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

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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: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-12-08 01:52:23 +00:00 committed by Paolo Bonzini
parent e422b88969
commit af52f5aa5c
3 changed files with 9 additions and 12 deletions
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14
arch/x86/kvm/svm/avic.c
View File

@ -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)

6
arch/x86/kvm/svm/svm.c
View File

@ -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;

1
arch/x86/kvm/svm/svm.h
View File

@ -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: