linux-kernel - Re: [PATCH v3 5/6] KVM: X86: Add NMI support to PV IPIs

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Message-ID: <CANRm+CwzG8jcsVhhGa2w55KcCTpwm-yokFR2Oi6LYaoS0ameqQ@mail.gmail.com>
Date:   Fri, 20 Jul 2018 11:53:05 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Radim Krcmar <rkrcmar@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH v3 5/6] KVM: X86: Add NMI support to PV IPIs

On Fri, 20 Jul 2018 at 00:31, Radim Krčmář <rkrcmar@...hat.com> wrote:
>
> 2018-07-03 14:21+0800, Wanpeng Li:
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > The NMI delivery mode of ICR is used to deliver an NMI to the processor,
> > and the vector information is ignored.
> >
> > Cc: Paolo Bonzini <pbonzini@...hat.com>
> > Cc: Radim Krčmář <rkrcmar@...hat.com>
> > Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> > Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> > ---
> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > @@ -479,7 +479,16 @@ static int __send_ipi_mask(const struct cpumask *mask, int vector)
> >               }
> >       }
> >
> > -     ret = kvm_hypercall3(KVM_HC_SEND_IPI, ipi_bitmap_low, ipi_bitmap_high, vector);
> > +     switch (vector) {
> > +     default:
> > +             icr = APIC_DM_FIXED | vector;
> > +             break;
> > +     case NMI_VECTOR:
> > +             icr = APIC_DM_NMI;
>
> I think it would be better to say that KVM interprets NMI_VECTOR and
> sends the interrupt as APIC_DM_NMI.

Yeah, in addition, SDM 10.6.1 also mentioned that:
Delivery mode:
    100 (NMI) Delivers an NMI interrupt to the target processor or
processors. The vector information is ignored.

Regards,
Wanpeng Li