1 files changed, 52 insertions, 8 deletions

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a1bc10d7116a..25c29107f13f 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -280,7 +280,7 @@ static u64 kvm_pmu_hyp_counter_mask(struct kvm_vcpu *vcpu)
 		return 0;
 
 	hpmn = SYS_FIELD_GET(MDCR_EL2, HPMN, __vcpu_sys_reg(vcpu, MDCR_EL2));
-	n = vcpu->kvm->arch.pmcr_n;
+	n = vcpu->kvm->arch.nr_pmu_counters;
 
 	/*
 	 * Programming HPMN to a value greater than PMCR_EL0.N is
@@ -608,14 +608,12 @@ void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val)
 		kvm_pmu_set_counter_value(vcpu, ARMV8_PMU_CYCLE_IDX, 0);
 
 	if (val & ARMV8_PMU_PMCR_P) {
-		/*
-		 * Unlike other PMU sysregs, the controls in PMCR_EL0 always apply
-		 * to the 'guest' range of counters and never the 'hyp' range.
-		 */
 		unsigned long mask = kvm_pmu_implemented_counter_mask(vcpu) &
-				     ~kvm_pmu_hyp_counter_mask(vcpu) &
 				     ~BIT(ARMV8_PMU_CYCLE_IDX);
 
+		if (!vcpu_is_el2(vcpu))
+			mask &= ~kvm_pmu_hyp_counter_mask(vcpu);
+
 		for_each_set_bit(i, &mask, 32)
 			kvm_pmu_set_pmc_value(kvm_vcpu_idx_to_pmc(vcpu, i), 0, true);
 	}
@@ -1027,12 +1025,30 @@ u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)
 	return bitmap_weight(arm_pmu->cntr_mask, ARMV8_PMU_MAX_GENERAL_COUNTERS);
 }
 
+static void kvm_arm_set_nr_counters(struct kvm *kvm, unsigned int nr)
+{
+	kvm->arch.nr_pmu_counters = nr;
+
+	/* Reset MDCR_EL2.HPMN behind the vcpus' back... */
+	if (test_bit(KVM_ARM_VCPU_HAS_EL2, kvm->arch.vcpu_features)) {
+		struct kvm_vcpu *vcpu;
+		unsigned long i;
+
+		kvm_for_each_vcpu(i, vcpu, kvm) {
+			u64 val = __vcpu_sys_reg(vcpu, MDCR_EL2);
+			val &= ~MDCR_EL2_HPMN;
+			val |= FIELD_PREP(MDCR_EL2_HPMN, kvm->arch.nr_pmu_counters);
+			__vcpu_sys_reg(vcpu, MDCR_EL2) = val;
+		}
+	}
+}
+
 static void kvm_arm_set_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
 {
 	lockdep_assert_held(&kvm->arch.config_lock);
 
 	kvm->arch.arm_pmu = arm_pmu;
-	kvm->arch.pmcr_n = kvm_arm_pmu_get_max_counters(kvm);
+	kvm_arm_set_nr_counters(kvm, kvm_arm_pmu_get_max_counters(kvm));
 }
 
 /**
@@ -1088,6 +1104,20 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
 	return ret;
 }
 
+static int kvm_arm_pmu_v3_set_nr_counters(struct kvm_vcpu *vcpu, unsigned int n)
+{
+	struct kvm *kvm = vcpu->kvm;
+
+	if (!kvm->arch.arm_pmu)
+		return -EINVAL;
+
+	if (n > kvm_arm_pmu_get_max_counters(kvm))
+		return -EINVAL;
+
+	kvm_arm_set_nr_counters(kvm, n);
+	return 0;
+}
+
 int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -1184,6 +1214,15 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 
 		return kvm_arm_pmu_v3_set_pmu(vcpu, pmu_id);
 	}
+	case KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS: {
+		unsigned int __user *uaddr = (unsigned int __user *)(long)attr->addr;
+		unsigned int n;
+
+		if (get_user(n, uaddr))
+			return -EFAULT;
+
+		return kvm_arm_pmu_v3_set_nr_counters(vcpu, n);
+	}
 	case KVM_ARM_VCPU_PMU_V3_INIT:
 		return kvm_arm_pmu_v3_init(vcpu);
 	}
@@ -1222,6 +1261,7 @@ int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 	case KVM_ARM_VCPU_PMU_V3_INIT:
 	case KVM_ARM_VCPU_PMU_V3_FILTER:
 	case KVM_ARM_VCPU_PMU_V3_SET_PMU:
+	case KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS:
 		if (kvm_vcpu_has_pmu(vcpu))
 			return 0;
 	}
@@ -1260,8 +1300,12 @@ u8 kvm_arm_pmu_get_pmuver_limit(void)
 u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
 {
 	u64 pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
+	u64 n = vcpu->kvm->arch.nr_pmu_counters;
+
+	if (vcpu_has_nv(vcpu) && !vcpu_is_el2(vcpu))
+		n = FIELD_GET(MDCR_EL2_HPMN, __vcpu_sys_reg(vcpu, MDCR_EL2));
 
-	return u64_replace_bits(pmcr, vcpu->kvm->arch.pmcr_n, ARMV8_PMU_PMCR_N);
+	return u64_replace_bits(pmcr, n, ARMV8_PMU_PMCR_N);
 }
 
 void kvm_pmu_nested_transition(struct kvm_vcpu *vcpu)