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- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
- "Suthikulpanit, Suravee"
| | | Subject | Re: [PATCH v2 11/15] svm: Temporary deactivate AVIC during ExtINT handling | From | Alexander Graf <> | Date | Mon, 19 Aug 2019 12:35:59 +0200 |
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On 15.08.19 18:25, Suthikulpanit, Suravee wrote: > AMD AVIC does not support ExtINT. Therefore, AVIC must be temporary > deactivated and fall back to using legacy interrupt injection via vINTR > and interrupt window. > > Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> > --- > arch/x86/kvm/svm.c | 49 +++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 45 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index cfa4b13..4690351 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -384,6 +384,7 @@ struct amd_svm_iommu_ir { > static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0); > static void svm_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa); > static void svm_complete_interrupts(struct vcpu_svm *svm); > +static void svm_request_activate_avic(struct kvm_vcpu *vcpu); > static bool svm_get_enable_apicv(struct kvm *kvm); > static inline void avic_post_state_restore(struct kvm_vcpu *vcpu); > > @@ -4494,6 +4495,15 @@ static int interrupt_window_interception(struct vcpu_svm *svm) > { > kvm_make_request(KVM_REQ_EVENT, &svm->vcpu); > svm_clear_vintr(svm); > + > + /* > + * For AVIC, the only reason to end up here is ExtINTs. > + * In this case AVIC was temporarily disabled for > + * requesting the IRQ window and we have to re-enable it. > + */ > + if (svm_get_enable_apicv(svm->vcpu.kvm)) > + svm_request_activate_avic(&svm->vcpu);
Would it make sense to add a trace point here and to the other call sites, so that it becomes obvious in a trace when and why exactly avic was active/inactive?
The trace point could add additional information on the why.
> + > svm->vmcb->control.int_ctl &= ~V_IRQ_MASK; > mark_dirty(svm->vmcb, VMCB_INTR); > ++svm->vcpu.stat.irq_window_exits; > @@ -5181,7 +5191,33 @@ static void svm_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr) > { > } > > -/* Note: Currently only used by Hyper-V. */ > +static bool is_avic_active(struct vcpu_svm *svm) > +{ > + return (svm_get_enable_apicv(svm->vcpu.kvm) && > + svm->vmcb->control.int_ctl & AVIC_ENABLE_MASK); > +} > + > +static void svm_request_activate_avic(struct kvm_vcpu *vcpu) > +{ > + struct vcpu_svm *svm = to_svm(vcpu); > + > + if (!lapic_in_kernel(vcpu) || is_avic_active(svm)) > + return; > + > + kvm_make_apicv_activate_request(vcpu); > +} > + > +static void svm_request_deactivate_avic(struct kvm_vcpu *vcpu) > +{ > + struct vcpu_svm *svm = to_svm(vcpu); > + > + if (!lapic_in_kernel(vcpu) || !is_avic_active(svm)) > + return; > + > + /* Request temporary deactivate apicv */ > + kvm_make_apicv_deactivate_request(vcpu, false); > +} > + > static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > @@ -5522,9 +5558,6 @@ static void enable_irq_window(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > > - if (kvm_vcpu_apicv_active(vcpu)) > - return; > - > /* > * In case GIF=0 we can't rely on the CPU to tell us when GIF becomes > * 1, because that's a separate STGI/VMRUN intercept. The next time we > @@ -5534,6 +5567,14 @@ static void enable_irq_window(struct kvm_vcpu *vcpu) > * window under the assumption that the hardware will set the GIF. > */ > if ((vgif_enabled(svm) || gif_set(svm)) && nested_svm_intr(svm)) { > + /* > + * IRQ window is not needed when AVIC is enabled, > + * unless we have pending ExtINT since it cannot be injected > + * via AVIC. In such case, we need to temporarily disable AVIC, > + * and fallback to injecting IRQ via V_IRQ. > + */ > + if (kvm_vcpu_apicv_active(vcpu)) > + svm_request_deactivate_avic(&svm->vcpu);
Did you test AVIC with nesting? Did you actually run across this issue there?
Alex
> svm_set_vintr(svm); > svm_inject_irq(svm, 0x0); > } >
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