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| author | Sean Christopherson <seanjc@google.com> | 2021-12-08 02:52:24 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-19 18:14:44 +0100 |
| commit | 782f64558de7bef84b90ea812deb38f0e53a8c7a (patch) | |
| tree | 18d8f8eb25fbc7d0478fdffa6acb605349fe8db5 /arch | |
| parent | KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption (diff) | |
| download | linux-782f64558de7bef84b90ea812deb38f0e53a8c7a.tar.xz linux-782f64558de7bef84b90ea812deb38f0e53a8c7a.zip | |
KVM: SVM: Skip AVIC and IRTE updates when loading blocking vCPU
Don't bother updating the Physical APIC table or IRTE when loading a vCPU
that is blocking, i.e. won't be marked IsRun{ning}=1, as the pCPU is
queried if and only if IsRunning is '1'. If the vCPU was migrated, the
new pCPU will be picked up when avic_vcpu_load() is called by
svm_vcpu_unblocking().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 368813320121..b7353e11da2e 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -975,7 +975,6 @@ 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); @@ -986,24 +985,25 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if (WARN_ON(h_physical_id > AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK)) return; + /* + * No need to update anything if the vCPU is blocking, i.e. if the vCPU + * is being scheduled in after being preempted. The CPU entries in the + * Physical APIC table and IRTE are consumed iff IsRun{ning} is '1'. + * If the vCPU was migrated, its new CPU value will be stuffed when the + * vCPU unblocks. + */ + if (kvm_vcpu_is_blocking(vcpu)) + return; + entry = READ_ONCE(*(svm->avic_physical_id_cache)); WARN_ON(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK); entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK; entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK); - - entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK; - - /* - * 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; + 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, !is_blocking); + avic_update_iommu_vcpu_affinity(vcpu, h_physical_id, true); } void avic_vcpu_put(struct kvm_vcpu *vcpu) @@ -1012,8 +1012,12 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu) struct vcpu_svm *svm = to_svm(vcpu); entry = READ_ONCE(*(svm->avic_physical_id_cache)); - if (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK) - avic_update_iommu_vcpu_affinity(vcpu, -1, 0); + + /* Nothing to do if IsRunning == '0' due to vCPU blocking. */ + if (!(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK)) + return; + + avic_update_iommu_vcpu_affinity(vcpu, -1, 0); entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK; WRITE_ONCE(*(svm->avic_physical_id_cache), entry); |