Declare the kvm_x86_ops hooks used to wire up paravirt TLB flushes when
running under Hyper-V if and only if CONFIG_HYPERV!=n. Wrapping yet more
code with IS_ENABLED(CONFIG_HYPERV) eliminates a handful of conditional
branches, and makes it super obvious why the hooks *might* be valid.
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231018192325.1893896-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Drop non-PA bits when getting GFN for guest's PGD with the maximum theoretical
mask for guest MAXPHYADDR.
Do it unconditionally because it's harmless for 32-bit guests, querying 64-bit
mode would be more expensive, and for EPT the mask isn't tied to guest mode.
Using PT_BASE_ADDR_MASK would be technically wrong (PAE paging has 64-bit
elements _except_ for CR3, which has only 32 valid bits), it wouldn't matter
in practice though.
Opportunistically use GENMASK_ULL() to define __PT_BASE_ADDR_MASK.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-6-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Introduce several new KVM uAPIs to ultimately create a guest-first memory
subsystem within KVM, a.k.a. guest_memfd. Guest-first memory allows KVM
to provide features, enhancements, and optimizations that are kludgly
or outright impossible to implement in a generic memory subsystem.
The core KVM ioctl() for guest_memfd is KVM_CREATE_GUEST_MEMFD, which
similar to the generic memfd_create(), creates an anonymous file and
returns a file descriptor that refers to it. Again like "regular"
memfd files, guest_memfd files live in RAM, have volatile storage,
and are automatically released when the last reference is dropped.
The key differences between memfd files (and every other memory subystem)
is that guest_memfd files are bound to their owning virtual machine,
cannot be mapped, read, or written by userspace, and cannot be resized.
guest_memfd files do however support PUNCH_HOLE, which can be used to
convert a guest memory area between the shared and guest-private states.
A second KVM ioctl(), KVM_SET_MEMORY_ATTRIBUTES, allows userspace to
specify attributes for a given page of guest memory. In the long term,
it will likely be extended to allow userspace to specify per-gfn RWX
protections, including allowing memory to be writable in the guest
without it also being writable in host userspace.
The immediate and driving use case for guest_memfd are Confidential
(CoCo) VMs, specifically AMD's SEV-SNP, Intel's TDX, and KVM's own pKVM.
For such use cases, being able to map memory into KVM guests without
requiring said memory to be mapped into the host is a hard requirement.
While SEV+ and TDX prevent untrusted software from reading guest private
data by encrypting guest memory, pKVM provides confidentiality and
integrity *without* relying on memory encryption. In addition, with
SEV-SNP and especially TDX, accessing guest private memory can be fatal
to the host, i.e. KVM must be prevent host userspace from accessing
guest memory irrespective of hardware behavior.
Long term, guest_memfd may be useful for use cases beyond CoCo VMs,
for example hardening userspace against unintentional accesses to guest
memory. As mentioned earlier, KVM's ABI uses userspace VMA protections to
define the allow guest protection (with an exception granted to mapping
guest memory executable), and similarly KVM currently requires the guest
mapping size to be a strict subset of the host userspace mapping size.
Decoupling the mappings sizes would allow userspace to precisely map
only what is needed and with the required permissions, without impacting
guest performance.
A guest-first memory subsystem also provides clearer line of sight to
things like a dedicated memory pool (for slice-of-hardware VMs) and
elimination of "struct page" (for offload setups where userspace _never_
needs to DMA from or into guest memory).
guest_memfd is the result of 3+ years of development and exploration;
taking on memory management responsibilities in KVM was not the first,
second, or even third choice for supporting CoCo VMs. But after many
failed attempts to avoid KVM-specific backing memory, and looking at
where things ended up, it is quite clear that of all approaches tried,
guest_memfd is the simplest, most robust, and most extensible, and the
right thing to do for KVM and the kernel at-large.
The "development cycle" for this version is going to be very short;
ideally, next week I will merge it as is in kvm/next, taking this through
the KVM tree for 6.8 immediately after the end of the merge window.
The series is still based on 6.6 (plus KVM changes for 6.7) so it
will require a small fixup for changes to get_file_rcu() introduced in
6.7 by commit 0ede61d858 ("file: convert to SLAB_TYPESAFE_BY_RCU").
The fixup will be done as part of the merge commit, and most of the text
above will become the commit message for the merge.
Pending post-merge work includes:
- hugepage support
- looking into using the restrictedmem framework for guest memory
- introducing a testing mechanism to poison memory, possibly using
the same memory attributes introduced here
- SNP and TDX support
There are two non-KVM patches buried in the middle of this series:
fs: Rename anon_inode_getfile_secure() and anon_inode_getfd_secure()
mm: Add AS_UNMOVABLE to mark mapping as completely unmovable
The first is small and mostly suggested-by Christian Brauner; the second
a bit less so but it was written by an mm person (Vlastimil Babka).
Let x86 track the number of address spaces on a per-VM basis so that KVM
can disallow SMM memslots for confidential VMs. Confidentials VMs are
fundamentally incompatible with emulating SMM, which as the name suggests
requires being able to read and write guest memory and register state.
Disallowing SMM will simplify support for guest private memory, as KVM
will not need to worry about tracking memory attributes for multiple
address spaces (SMM is the only "non-default" address space across all
architectures).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add support for resolving page faults on guest private memory for VMs
that differentiate between "shared" and "private" memory. For such VMs,
KVM_MEM_GUEST_MEMFD memslots can include both fd-based private memory and
hva-based shared memory, and KVM needs to map in the "correct" variant,
i.e. KVM needs to map the gfn shared/private as appropriate based on the
current state of the gfn's KVM_MEMORY_ATTRIBUTE_PRIVATE flag.
For AMD's SEV-SNP and Intel's TDX, the guest effectively gets to request
shared vs. private via a bit in the guest page tables, i.e. what the guest
wants may conflict with the current memory attributes. To support such
"implicit" conversion requests, exit to user with KVM_EXIT_MEMORY_FAULT
to forward the request to userspace. Add a new flag for memory faults,
KVM_MEMORY_EXIT_FLAG_PRIVATE, to communicate whether the guest wants to
map memory as shared vs. private.
Like KVM_MEMORY_ATTRIBUTE_PRIVATE, use bit 3 for flagging private memory
so that KVM can use bits 0-2 for capturing RWX behavior if/when userspace
needs such information, e.g. a likely user of KVM_EXIT_MEMORY_FAULT is to
exit on missing mappings when handling guest page fault VM-Exits. In
that case, userspace will want to know RWX information in order to
correctly/precisely resolve the fault.
Note, private memory *must* be backed by guest_memfd, i.e. shared mappings
always come from the host userspace page tables, and private mappings
always come from a guest_memfd instance.
Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Disallow creating hugepages with mixed memory attributes, e.g. shared
versus private, as mapping a hugepage in this case would allow the guest
to access memory with the wrong attributes, e.g. overlaying private memory
with a shared hugepage.
Tracking whether or not attributes are mixed via the existing
disallow_lpage field, but use the most significant bit in 'disallow_lpage'
to indicate a hugepage has mixed attributes instead using the normal
refcounting. Whether or not attributes are mixed is binary; either they
are or they aren't. Attempting to squeeze that info into the refcount is
unnecessarily complex as it would require knowing the previous state of
the mixed count when updating attributes. Using a flag means KVM just
needs to ensure the current status is reflected in the memslots.
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently in mmu_notifier invalidate path, hva range is recorded and then
checked against by mmu_invalidate_retry_hva() in the page fault handling
path. However, for the soon-to-be-introduced private memory, a page fault
may not have a hva associated, checking gfn(gpa) makes more sense.
For existing hva based shared memory, gfn is expected to also work. The
only downside is when aliasing multiple gfns to a single hva, the
current algorithm of checking multiple ranges could result in a much
larger range being rejected. Such aliasing should be uncommon, so the
impact is expected small.
Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
[sean: convert vmx_set_apic_access_page_addr() to gfn-based API]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Xu Yilun <yilun.xu@linux.intel.com>
Message-Id: <20231027182217.3615211-4-seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series "Fixes and cleanups to compaction".
- Joel Fernandes has a patchset ("Optimize mremap during mutual
alignment within PMD") which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested.
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i the
following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series "Do not try to access unaccepted memory" Adrian Hunter
provides some fixups for the recently-added "unaccepted memory' feature.
To increase the feature's checking coverage. "Plug a few gaps where
RAM is exposed without checking if it is unaccepted memory".
- In the series "cleanups for lockless slab shrink" Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code.
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series "use refcount+RCU method to implement
lockless slab shrink".
