linux-kernel - Re: [RFC Part2 PATCH v3 24/26] KVM: SVM: Clear C-bit from the page fault address

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Date:   Thu, 14 Sep 2017 16:35:26 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        \"Radim Krčmář\" <rkrcmar@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC Part2 PATCH v3 24/26] KVM: SVM: Clear C-bit from the page
 fault address

On Mon, Jul 24, 2017 at 03:03:01PM -0500, Brijesh Singh wrote:
> When SEV is active, on #NPF the page fault address will contain C-bit.

"... contain the C-bit."

> We must clear the C-bit before handling the fault.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/kvm/svm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 0bbd050..64b9f60 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2321,7 +2321,7 @@ static void svm_set_dr7(struct kvm_vcpu *vcpu, unsigned long value)
>  
>  static int pf_interception(struct vcpu_svm *svm)
>  {
> -	u64 fault_address = svm->vmcb->control.exit_info_2;
> +	u64 fault_address = __sme_clr(svm->vmcb->control.exit_info_2);
>  	u64 error_code = svm->vmcb->control.exit_info_1;
>  
>  	return kvm_handle_page_fault(&svm->vcpu, error_code, fault_address,
> -- 

Otherwise:

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--