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| author | Sean Christopherson <seanjc@google.com> | 2021-12-08 01:52:20 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-19 12:14:41 -0500 |
| commit | 31f251d4ddfa464c6dd92ee873b9b223e992a085 (patch) | |
| tree | 78f4398a71ad14fa286fec0948c04c3d6f543782 /arch/x86 | |
| parent | c3e8abf0f3536a46a235b0533149c2b2c2bbac27 (diff) | |
| download | linux-stable-31f251d4ddfa464c6dd92ee873b9b223e992a085.tar.gz linux-stable-31f251d4ddfa464c6dd92ee873b9b223e992a085.tar.bz2 linux-stable-31f251d4ddfa464c6dd92ee873b9b223e992a085.zip | |
KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode
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>
Message-Id: <20211208015236.1616697-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 0e5b49294086..40039477bebb 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -672,9 +672,22 @@ int svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec) return -1; kvm_lapic_set_irr(vec, vcpu->arch.apic); + + /* + * Pairs with the smp_mb_*() after setting vcpu->guest_mode in + * vcpu_enter_guest() to ensure the write to the vIRR is ordered before + * the read of guest_mode, which guarantees that either VMRUN will see + * and process the new vIRR entry, or that the below code will signal + * the doorbell if the vCPU is already running in the guest. + */ 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); /* @@ -688,8 +701,13 @@ 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; } |