[PATCH v3 10/10] KVM: arm/arm64: PMU: remove request-less vcpu kick

Andrew Jones
2017-05-03T16:06:35Z

Refactor PMU overflow handling in order to remove the request-less
vcpu kick. Now, since kvm_vgic_inject_irq() uses vcpu requests,
there should be no chance that a kick sent at just the wrong time
(between the VCPU's call to kvm_pmu_flush_hwstate() and before it
enters guest mode) results in a failure for the guest to see updated
GIC state until its next exit some time later for some other reason.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
virt/kvm/arm/pmu.c | 40 +++++++++++++++++++---------------------
1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 4b43e7f3b158..2451607dc25e 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -203,6 +203,23 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
return reg;
}

+static void kvm_pmu_check_overflow(struct kvm_vcpu *vcpu)
+{
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+ bool overflow = !!kvm_pmu_overflow_status(vcpu);
+
+ if (pmu->irq_level == overflow)
+ return;
+
+ pmu->irq_level = overflow;
+
+ if (likely(irqchip_in_kernel(vcpu->kvm))) {
+ int ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+ pmu->irq_num, overflow);
+ WARN_ON(ret);
+ }
+}
+
/**
* kvm_pmu_overflow_set - set PMU overflow interrupt
* @vcpu: The vcpu pointer
@@ -210,37 +227,18 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
*/
void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val)
{
- u64 reg;
-
if (val == 0)
return;

vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= val;
- reg = kvm_pmu_overflow_status(vcpu);
- if (reg != 0)
- kvm_vcpu_kick(vcpu);
+ kvm_pmu_check_overflow(vcpu);
}

static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
{
- struct kvm_pmu *pmu = &vcpu->arch.pmu;
- bool overflow;
-
if (!kvm_arm_pmu_v3_ready(vcpu))
return;
-
- overflow = !!kvm_pmu_overflow_status(vcpu);
- if (pmu->irq_level == overflow)
- return;
-
- pmu->irq_level = overflow;
-
- if (likely(irqchip_in_kernel(vcpu->kvm))) {
- int ret;
- ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
- pmu->irq_num, overflow);
- WARN_ON(ret);
- }
+ kvm_pmu_check_overflow(vcpu);
}

bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu)
--
2.9.3