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Groups > linux.kernel > #1618337

[PATCH 6/6] KVM: perform a wake_up in kvm_make_all_cpus_request

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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.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 virt/kvm/kvm_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a486c6ad27a6..1db503bab3dc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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_arch_vcpu_should_kick(vcpu))
 			cpumask_set_cpu(cpu, cpus);
-- 
2.12.0

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[PATCH 0/6] KVM: towards maintainable kvm_make_all_cpus_request() Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
  [PATCH 4/6] KVM: remove #ifndef CONFIG_S390 around kvm_vcpu_wake_up Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
    Re: [PATCH 4/6] KVM: remove #ifndef CONFIG_S390 around  kvm_vcpu_wake_up Christian Borntraeger <borntraeger@de.ibm.com> - 2017-04-07 13:10 +0200
  [PATCH RFC 1/6] KVM: fix guest_mode optimization in kvm_make_all_cpus_request() Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
    Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in  kvm_make_all_cpus_request() James Hogan <james.hogan@imgtec.com> - 2017-04-06 23:10 +0200
    Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in  kvm_make_all_cpus_request() Christian Borntraeger <borntraeger@de.ibm.com> - 2017-04-07 12:50 +0200
  [PATCH 3/6] KVM: x86: use kvm_make_request instead of set_bit Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
    Re: [PATCH 3/6] KVM: x86: use kvm_make_request instead of set_bit David Hildenbrand <david@redhat.com> - 2017-04-07 10:20 +0200
  [PATCH 6/6] KVM: perform a wake_up in kvm_make_all_cpus_request Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
    Re: [PATCH 6/6] KVM: perform a wake_up in kvm_make_all_cpus_request Andrew Jones <drjones@redhat.com> - 2017-04-10 13:20 +0200
  [PATCH 2/6] KVM: use kvm_{test,clear}_request instead of {test,clear}_bit Radim Krčmář <rkrcmar@redhat.com> - 2017-04-06 22:30 +0200
    Re: [PATCH 2/6] KVM: use kvm_{test,clear}_request instead of  {test,clear}_bit Christian Borntraeger <borntraeger@de.ibm.com> - 2017-04-07 13:00 +0200
      Re: [PATCH 2/6] KVM: use kvm_{test,clear}_request instead of  {test,clear}_bit Radim Krčmář <rkrcmar@redhat.com> - 2017-04-07 14:30 +0200
        Re: [PATCH 2/6] KVM: use kvm_{test,clear}_request instead of  {test,clear}_bit Radim Krčmář <rkrcmar@redhat.com> - 2017-04-07 16:10 +0200

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