- David Hildenbrand contributes some maintenance work for the rmap code
in the series "Anon rmap cleanups".
- Kefeng Wang does more folio conversions and some maintenance work in
the migration code. Series "mm: migrate: more folio conversion and
unification".
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series "Add and use bdev_getblk()".
- In the series "Use nth_page() in place of direct struct page
manipulation" Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames.
- In the series "mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO" has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of gigantic
pages are in use.
- Matthew Wilcox has sent the series "Small hugetlb cleanups" - code
rationalization and folio conversions in the hugetlb code.
- Yin Fengwei has improved mlock()'s handling of large folios in the
series "support large folio for mlock"
- In the series "Expose swapcache stat for memcg v1" Liu Shixin has
added statistics for memcg v1 users which are available (and useful)
under memcg v2.
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named "MDWE
without inheritance".
- Kefeng Wang has provided the series "mm: convert numa balancing
functions to use a folio" which does what it says.
- In the series "mm/ksm: add fork-exec support for prctl" Stefan Roesch
makes is possible for a process to propagate KSM treatment across
exec().
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use "high
bandwidth memory" in addition to Optane Data Center Persistent Memory
Modules (DCPMM). The series is named "memory tiering: calculate
abstract distance based on ACPI HMAT"
- In the series "Smart scanning mode for KSM" Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans.
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in the
series "mm: memcg: fix tracking of pending stats updates values".
- In the series "Implement IOCTL to get and optionally clear info about
PTEs" Peter Xu has added an ioctl to /proc/<pid>/pagemap which permits
us to atomically read-then-clear page softdirty state. This is mainly
used by CRIU.
- Hugh Dickins contributed the series "shmem,tmpfs: general maintenance"
- a bunch of relatively minor maintenance tweaks to this code.
- Matthew Wilcox has increased the use of the VMA lock over file-backed
page faults in the series "Handle more faults under the VMA lock". Some
rationalizations of the fault path became possible as a result.
- In the series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()" David Hildenbrand has implemented some cleanups
and folio conversions.
- In the series "various improvements to the GUP interface" Lorenzo
Stoakes has simplified and improved the GUP interface with an eye to
providing groundwork for future improvements.
- Andrey Konovalov has sent along the series "kasan: assorted fixes and
improvements" which does those things.
- Some page allocator maintenance work from Kemeng Shi in the series
"Two minor cleanups to break_down_buddy_pages".
- In thes series "New selftest for mm" Breno Leitao has developed
another MM self test which tickles a race we had between madvise() and
page faults.
- In the series "Add folio_end_read" Matthew Wilcox provides cleanups
and an optimization to the core pagecache code.
- Nhat Pham has added memcg accounting for hugetlb memory in the series
"hugetlb memcg accounting".
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series "Abstract vma_merge() and split_vma()".
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series "Fix page_owner's use of free timestamps".
- Lorenzo Stoakes has fixed the handling of new mappings of sealed files
in the series "permit write-sealed memfd read-only shared mappings".
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series "Batch hugetlb vmemmap modification operations".
- Some buffer_head folio conversions and cleanups from Matthew Wilcox in
the series "Finish the create_empty_buffers() transition".
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the series
"mm: PCP high auto-tuning".
- Roman Gushchin has contributed the patchset "mm: improve performance
of accounted kernel memory allocations" which improves their performance
by ~30% as measured by a micro-benchmark.
- folio conversions from Kefeng Wang in the series "mm: convert page
cpupid functions to folios".
- Some kmemleak fixups in Liu Shixin's series "Some bugfix about
kmemleak".
- Qi Zheng has improved our handling of memoryless nodes by keeping them
off the allocation fallback list. This is done in the series "handle
memoryless nodes more appropriately".
- khugepaged conversions from Vishal Moola in the series "Some
khugepaged folio conversions".
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Merge tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"Many singleton patches against the MM code. The patch series which are
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series 'Fixes and cleanups to compaction'
- Joel Fernandes has a patchset ('Optimize mremap during mutual
alignment within PMD') which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i
the following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series 'Do not try to access unaccepted memory' Adrian
Hunter provides some fixups for the recently-added 'unaccepted
memory' feature. To increase the feature's checking coverage. 'Plug
a few gaps where RAM is exposed without checking if it is
unaccepted memory'
- In the series 'cleanups for lockless slab shrink' Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series 'use refcount+RCU method to
implement lockless slab shrink'
- David Hildenbrand contributes some maintenance work for the rmap
code in the series 'Anon rmap cleanups'
- Kefeng Wang does more folio conversions and some maintenance work
in the migration code. Series 'mm: migrate: more folio conversion
and unification'
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series 'Add and use bdev_getblk()'
- In the series 'Use nth_page() in place of direct struct page
manipulation' Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames
- In the series 'mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO' has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of
gigantic pages are in use
- Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code
rationalization and folio conversions in the hugetlb code
- Yin Fengwei has improved mlock()'s handling of large folios in the
series 'support large folio for mlock'
- In the series 'Expose swapcache stat for memcg v1' Liu Shixin has
added statistics for memcg v1 users which are available (and
useful) under memcg v2
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named 'MDWE
without inheritance'
- Kefeng Wang has provided the series 'mm: convert numa balancing
functions to use a folio' which does what it says
- In the series 'mm/ksm: add fork-exec support for prctl' Stefan
Roesch makes is possible for a process to propagate KSM treatment
across exec()
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use 'high
bandwidth memory' in addition to Optane Data Center Persistent
Memory Modules (DCPMM). The series is named 'memory tiering:
calculate abstract distance based on ACPI HMAT'
- In the series 'Smart scanning mode for KSM' Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in
the series 'mm: memcg: fix tracking of pending stats updates
values'
- In the series 'Implement IOCTL to get and optionally clear info
about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap
which permits us to atomically read-then-clear page softdirty
state. This is mainly used by CRIU
- Hugh Dickins contributed the series 'shmem,tmpfs: general
maintenance', a bunch of relatively minor maintenance tweaks to
this code
- Matthew Wilcox has increased the use of the VMA lock over
file-backed page faults in the series 'Handle more faults under the
VMA lock'. Some rationalizations of the fault path became possible
as a result
- In the series 'mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()' David Hildenbrand has implemented some
cleanups and folio conversions
- In the series 'various improvements to the GUP interface' Lorenzo
Stoakes has simplified and improved the GUP interface with an eye
to providing groundwork for future improvements
- Andrey Konovalov has sent along the series 'kasan: assorted fixes
and improvements' which does those things
- Some page allocator maintenance work from Kemeng Shi in the series
'Two minor cleanups to break_down_buddy_pages'
- In thes series 'New selftest for mm' Breno Leitao has developed
another MM self test which tickles a race we had between madvise()
and page faults
- In the series 'Add folio_end_read' Matthew Wilcox provides cleanups
and an optimization to the core pagecache code
- Nhat Pham has added memcg accounting for hugetlb memory in the
series 'hugetlb memcg accounting'
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series 'Abstract vma_merge() and split_vma()'
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series 'Fix page_owner's use of free timestamps'
- Lorenzo Stoakes has fixed the handling of new mappings of sealed
files in the series 'permit write-sealed memfd read-only shared
mappings'
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series 'Batch hugetlb vmemmap modification operations'
- Some buffer_head folio conversions and cleanups from Matthew Wilcox
in the series 'Finish the create_empty_buffers() transition'
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the
series 'mm: PCP high auto-tuning'
- Roman Gushchin has contributed the patchset 'mm: improve
performance of accounted kernel memory allocations' which improves
their performance by ~30% as measured by a micro-benchmark
- folio conversions from Kefeng Wang in the series 'mm: convert page
cpupid functions to folios'
- Some kmemleak fixups in Liu Shixin's series 'Some bugfix about
kmemleak'
- Qi Zheng has improved our handling of memoryless nodes by keeping
them off the allocation fallback list. This is done in the series
'handle memoryless nodes more appropriately'
- khugepaged conversions from Vishal Moola in the series 'Some
khugepaged folio conversions'"
[ bcachefs conflicts with the dynamically allocated shrinkers have been
resolved as per Stephen Rothwell in
https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/
with help from Qi Zheng.
