KVM: SVM: extract avic_ring_doorbell
The check on the current CPU adds an extra level of indentation to
svm_deliver_avic_intr and conflates documentation on what happens
if the vCPU exits (of interest to svm_deliver_avic_intr) and migrates
(only of interest to avic_ring_doorbell, which calls get/put_cpu()).
Extract the wrmsr to a separate function and rewrite the
comment in svm_deliver_avic_intr().
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 3f9b487..242cb22 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -269,6 +269,22 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu)
return 0;
}
+static void avic_ring_doorbell(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Note, the vCPU could get migrated to a different pCPU at any point,
+ * which could result in signalling the wrong/previous pCPU. But if
+ * that happens the vCPU is guaranteed to do a VMRUN (after being
+ * migrated) and thus will process pending interrupts, i.e. a doorbell
+ * is not needed (and the spurious one is harmless).
+ */
+ int cpu = READ_ONCE(vcpu->cpu);
+
+ if (cpu != get_cpu())
+ wrmsrl(MSR_AMD64_SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpu));
+ put_cpu();
+}
+
static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
u32 icrl, u32 icrh)
{
@@ -669,19 +685,12 @@ int svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
* automatically process AVIC interrupts at VMRUN.
*/
if (vcpu->mode == IN_GUEST_MODE) {
- int cpu = READ_ONCE(vcpu->cpu);
-
/*
- * Note, the vCPU could get migrated to a different pCPU at any
- * point, which could result in signalling the wrong/previous
- * pCPU. But if that happens the vCPU is guaranteed to do a
- * VMRUN (after being migrated) and thus will process pending
- * interrupts, i.e. a doorbell is not needed (and the spurious
- * one is harmless).
+ * Signal the doorbell to tell hardware to inject the IRQ. If
+ * the vCPU exits the guest before the doorbell chimes, hardware
+ * will automatically process AVIC interrupts at the next VMRUN.
*/
- if (cpu != get_cpu())
- wrmsrl(MSR_AMD64_SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpu));
- put_cpu();
+ avic_ring_doorbell(vcpu);
} else {
/*
* Wake the vCPU if it was blocking. KVM will then detect the