linux-kernel - Re: [PATCH] KVM: MMU: fix check the reserved bits on the gpte of L2

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Message-ID: <52025481.8050705@redhat.com>
Date:	Wed, 07 Aug 2013 16:06:57 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Gleb Natapov <gleb@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: MMU: fix check the reserved bits on the gpte of
 L2

On 08/05/2013 06:59 AM, Xiao Guangrong wrote:
> Current code always uses arch.mmu to check the reserved bits on guest gpte
> which is valid only for L1 guest, we should use arch.nested_mmu instead when
> we translate gva to gpa for the L2 guest
>
> Fix it by using @mmu instead since it is adapted to the current mmu mode
> automatically
>
> The bug can be triggered when nested npt is used and L1 guest and L2 guest
> use different mmu mode
>
> Reported-by: Jan Kiszka <jan.kiszka@...mens.com>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
> ---
>   arch/x86/kvm/paging_tmpl.h | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index 7769699..3a75828 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -218,8 +218,7 @@ retry_walk:
>   		if (unlikely(!is_present_gpte(pte)))
>   			goto error;
>
> -		if (unlikely(is_rsvd_bits_set(&vcpu->arch.mmu, pte,
> -					      walker->level))) {
> +		if (unlikely(is_rsvd_bits_set(mmu, pte, walker->level))) {
>   			errcode |= PFERR_RSVD_MASK | PFERR_PRESENT_MASK;
>   			goto error;
>   		}
>

Applied, thanks.

Paolo
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