From: Shannon Zhao <redacted>

According to ARMv8 spec, when writing 1 to PMCR.E, all counters are
enabled by PMCNTENSET, while writing 0 to PMCR.E, all counters are
disabled. When writing 1 to PMCR.P, reset all event counters, not
including PMCCNTR, to zero. When writing 1 to PMCR.C, reset PMCCNTR to
zero.

Signed-off-by: Shannon Zhao <redacted>
---
 arch/arm64/kvm/sys_regs.c |  1 +
 include/kvm/arm_pmu.h     |  2 ++
 virt/kvm/arm/pmu.c        | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 92021dc..04281f1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -464,6 +464,7 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 		val &= ~ARMV8_PMCR_MASK;
 		val |= p->regval & ARMV8_PMCR_MASK;
 		vcpu_sys_reg(vcpu, r->reg) = val;
+		kvm_pmu_handle_pmcr(vcpu, val);
 	} else {
 		/* PMCR.P & PMCR.C are RAZ */
 		val = vcpu_sys_reg(vcpu, r->reg)

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 67d168c..7ec7706 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h

@@ -41,6 +41,7 @@ void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val);
 void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val);
 void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val);
 void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val);
+void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val);
 void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
 				    u64 select_idx);
 #else

@@ -59,6 +60,7 @@ void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val) {}
 void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val) {}
 void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val) {}
 void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val) {}
+void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) {}
 void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
 				    u64 select_idx) {}
 #endif

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 409f3c4..fda32cb 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c

@@ -189,6 +189,48 @@ void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
 	}
 }
 
+/**
+ * kvm_pmu_handle_pmcr - handle PMCR register
+ * @vcpu: The vcpu pointer
+ * @val: the value guest writes to PMCR register
+ */
+void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val)
+{
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+	struct kvm_pmc *pmc;
+	u64 mask;
+	int i;
+
+	mask = kvm_pmu_valid_counter_mask(vcpu);
+	if (val & ARMV8_PMCR_E) {
+		kvm_pmu_enable_counter(vcpu,
+				     vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask);
+	} else {
+		kvm_pmu_disable_counter(vcpu, mask);
+	}
+
+	if (val & ARMV8_PMCR_C) {
+		pmc = &pmu->pmc[ARMV8_CYCLE_IDX];
+		if (pmc->perf_event)
+			local64_set(&pmc->perf_event->count, 0);
+		vcpu_sys_reg(vcpu, PMCCNTR_EL0) = 0;
+	}
+
+	if (val & ARMV8_PMCR_P) {
+		for (i = 0; i < ARMV8_CYCLE_IDX; i++) {
+			pmc = &pmu->pmc[i];
+			if (pmc->perf_event)
+				local64_set(&pmc->perf_event->count, 0);