page fault in that period, we
just spin — fixing that in a future patch by implementing an actual
*wait* may be another part of shaving this particularly hirsute yak.
As noted in the comments in the function itself, the only case where
the invalidate_range_start notifier is expected to be called *without*
being able to sleep is when the OOM reaper is killing the process. In
that case, we expect the vCPU threads already to have exited, and thus
there will be nothing to wake, and no reason to wait. So we clear the
KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly
if there actually *was* anything to wake up.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The various kvm_write_guest() and mark_page_dirty() functions must only
ever be called in the context of an active vCPU, because if dirty ring
tracking is enabled it may simply oops when kvm_get_running_vcpu()
returns NULL for the vcpu and then kvm_dirty_ring_get() dereferences it.
This oops was reported by "butt3rflyh4ck" <butterflyhuangxx@gmail.com> in
https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/
That actual bug will be fixed under separate cover but this warning
should help to prevent new ones from being added.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211210163625.2886-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
I'd like to make the build include dirty_ring.c based on whether the
arch wants it or not. That's a whole lot simpler if there's a config
symbol instead of doing it implicitly on KVM_DIRTY_LOG_PAGE_OFFSET
being set to something non-zero.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20211121125451.9489-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add helpers to wake and query a blocking vCPU. In addition to providing
nice names, the helpers reduce the probability of KVM neglecting to use
kvm_arch_vcpu_get_wait().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Calculate the halt-polling "stop" time using "start" instead of redoing
ktime_get(). In practice, the numbers involved are in the noise (e.g.,
in the happy case where hardware correctly predicts do_halt_poll and
there are no interrupts, "start" is probably only a few cycles old)
and either approach is perfectly ok. But it's more precise to count
any extra latency toward the halt-polling time.
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a "blocking" stat that userspace can use to detect the case where a
vCPU is not being run because of an vCPU/guest action, e.g. HLT or WFS on
x86, WFI on arm64, etc... Current guest/host/halt stats don't show this
well, e.g. if a guest halts for a long period of time then the vCPU could
could appear pathologically blocked due to a host condition, when in
reality the vCPU has been put into a not-runnable state by the guest.
Originally-by: Cannon Matthews <cannonmatthews@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
[sean: renamed stat to "blocking", massaged changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate
non-halt wait/sleep/block conditions that should not be subjected to
halt-polling.
No functional change intended.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename kvm_vcpu_block() to kvm_vcpu_halt() in preparation for splitting
the actual "block" sequences into a separate helper (to be named
kvm_vcpu_block()). x86 will use the standalone block-only path to handle
non-halt cases where the vCPU is not runnable.
Rename block_ns to halt_ns to match the new function name.
No functional change intended.
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop kvm_arch_vcpu_block_finish() now that all arch implementations are
nops.
No functional change intended.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Invoke the arch hooks for block+unblock if and only if KVM actually
attempts to block the vCPU. The only non-nop implementation is on x86,
specifically SVM's AVIC, and there is no need to put the AVIC prior to
halt-polling; KVM x86's kvm_vcpu_has_events() will scour the full vIRR
to find pending IRQs regardless of whether the AVIC is loaded/"running".
The primary motivation is to allow future cleanup to split out "block"
from "halt", but this is also likely a small performance boost on x86 SVM
when halt-polling is successful.
Adjust the post-block path to update "cur" after unblocking, i.e. include
AVIC load time in halt_wait_ns and halt_wait_hist, so that the behavior
is consistent. Moving just the pre-block arch hook would result in only
the AVIC put latency being included in the halt_wait stats. There is no
obvious evidence that one way or the other is correct, so just ensure KVM
is consistent.
Note, x86 has two separate paths for handling APICv with respect to vCPU
blocking. VMX uses hooks in x86's vcpu_block(), while SVM uses the arch
hooks in kvm_vcpu_block(). Prior to this path, the two paths were more
or less functionally identical. That is very much not the case after
this patch, as the hooks used by VMX _must_ fire before halt-polling.
x86's entire mess will be cleaned up in future patches.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the halt-polling "success" and histogram stats update into the
dedicated helper to fix a discrepancy where the success/fail "time" stats
consider polling successful so long as the wait is avoided, but the main
"success" and histogram stats consider polling successful if and only if
a wake event was detected by the halt-polling loop.
Move halt_attempted_poll to the helper as well so that all the stats are
updated in a single location. While it's a bit odd to update the stat
well after the fact, practically speaking there's no meaningful advantage
to updating before polling.
Note, there is a functional change in addition to the success vs. fail
change. The histogram updates previously called ktime_get() instead of
using "cur". But that change is desirable as it means all the stats are
now updated with the same polling time, and avoids the extra ktime_get(),
which isn't expensive but isn't free either.
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a comment to document that halt-polling is considered successful even
if the polling loop itself didn't detect a wake event, i.e. if a wake
event was detect in the final kvm_vcpu_check_block(). Invert the param
to update helper so that the helper is a dumb function that is "told"
whether or not polling was successful, as opposed to determining success
based on blocking behavior.
Opportunistically tweak the params to the update helper to reduce the
line length for the call site so that it fits on a single line, and so
that the prototype conforms to the more traditional kernel style.
No functional change intended.
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't update halt-polling stats if halt-polling wasn't attempted. This is
a nop as @poll_ns is guaranteed to be '0' (poll_end == start); in a future
patch (to move the histogram stats into the helper), it will avoid to
avoid a discrepancy in what is considered a "successful" halt-poll.
No functional change intended.
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Do not define/reference kvm_vcpu.wait if __KVM_HAVE_ARCH_WQP is true, and
instead force the architecture (PPC) to define its own rcuwait object.
