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@xxxxxxx> --- 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); }
