On Wed, Sep 06, 2023, Mi, Dapeng wrote: > On 9/2/2023 2:56 AM, Jim Mattson wrote: > > When the irq_work callback, kvm_pmi_trigger_fn(), is invoked during a > > VM-exit that also invokes __kvm_perf_overflow() as a result of > > instruction emulation, kvm_pmu_deliver_pmi() will be called twice > > before the next VM-entry. > > > Do we have a way to reproduce this spurious NMI error constantly? > I think I shared with you in another thread. I also shared the event list and command here: https://lore.kernel.org/all/ZKCD30QrE5g9XGIh@xxxxxxxxxx/ To observe the spurious NMIs, you can just continously look at the NMIs/PMIs in /proc/interrupts and see if you have huge number within 2 minutes when running the above command in a 8-vcpu QEMU VM on Intel SPR machine. Huge here means more than 10K. In addition, you may observe the following warning from kernel dmesg: [3939579.462832] Uhhuh. NMI received for unknown reason 30 on CPU 43. [3939579.462836] Dazed and confused, but trying to continue > > > > > That shouldn't be a problem. The local APIC is supposed to > > automatically set the mask flag in LVTPC when it handles a PMI, so the > > second PMI should be inhibited. However, KVM's local APIC emulation > > fails to set the mask flag in LVTPC when it handles a PMI, so two PMIs > > are delivered via the local APIC. In the common case, where LVTPC is > > configured to deliver an NMI, the first NMI is vectored through the > > guest IDT, and the second one is held pending. When the NMI handler > > returns, the second NMI is vectored through the IDT. For Linux guests, > > this results in the "dazed and confused" spurious NMI message. > > > > Though the obvious fix is to set the mask flag in LVTPC when handling > > a PMI, KVM's logic around synthesizing a PMI is unnecessarily > > convoluted. > > > > Remove the irq_work callback for synthesizing a PMI, and all of the > > logic for invoking it. Instead, to prevent a vcpu from leaving C0 with > > a PMI pending, add a check for KVM_REQ_PMI to kvm_vcpu_has_events(). > > > > Fixes: 9cd803d496e7 ("KVM: x86: Update vPMCs when retiring instructions") > > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx> > > --- > > arch/x86/include/asm/kvm_host.h | 1 - > > arch/x86/kvm/pmu.c | 27 +-------------------------- > > arch/x86/kvm/x86.c | 3 +++ > > 3 files changed, 4 insertions(+), 27 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 3bc146dfd38d..f6b9e3ae08bf 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -528,7 +528,6 @@ struct kvm_pmu { > > u64 raw_event_mask; > > struct kvm_pmc gp_counters[KVM_INTEL_PMC_MAX_GENERIC]; > > struct kvm_pmc fixed_counters[KVM_PMC_MAX_FIXED]; > > - struct irq_work irq_work; > > /* > > * Overlay the bitmap with a 64-bit atomic so that all bits can be > > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c > > index bf653df86112..0c117cd24077 100644 > > --- a/arch/x86/kvm/pmu.c > > +++ b/arch/x86/kvm/pmu.c > > @@ -93,14 +93,6 @@ void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops) > > #undef __KVM_X86_PMU_OP > > } > > -static void kvm_pmi_trigger_fn(struct irq_work *irq_work) > > -{ > > - struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu, irq_work); > > - struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu); > > - > > - kvm_pmu_deliver_pmi(vcpu); > > -} > > - > > static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi) > > { > > struct kvm_pmu *pmu = pmc_to_pmu(pmc); > > @@ -124,20 +116,7 @@ static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi) > > __set_bit(pmc->idx, (unsigned long *)&pmu->global_status); > > } > > - if (!pmc->intr || skip_pmi) > > - return; > > - > > - /* > > - * Inject PMI. If vcpu was in a guest mode during NMI PMI > > - * can be ejected on a guest mode re-entry. Otherwise we can't > > - * be sure that vcpu wasn't executing hlt instruction at the > > - * time of vmexit and is not going to re-enter guest mode until > > - * woken up. So we should wake it, but this is impossible from > > - * NMI context. Do it from irq work instead. > > - */ > > - if (in_pmi && !kvm_handling_nmi_from_guest(pmc->vcpu)) > > - irq_work_queue(&pmc_to_pmu(pmc)->irq_work); > > - else > > + if (pmc->intr && !skip_pmi) > > kvm_make_request(KVM_REQ_PMI, pmc->vcpu); > > } > > @@ -677,9 +656,6 @@ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) > > void kvm_pmu_reset(struct kvm_vcpu *vcpu) > > { > > - struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); > > - > > - irq_work_sync(&pmu->irq_work); > > static_call(kvm_x86_pmu_reset)(vcpu); > > } > > @@ -689,7 +665,6 @@ void kvm_pmu_init(struct kvm_vcpu *vcpu) > > memset(pmu, 0, sizeof(*pmu)); > > static_call(kvm_x86_pmu_init)(vcpu); > > - init_irq_work(&pmu->irq_work, kvm_pmi_trigger_fn); > > pmu->event_count = 0; > > pmu->need_cleanup = false; > > kvm_pmu_refresh(vcpu); > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index c381770bcbf1..0732c09fbd2d 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -12841,6 +12841,9 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu) > > return true; > > #endif > > + if (kvm_test_request(KVM_REQ_PMI, vcpu)) > > + return true; > > + > > if (kvm_arch_interrupt_allowed(vcpu) && > > (kvm_cpu_has_interrupt(vcpu) || > > kvm_guest_apic_has_interrupt(vcpu)))
