KVM: x86: More precisely identify NMI from guest when handling PMI

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Differentiate between IRQ and NMI for KVM's PMC overflow callback, which
was originally invoked in response to an NMI that arrived while the guest
was running, but was inadvertantly changed to fire on IRQs as well when
support for perf without PMU/NMI was added to KVM.  In practice, this
should be a nop as the PMC overflow callback shouldn't be reached, but
it's a cheap and easy fix that also better documents the situation.

Note, this also doesn't completely prevent false positives if perf
somehow ends up calling into KVM, e.g. an NMI can arrive in host after
KVM sets its flag.

Fixes: dd60d21706 ("KVM: x86: Fix perf timer mode IP reporting")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-12-seanjc@google.com

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Sean Christopherson 2021-11-11 02:07:32 +00:00 • committed by Peter Zijlstra

parent 73cd107b96

commit db215756ae

4 changed files with 15 additions and 6 deletions

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arch/x86/kvm/svm/svm.c

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arch/x86/kvm/vmx/vmx.c

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arch/x86/kvm/x86.c

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arch/x86/kvm/x86.h

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