2013-08-05 04:59:29

by Xiao Guangrong

Subject: [PATCH] KVM: MMU: fix check the reserved bits on the gpte of L2

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 <[email protected]>
Signed-off-by: Xiao Guangrong <[email protected]>
---
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;
}
--
1.8.1.4

2013-08-05 06:03:33

by Gleb Natapov

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

On Mon, Aug 05, 2013 at 12:59:19PM +0800, 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 <[email protected]>
> Signed-off-by: Xiao Guangrong <[email protected]>
Reviewed-by: Gleb Natapov <[email protected]>

> ---
> 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;
> }
> --
> 1.8.1.4

--
Gleb.

2013-08-07 14:07:05

by Paolo Bonzini

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 <[email protected]>
> Signed-off-by: Xiao Guangrong <[email protected]>
> ---
> 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