Allowing common KVM to directly access vcpu->wait without a guard makes
it all too easy to introduce potential bugs, e.g. kvm_vcpu_block(),
kvm_vcpu_on_spin(), and async_pf_execute() all operate on vcpu->wait, not
the result of kvm_arch_vcpu_get_wait(), and so may do the wrong thing for
PPC.
Due to PPC's shenanigans with respect to callbacks and waits (it switches
to the virtual core's wait object at KVM_RUN!?!?), it's not clear whether
or not this fixes any bugs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Wrap s390's halt_poll_max_steal with READ_ONCE and snapshot the result of
kvm_arch_no_poll() in kvm_vcpu_block() to avoid a mostly-theoretical,
largely benign bug on s390 where the result of kvm_arch_no_poll() could
change due to userspace modifying halt_poll_max_steal while the vCPU is
blocking. The bug is largely benign as it will either cause KVM to skip
updating halt-polling times (no_poll toggles false=>true) or to update
halt-polling times with a slightly flawed block_ns.
Note, READ_ONCE is unnecessary in the current code, add it in case the
arch hook is ever inlined, and to provide a hint that userspace can
change the param at will.
Fixes: 8b905d28ee ("KVM: s390: provide kvm_arch_no_poll function")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If we do have the vcpu mutex, as is the case if kvm_running_vcpu is set
to the target vcpu of the kick, changes to vcpu->mode do not need atomic
operations; cmpxchg is only needed _outside_ the mutex to ensure that
the IN_GUEST_MODE->EXITING_GUEST_MODE change does not race with the vcpu
thread going OUTSIDE_GUEST_MODE.
Use this to optimize the case of a vCPU sending an interrupt to itself.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation for implementing in-place hugepage promotion, various
functions will need to be called from zap_collapsible_spte_range, which
has the const qualifier on its memslot argument. Propagate the const
qualifier to the various functions which will be needed. This just serves
to simplify the following patch.
No functional change intended.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211115234603.2908381-11-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allocate the "new" memslot for !DELETE memslot updates straight away
instead of filling an intermediate on-stack object and forcing
kvm_set_memslot() to juggle the allocation and do weird things like reuse
the old memslot object in MOVE.
In the MOVE case, this results in an "extra" memslot allocation due to
allocating both the "new" slot and the "invalid" slot, but that's a
temporary and not-huge allocation, and MOVE is a relatively rare memslot
operation.
Regarding MOVE, drop the open-coded management of the gfn tree with a
call to kvm_replace_memslot(), which already handles the case where
new->base_gfn != old->base_gfn. This is made possible by virtue of not
having to copy the "new" memslot data after erasing the old memslot from
the gfn tree. Using kvm_replace_memslot(), and more specifically not
reusing the old memslot, means the MOVE case now does hva tree and hash
list updates, but that's a small price to pay for simplifying the code
and making MOVE align with all the other flavors of updates. The "extra"
updates are firmly in the noise from a performance perspective, e.g. the
"move (in)active area" selfttests show a (very, very) slight improvement.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <f0d8c72727aa825cf682bd4e3da4b3fa68215dd4.1638817641.git.maciej.szmigiero@oracle.com>
Initialize the "new" memslot in the !DELETE path only after the various
sanity checks have passed. This will allow a future commit to allocate
@new dynamically without having to copy a memslot, and without having to
deal with freeing @new in error paths and in the "nothing to change" path
that's hiding in the sanity checks.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <a084d0531ca3a826a7f861eb2b08b5d1c06ef265.1638817641.git.maciej.szmigiero@oracle.com>
Do a quick lookup for possibly overlapping gfns when creating or moving
a memslot instead of performing a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[sean: tweaked params to avoid churn in future cleanup]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <a4795e5c2f624754e9c0aab023ebda1966feb3e1.1638817641.git.maciej.szmigiero@oracle.com>
kvm_invalidate_memslot() calls kvm_arch_flush_shadow_memslot() on the
active, but KVM_MEMSLOT_INVALID slot.
Do it on the inactive (but valid) old slot instead since arch code really
should not get passed such invalid slot.
Note that this means that the "arch" field of the slot provided to
kvm_arch_flush_shadow_memslot() may have stale data since this function
is called with slots_arch_lock released.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <813595ecc193d6ae39a87709899d4251523b05f8.1638817641.git.maciej.szmigiero@oracle.com>
The current memslot code uses a (reverse gfn-ordered) memslot array for
keeping track of them.
Because the memslot array that is currently in use cannot be modified
every memslot management operation (create, delete, move, change flags)
has to make a copy of the whole array so it has a scratch copy to work on.
Strictly speaking, however, it is only necessary to make copy of the
memslot that is being modified, copying all the memslots currently present
is just a limitation of the array-based memslot implementation.
Two memslot sets, however, are still needed so the VM continues to run
on the currently active set while the requested operation is being
performed on the second, currently inactive one.
In order to have two memslot sets, but only one copy of actual memslots
it is necessary to split out the memslot data from the memslot sets.
The memslots themselves should be also kept independent of each other
so they can be individually added or deleted.
These two memslot sets should normally point to the same set of
memslots. They can, however, be desynchronized when performing a
memslot management operation by replacing the memslot to be modified
by its copy. After the operation is complete, both memslot sets once
again point to the same, common set of memslot data.
This commit implements the aforementioned idea.
For tracking of gfns an ordinary rbtree is used since memslots cannot
overlap in the guest address space and so this data structure is
sufficient for ensuring that lookups are done quickly.
The "last used slot" mini-caches (both per-slot set one and per-vCPU one),
that keep track of the last found-by-gfn memslot, are still present in the
new code.
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <17c0cf3663b760a0d3753d4ac08c0753e941b811.1638817641.git.maciej.szmigiero@oracle.com>
