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RISC-V: KVM: Save/restore HSTATUS in C source

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We will be optimizing HSTATUS CSR access via shared memory setup
using the SBI nested acceleration extension. To facilitate this,
we first move HSTATUS save/restore in kvm_riscv_vcpu_enter_exit().

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-3-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Anup Patel
2024-10-21 01:17:23 +05:30
committed by Anup Patel
parent e403a90ad6
commit b6114a7e24
2 changed files with 22 additions and 23 deletions
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9
arch/riscv/kvm/vcpu.c
View File

@@ -727,9 +727,18 @@ static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *v
*/
static void noinstr kvm_riscv_vcpu_enter_exit(struct kvm_vcpu *vcpu)
{
struct kvm_cpu_context *gcntx = &vcpu->arch.guest_context;
struct kvm_cpu_context *hcntx = &vcpu->arch.host_context;
kvm_riscv_vcpu_swap_in_guest_state(vcpu);
guest_state_enter_irqoff();
hcntx->hstatus = csr_swap(CSR_HSTATUS, gcntx->hstatus);
__kvm_riscv_switch_to(&vcpu->arch);
gcntx->hstatus = csr_swap(CSR_HSTATUS, hcntx->hstatus);
vcpu->arch.last_exit_cpu = vcpu->cpu;
guest_state_exit_irqoff();
kvm_riscv_vcpu_swap_in_host_state(vcpu);

36
arch/riscv/kvm/vcpu_switch.S
View File

@@ -43,35 +43,30 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
/* Load Guest CSR values */
REG_L t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
REG_L t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
REG_L t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
la t4, .Lkvm_switch_return
REG_L t5, (KVM_ARCH_GUEST_SEPC)(a0)
REG_L t1, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
la t3, .Lkvm_switch_return
REG_L t4, (KVM_ARCH_GUEST_SEPC)(a0)
/* Save Host and Restore Guest SSTATUS */
csrrw t0, CSR_SSTATUS, t0
/* Save Host and Restore Guest HSTATUS */
csrrw t1, CSR_HSTATUS, t1
/* Save Host and Restore Guest SCOUNTEREN */
csrrw t2, CSR_SCOUNTEREN, t2
csrrw t1, CSR_SCOUNTEREN, t1
/* Save Host STVEC and change it to return path */
csrrw t4, CSR_STVEC, t4
csrrw t3, CSR_STVEC, t3
/* Save Host SSCRATCH and change it to struct kvm_vcpu_arch pointer */
csrrw t3, CSR_SSCRATCH, a0
csrrw t2, CSR_SSCRATCH, a0
/* Restore Guest SEPC */
csrw CSR_SEPC, t5
csrw CSR_SEPC, t4
/* Store Host CSR values */
REG_S t0, (KVM_ARCH_HOST_SSTATUS)(a0)
REG_S t1, (KVM_ARCH_HOST_HSTATUS)(a0)
REG_S t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
REG_S t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
REG_S t4, (KVM_ARCH_HOST_STVEC)(a0)
REG_S t1, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
REG_S t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
REG_S t3, (KVM_ARCH_HOST_STVEC)(a0)
/* Restore Guest GPRs (except A0) */
REG_L ra, (KVM_ARCH_GUEST_RA)(a0)
@@ -153,8 +148,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_L t1, (KVM_ARCH_HOST_STVEC)(a0)
REG_L t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
REG_L t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
REG_L t4, (KVM_ARCH_HOST_HSTATUS)(a0)
REG_L t5, (KVM_ARCH_HOST_SSTATUS)(a0)
REG_L t4, (KVM_ARCH_HOST_SSTATUS)(a0)
/* Save Guest SEPC */
csrr t0, CSR_SEPC
@@ -168,18 +162,14 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
/* Save Guest and Restore Host SCOUNTEREN */
csrrw t3, CSR_SCOUNTEREN, t3
/* Save Guest and Restore Host HSTATUS */
csrrw t4, CSR_HSTATUS, t4
/* Save Guest and Restore Host SSTATUS */
csrrw t5, CSR_SSTATUS, t5
csrrw t4, CSR_SSTATUS, t4
/* Store Guest CSR values */
REG_S t0, (KVM_ARCH_GUEST_SEPC)(a0)
REG_S t2, (KVM_ARCH_GUEST_A0)(a0)
REG_S t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
REG_S t4, (KVM_ARCH_GUEST_HSTATUS)(a0)
REG_S t5, (KVM_ARCH_GUEST_SSTATUS)(a0)
REG_S t4, (KVM_ARCH_GUEST_SSTATUS)(a0)
/* Restore Host GPRs (except A0 and T0-T6) */
REG_L ra, (KVM_ARCH_HOST_RA)(a0)