diff options
| author | Michal Luczaj <mhal@rbox.co> | 2023-01-07 01:12:51 +0100 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-02-03 15:19:22 -0800 |
| commit | 95744a90db18437410aa94620b8a330311bd9cf6 (patch) | |
| tree | 45b81654bc9fc3e804da4f37f1fc832905fab0d0 /arch/x86/kvm | |
| parent | 096691e0d2a1a97ce5a0d68cffdc84ce97bce304 (diff) | |
KVM: x86: Optimize kvm->lock and SRCU interaction (KVM_SET_PMU_EVENT_FILTER)
Reduce time spent holding kvm->lock: unlock mutex before calling
synchronize_srcu_expedited(). There is no need to hold kvm->lock until
all vCPUs have been kicked, KVM only needs to guarantee that all vCPUs
will switch to the new filter before exiting to userspace. Protecting
the write to __reprogram_pmi is also unnecessary as a vCPU may process
a set bit before receiving the final KVM_REQ_PMU, but the per-vCPU writes
are guaranteed to occur after all vCPUs have switched to the new filter.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://lore.kernel.org/r/20230107001256.2365304-2-mhal@rbox.co
[sean: expand changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/pmu.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index d939d3b84e6f..58e5a456273a 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -634,6 +634,7 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp) mutex_lock(&kvm->lock); filter = rcu_replace_pointer(kvm->arch.pmu_event_filter, filter, mutex_is_locked(&kvm->lock)); + mutex_unlock(&kvm->lock); synchronize_srcu_expedited(&kvm->srcu); BUILD_BUG_ON(sizeof(((struct kvm_pmu *)0)->reprogram_pmi) > @@ -644,8 +645,6 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp) kvm_make_all_cpus_request(kvm, KVM_REQ_PMU); - mutex_unlock(&kvm->lock); - r = 0; cleanup: kfree(filter); |