[PATCH 1/4] KVM: arm64: PMU: Introduce a helper to set the guest's PMU

[Reiji Watanabe]

Introduce a new helper function to set the guest's PMU
(kvm->arch.arm_pmu), and use it when the guest's PMU needs
to be set. This helper will make it easier for the following
patches to modify the relevant code.

No functional change intended.

Signed-off-by: Reiji Watanabe <reijiw at google.com>
---
 arch/arm64/kvm/pmu-emul.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 45727d50d18d..d50c8f7a2410 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -869,6 +869,21 @@ static bool pmu_irq_is_valid(struct kvm *kvm, int irq)
 	return true;
 }
 
+static int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
+{
+	lockdep_assert_held(&kvm->arch.config_lock);
+
+	if (!arm_pmu) {
+		arm_pmu = kvm_pmu_probe_armpmu();
+		if (!arm_pmu)
+			return -ENODEV;
+	}
+
+	kvm->arch.arm_pmu = arm_pmu;
+
+	return 0;
+}
+
 static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -888,7 +903,7 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
 				break;
 			}
 
-			kvm->arch.arm_pmu = arm_pmu;
+			WARN_ON_ONCE(kvm_arm_set_vm_pmu(kvm, arm_pmu));
 			cpumask_copy(kvm->arch.supported_cpus, &arm_pmu->supported_cpus);
 			ret = 0;
 			break;
@@ -913,9 +928,10 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 
 	if (!kvm->arch.arm_pmu) {
 		/* No PMU set, get the default one */
-		kvm->arch.arm_pmu = kvm_pmu_probe_armpmu();
-		if (!kvm->arch.arm_pmu)
-			return -ENODEV;
+		int ret = kvm_arm_set_vm_pmu(kvm, NULL);
+
+		if (ret)
+			return ret;
 	}
 
 	switch (attr->attr) {
-- 
2.41.0.rc0.172.g3f132b7071-goog