diff mbox series

[09/24] kvm: x86/mmu: Don't redundantly clear TDP MMU pt memory

Message ID 20210112181041.356734-10-bgardon@google.com (mailing list archive)
State New, archived
Headers show
Series Allow parallel page faults with TDP MMU | expand

Commit Message

Ben Gardon Jan. 12, 2021, 6:10 p.m. UTC 
The KVM MMU caches already guarantee that shadow page table memory will
be zeroed, so there is no reason to re-zero the page in the TDP MMU page
fault handler.

No functional change intended.

Reviewed-by: Peter Feiner <pfeiner@google.com>

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Sean Christopherson Jan. 20, 2021, 8:06 p.m. UTC | #1 
On Tue, Jan 12, 2021, Ben Gardon wrote:
> The KVM MMU caches already guarantee that shadow page table memory will
> be zeroed, so there is no reason to re-zero the page in the TDP MMU page
> fault handler.
> 
> No functional change intended.
> 
> Reviewed-by: Peter Feiner <pfeiner@google.com>
> 
> Signed-off-by: Ben Gardon <bgardon@google.com>

Reviewed-by: Sean Christopherson <seanjc@google.com>
Paolo Bonzini Jan. 26, 2021, 2:14 p.m. UTC | #2 
On 12/01/21 19:10, Ben Gardon wrote:
> The KVM MMU caches already guarantee that shadow page table memory will
> be zeroed, so there is no reason to re-zero the page in the TDP MMU page
> fault handler.
> 
> No functional change intended.
> 
> Reviewed-by: Peter Feiner <pfeiner@google.com>
> 
> Signed-off-by: Ben Gardon <bgardon@google.com>
> ---
>   arch/x86/kvm/mmu/tdp_mmu.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 411938e97a00..55df596696c7 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -665,7 +665,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>   			sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level);
>   			list_add(&sp->link, &vcpu->kvm->arch.tdp_mmu_pages);
>   			child_pt = sp->spt;
> -			clear_page(child_pt);
>   			new_spte = make_nonleaf_spte(child_pt,
>   						     !shadow_accessed_mask);
>   
> 

Queued, thanks.

Paolo
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 411938e97a00..55df596696c7 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -665,7 +665,6 @@  int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 			sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level);
 			list_add(&sp->link, &vcpu->kvm->arch.tdp_mmu_pages);
 			child_pt = sp->spt;
-			clear_page(child_pt);
 			new_spte = make_nonleaf_spte(child_pt,
 						     !shadow_accessed_mask);