> -----Original Message-----
> From: Jim Mattson <jmattson@xxxxxxxxxx>
> Sent: Saturday, September 2, 2023 2:57 AM
> To: kvm@xxxxxxxxxxxxxxx; Christopherson,, Sean <seanjc@xxxxxxxxxx>; Paolo
> Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Xu, Like <likexu@xxxxxxxxxxx>; Mingwei Zhang <mizhang@xxxxxxxxxx>;
> Roman Kagan <rkagan@xxxxxxxxx>; Liang, Kan <kan.liang@xxxxxxxxx>; Mi,
> Dapeng1 <dapeng1.mi@xxxxxxxxx>; Jim Mattson <jmattson@xxxxxxxxxx>
> Subject: [PATCH 2/2] KVM: x86: Mask LVTPC when handling a PMI
>
> Per the SDM, "When the local APIC handles a performance-monitoring counters
> interrupt, it automatically sets the mask flag in the LVT performance counter
> register."
>
> Add this behavior to KVM's local APIC emulation, to reduce the incidence of
> "dazed and confused" spurious NMI warnings in Linux guests (at least, those that
> use a PMI handler with "late_ack").
>
> Fixes: 23930f9521c9 ("KVM: x86: Enable NMI Watchdog via in-kernel PIT source")
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> ---
> arch/x86/kvm/lapic.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index
> a983a16163b1..1a79ec54ae1e 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2743,6 +2743,8 @@ int kvm_apic_local_deliver(struct kvm_lapic *apic, int
> lvt_type)
> vector = reg & APIC_VECTOR_MASK;
> mode = reg & APIC_MODE_MASK;
> trig_mode = reg & APIC_LVT_LEVEL_TRIGGER;
> + if (lvt_type == APIC_LVTPC)
> + kvm_lapic_set_reg(apic, lvt_type, reg |
> APIC_LVT_MASKED);
Reviewed-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
> return __apic_accept_irq(apic, mode, vector, 1, trig_mode,
> NULL);
> }
> --
> 2.42.0.283.g2d96d420d3-goog
