[PATCH 15/18] KVM: ARM64: Add reset and access handlers for PMSWINC_EL0 register

[shannon.zhao at linaro.org]

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

Add access handler which emulates writing and reading PMSWINC_EL0
register and add support for creating software increment event.

Signed-off-by: Shannon Zhao <shannon.zhao at linaro.org>
---
 arch/arm64/kvm/sys_regs.c | 15 ++++++++++++++-
 include/kvm/arm_pmu.h     |  2 ++
 virt/kvm/arm/pmu.c        | 20 ++++++++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d5984d0..70afcba 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -535,6 +535,19 @@ static bool access_pmuserenr(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+/* PMSWINC_EL0 accessor. */
+static bool access_pmswinc(struct kvm_vcpu *vcpu,
+			   const struct sys_reg_params *p,
+			   const struct sys_reg_desc *r)
+{
+	if (p->is_write)
+		kvm_pmu_software_increment(vcpu, *vcpu_reg(vcpu, p->Rt));
+	else
+		return read_zero(vcpu, p);
+
+	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 */						\
@@ -738,7 +751,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  access_pmovsclr, reset_unknown, PMOVSCLR_EL0 },
 	/* PMSWINC_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b100),
-	  trap_raz_wi },
+	  access_pmswinc, reset_unknown, PMSWINC_EL0 },
 	/* PMSELR_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b101),
 	  access_pmselr, reset_unknown, PMSELR_EL0 },
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 4f3d8a6..6985809 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -54,6 +54,7 @@ void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, unsigned long val);
 void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, unsigned long val);
 void kvm_pmu_disable_interrupt(struct kvm_vcpu *vcpu, unsigned long val);
 void kvm_pmu_enable_interrupt(struct kvm_vcpu *vcpu, unsigned long val);
+void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, unsigned long val);
 void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
 				    unsigned long select_idx);
 void kvm_pmu_init(struct kvm_vcpu *vcpu);
@@ -70,6 +71,7 @@ void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, unsigned long val) {}
 void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, unsigned long val) {}
 void kvm_pmu_disable_interrupt(struct kvm_vcpu *vcpu, unsigned long val) {}
 void kvm_pmu_enable_interrupt(struct kvm_vcpu *vcpu, unsigned long val) {}
+void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, unsigned long val) {}
 void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
 				    unsigned long select_idx) {}
 static inline void kvm_pmu_init(struct kvm_vcpu *vcpu) {}
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 7023ad5..e655426 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -203,6 +203,22 @@ void kvm_pmu_disable_interrupt(struct kvm_vcpu *vcpu, unsigned long val)
 }
 
 /**
+ * kvm_pmu_software_increment - do software increment
+ * @vcpu: The vcpu pointer
+ * @val: the value guest writes to PMSWINC_EL0 register
+ */
+void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, unsigned long val)
+{
+	int select_idx = find_first_bit(&val, 31);
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+	struct kvm_pmc *pmc = &pmu->pmc[select_idx];
+
+	if (pmu->user_enable & 0x3)
+		if ((pmc->eventsel == 0) && (pmc->enable == true))
+			pmc->counter++;
+}
+
+/**
  * kvm_pmu_find_hw_event - find hardware event
  * @pmu: The pmu pointer
  * @event_select: The number of selected event type
@@ -280,6 +296,10 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
 	kvm_pmu_stop_counter(vcpu, select_idx);
 	pmc->eventsel = data & ARMV8_EVTYPE_EVENT;
 
+	/* For software increment event we don't need to create perf event */
+	if (pmc->eventsel == 0)
+		return;
+
 	config = kvm_pmu_find_hw_event(pmu, pmc->eventsel);
 	if (config != PERF_COUNT_HW_MAX) {
 		type = PERF_TYPE_HARDWARE;
-- 
2.1.0