The clone3 test filtering conflict was half-arsed by yours truly ]
* tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits)
mm/damon/sysfs: update monitoring target regions for online input commit
mm/damon/sysfs: remove requested targets when online-commit inputs
selftests: add a sanity check for zswap
Documentation: maple_tree: fix word spelling error
mm/vmalloc: fix the unchecked dereference warning in vread_iter()
zswap: export compression failure stats
Documentation: ubsan: drop "the" from article title
mempolicy: migration attempt to match interleave nodes
mempolicy: mmap_lock is not needed while migrating folios
mempolicy: alloc_pages_mpol() for NUMA policy without vma
mm: add page_rmappable_folio() wrapper
mempolicy: remove confusing MPOL_MF_LAZY dead code
mempolicy: mpol_shared_policy_init() without pseudo-vma
mempolicy trivia: use pgoff_t in shared mempolicy tree
mempolicy trivia: slightly more consistent naming
mempolicy trivia: delete those ancient pr_debug()s
mempolicy: fix migrate_pages(2) syscall return nr_failed
kernfs: drop shared NUMA mempolicy hooks
hugetlbfs: drop shared NUMA mempolicy pretence
mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()
...
Don't initialize "spte" and "sptep" in fast_page_fault() as they are both
guaranteed (for all intents and purposes) to be written at the start of
every loop iteration. Add a sanity check that "sptep" is non-NULL after
walking the shadow page tables, as encountering a NULL root would result
in "spte" not being written, i.e. would lead to uninitialized data or the
previous value being consumed.
Signed-off-by: Li zeming <zeming@nfschina.com>
Link: https://lore.kernel.org/r/20230905182006.2964-1-zeming@nfschina.com
[sean: rewrite changelog with --verbose]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add helpers to check if KVM honors guest MTRRs instead of open coding the
logic in kvm_tdp_page_fault(). Future fixes and cleanups will also need
to determine if KVM should honor guest MTRRs, e.g. for CR0.CD toggling and
and non-coherent DMA transitions.
Provide an inner helper, __kvm_mmu_honors_guest_mtrrs(), so that KVM can
check if guest MTRRs were honored when stopping non-coherent DMA.
Note, there is no need to explicitly check that TDP is enabled, KVM clears
shadow_memtype_mask when TDP is disabled, i.e. it's non-zero if and only
if EPT is enabled.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20230714065006.20201-1-yan.y.zhao@intel.com
Link: https://lore.kernel.org/r/20230714065043.20258-1-yan.y.zhao@intel.com
[sean: squash into a one patch, drop explicit TDP check massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stop zapping invalidate TDP MMU roots via work queue now that KVM
preserves TDP MMU roots until they are explicitly invalidated. Zapping
roots asynchronously was effectively a workaround to avoid stalling a vCPU
for an extended during if a vCPU unloaded a root, which at the time
happened whenever the guest toggled CR0.WP (a frequent operation for some
guest kernels).
While a clever hack, zapping roots via an unbound worker had subtle,
unintended consequences on host scheduling, especially when zapping
multiple roots, e.g. as part of a memslot. Because the work of zapping a
root is no longer bound to the task that initiated the zap, things like
the CPU affinity and priority of the original task get lost. Losing the
affinity and priority can be especially problematic if unbound workqueues
aren't affined to a small number of CPUs, as zapping multiple roots can
cause KVM to heavily utilize the majority of CPUs in the system, *beyond*
the CPUs KVM is already using to run vCPUs.
When deleting a memslot via KVM_SET_USER_MEMORY_REGION, the async root
zap can result in KVM occupying all logical CPUs for ~8ms, and result in
high priority tasks not being scheduled in in a timely manner. In v5.15,
which doesn't preserve unloaded roots, the issues were even more noticeable
as KVM would zap roots more frequently and could occupy all CPUs for 50ms+.
Consuming all CPUs for an extended duration can lead to significant jitter
throughout the system, e.g. on ChromeOS with virtio-gpu, deleting memslots
is a semi-frequent operation as memslots are deleted and recreated with
different host virtual addresses to react to host GPU drivers allocating
and freeing GPU blobs. On ChromeOS, the jitter manifests as audio blips
during games due to the audio server's tasks not getting scheduled in
promptly, despite the tasks having a high realtime priority.
Deleting memslots isn't exactly a fast path and should be avoided when
possible, and ChromeOS is working towards utilizing MAP_FIXED to avoid the
memslot shenanigans, but KVM is squarely in the wrong. Not to mention
that removing the async zapping eliminates a non-trivial amount of
complexity.
Note, one of the subtle behaviors hidden behind the async zapping is that
KVM would zap invalidated roots only once (ignoring partial zaps from
things like mmu_notifier events). Preserve this behavior by adding a flag
to identify roots that are scheduled to be zapped versus roots that have
already been zapped but not yet freed.
Add a comment calling out why kvm_tdp_mmu_invalidate_all_roots() can
encounter invalid roots, as it's not at all obvious why zapping
invalidated roots shouldn't simply zap all invalid roots.
Reported-by: Pattara Teerapong <pteerapong@google.com>
Cc: David Stevens <stevensd@google.com>
Cc: Yiwei Zhang<zzyiwei@google.com>
Cc: Paul Hsia <paulhsia@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230916003916.2545000-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All callers except the MMU notifier want to process all address spaces.
Remove the address space ID argument of for_each_tdp_mmu_root_yield_safe()
and switch the MMU notifier to use __for_each_tdp_mmu_root_yield_safe().
Extracted out of a patch by Sean Christopherson <seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The mmu_notifier path is a bit of a special snowflake, e.g. it zaps only a
single address space (because it's per-slot), and can't always yield.
Because of this, it calls kvm_tdp_mmu_zap_leafs() in ways that no one
else does.
Iterate manually over the leafs in response to an mmu_notifier
invalidation, instead of invoking kvm_tdp_mmu_zap_leafs(). Drop the
@can_yield param from kvm_tdp_mmu_zap_leafs() as its sole remaining
caller unconditionally passes "true".
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230916003916.2545000-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When attempting to allocate a shadow root for a !visible guest root gfn,
e.g. that resides in MMIO space, load a dummy root that is backed by the
zero page instead of immediately synthesizing a triple fault shutdown
(using the zero page ensures any attempt to translate memory will generate
a !PRESENT fault and thus VM-Exit).
Unless the vCPU is racing with memslot activity, KVM will inject a page
fault due to not finding a visible slot in FNAME(walk_addr_generic), i.e.
the end result is mostly same, but critically KVM will inject a fault only
*after* KVM runs the vCPU with the bogus root.
Waiting to inject a fault until after running the vCPU fixes a bug where
KVM would bail from nested VM-Enter if L1 tried to run L2 with TDP enabled
and a !visible root. Even though a bad root will *probably* lead to
shutdown, (a) it's not guaranteed and (b) the CPU won't read the
underlying memory until after VM-Enter succeeds. E.g. if L1 runs L2 with
a VMX preemption timer value of '0', then architecturally the preemption
timer VM-Exit is guaranteed to occur before the CPU executes any
instruction, i.e. before the CPU needs to translate a GPA to a HPA (so
long as there are no injected events with higher priority than the
preemption timer).
If KVM manages to get to FNAME(fetch) with a dummy root, e.g. because
userspace created a memslot between installing the dummy root and handling
the page fault, simply unload the MMU to allocate a new root and retry the
instruction. Use KVM_REQ_MMU_FREE_OBSOLETE_ROOTS to drop the root, as
invoking kvm_mmu_free_roots() while holding mmu_lock would deadlock, and
conceptually the dummy root has indeeed become obsolete. The only
difference versus existing usage of KVM_REQ_MMU_FREE_OBSOLETE_ROOTS is
that the root has become obsolete due to memslot *creation*, not memslot
deletion or movement.
Reported-by: Reima Ishii <ishiir@g.ecc.u-tokyo.ac.jp>
Cc: Yu Zhang <yu.c.zhang@linux.intel.com>
Link: https://lore.kernel.org/r/20230729005200.1057358-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Harden kvm_mmu_new_pgd() against NULL pointer dereference bugs by sanity
checking that the target root has an associated shadow page prior to
dereferencing said shadow page. The code in question is guaranteed to
only see roots with shadow pages as fast_pgd_switch() explicitly frees the
current root if it doesn't have a shadow page, i.e. is a PAE root, and
that in turn prevents valid roots from being cached, but that's all very
subtle.
Link: https://lore.kernel.org/r/20230729005200.1057358-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a dedicated helper for converting a root hpa to a shadow page in
anticipation of using a "dummy" root to handle the scenario where KVM
needs to load a valid shadow root (from hardware's perspective), but
the guest doesn't have a visible root to shadow. Similar to PAE roots,
the dummy root won't have an associated kvm_mmu_page and will need special
handling when finding a shadow page given a root.
Opportunistically retrieve the root shadow page in kvm_mmu_sync_roots()
*after* verifying the root is unsync (the dummy root can never be unsync).
