Commit 0a5f7842 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0316dbb9

arch/x86/kvm/svm/avic.c

+20 −11
Original line number Diff line number Diff line
@@ -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