linux-kernel - Re: [PATCH 1/9] KVM: x86/mmu: Use SHADOW_NONPRESENT

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Date: Mon, 20 May 2024 12:38:22 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/9] KVM: x86/mmu: Use SHADOW_NONPRESENT_VALUE for atomic
 zap in TDP MMU

On Fri, 2024-05-17 at 17:04 -0700, Sean Christopherson wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> Use SHADOW_NONPRESENT_VALUE when zapping TDP MMU SPTEs with mmu_lock held
> for read, tdp_mmu_zap_spte_atomic() was simply missed during the initial
> development.
> 
> Fixes: 7f01cab84928 ("KVM: x86/mmu: Allow non-zero value for non-present SPTE and removed SPTE")
> Not-yet-signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> [sean: write changelog]
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 1259dd63defc..36539c1b36cd 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -626,7 +626,7 @@ static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm,
>  	 * SPTEs.
>  	 */
>  	handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
> -			    0, iter->level, true);
> +			    SHADOW_NONPRESENT_VALUE, iter->level, true);
>  
>  	return 0;
>  }

Reviewed-by: Kai Huang <kai.huang@...el.com>