Iterating over set bits in 'vcpu_bitmap' should be faster than going
through all vCPUs, especially when just a few bits are set.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 49 +++++++++++++++++++++++++++++----------------
1 file changed, 32 insertions(+), 17 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3e67c93ca403..0f873c5ed538 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -257,34 +257,49 @@ static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait)
return true;
}
+static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
+ unsigned int req, cpumask_var_t tmp)
+{
+ int cpu = vcpu->cpu;
+
+ kvm_make_request(req, vcpu);
+
+ if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
+ return;
+
+ if (tmp != NULL && cpu != -1 && cpu != raw_smp_processor_id() &&
+ kvm_request_needs_ipi(vcpu, req))
+ __cpumask_set_cpu(cpu, tmp);
+}
+
bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
struct kvm_vcpu *except,
unsigned long *vcpu_bitmap, cpumask_var_t tmp)
{
- int i, cpu, me;
+ int i;
struct kvm_vcpu *vcpu;
bool called;
- me = get_cpu();
-
- kvm_for_each_vcpu(i, vcpu, kvm) {
- if ((vcpu_bitmap && !test_bit(i, vcpu_bitmap)) ||
- vcpu == except)
- continue;
-
- kvm_make_request(req, vcpu);
- cpu = vcpu->cpu;
-
- if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
- continue;
+ preempt_disable();
- if (tmp != NULL && cpu != -1 && cpu != me &&
- kvm_request_needs_ipi(vcpu, req))
- __cpumask_set_cpu(cpu, tmp);
+ if (likely(vcpu_bitmap)) {
+ for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) {
+ vcpu = kvm_get_vcpu(kvm, i);
+ if (!vcpu || vcpu == except)
+ continue;
+ kvm_make_vcpu_request(kvm, vcpu, req, tmp);
+ }
+ } else {
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (vcpu == except)
+ continue;
+ kvm_make_vcpu_request(kvm, vcpu, req, tmp);
+ }
}
called = kvm_kick_many_cpus(tmp, !!(req & KVM_REQUEST_WAIT));
- put_cpu();
+
+ preempt_enable();
return called;
}
--
2.31.1
