[v2] KVM: x86/mmu: Check every prev_roots in __kvm_mmu_free_obsolete_roots()

Commit Message

Huang, Shaoqin June 7, 2022, 12:59 a.m. UTC

From: Shaoqin Huang <[e-mail]>

When freeing obsolete previous roots, check prev_roots as intended, not
the current root.

Signed-off-by: Shaoqin Huang <[e-mail]>
Fixes: 527d5cd7eece ("KVM: x86/mmu: Zap only obsolete roots if a root shadow page is zapped")
---
Changes in v2:
  - Make the commit message more clearer.
  - Fixed the missing idx.

 arch/x86/kvm/mmu/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Sean Christopherson June 6, 2022, 4:56 p.m. UTC | #1

On Mon, Jun 06, 2022, [e-mail] wrote:
> From: Shaoqin Huang <[e-mail]>
> 
> When freeing obsolete previous roots, check prev_roots as intended, not
> the current root.
> 
> Signed-off-by: Shaoqin Huang <[e-mail]>
> Fixes: 527d5cd7eece ("KVM: x86/mmu: Zap only obsolete roots if a root shadow page is zapped")

Because KVM patches aren't guaranteed to be backported without it (though it's
"only" v5.18 that's affected), this needs:

  Cc: [e-mail] 

Reviewed-by: Sean Christopherson <[e-mail]>

Huang, Shaoqin June 7, 2022, 3 p.m. UTC | #2

Thanks Sean!

On 6/7/2022 12:56 AM, Sean Christopherson wrote:
> On Mon, Jun 06, 2022, [e-mail] wrote:
>> From: Shaoqin Huang <[e-mail]>
>>
>> When freeing obsolete previous roots, check prev_roots as intended, not
>> the current root.
>>
>> Signed-off-by: Shaoqin Huang <[e-mail]>
>> Fixes: 527d5cd7eece ("KVM: x86/mmu: Zap only obsolete roots if a root shadow page is zapped")
> 
> Because KVM patches aren't guaranteed to be backported without it (though it's
> "only" v5.18 that's affected), this needs:
> 
>    Cc: [e-mail]
> 
> Reviewed-by: Sean Christopherson <[e-mail]>

Paolo Bonzini June 7, 2022, 3:14 p.m. UTC | #3

On 6/7/22 02:59, [e-mail] wrote:
> From: Shaoqin Huang <[e-mail]>
> 
> When freeing obsolete previous roots, check prev_roots as intended, not
> the current root.
> 
> Signed-off-by: Shaoqin Huang <[e-mail]>
> Fixes: 527d5cd7eece ("KVM: x86/mmu: Zap only obsolete roots if a root shadow page is zapped")
> ---
> Changes in v2:
>    - Make the commit message more clearer.
>    - Fixed the missing idx.
> 
>   arch/x86/kvm/mmu/mmu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index f4653688fa6d..e826ee9138fa 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5179,7 +5179,7 @@ static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu)
>   		roots_to_free |= KVM_MMU_ROOT_CURRENT;
>   
>   	for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
> -		if (is_obsolete_root(kvm, mmu->root.hpa))
> +		if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa))
>   			roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i);
>   	}
>   

Queued, thanks.

Paolo

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index f4653688fa6d..e826ee9138fa 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5179,7 +5179,7 @@  static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu)
 		roots_to_free |= KVM_MMU_ROOT_CURRENT;
 
 	for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
-		if (is_obsolete_root(kvm, mmu->root.hpa))
+		if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa))
 			roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i);
 	}