diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-12-08 01:52:21 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-19 12:14:42 -0500 |
| commit | 202470d536b2cad22fa859f3e01202571c49ded9 (patch) | |
| tree | aea968b406e49eb94823f86e6a8ccc9ea524149f /arch/x86 | |
| parent | 31f251d4ddfa464c6dd92ee873b9b223e992a085 (diff) | |
| download | linux-202470d536b2cad22fa859f3e01202571c49ded9.tar.bz2 | |
KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs
Drop the avic_vcpu_is_running() check when waking vCPUs in response to a
VM-Exit due to incomplete IPI delivery. The check isn't wrong per se, but
it's not 100% accurate in the sense that it doesn't guarantee that the vCPU
was one of the vCPUs that didn't receive the IPI.
The check isn't required for correctness as blocking == !running in this
context.
From a performance perspective, waking a live task is not expensive as the
only moderately costly operation is a locked operation to temporarily
disable preemption. And if that is indeed a performance issue,
kvm_vcpu_is_blocking() would be a better check than poking into the AVIC.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 15 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/svm.h | 11 |
2 files changed, 9 insertions, 17 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 40039477bebb..2d8278167c0f 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -295,13 +295,16 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source, struct kvm_vcpu *vcpu; unsigned long i; + /* + * Wake any target vCPUs that are blocking, i.e. waiting for a wake + * event. There's no need to signal doorbells, as hardware has handled + * vCPUs that were in guest at the time of the IPI, and vCPUs that have + * since entered the guest will have processed pending IRQs at VMRUN. + */ kvm_for_each_vcpu(i, vcpu, kvm) { - bool m = kvm_apic_match_dest(vcpu, source, - icrl & APIC_SHORT_MASK, - GET_APIC_DEST_FIELD(icrh), - icrl & APIC_DEST_MASK); - - if (m && !avic_vcpu_is_running(vcpu)) + if (kvm_apic_match_dest(vcpu, source, icrl & APIC_SHORT_MASK, + GET_APIC_DEST_FIELD(icrh), + icrl & APIC_DEST_MASK)) kvm_vcpu_wake_up(vcpu); } } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 6d29421dd4bf..fd0685b2ce55 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -573,17 +573,6 @@ extern struct kvm_x86_nested_ops svm_nested_ops; #define VMCB_AVIC_APIC_BAR_MASK 0xFFFFFFFFFF000ULL -static inline bool avic_vcpu_is_running(struct kvm_vcpu *vcpu) -{ - struct vcpu_svm *svm = to_svm(vcpu); - u64 *entry = svm->avic_physical_id_cache; - - if (!entry) - return false; - - return (READ_ONCE(*entry) & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK); -} - int avic_ga_log_notifier(u32 ga_tag); void avic_vm_destroy(struct kvm *kvm); int avic_vm_init(struct kvm *kvm); |