[PATCH 3/5] KVM: optimize kvm_make_all_cpus_request

From: "Radim Krčmář" <rkrcmar@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Andrew Jones <drjones@redhat.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	James Hogan <james.hogan@imgtec.com>,
	Paul Mackerras <paulus@ozlabs.org>,
	Christoffer Dall <christoffer.dall@linaro.org>
Subject: [PATCH 3/5] KVM: optimize kvm_make_all_cpus_request
Date: Thu, 16 Feb 2017 17:04:47 +0100	[thread overview]
Message-ID: <20170216160449.13094-4-rkrcmar@redhat.com> (raw)
In-Reply-To: <20170216160449.13094-1-rkrcmar@redhat.com>

Use __kvm_request_set to avoid repeated use of wmb().
kvm_make_all_cpus_request is also a candidate for renaming.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 virt/kvm/kvm_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 934f135c0d23..2250920ec965 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -177,8 +177,12 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 	zalloc_cpumask_var(&cpus, GFP_ATOMIC);
 
 	me = get_cpu();
+
+	/* Paired with the smp_mb__after_atomic in kvm_request_test_and_clear. */
+	smp_wmb();
+
 	kvm_for_each_vcpu(i, vcpu, kvm) {
-		kvm_request_set(req, vcpu);
+		__kvm_request_set(req, vcpu);
 		cpu = vcpu->cpu;
 
 		/* Set ->requests bit before we read ->mode. */
-- 
2.11.1
