[PATCH v3 07/10] KVM: arm/arm64: optimize VCPU RUN

[Andrew Jones <drjones@redhat.com>]

We can make a small optimization by not checking the state of
the power_off field on each run. This is done by treating
power_off like pause, only checking it when we get the EXIT
VCPU request. When a VCPU powers off another VCPU the EXIT
request is already made, so we just need to make sure the
request is also made on self power off. kvm_vcpu_kick() isn't
necessary for these cases, as the VCPU would just be kicking
itself, but we add it anyway as a self kick doesn't cost much,
and it makes the code more future-proof.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm/kvm/arm.c  | 16 ++++++++++------
 arch/arm/kvm/psci.c |  2 ++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 26d9d4d72853..24bbc7671d89 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -371,6 +371,13 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	kvm_timer_vcpu_put(vcpu);
 }
 
+static void vcpu_power_off(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.power_off = true;
+	kvm_make_request(KVM_REQ_VCPU_EXIT, vcpu);
+	kvm_vcpu_kick(vcpu);
+}
+
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
@@ -390,7 +397,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 		vcpu->arch.power_off = false;
 		break;
 	case KVM_MP_STATE_STOPPED:
-		vcpu->arch.power_off = true;
+		vcpu_power_off(vcpu);
 		break;
 	default:
 		return -EINVAL;
@@ -626,14 +633,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 		if (kvm_request_pending(vcpu)) {
 			if (kvm_check_request(KVM_REQ_VCPU_EXIT, vcpu)) {
-				if (vcpu->arch.pause)
+				if (vcpu->arch.power_off || vcpu->arch.pause)
 					vcpu_sleep(vcpu);
 			}
 		}
 
-		if (vcpu->arch.power_off)
-			vcpu_sleep(vcpu);
-
 		/*
 		 * Preparing the interrupts to be injected also
 		 * involves poking the GIC, which must be done in a
@@ -903,7 +907,7 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 	 * Handle the "start in power-off" case.
 	 */
 	if (test_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features))
-		vcpu->arch.power_off = true;
+		vcpu_power_off(vcpu);
 	else
 		vcpu->arch.power_off = false;
 
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index f189d0ad30d5..4a436685c552 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -65,6 +65,8 @@ static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.power_off = true;
+	kvm_make_request(KVM_REQ_VCPU_EXIT, vcpu);
+	kvm_vcpu_kick(vcpu);
 }
 
 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
-- 
2.9.3