[PATCH v2 35/43] KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode
From: Sean Christopherson <seanjc@google.com>
Date: 2021-10-09 02:16:36
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-riscv, lkml
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Signal the AVIC doorbell iff the vCPU is running in the guest. If the vCPU is not IN_GUEST_MODE, it's guaranteed to pick up any pending IRQs on the next VMRUN, which unconditionally processes the vIRR. Add comments to document the logic. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/svm/avic.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 208c5c71e827..cbf02e7e20d0 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c@@ -674,7 +674,12 @@ int svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec) kvm_lapic_set_irr(vec, vcpu->arch.apic); smp_mb__after_atomic(); - if (avic_vcpu_is_running(vcpu)) { + /* + * Signal the doorbell to tell hardware to inject the IRQ if the vCPU + * is in the guest. If the vCPU is not in the guest, hardware will + * automatically process AVIC interrupts at VMRUN. + */ + if (vcpu->mode == IN_GUEST_MODE) { int cpu = READ_ONCE(vcpu->cpu); /*
@@ -687,8 +692,13 @@ int svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec) if (cpu != get_cpu()) wrmsrl(SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpu)); put_cpu(); - } else + } else { + /* + * Wake the vCPU if it was blocking. KVM will then detect the + * pending IRQ when checking if the vCPU has a wake event. + */ kvm_vcpu_wake_up(vcpu); + } return 0; }
--
2.33.0.882.g93a45727a2-goog