Link: https://lore.kernel.org/r/20230729005200.1057358-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Refactor KVM's exported/external page-track, a.k.a. write-track, APIs
to take only the gfn and do the required memslot lookup in KVM proper.
Forcing users of the APIs to get the memslot unnecessarily bleeds
KVM internals into KVMGT and complicates usage of the APIs.
No functional change intended.
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-28-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename the page-track APIs to capture that they're all about tracking
writes, now that the facade of supporting multiple modes is gone.
Opportunstically replace "slot" with "gfn" in anticipation of removing
the @slot param from the external APIs.
No functional change intended.
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-25-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop "support" for multiple page-track modes, as there is no evidence
that array-based and refcounted metadata is the optimal solution for
other modes, nor is there any evidence that other use cases, e.g. for
access-tracking, will be a good fit for the page-track machinery in
general.
E.g. one potential use case of access-tracking would be to prevent guest
access to poisoned memory (from the guest's perspective). In that case,
the number of poisoned pages is likely to be a very small percentage of
the guest memory, and there is no need to reference count the number of
access-tracking users, i.e. expanding gfn_track[] for a new mode would be
grossly inefficient. And for poisoned memory, host userspace would also
likely want to trap accesses, e.g. to inject #MC into the guest, and that
isn't currently supported by the page-track framework.
A better alternative for that poisoned page use case is likely a
variation of the proposed per-gfn attributes overlay (linked), which
would allow efficiently tracking the sparse set of poisoned pages, and by
default would exit to userspace on access.
Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com
Cc: Ben Gardon <bgardon@google.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-24-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Bury the declaration of the page-track helpers that are intended only for
internal KVM use in a "private" header. In addition to guarding against
unwanted usage of the internal-only helpers, dropping their definitions
avoids exposing other structures that should be KVM-internal, e.g. for
memslots. This is a baby step toward making kvm_host.h a KVM-internal
header in the very distant future.
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-22-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove ->track_remove_slot(), there are no longer any users and it's
unlikely a "flush" hook will ever be the correct API to provide to an
external page-track user.
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-21-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't use the generic page-track mechanism to handle writes to guest PTEs
in KVM's MMU. KVM's MMU needs access to information that should not be
exposed to external page-track users, e.g. KVM needs (for some definitions
of "need") the vCPU to query the current paging mode, whereas external
users, i.e. KVMGT, have no ties to the current vCPU and so should never
need the vCPU.
Moving away from the page-track mechanism will allow dropping use of the
page-track mechanism for KVM's own MMU, and will also allow simplifying
and cleaning up the page-track APIs.
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Call kvm_mmu_zap_all_fast() directly when flushing a memslot instead of
bouncing through the page-track mechanism. KVM (unfortunately) needs to
zap and flush all page tables on memslot DELETE/MOVE irrespective of
whether KVM is shadowing guest page tables.
This will allow changing KVM to register a page-track notifier on the
first shadow root allocation, and will also allow deleting the misguided
kvm_page_track_flush_slot() hook itself once KVM-GT also moves to a
different method for reacting to memslot changes.
No functional change intended.
Cc: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20221110014821.1548347-2-seanjc@google.com
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-14-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move x86's implementation of kvm_arch_flush_shadow_{all,memslot}() into
mmu.c, and make kvm_mmu_zap_all() static as it was globally visible only
for kvm_arch_flush_shadow_all(). This will allow refactoring
kvm_arch_flush_shadow_memslot() to call kvm_mmu_zap_all() directly without
having to expose kvm_mmu_zap_all_fast() outside of mmu.c. Keeping
everything in mmu.c will also likely simplify supporting TDX, which
intends to do zap only relevant SPTEs on memslot updates.
No functional change intended.
Suggested-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce KVM_BUG_ON_DATA_CORRUPTION() and use it in the low-level rmap
helpers to convert the existing BUG()s to WARN_ON_ONCE() when the kernel
is built with CONFIG_BUG_ON_DATA_CORRUPTION=n, i.e. does NOT want to BUG()
on corruption of host kernel data structures. Environments that don't
have infrastructure to automatically capture crash dumps, i.e. aren't
likely to enable CONFIG_BUG_ON_DATA_CORRUPTION=y, are typically better
served overall by WARN-and-continue behavior (for the kernel, the VM is
dead regardless), as a BUG() while holding mmu_lock all but guarantees
the _best_ case scenario is a panic().
Make the BUG()s conditional instead of removing/replacing them entirely as
there's a non-zero chance (though by no means a guarantee) that the damage
isn't contained to the target VM, e.g. if no rmap is found for a SPTE then
KVM may be double-zapping the SPTE, i.e. has already freed the memory the
SPTE pointed at and thus KVM is reading/writing memory that KVM no longer
owns.
Link: https://lore.kernel.org/all/20221129191237.31447-1-mizhang@google.com
Suggested-by: Mingwei Zhang <mizhang@google.com>
Cc: David Matlack <dmatlack@google.com>
Cc: Jim Mattson <jmattson@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20230729004722.1056172-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Plumb "struct kvm" all the way to pte_list_remove() to allow the usage of
KVM_BUG() and/or KVM_BUG_ON(). This will allow killing only the offending
VM instead of doing BUG() if the kernel is built with
CONFIG_BUG_ON_DATA_CORRUPTION=n, i.e. does NOT want to BUG() if KVM's data
structures (rmaps) appear to be corrupted.
Signed-off-by: Mingwei Zhang <mizhang@google.com>
[sean: tweak changelog]
Link: https://lore.kernel.org/r/20230729004722.1056172-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Replace MMU_DEBUG, which requires manually modifying KVM to enable the
macro, with a proper Kconfig, KVM_PROVE_MMU. Now that pgprintk() and
rmap_printk() are gone, i.e. the macro guards only KVM_MMU_WARN_ON() and
won't flood the kernel logs, enabling the option for debug kernels is both
desirable and feasible.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/20230729004722.1056172-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Convert all "runtime" assertions, i.e. assertions that can be triggered
while running vCPUs, from WARN_ON() to WARN_ON_ONCE(). Every WARN in the
MMU that is tied to running vCPUs, i.e. not contained to loading and
initializing KVM, is likely to fire _a lot_ when it does trigger. E.g. if
KVM ends up with a bug that causes a root to be invalidated before the
page fault handler is invoked, pretty much _every_ page fault VM-Exit
triggers the WARN.
If a WARN is triggered frequently, the resulting spam usually causes a lot
of damage of its own, e.g. consumes resources to log the WARN and pollutes
the kernel log, often to the point where other useful information can be
lost. In many case, the damage caused by the spam is actually worse than
the bug itself, e.g. KVM can almost always recover from an unexpectedly
invalid root.
On the flip side, warning every time is rarely helpful for debug and
triage, i.e. a single splat is usually sufficient to point a debugger in
the right direction, and automated testing, e.g. syzkaller, typically runs
with warn_on_panic=1, i.e. will never get past the first WARN anyways.
Lastly, when an assertions fails multiple times, the stack traces in KVM
are almost always identical, i.e. the full splat only needs to be captured
once. And _if_ there is value in captruing information about the failed
assert, a ratelimited printk() is sufficient and less likely to rack up a
large amount of collateral damage.
Link: https://lore.kernel.org/r/20230729004722.1056172-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename MMU_WARN_ON() to make it super obvious that the assertions are
all about KVM's MMU, not the primary MMU.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/20230729004722.1056172-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Massage the error message for the sanity check on SPTEs when freeing a
shadow page to be more verbose, and to print out all shadow-present SPTEs,
not just the first SPTE encountered. Printing all SPTEs can be quite
valuable for debug, e.g. highlights whether the leak is a one-off or
widepsread, or possibly the result of memory corruption (something else
in the kernel stomping on KVM's SPTEs).
Opportunistically move the MMU_WARN_ON() into the helper itself, which
will allow a future cleanup to use BUILD_BUG_ON_INVALID() as the stub for
MMU_WARN_ON(). BUILD_BUG_ON_INVALID() works as intended and results in
the compiler complaining about is_empty_shadow_page() not being declared.
Link: https://lore.kernel.org/r/20230729004722.1056172-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Replace the pointer arithmetic used to iterate over SPTEs in
is_empty_shadow_page() with more standard interger-based iteration.
No functional change intended.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/20230729004722.1056172-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Delete KVM's "dbg" module param now that its usage in KVM is gone (it
used to guard pgprintk() and rmap_printk()).
