KVM: arm/arm64: optimize VCPU RUN

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>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 21a4db90073f22a7ff3a2b916578fba3f428c609..9379b1d75ad3fd09d4921dc4476f9b3f19b7c1b7 100644 (file)
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -368,6 +368,13 @@ 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)
 {
@@ -387,7 +394,7 @@ 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;
@@ -557,7 +564,7 @@ static void vcpu_sleep(struct kvm_vcpu *vcpu)
        swait_event_interruptible(*wq, ((!vcpu->arch.power_off) &&
                                       (!vcpu->arch.pause)));
 
-       if (vcpu->arch.pause) {
+       if (vcpu->arch.power_off || vcpu->arch.pause) {
                /* Awaken to handle a signal, request we sleep again later. */
                kvm_make_request(KVM_REQ_VCPU_EXIT, vcpu);
        }
@@ -623,9 +630,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
                check_vcpu_requests(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
@@ -662,8 +666,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
                smp_store_mb(vcpu->mode, IN_GUEST_MODE);
 
                if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) ||
-                   kvm_request_pending(vcpu) ||
-                   vcpu->arch.power_off) {
+                   kvm_request_pending(vcpu)) {
                        vcpu->mode = OUTSIDE_GUEST_MODE;
                        local_irq_enable();
                        kvm_pmu_sync_hwstate(vcpu);
@@ -896,7 +899,7 @@ 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/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index f189d0ad30d5028dba6ccda12265fcb356af39e1..4a436685c552e5e3eb97038c18e21674afaae697 100644 (file)
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/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)