linux-kernel - Re: [PATCH] KVM: MMU: Reset mmu->pkru

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Date:   Thu, 21 Oct 2021 17:09:48 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Chenyi Qiang <chenyi.qiang@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: MMU: Reset mmu->pkru_mask to avoid stale data

On 21/10/21 09:10, Chenyi Qiang wrote:
> When updating mmu->pkru_mask, the value can only be added but it isn't
> reset in advance. This will make mmu->pkru_mask keep the stale data.
> Fix this issue.
> 
> Fixes: commit 2d344105f57c ("KVM, pkeys: introduce pkru_mask to cache conditions")
> Signed-off-by: Chenyi Qiang <chenyi.qiang@...el.com>
> ---
>   arch/x86/kvm/mmu/mmu.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index c6ddb042b281..fe73d7ee5492 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4556,10 +4556,10 @@ static void update_pkru_bitmask(struct kvm_mmu *mmu)
>   	unsigned bit;
>   	bool wp;
>   
> -	if (!is_cr4_pke(mmu)) {
> -		mmu->pkru_mask = 0;
> +	mmu->pkru_mask = 0;
> +
> +	if (!is_cr4_pke(mmu))
>   		return;
> -	}
>   
>   	wp = is_cr0_wp(mmu);
>   
> 

Queued, thanks.

Paolo