Link: https://lore.kernel.org/r/20230729004722.1056172-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Delete rmap_printk() so that MMU_WARN_ON() and MMU_DEBUG can be morphed
into something that can be regularly enabled for debug kernels. The
information provided by rmap_printk() isn't all that useful now that the
rmap and unsync code is mature, as the prints are simultaneously too
verbose (_lots_ of message) and yet not verbose enough to be helpful for
debug (most instances print just the SPTE pointer/value, which is rarely
sufficient to root cause anything but trivial bugs).
Alternatively, rmap_printk() could be reworked to into tracepoints, but
it's not clear there is a real need as rmap bugs rarely escape initial
development, and when bugs do escape to production, they are often edge
cases and/or reside in code that isn't directly related to the rmaps.
In other words, the problems with rmap_printk() being unhelpful also apply
to tracepoints. And deleting rmap_printk() doesn't preclude adding
tracepoints in the future.
Link: https://lore.kernel.org/r/20230729004722.1056172-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Delete KVM's pgprintk() and all its usage, as the code is very prone
to bitrot due to being buried behind MMU_DEBUG, and the functionality has
been rendered almost entirely obsolete by the tracepoints KVM has gained
over the years. And for the situations where the information provided by
KVM's tracepoints is insufficient, pgprintk() rarely fills in the gaps,
and is almost always far too noisy, i.e. developers end up implementing
custom prints anyways.
Link: https://lore.kernel.org/r/20230729004722.1056172-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add an assertion in kvm_mmu_page_fault() to ensure the error code provided
by hardware doesn't conflict with KVM's software-defined IMPLICIT_ACCESS
flag. In the unlikely scenario that future hardware starts using bit 48
for a hardware-defined flag, preserving the bit could result in KVM
incorrectly interpreting the unknown flag as KVM's IMPLICIT_ACCESS flag.
WARN so that any such conflict can be surfaced to KVM developers and
resolved, but otherwise ignore the bit as KVM can't possibly rely on a
flag it knows nothing about.
Fixes: 4f4aa80e3b ("KVM: X86: Handle implicit supervisor access with SMAP")
Acked-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20230721223711.2334426-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Misc cleanups
- Retry APIC optimized recalculation if a vCPU is added/enabled
- Overhaul emergency reboot code to bring SVM up to par with VMX, tie the
"emergency disabling" behavior to KVM actually being loaded, and move all of
the logic within KVM
- Fix user triggerable WARNs in SVM where KVM incorrectly assumes the TSC
ratio MSR can diverge from the default iff TSC scaling is enabled, and clean
up related code
- Add a framework to allow "caching" feature flags so that KVM can check if
the guest can use a feature without needing to search guest CPUID
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Merge tag 'kvm-x86-misc-6.6' of https://github.com/kvm-x86/linux into HEAD
KVM x86 changes for 6.6:
- Misc cleanups
- Retry APIC optimized recalculation if a vCPU is added/enabled
- Overhaul emergency reboot code to bring SVM up to par with VMX, tie the
"emergency disabling" behavior to KVM actually being loaded, and move all of
the logic within KVM
- Fix user triggerable WARNs in SVM where KVM incorrectly assumes the TSC
ratio MSR can diverge from the default iff TSC scaling is enabled, and clean
up related code
- Add a framework to allow "caching" feature flags so that KVM can check if
the guest can use a feature without needing to search guest CPUID
- Wrap kvm_{gfn,hva}_range.pte in a union to allow mmu_notifier events to pass
action specific data without needing to constantly update the main handlers.
- Drop unused function declarations
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Merge tag 'kvm-x86-generic-6.6' of https://github.com/kvm-x86/linux into HEAD
Common KVM changes for 6.6:
- Wrap kvm_{gfn,hva}_range.pte in a union to allow mmu_notifier events to pass
action specific data without needing to constantly update the main handlers.
- Drop unused function declarations
Use the governed feature framework to track whether or not the guest can
use 1GiB pages, and drop the one-off helper that wraps the surprisingly
non-trivial logic surrounding 1GiB page usage in the guest.
No functional change intended.
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20230815203653.519297-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Wrap kvm_{gfn,hva}_range.pte in a union so that future notifier events can
pass event specific information up and down the stack without needing to
constantly expand and churn the APIs. Lockless aging of SPTEs will pass
around a bitmap, and support for memory attributes will pass around the
new attributes for the range.
Add a "KVM_NO_ARG" placeholder to simplify handling events without an
argument (creating a dummy union variable is midly annoying).
Opportunstically drop explicit zero-initialization of the "pte" field, as
omitting the field (now a union) has the same effect.
Cc: Yu Zhao <yuzhao@google.com>
Link: https://lore.kernel.org/all/CAOUHufagkd2Jk3_HrVoFFptRXM=hX2CV8f+M-dka-hJU4bP8kw@mail.gmail.com
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Yu Zhao <yuzhao@google.com>
Link: https://lore.kernel.org/r/20230729004144.1054885-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Move kvm_arch_flush_remote_tlbs_memslot() to common code and drop
"arch_" from the name. kvm_arch_flush_remote_tlbs_memslot() is just a
range-based TLB invalidation where the range is defined by the memslot.
Now that kvm_flush_remote_tlbs_range() can be called from common code we
can just use that and drop a bunch of duplicate code from the arch
directories.
Note this adds a lockdep assertion for slots_lock being held when
calling kvm_flush_remote_tlbs_memslot(), which was previously only
asserted on x86. MIPS has calls to kvm_flush_remote_tlbs_memslot(),
but they all hold the slots_lock, so the lockdep assertion continues to
hold true.
Also drop the CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT ifdef gating
kvm_flush_remote_tlbs_memslot(), since it is no longer necessary.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Acked-by: Anup Patel <anup@brainfault.org>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230811045127.3308641-7-rananta@google.com
Make kvm_flush_remote_tlbs_range() visible in common code and create a
default implementation that just invalidates the whole TLB.
This paves the way for several future features/cleanups:
- Introduction of range-based TLBI on ARM.
- Eliminating kvm_arch_flush_remote_tlbs_memslot()
- Moving the KVM/x86 TDP MMU to common code.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230811045127.3308641-6-rananta@google.com
Use sysfs_emit() instead of the sprintf() for sysfs entries. sysfs_emit()
knows the maximum of the temporary buffer used for outputting sysfs
content and avoids overrunning the buffer length.
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230625073438.57427-1-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
- Add back a comment about the subtle side effect of try_cmpxchg64() in
tdp_mmu_set_spte_atomic()
- Add an assertion in __kvm_mmu_invalidate_addr() to verify that the target
KVM MMU is the current MMU
- Add a "never" option to effectively avoid creating NX hugepage recovery
threads
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Merge tag 'kvm-x86-mmu-6.5' of https://github.com/kvm-x86/linux into HEAD
KVM x86/mmu changes for 6.5:
- Add back a comment about the subtle side effect of try_cmpxchg64() in
tdp_mmu_set_spte_atomic()
- Add an assertion in __kvm_mmu_invalidate_addr() to verify that the target
KVM MMU is the current MMU
- Add a "never" option to effectively avoid creating NX hugepage recovery
threads
Add a "never" option to the nx_huge_pages module param to allow userspace
to do a one-way hard disabling of the mitigation, and don't create the
per-VM recovery threads when the mitigation is hard disabled. Letting
userspace pinky swear that userspace doesn't want to enable NX mitigation
(without reloading KVM) allows certain use cases to avoid the latency
problems associated with spawning a kthread for each VM.
E.g. in FaaS use cases, the guest kernel is trusted and the host may
create 100+ VMs per logical CPU, which can result in 100ms+ latencies when
a burst of VMs is created.
Reported-by: Li RongQing <lirongqing@baidu.com>
Closes: https://lore.kernel.org/all/1679555884-32544-1-git-send-email-lirongqing@baidu.com
Cc: Yong He <zhuangel570@gmail.com>
Cc: Robert Hoo <robert.hoo.linux@gmail.com>
Cc: Kai Huang <kai.huang@intel.com>
Reviewed-by: Robert Hoo <robert.hoo.linux@gmail.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Luiz Capitulino <luizcap@amazon.com>
Reviewed-by: Li RongQing <lirongqing@baidu.com>
Link: https://lore.kernel.org/r/20230602005859.784190-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Request an APIC-access page reload when the backing page is migrated (or
unmapped) if and only if vendor code actually plugs the backing pfn into
structures that reside outside of KVM's MMU. This avoids kicking all
vCPUs in the (hopefully infrequent) scenario where the backing page is
migrated/invalidated.
Unlike VMX's APICv, SVM's AVIC doesn't plug the backing pfn directly into
the VMCB and so doesn't need a hook to invalidate an out-of-MMU "mapping".
