From: Maxim Levitsky <mlevitsk@redhat.com>
To: Santosh Shukla <santosh.shukla@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/7] KVM: SVM: Report NMI not allowed when Guest busy handling VNMI
Date: Tue, 07 Jun 2022 16:12:07 +0300 [thread overview]
Message-ID: <45e9ccafcdb48c7521b697b41e849dab98a7a76c.camel@redhat.com> (raw)
In-Reply-To: <da6e0e9375d1286d3d9d4b6ab669d234850261eb.camel@redhat.com>
On Tue, 2022-06-07 at 16:10 +0300, Maxim Levitsky wrote:
> On Thu, 2022-06-02 at 19:56 +0530, Santosh Shukla wrote:
> > In the VNMI case, Report NMI is not allowed when the processor set the
> > V_NMI_MASK to 1 which means the Guest is busy handling VNMI.
> >
> > Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
> > ---
> > arch/x86/kvm/svm/svm.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index d67a54517d95..a405e414cae4 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -3483,6 +3483,9 @@ bool svm_nmi_blocked(struct kvm_vcpu *vcpu)
> > struct vmcb *vmcb = svm->vmcb;
> > bool ret;
> >
> > + if (is_vnmi_enabled(vmcb) && is_vnmi_mask_set(vmcb))
> > + return true;
>
> How does this interact with GIF? if the guest does clgi, will the
> CPU update the V_NMI_MASK on its own If vGIF is enabled?
>
> What happens if vGIF is disabled and vNMI is enabled? KVM then intercepts
> the stgi/clgi, and it should then update the V_NMI_MASK?
>
>
>
>
> > +
> > if (!gif_set(svm))
> > return true;
> >
> > @@ -3618,6 +3621,9 @@ static void svm_enable_nmi_window(struct kvm_vcpu *vcpu)
> > {
> > struct vcpu_svm *svm = to_svm(vcpu);
> >
> > + if (is_vnmi_enabled(svm->vmcb) && is_vnmi_mask_set(svm->vmcb))
> > + return;
>
> This might have hidden assumption that we will only enable NMI window when vNMI is masked.
Also what if vNMI is already pending?
Best regards,
Maxim Levitsky
>
>
>
> > +
> > if ((vcpu->arch.hflags & (HF_NMI_MASK | HF_IRET_MASK)) == HF_NMI_MASK)
> > return; /* IRET will cause a vm exit */
> >
>
>
> Best regards,
> Maxim Levitsky
next prev parent reply other threads:[~2022-06-07 13:12 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-02 14:26 [PATCH 0/7] Virtual NMI feature Santosh Shukla
2022-06-02 14:26 ` [PATCH 1/7] x86/cpu: Add CPUID feature bit for VNMI Santosh Shukla
2022-06-07 12:32 ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 2/7] KVM: SVM: Add VNMI bit definition Santosh Shukla
2022-06-07 12:55 ` Maxim Levitsky
2022-06-17 14:42 ` Shukla, Santosh
2022-06-02 14:26 ` [PATCH 3/7] KVM: SVM: Add VNMI support in get/set_nmi_mask Santosh Shukla
2022-06-07 13:07 ` Maxim Levitsky
2022-06-17 14:45 ` Shukla, Santosh
2022-06-17 14:48 ` Shukla, Santosh
2022-07-10 16:09 ` Maxim Levitsky
2022-07-21 9:25 ` Shukla, Santosh
2022-07-10 18:39 ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 4/7] KVM: SVM: Report NMI not allowed when Guest busy handling VNMI Santosh Shukla
2022-06-07 13:10 ` Maxim Levitsky
2022-06-07 13:12 ` Maxim Levitsky [this message]
2022-06-17 14:59 ` Shukla, Santosh
2022-07-10 16:08 ` Maxim Levitsky
2022-07-21 9:31 ` Shukla, Santosh
2022-07-21 11:56 ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 5/7] KVM: SVM: Add VNMI support in inject_nmi Santosh Shukla
2022-06-07 13:14 ` Maxim Levitsky
2022-06-17 15:05 ` Shukla, Santosh
2022-07-10 16:07 ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 6/7] KVM: nSVM: implement nested VNMI Santosh Shukla
2022-06-07 13:22 ` Maxim Levitsky
2022-06-17 15:08 ` Shukla, Santosh
2022-06-02 14:26 ` [PATCH 7/7] KVM: SVM: Enable VNMI feature Santosh Shukla
2022-06-06 23:01 ` [PATCH 0/7] Virtual NMI feature Jim Mattson
2022-06-08 8:23 ` Shukla, Santosh
2022-09-05 19:45 ` Jim Mattson
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