Commit af52f5aa authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption 



Use kvm_vcpu_is_blocking() to determine whether or not the vCPU should be
marked running during avic_vcpu_load().  Drop avic_is_running, which
really should have been named "vcpu_is_not_blocking", as it tracked if
the vCPU was blocking, not if it was actually running, e.g. it was set
during svm_create_vcpu() when the vCPU was obviously not running.

This is technically a teeny tiny functional change, as the vCPU will be
marked IsRunning=1 on being reloaded if the vCPU is preempted between
svm_vcpu_blocking() and prepare_to_rcuwait().  But that's a benign change
as the vCPU will be marked IsRunning=0 when KVM voluntarily schedules out
the vCPU.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-14-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e422b889

arch/x86/kvm/svm/avic.c

+9 −5
Original line number Diff line number Diff line
@@ -975,6 +975,7 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
{

	u64 entry;

	/* ID = 0xff (broadcast), ID > 0xff (reserved) */

	bool is_blocking = kvm_vcpu_is_blocking(vcpu);

	int h_physical_id = kvm_cpu_get_apicid(cpu);

	struct vcpu_svm *svm = to_svm(vcpu);
@@ -992,12 +993,17 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
	entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);



	entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;

	if (svm->avic_is_running)



	/*

	 * Don't mark the vCPU as running if its blocking, i.e. if the vCPU is

	 * preempted after svm_vcpu_blocking() but before KVM voluntarily

	 * schedules out the vCPU.

	 */

	if (!is_blocking)

		entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;



	WRITE_ONCE(*(svm->avic_physical_id_cache), entry);

	avic_update_iommu_vcpu_affinity(vcpu, h_physical_id,

					svm->avic_is_running);

	avic_update_iommu_vcpu_affinity(vcpu, h_physical_id, !is_blocking);

}



void avic_vcpu_put(struct kvm_vcpu *vcpu)
@@ -1018,11 +1024,9 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu) 
 */

static void avic_set_running(struct kvm_vcpu *vcpu, bool is_run)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	int cpu = get_cpu();



	WARN_ON(cpu != vcpu->cpu);

	svm->avic_is_running = is_run;



	if (kvm_vcpu_apicv_active(vcpu)) {

		if (is_run)

arch/x86/kvm/svm/svm.c

+0 −6
Original line number Diff line number Diff line
@@ -1440,12 +1440,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) 
	if (err)

		goto error_free_vmsa_page;



	/* We initialize this flag to true to make sure that the is_running

	 * bit would be set the first time the vcpu is loaded.

	 */

	if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm))

		svm->avic_is_running = true;



	svm->msrpm = svm_vcpu_alloc_msrpm();

	if (!svm->msrpm) {

		err = -ENOMEM;

arch/x86/kvm/svm/svm.h

+0 −1
Original line number Diff line number Diff line
@@ -225,7 +225,6 @@ struct vcpu_svm { 
	u32 dfr_reg;

	struct page *avic_backing_page;

	u64 *avic_physical_id_cache;

	bool avic_is_running;



	/*

	 * Per-vcpu list of struct amd_svm_iommu_ir: