[PATCH v7 10/19] KVM: ARM64: Add access handler for PMCNTENSET and PMCNTENCLR register

Shannon Zhao
2015-12-15T08:49:30Z

From: Shannon Zhao <shannon.zhao@linaro.org>

Since the reset value of PMCNTENSET and PMCNTENCLR is UNKNOWN, use
reset_unknown for its reset handler. Add a handler to emulate writing
PMCNTENSET or PMCNTENCLR register.

When writing to PMCNTENSET, call perf_event_enable to enable the perf
event. When writing to PMCNTENCLR, call perf_event_disable to disable
the perf event.

Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
---
arch/arm64/kvm/sys_regs.c | 41 +++++++++++++++++++++++++++++++----
include/kvm/arm_pmu.h | 4 ++++
virt/kvm/arm/pmu.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 96 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index dc6bb26..f216da7 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -615,6 +615,39 @@ static bool access_pmu_evcntr(struct kvm_vcpu *vcpu,
return true;
}

+static inline u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
+{
+ u64 val = vcpu_sys_reg(vcpu, PMCR_EL0) >> ARMV8_PMCR_N_SHIFT;
+
+ val &= ARMV8_PMCR_N_MASK;
+ return GENMASK(val - 1, 0) | BIT(ARMV8_CYCLE_IDX);
+}
+
+static bool access_pmcntenset(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ u64 val, mask;
+
+ mask = kvm_pmu_valid_counter_mask(vcpu);
+ if (p->is_write) {
+ val = p->regval & mask;
+ if (r->Op2 & 0x1) {
+ /* accessing PMCNTENSET_EL0 */
+ vcpu_sys_reg(vcpu, r->reg) |= val;
+ kvm_pmu_enable_counter(vcpu, val);
+ } else {
+ /* accessing PMCNTENCLR_EL0 */
+ vcpu_sys_reg(vcpu, r->reg) &= mask;
+ vcpu_sys_reg(vcpu, r->reg) &= ~val;
+ kvm_pmu_disable_counter(vcpu, val);
+ }
+ } else {
+ p->regval = vcpu_sys_reg(vcpu, r->reg) & mask;
+ }
+
+ return true;
+}
+
/* Silly macro to expand the DBG{BCR,BVR,WVR,WCR}n_EL1 registers in one go */
#define DBG_BCR_BVR_WCR_WVR_EL1(n) \
/* DBGBVRn_EL1 */ \
@@ -816,10 +849,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
access_pmcr, reset_pmcr, PMCR_EL0, },
/* PMCNTENSET_EL0 */
{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b001),
- trap_raz_wi },
+ access_pmcntenset, reset_unknown, PMCNTENSET_EL0 },
/* PMCNTENCLR_EL0 */
{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b010),
- trap_raz_wi },
+ access_pmcntenset, NULL, PMCNTENSET_EL0 },
/* PMOVSCLR_EL0 */
{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b011),
trap_raz_wi },
@@ -1161,8 +1194,8 @@ static const struct sys_reg_desc cp15_regs[] = {

/* PMU */
{ Op1( 0), CRn( 9), CRm(12), Op2( 0), access_pmcr },
- { Op1( 0), CRn( 9), CRm(12), Op2( 1), trap_raz_wi },
- { Op1( 0), CRn( 9), CRm(12), Op2( 2), trap_raz_wi },
+ { Op1( 0), CRn( 9), CRm(12), Op2( 1), access_pmcntenset },
+ { Op1( 0), CRn( 9), CRm(12), Op2( 2), access_pmcntenset },
{ Op1( 0), CRn( 9), CRm(12), Op2( 3), trap_raz_wi },
{ Op1( 0), CRn( 9), CRm(12), Op2( 5), access_pmselr },
{ Op1( 0), CRn( 9), CRm(12), Op2( 6), access_pmceid },
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 14bedb0..43c4117 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -36,6 +36,8 @@ struct kvm_pmu {
};

u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
+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_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
u64 select_idx);
#else
@@ -46,6 +48,8 @@ u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx)
{
return 0;
}
+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_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 b107fb8..94bff0e 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -75,6 +75,61 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
}

/**
+ * kvm_pmu_enable_counter - enable selected PMU counter
+ * @vcpu: The vcpu pointer
+ * @val: the value guest writes to PMCNTENSET register
+ *
+ * Call perf_event_enable to start counting the perf event
+ */
+void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val)
+{
+ int i;
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+ struct kvm_pmc *pmc;
+
+ if (!(vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMCR_E) || !val)
+ return;
+
+ for (i = 0; i < ARMV8_MAX_COUNTERS; i++) {
+ if (!((val >> i) & 0x1))
+ continue;
+
+ pmc = &pmu->pmc[i];
+ if (pmc->perf_event) {
+ perf_event_enable(pmc->perf_event);
+ if (pmc->perf_event->state != PERF_EVENT_STATE_ACTIVE)
+ kvm_debug("fail to enable perf event\n");
+ }
+ }
+}
+
+/**
+ * kvm_pmu_disable_counter - disable selected PMU counter
+ * @vcpu: The vcpu pointer
+ * @val: the value guest writes to PMCNTENCLR register
+ *
+ * Call perf_event_disable to stop counting the perf event
+ */
+void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val)
+{
+ int i;
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+ struct kvm_pmc *pmc;
+
+ if (!val)
+ return;
+
+ for (i = 0; i < ARMV8_MAX_COUNTERS; i++) {
+ if (!((val >> i) & 0x1))
+ continue;
+
+ pmc = &pmu->pmc[i];
+ if (pmc->perf_event)
+ perf_event_disable(pmc->perf_event);
+ }
+}
+
+/**
* kvm_pmu_set_counter_event_type - set selected counter to monitor some event
* @vcpu: The vcpu pointer
* @data: The data guest writes to PMXEVTYPER_EL0
--
2.0.4