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KVM: perform a wake_up in kvm_make_all_cpus_request 

We want to have kvm_make_all_cpus_request() to be an optmized version of

  kvm_for_each_vcpu(i, vcpu, kvm) {
    kvm_make_request(vcpu, request);
    kvm_vcpu_kick(vcpu);
  }

and kvm_vcpu_kick() wakes up the target vcpu.  We know which requests do
not need the wake up and use it to optimize the loop.

Thanks to that, this patch doesn't change the behavior of current users
(the all don't need the wake up) and only prepares for future where the
wake up is going to be needed.

I think that most requests do not need the wake up, so we would flip the
bit then.

Later on, kvm_make_request() will take care of kicking too, using this
bit to make the decision whether to kick or not.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Radim Krčmář 2017-04-26 22:32:23 +02:00 committed by Paolo Bonzini
parent 930f7fd6da
commit 6c6e8360b3
1 changed files with 3 additions and 0 deletions
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3
virt/kvm/kvm_main.c
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@ -186,6 +186,9 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
/* Set ->requests bit before we read ->mode. */
smp_mb__after_atomic();
if (!(req & KVM_REQUEST_NO_WAKEUP))
kvm_vcpu_wake_up(vcpu);
if (cpus != NULL && cpu != -1 && cpu != me &&
kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE)
cpumask_set_cpu(cpu, cpus);