2022-08-24 09:35:52

by Hou Wenlong

Subject: [PATCH v2 3/6] KVM: x86/mmu: Reduce gfn range of tlb flushing in tdp_mmu_map_handle_target_level()

Since the children SP is zapped, the gfn range of tlb flushing should be
the range covered by children SP not parent SP. Replace sp->gfn which is
the base gfn of parent SP with iter->gfn and use the correct size of
gfn range for children SP to reduce tlb flushing range.

Signed-off-by: Hou Wenlong <[email protected]>
---
arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index bf2ccf9debca..08b7932122ec 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1071,8 +1071,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
return RET_PF_RETRY;
else if (is_shadow_present_pte(iter->old_spte) &&
!is_last_spte(iter->old_spte, iter->level))
- kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
- KVM_PAGES_PER_HPAGE(iter->level + 1));
+ kvm_flush_remote_tlbs_with_address(vcpu->kvm, iter->gfn,
+ KVM_PAGES_PER_HPAGE(iter->level));

/*
* If the page fault was caused by a write but the page is write
--
2.31.1

2022-09-07 18:24:32

by David Matlack

Subject: Re: [PATCH v2 3/6] KVM: x86/mmu: Reduce gfn range of tlb flushing in tdp_mmu_map_handle_target_level()

On Wed, Aug 24, 2022 at 05:29:20PM +0800, Hou Wenlong wrote:
> Since the children SP is zapped, the gfn range of tlb flushing should be
> the range covered by children SP not parent SP. Replace sp->gfn which is
> the base gfn of parent SP with iter->gfn and use the correct size of
> gfn range for children SP to reduce tlb flushing range.
>

Fixes: bb95dfb9e2df ("KVM: x86/mmu: Defer TLB flush to caller when freeing TDP MMU shadow pages")

> Signed-off-by: Hou Wenlong <[email protected]>

Reviewed-by: David Matlack <[email protected]>

> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index bf2ccf9debca..08b7932122ec 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1071,8 +1071,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
> return RET_PF_RETRY;
> else if (is_shadow_present_pte(iter->old_spte) &&
> !is_last_spte(iter->old_spte, iter->level))
> - kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
> - KVM_PAGES_PER_HPAGE(iter->level + 1));
> + kvm_flush_remote_tlbs_with_address(vcpu->kvm, iter->gfn,
> + KVM_PAGES_PER_HPAGE(iter->level));
>
> /*
> * If the page fault was caused by a write but the page is write
> --
> 2.31.1
>