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20230602011518.787006-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Now that KVM honors past and in-progress mmu_notifier invalidations when
reloading the APIC-access page, use KVM's "standard" invalidation hooks
to trigger a reload and delete the one-off usage of invalidate_range().
Aside from eliminating one-off code in KVM, dropping KVM's use of
invalidate_range() will allow common mmu_notifier to redefine the API to
be more strictly focused on invalidating secondary TLBs that share the
primary MMU's page tables.
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20230602011518.787006-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Factor in the address space (non-SMM vs. SMM) of the target shadow page
when recovering potential NX huge pages, otherwise KVM will retrieve the
wrong memslot when zapping shadow pages that were created for SMM. The
bug most visibly manifests as a WARN on the memslot being non-NULL, but
the worst case scenario is that KVM could unaccount the shadow page
without ensuring KVM won't install a huge page, i.e. if the non-SMM slot
is being dirty logged, but the SMM slot is not.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 3911 at arch/x86/kvm/mmu/mmu.c:7015
kvm_nx_huge_page_recovery_worker+0x38c/0x3d0 [kvm]
CPU: 1 PID: 3911 Comm: kvm-nx-lpage-re
RIP: 0010:kvm_nx_huge_page_recovery_worker+0x38c/0x3d0 [kvm]
RSP: 0018:ffff99b284f0be68 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff99b284edd000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff9271397024e0 R08: 0000000000000000 R09: ffff927139702450
R10: 0000000000000000 R11: 0000000000000001 R12: ffff99b284f0be98
R13: 0000000000000000 R14: ffff9270991fcd80 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff927f9f640000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0aacad3ae0 CR3: 000000088fc2c005 CR4: 00000000003726e0
Call Trace:
<TASK>
__pfx_kvm_nx_huge_page_recovery_worker+0x10/0x10 [kvm]
kvm_vm_worker_thread+0x106/0x1c0 [kvm]
kthread+0xd9/0x100
ret_from_fork+0x2c/0x50
</TASK>
---[ end trace 0000000000000000 ]---
This bug was exposed by commit edbdb43fc9 ("KVM: x86: Preserve TDP MMU
roots until they are explicitly invalidated"), which allowed KVM to retain
SMM TDP MMU roots effectively indefinitely. Before commit edbdb43fc9,
KVM would zap all SMM TDP MMU roots and thus all SMM TDP MMU shadow pages
once all vCPUs exited SMM, which made the window where this bug (recovering
an SMM NX huge page) could be encountered quite tiny. To hit the bug, the
NX recovery thread would have to run while at least one vCPU was in SMM.
Most VMs typically only use SMM during boot, and so the problematic shadow
pages were gone by the time the NX recovery thread ran.
Now that KVM preserves TDP MMU roots until they are explicitly invalidated
(e.g. by a memslot deletion), the window to trigger the bug is effectively
never closed because most VMMs don't delete memslots after boot (except
for a handful of special scenarios).
Fixes: eb29860570 ("KVM: x86/mmu: Do not recover dirty-tracked NX Huge Pages")
Reported-by: Fabio Coatti <fabio.coatti@gmail.com>
Closes: https://lore.kernel.org/all/CADpTngX9LESCdHVu_2mQkNGena_Ng2CphWNwsRGSMxzDsTjU2A@mail.gmail.com
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230602010137.784664-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add assertion to track that "mmu == vcpu->arch.mmu" is always true in the
context of __kvm_mmu_invalidate_addr(). for_each_shadow_entry_using_root()
and kvm_sync_spte() operate on vcpu->arch.mmu, but the only reason that
doesn't cause explosions is because handle_invept() frees roots instead of
doing a manual invalidation. As of now, there are no major roadblocks
to switching INVEPT emulation over to use kvm_mmu_invalidate_addr().
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230523032947.60041-1-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
- Disallow virtualizing legacy LBRs if architectural LBRs are available,
the two are mutually exclusive in hardware
- Disallow writes to immutable feature MSRs (notably PERF_CAPABILITIES)
after KVM_RUN, and overhaul the vmx_pmu_caps selftest to better
validate PERF_CAPABILITIES
- Apply PMU filters to emulated events and add test coverage to the
pmu_event_filter selftest
- Misc cleanups and fixes
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Merge tag 'kvm-x86-pmu-6.4' of https://github.com/kvm-x86/linux into HEAD
KVM x86 PMU changes for 6.4:
- Disallow virtualizing legacy LBRs if architectural LBRs are available,
the two are mutually exclusive in hardware
- Disallow writes to immutable feature MSRs (notably PERF_CAPABILITIES)
after KVM_RUN, and overhaul the vmx_pmu_caps selftest to better
validate PERF_CAPABILITIES
- Apply PMU filters to emulated events and add test coverage to the
pmu_event_filter selftest
- Misc cleanups and fixes
- Tweak FNAME(sync_spte) to avoid unnecessary writes+flushes when the
guest is only adding new PTEs
- Overhaul .sync_page() and .invlpg() to share the .sync_page()
implementation, i.e. utilize .sync_page()'s optimizations when emulating
invalidations
- Clean up the range-based flushing APIs
- Revamp the TDP MMU's reaping of Accessed/Dirty bits to clear a single
A/D bit using a LOCK AND instead of XCHG, and skip all of the "handle
changed SPTE" overhead associated with writing the entire entry
- Track the number of "tail" entries in a pte_list_desc to avoid having
to walk (potentially) all descriptors during insertion and deletion,
which gets quite expensive if the guest is spamming fork()
- Misc cleanups
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Merge tag 'kvm-x86-mmu-6.4' of https://github.com/kvm-x86/linux into HEAD
KVM x86 MMU changes for 6.4:
- Tweak FNAME(sync_spte) to avoid unnecessary writes+flushes when the
guest is only adding new PTEs
- Overhaul .sync_page() and .invlpg() to share the .sync_page()
implementation, i.e. utilize .sync_page()'s optimizations when emulating
invalidations
- Clean up the range-based flushing APIs
- Revamp the TDP MMU's reaping of Accessed/Dirty bits to clear a single
A/D bit using a LOCK AND instead of XCHG, and skip all of the "handle
changed SPTE" overhead associated with writing the entire entry
- Track the number of "tail" entries in a pte_list_desc to avoid having
to walk (potentially) all descriptors during insertion and deletion,
which gets quite expensive if the guest is spamming fork()
- Misc cleanups
Refresh the MMU's snapshot of the vCPU's CR0.WP prior to checking for
permission faults when emulating a guest memory access and CR0.WP may be
guest owned. If the guest toggles only CR0.WP and triggers emulation of
a supervisor write, e.g. when KVM is emulating UMIP, KVM may consume a
stale CR0.WP, i.e. use stale protection bits metadata.
Note, KVM passes through CR0.WP if and only if EPT is enabled as CR0.WP
is part of the MMU role for legacy shadow paging, and SVM (NPT) doesn't
support per-bit interception controls for CR0. Don't bother checking for
EPT vs. NPT as the "old == new" check will always be true under NPT, i.e.
the only cost is the read of vcpu->arch.cr4 (SVM unconditionally grabs CR0
from the VMCB on VM-Exit).
Reported-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lkml.kernel.org/r/677169b4-051f-fcae-756b-9a3e1bb9f8fe%40grsecurity.net
Fixes: fb509f76ac ("KVM: VMX: Make CR0.WP a guest owned bit")
Tested-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20230405002608.418442-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Refactor Hyper-V's range-based TLB flushing API to take a gfn+nr_pages
pair instead of a struct, and bury said struct in Hyper-V specific code.
Passing along two params generates much better code for the common case
where KVM is _not_ running on Hyper-V, as forwarding the flush on to
Hyper-V's hv_flush_remote_tlbs_range() from kvm_flush_remote_tlbs_range()
becomes a tail call.
Cc: David Matlack <dmatlack@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20230405003133.419177-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rename the Hyper-V hooks for TLB flushing to match the naming scheme used
by all the other TLB flushing hooks, e.g. in kvm_x86_ops, vendor code,
arch hooks from common code, etc.
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20230405003133.419177-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add a helper to query if a vCPU has run so that KVM doesn't have to open
code the check on last_vmentry_cpu being set to a magic value.
No functional change intended.
Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Like Xu <like.xu.linux@gmail.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20230311004618.920745-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Most of the time, calls to get_guest_pgd result in calling
kvm_read_cr3 (the exception is only nested TDP). Hardcode
the default instead of using the get_cr3 function, avoiding
a retpoline if they are enabled.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20230322013731.102955-2-minipli@grsecurity.net
Signed-off-by: Sean Christopherson <seanjc@google.com>
Adjust a variety of functions in mmu.c to put the function return type on
the same line as the function declaration. As stated in the Linus
specification:
But the "on their own line" is complete garbage to begin with. That
will NEVER be a kernel rule. We should never have a rule that assumes
things are so long that they need to be on multiple lines.
