lkml.org 
[lkml]   [2021]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 03/14] KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround
From
Date
On 14/09/21 17:48, Maxim Levitsky wrote:
> GP SVM errata workaround made the #GP handler always emulate
> the SVM instructions.
>
> However these instructions #GP in case the operand is not 4K aligned,
> but the workaround code didn't check this and we ended up
> emulating these instructions anyway.
>
> This is only an emulation accuracy check bug as there is no harm for
> KVM to read/write unaligned vmcb images.
>
> Fixes: 82a11e9c6fa2 ("KVM: SVM: Add emulation support for #GP triggered by SVM instructions")
>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
> arch/x86/kvm/svm/svm.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index b2e710a3fff6..6645542df9bd 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2224,6 +2224,10 @@ static int gp_interception(struct kvm_vcpu *vcpu)
> if (error_code)
> goto reinject;
>
> + /* All SVM instructions expect page aligned RAX */
> + if (svm->vmcb->save.rax & ~PAGE_MASK)
> + goto reinject;
> +
> /* Decode the instruction for usage later */
> if (x86_decode_emulated_instruction(vcpu, 0, NULL, 0) != EMULATION_OK)
> goto reinject;
>


Queued, thanks.

Paolo

\
 
 \ /
  Last update: 2021-09-23 16:07    [W:0.107 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site