Re: [PATCH MANUALSEL 5.14 5/5] KVM: MMU: Reset mmu->pkru_mask to avoid stale data

[Paolo Bonzini]

On 25/10/21 22:38, Sasha Levin wrote:
> From: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
>
> [ Upstream commit a3ca5281bb771d8103ea16f0a6a8a5df9a7fb4f3 ]
>
> 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: 2d344105f57c ("KVM, pkeys: introduce pkru_mask to cache conditions")
> Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
> Message-Id: <20211021071022.1140-1-chenyi.qiang@xxxxxxxxx>
> Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>   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 c268fb59f779..6719a8041f59 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4465,10 +4465,10 @@ 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);
>   

Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>