We don't put function return types on their own lines either, even if
some other projects have that rule (just to get function names at the
beginning of lines or some other odd reason).
Leave the functions generated by BUILD_MMU_ROLE_REGS_ACCESSOR() as-is,
that code is basically illegible no matter how it's formatted.
No functional change intended.
Link: https://lore.kernel.org/mm-commits/CAHk-=wjS-Jg7sGMwUPpDsjv392nDOOs0CtUtVkp=S6Q7JzFJRw@mail.gmail.com
Signed-off-by: Ben Gardon <bgardon@google.com>
Link: https://lore.kernel.org/r/20230202182809.1929122-4-bgardon@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Assert that mmu_lock is held for write in __walk_slot_rmaps() instead of
hoping the function comment will magically prevent introducing bugs.
Signed-off-by: Ben Gardon <bgardon@google.com>
Link: https://lore.kernel.org/r/20230202182809.1929122-3-bgardon@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use gfn_t instead of u64 for kvm_flush_remote_tlbs_range()'s parameters,
since gfn_t is the standard type for GFNs throughout KVM.
Opportunistically rename pages to nr_pages to make its role even more
obvious.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20230126184025.2294823-6-dmatlack@google.com
[sean: convert pages to gfn_t too, and rename]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rename kvm_flush_remote_tlbs_with_address() to
kvm_flush_remote_tlbs_range(). This name is shorter, which reduces the
number of callsites that need to be broken up across multiple lines, and
more readable since it conveys a range of memory is being flushed rather
than a single address.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20230126184025.2294823-5-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Collapse kvm_flush_remote_tlbs_with_range() and
kvm_flush_remote_tlbs_with_address() into a single function. This
eliminates some lines of code and a useless NULL check on the range
struct.
Opportunistically switch from ENOTSUPP to EOPNOTSUPP to make checkpatch
happy.
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20230126184025.2294823-4-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rework "struct pte_list_desc" and pte_list_{add|remove} to track the tail
count, i.e. number of PTEs in non-head descriptors, and to always keep all
tail descriptors full so that adding a new entry and counting the number
of entries is done in constant time instead of linear time.
No visible performace is changed in tests. But pte_list_add() is no longer
shown in the perf result for the COWed pages even the guest forks millions
of tasks.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230113122910.672417-1-jiangshanlai@gmail.com
[sean: reword shortlog, tweak changelog, add lots of comments, add BUG_ON()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Sync the spte only when the spte is set and avoid the indirect branch.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216235321.735214-5-jiangshanlai@gmail.com
[sean: add wrapper instead of open coding each check]
Signed-off-by: Sean Christopherson <seanjc@google.com>
In hardware TLB, invalidating TLB entries means the translations are
removed from the TLB.
In KVM shadowed vTLB, the translations (combinations of shadow paging
and hardware TLB) are generally maintained as long as they remain "clean"
when the TLB of an address space (i.e. a PCID or all) is flushed with
the help of write-protections, sp->unsync, and kvm_sync_page(), where
"clean" in this context means that no updates to KVM's SPTEs are needed.
However, FNAME(invlpg) always zaps/removes the vTLB if the shadow page is
unsync, and thus triggers a remote flush even if the original vTLB entry
is clean, i.e. is usable as-is.
Besides this, FNAME(invlpg) is largely is a duplicate implementation of
FNAME(sync_spte) to invalidate a vTLB entry.
To address both issues, reuse FNAME(sync_spte) to share the code and
slightly modify the semantics, i.e. keep the vTLB entry if it's "clean"
and avoid remote TLB flush.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216235321.735214-3-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Don't assume the current root to be valid, just check it and remove
the WARN().
Also move the code to check if the root is valid into FNAME(invlpg)
to simplify the code.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216235321.735214-2-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use kvm_mmu_invalidate_addr() instead open calls to mmu->invlpg().
No functional change intended.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216235321.735214-1-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
The @root_hpa for kvm_mmu_invalidate_addr() is called with @mmu->root.hpa
or INVALID_PAGE where @mmu->root.hpa is to invalidate gva for the current
root (the same meaning as KVM_MMU_ROOT_CURRENT) and INVALID_PAGE is to
invalidate gva for all roots (the same meaning as KVM_MMU_ROOTS_ALL).
Change the argument type of kvm_mmu_invalidate_addr() and use
KVM_MMU_ROOT_XXX instead so that we can reuse the function for
kvm_mmu_invpcid_gva() and nested_ept_invalidate_addr() for invalidating
gva for different set of roots.
No fuctionalities changed.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-9-jiangshanlai@gmail.com
[sean: massage comment slightly]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tweak KVM_MMU_ROOTS_ALL to precisely cover all current+previous root
flags, and add a sanity in kvm_mmu_free_roots() to verify that the set
of roots to free doesn't stray outside KVM_MMU_ROOTS_ALL.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-8-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rename mmu->sync_page to mmu->sync_spte and move the code out
of FNAME(sync_page)'s loop body into mmu.c.
No functionalities change intended.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-6-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
mmu->sync_page for direct paging is never called.
And both mmu->sync_page and mm->invlpg only make sense in shadow paging.
Setting mmu->sync_page as NULL for direct paging makes it consistent
with mm->invlpg which is set NULL for the case.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-5-jiangshanlai@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Assert that mmu->sync_page is non-NULL as part of the sanity checks
performed before attempting to sync a shadow page. Explicitly checking
mmu->sync_page is all but guaranteed to be redundant with the existing
sanity check that the MMU is indirect, but the cost is negligible, and
the explicit check also serves as documentation.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-4-jiangshanlai@gmail.com
[sean: increase verbosity of changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
FNAME(invlpg)() and kvm_mmu_invalidate_gva() take a gva_t, i.e. unsigned
long, as the type of the address to invalidate. On 32-bit kernels, the
upper 32 bits of the GPA will get dropped when an L2 GPA address is
invalidated in the shadowed nested TDP MMU.
Convert it to u64 to fix the problem.
Reported-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-2-jiangshanlai@gmail.com
[sean: tweak changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use a new EMULTYPE flag, EMULTYPE_WRITE_PF_TO_SP, to track page faults
on self-changing writes to shadowed page tables instead of propagating
that information to the emulator via a semi-persistent vCPU flag. Using
a flag in "struct kvm_vcpu_arch" is confusing, especially as implemented,
as it's not at all obvious that clearing the flag only when emulation
actually occurs is correct.
E.g. if KVM sets the flag and then retries the fault without ever getting
to the emulator, the flag will be left set for future calls into the
emulator. But because the flag is consumed if and only if both
EMULTYPE_PF and EMULTYPE_ALLOW_RETRY_PF are set, and because
EMULTYPE_ALLOW_RETRY_PF is deliberately not set for direct MMUs, emulated
MMIO, or while L2 is active, KVM avoids false positives on a stale flag
since FNAME(page_fault) is guaranteed to be run and refresh the flag
before it's ultimately consumed by the tail end of reexecute_instruction().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230202182817.407394-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make tdp_mmu_allowed static since it is only ever used within
arch/x86/kvm/mmu/mmu.c.
Link: https://lore.kernel.org/kvm/202302072055.odjDVd5V-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20230213212844.3062733-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
strtobool() is the same as kstrtobool().
However, the latter is more used within the kernel.
In order to remove strtobool() and slightly simplify kstrtox.h, switch to
the other function name.
While at it, include the corresponding header file (<linux/kstrtox.h>)
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/670882aa04dbdd171b46d3b20ffab87158454616.1673689135.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Sean Christopherson <seanjc@google.com>
The spte pointing to the children SP is dropped, so the whole gfn range
covered by the children SP should be flushed. Although, Hyper-V may
treat a 1-page flush the same if the address points to a huge page, it
still would be better to use the correct size of huge page.
Fixes: c3134ce240 ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/5f297c566f7d7ff2ea6da3c66d050f69ce1b8ede.1665214747.git.houwenlong.hwl@antgroup.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
When a spte is dropped, the start gfn of tlb flushing should be the gfn
of spte not the base gfn of SP which contains the spte. Also introduce a
helper function to do range-based flushing when a spte is dropped, which
would help prevent future buggy use of
kvm_flush_remote_tlbs_with_address() in such case.
