linux-kernel - Re: [PATCH] KVM: SVM: fix NMI window after iret

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Message-ID: <5303255D.8000501@redhat.com>
Date:	Tue, 18 Feb 2014 10:18:21 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>,
	linux-kernel@...r.kernel.org
CC:	kvm@...r.kernel.org, joro@...tes.org, stable@...r.kernel.org
Subject: Re: [PATCH] KVM: SVM: fix NMI window after iret

Il 17/01/2014 20:52, Radim Krčmář ha scritto:
> We should open NMI window right after an iret, but SVM exits before it.
> We wanted to single step using the trap flag and then open it.
> (or we could emulate the iret instead)
> We don't do it since commit 3842d135ff2 (likely), because the iret exit
> handler does not request an event, so NMI window remains closed until
> the next exit.
>
> Fix this by making KVM_REQ_EVENT request in the iret handler.
>
> Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
> ---
>  (btw. kvm-unit-tests weren't executed on SVM since Nov 2010, at least)
>
>  arch/x86/kvm/svm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index c7168a5..b5a735b 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2829,6 +2829,7 @@ static int iret_interception(struct vcpu_svm *svm)
>  	clr_intercept(svm, INTERCEPT_IRET);
>  	svm->vcpu.arch.hflags |= HF_IRET_MASK;
>  	svm->nmi_iret_rip = kvm_rip_read(&svm->vcpu);
> +	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
>  	return 1;
>  }
>
>

Applying to kvm/queue, thanks.

Paolo
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