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| author | Sean Christopherson <seanjc@google.com> | 2021-10-21 17:49:27 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-10-22 11:20:16 -0400 |
| commit | 187c8833def8a191c7f01d7932eac1bd2ab84af1 (patch) | |
| tree | 5a76d19edb25bbc663c4eafec41c37875625bc68 /arch/x86/kvm | |
| parent | ee49a89329711f84601bcb65ac8e8ef54fdac771 (diff) | |
| download | lwn-187c8833def8a191c7f01d7932eac1bd2ab84af1.tar.gz lwn-187c8833def8a191c7f01d7932eac1bd2ab84af1.zip | |
KVM: x86: Use rw_semaphore for APICv lock to allow vCPU parallelism
Use a rw_semaphore instead of a mutex to coordinate APICv updates so that
vCPUs responding to requests can take the lock for read and run in
parallel. Using a mutex forces serialization of vCPUs even though
kvm_vcpu_update_apicv() only touches data local to that vCPU or is
protected by a different lock, e.g. SVM's ir_list_lock.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211022004927.1448382-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/hyperv.c | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 12 |
2 files changed, 9 insertions, 7 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 6f11cda2bfa4..4f15c0165c05 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -112,7 +112,7 @@ static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, if (!!auto_eoi_old == !!auto_eoi_new) return; - mutex_lock(&vcpu->kvm->arch.apicv_update_lock); + down_write(&vcpu->kvm->arch.apicv_update_lock); if (auto_eoi_new) hv->synic_auto_eoi_used++; @@ -123,7 +123,7 @@ static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, !hv->synic_auto_eoi_used, APICV_INHIBIT_REASON_HYPERV); - mutex_unlock(&vcpu->kvm->arch.apicv_update_lock); + up_write(&vcpu->kvm->arch.apicv_update_lock); } static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a09365ecdf01..0377e61b8fc0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8778,7 +8778,7 @@ EXPORT_SYMBOL_GPL(kvm_apicv_activated); static void kvm_apicv_init(struct kvm *kvm) { - mutex_init(&kvm->arch.apicv_update_lock); + init_rwsem(&kvm->arch.apicv_update_lock); if (enable_apicv) clear_bit(APICV_INHIBIT_REASON_DISABLE, @@ -9440,7 +9440,7 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu) if (!lapic_in_kernel(vcpu)) return; - mutex_lock(&vcpu->kvm->arch.apicv_update_lock); + down_read(&vcpu->kvm->arch.apicv_update_lock); activate = kvm_apicv_activated(vcpu->kvm); if (vcpu->arch.apicv_active == activate) @@ -9460,7 +9460,7 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu) kvm_make_request(KVM_REQ_EVENT, vcpu); out: - mutex_unlock(&vcpu->kvm->arch.apicv_update_lock); + up_read(&vcpu->kvm->arch.apicv_update_lock); } EXPORT_SYMBOL_GPL(kvm_vcpu_update_apicv); @@ -9468,6 +9468,8 @@ void __kvm_request_apicv_update(struct kvm *kvm, bool activate, ulong bit) { unsigned long old, new; + lockdep_assert_held_write(&kvm->arch.apicv_update_lock); + if (!kvm_x86_ops.check_apicv_inhibit_reasons || !static_call(kvm_x86_check_apicv_inhibit_reasons)(bit)) return; @@ -9506,9 +9508,9 @@ EXPORT_SYMBOL_GPL(__kvm_request_apicv_update); void kvm_request_apicv_update(struct kvm *kvm, bool activate, ulong bit) { - mutex_lock(&kvm->arch.apicv_update_lock); + down_write(&kvm->arch.apicv_update_lock); __kvm_request_apicv_update(kvm, activate, bit); - mutex_unlock(&kvm->arch.apicv_update_lock); + up_write(&kvm->arch.apicv_update_lock); } EXPORT_SYMBOL_GPL(kvm_request_apicv_update); |