Fixes: c3134ce240 ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Suggested-by: David Matlack <dmatlack@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/72ac2169a261976f00c1703e88cda676dfb960f5.1665214747.git.houwenlong.hwl@antgroup.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
When the spte of hupe page is dropped in kvm_set_pte_rmapp(), the whole
gfn range covered by the spte should be flushed. However,
rmap_walk_init_level() doesn't align down the gfn for new level like tdp
iterator does, then the gfn used in kvm_set_pte_rmapp() is not the base
gfn of huge page. And the size of gfn range is wrong too for huge page.
Use the base gfn of huge page and the size of huge page for flushing
tlbs for huge page. Also introduce a helper function to flush the given
page (huge or not) of guest memory, which would help prevent future
buggy use of kvm_flush_remote_tlbs_with_address() in such case.
Fixes: c3134ce240 ("KVM: Replace old tlb flush function with new one to flush a specified range.")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/0ce24d7078fa5f1f8d64b0c59826c50f32f8065e.1665214747.git.houwenlong.hwl@antgroup.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Rounding down the GFN to a huge page size is a common pattern throughout
KVM, so move round_gfn_for_level() helper in tdp_iter.c to
mmu_internal.h for common usage. Also rename it as gfn_round_for_level()
to use gfn_* prefix and clean up the other call sites.
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/415c64782f27444898db650e21cf28eeb6441dfa.1665214747.git.houwenlong.hwl@antgroup.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
There is no function named kvm_mmu_ensure_valid_pgd().
Fix the comment and remove the pair of braces to conform to Linux kernel
coding style.
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221128214709.224710-1-wei.liu@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Define pr_fmt using KBUILD_MODNAME for all KVM x86 code so that printks
use consistent formatting across common x86, Intel, and AMD code. In
addition to providing consistent print formatting, using KBUILD_MODNAME,
e.g. kvm_amd and kvm_intel, allows referencing SVM and VMX (and SEV and
SGX and ...) as technologies without generating weird messages, and
without causing naming conflicts with other kernel code, e.g. "SEV: ",
"tdx: ", "sgx: " etc.. are all used by the kernel for non-KVM subsystems.
Opportunistically move away from printk() for prints that need to be
modified anyways, e.g. to drop a manual "kvm: " prefix.
Opportunistically convert a few SGX WARNs that are similarly modified to
WARN_ONCE; in the very unlikely event that the WARNs fire, odds are good
that they would fire repeatedly and spam the kernel log without providing
unique information in each print.
Note, defining pr_fmt yields undesirable results for code that uses KVM's
printk wrappers, e.g. vcpu_unimpl(). But, that's a pre-existing problem
as SVM/kvm_amd already defines a pr_fmt, and thankfully use of KVM's
wrappers is relatively limited in KVM x86 code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-Id: <20221130230934.1014142-35-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x86:
* Change tdp_mmu to a read-only parameter
* Separate TDP and shadow MMU page fault paths
* Enable Hyper-V invariant TSC control
selftests:
* Use TAP interface for kvm_binary_stats_test and tsc_msrs_test
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When handling direct page faults, pivot on the TDP MMU being globally
enabled instead of checking if the target MMU is a TDP MMU. Now that the
TDP MMU is all-or-nothing, if the TDP MMU is enabled, KVM will reach
direct_page_fault() if and only if the MMU is a TDP MMU. When TDP is
enabled (obviously required for the TDP MMU), only non-nested TDP page
faults reach direct_page_fault(), i.e. nonpaging MMUs are impossible, as
NPT requires paging to be enabled and EPT faults use ept_page_fault().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221012181702.3663607-8-seanjc@google.com>
[Use tdp_mmu_enabled variable. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Simplify and optimize the logic for detecting if the current/active MMU
is a TDP MMU. If the TDP MMU is globally enabled, then the active MMU is
a TDP MMU if it is direct. When TDP is enabled, so called nonpaging MMUs
are never used as the only form of shadow paging KVM uses is for nested
TDP, and the active MMU can't be direct in that case.
Rename the helper and take the vCPU instead of an arbitrary MMU, as
nonpaging MMUs can show up in the walk_mmu if L1 is using nested TDP and
L2 has paging disabled. Taking the vCPU has the added bonus of cleaning
up the callers, all of which check the current MMU but wrap code that
consumes the vCPU.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221012181702.3663607-9-seanjc@google.com>
[Use tdp_mmu_enabled variable. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use is_tdp_mmu_page() instead of querying sp->tdp_mmu_page directly so
that all users benefit if KVM ever finds a way to optimize the logic.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221012181702.3663607-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename __direct_map() to direct_map() since the leading underscores are
unnecessary. This also makes the page fault handler names more
consistent: kvm_tdp_mmu_page_fault() calls kvm_tdp_mmu_map() and
direct_page_fault() calls direct_map().
Opportunistically make some trivial cleanups to comments that had to be
modified anyway since they mentioned __direct_map(). Specifically, use
"()" when referring to functions, and include kvm_tdp_mmu_map() among
the various callers of disallowed_hugepage_adjust().
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-11-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stop calling make_mmu_pages_available() when handling TDP MMU faults.
The TDP MMU does not participate in the "available MMU pages" tracking
and limiting so calling this function is unnecessary work when handling
TDP MMU faults.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-10-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Split out the page fault handling for the TDP MMU to a separate
function. This creates some duplicate code, but makes the TDP MMU fault
handler simpler to read by eliminating branches and will enable future
cleanups by allowing the TDP MMU and non-TDP MMU fault paths to diverge.
Only compile in the TDP MMU fault handler for 64-bit builds since
kvm_tdp_mmu_map() does not exist in 32-bit builds.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-9-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the initialization of fault.{gfn,slot} earlier in the page fault
handling code for fully direct MMUs. This will enable a future commit to
split out TDP MMU page fault handling without needing to duplicate the
initialization of these 2 fields.
Opportunistically take advantage of the fact that fault.gfn is
initialized in kvm_tdp_page_fault() rather than recomputing it from
fault->addr.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-8-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Handle faults on GFNs that do not have a backing memslot in
kvm_faultin_pfn() and drop handle_abnormal_pfn(). This eliminates
duplicate code in the various page fault handlers.
Opportunistically tweak the comment about handling gfn > host.MAXPHYADDR
to reflect that the effect of returning RET_PF_EMULATE at that point is
to avoid creating an MMIO SPTE for such GFNs.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-7-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pass the kvm_page_fault struct down to kvm_handle_error_pfn() to avoid a
memslot lookup when handling KVM_PFN_ERR_HWPOISON. Opportunistically
move the gfn_to_hva_memslot() call and @current down into
kvm_send_hwpoison_signal() to cut down on line lengths.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-6-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Handle error PFNs in kvm_faultin_pfn() rather than relying on the caller
to invoke handle_abnormal_pfn() after kvm_faultin_pfn().
Opportunistically rename kvm_handle_bad_page() to kvm_handle_error_pfn()
to make it more consistent with is_error_pfn().
This commit moves KVM closer to being able to drop
handle_abnormal_pfn(), which will reduce the amount of duplicate code in
the various page fault handlers.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-5-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Grab mmu_invalidate_seq in kvm_faultin_pfn() and stash it in struct
kvm_page_fault. The eliminates duplicate code and reduces the amount of
parameters needed for is_page_fault_stale().
Preemptively split out __kvm_faultin_pfn() to a separate function for
use in subsequent commits.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move kvm_mmu_{init,uninit}_tdp_mmu() behind tdp_mmu_enabled. This makes
these functions consistent with the rest of the calls into the TDP MMU
from mmu.c, and which is now possible since tdp_mmu_enabled is only
modified when the x86 vendor module is loaded. i.e. It will never change
during the lifetime of a VM.
This change also enabled removing the stub definitions for 32-bit KVM,
as the compiler will just optimize the calls out like it does for all
the other TDP MMU functions.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Change tdp_mmu to a read-only parameter and drop the per-vm
tdp_mmu_enabled. For 32-bit KVM, make tdp_mmu_enabled a macro that is
always false so that the compiler can continue omitting cals to the TDP
MMU.
The TDP MMU was introduced in 5.10 and has been enabled by default since
5.15. At this point there are no known functionality gaps between the
TDP MMU and the shadow MMU, and the TDP MMU uses less memory and scales
better with the number of vCPUs. In other words, there is no good reason
to disable the TDP MMU on a live system.
Purposely do not drop tdp_mmu=N support (i.e. do not force 64-bit KVM to
always use the TDP MMU) since tdp_mmu=N is still used to get test
coverage of KVM's shadow MMU TDP support, which is used in 32-bit KVM.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220921173546.2674386-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
