On Fri, May 14, 2021, Like Xu wrote:
> When a PT perf user is running in system-wide mode on the host,
> the guest (w/ pt_mode=0) will warn about anonymous NMIs from
> kvm_handle_intel_pt_intr():
>
> [ 18.126444] Uhhuh. NMI received for unknown reason 10 on CPU 0.
> [ 18.126447] Do you have a strange power saving mode enabled?
> [ 18.126448] Dazed and confused, but trying to continue
>
> In this case, these PMIs should be handled by the host PT handler().
> When PT is used in guest-only mode, it's harmless to call host handler.
>
> Fix: 8479e04e7d("KVM: x86: Inject PMI for KVM guest")
s/Fix/Fixes
> Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
> ---
> arch/x86/events/intel/core.c | 3 +--
> arch/x86/kvm/x86.c | 3 +++
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 2521d03de5e0..2f09eb0853de 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -2853,8 +2853,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
> if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() &&
> perf_guest_cbs->handle_intel_pt_intr))
> perf_guest_cbs->handle_intel_pt_intr();
> - else
> - intel_pt_interrupt();
> + intel_pt_interrupt();
Would it make sense to instead do something like:
bool host_pmi = true;
...
if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() &&
perf_guest_cbs->handle_intel_pt_intr)
host_pmi = !perf_guest_cbs->handle_intel_pt_intr();
if (likely(host_pmi))
intel_pt_interrupt();
> }
>
> /*
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6529e2023147..6660f3948cea 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8087,6 +8087,9 @@ static void kvm_handle_intel_pt_intr(void)
> {
> struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
>
> + if (!guest_cpuid_has(vcpu, X86_FEATURE_INTEL_PT))
> + return;
> +
> kvm_make_request(KVM_REQ_PMI, vcpu);
> __set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
> (unsigned long *)&vcpu->arch.pmu.global_status);
> --
> 2.31.1
>
