[PATCH v4 09/21] KVM: ARM64: Add reset and access handlers for PMXEVCNTR register

[Shannon Zhao]

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

Since the reset value of PMXEVCNTR is UNKNOWN, use reset_unknown for
its reset handler. Add access handler which emulates writing and reading
PMXEVCNTR register. When reading PMXEVCNTR, call perf_event_read_value
to get the count value of the perf event.

Signed-off-by: Shannon Zhao <shannon.zhao at linaro.org>
---
 arch/arm64/kvm/sys_regs.c | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4e606ea..b7ca2cd 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -491,6 +491,16 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
 
 	if (p->is_write) {
 		switch (r->reg) {
+		case PMXEVCNTR_EL0: {
+			int index = PMEVCNTR0_EL0
+				    + vcpu_sys_reg(vcpu, PMSELR_EL0);
+
+			val = kvm_pmu_get_counter_value(vcpu,
+						vcpu_sys_reg(vcpu, PMSELR_EL0));
+			vcpu_sys_reg(vcpu, index) += (s64)*vcpu_reg(vcpu, p->Rt)
+						     - val;
+			break;
+		}
 		case PMXEVTYPER_EL0: {
 			val = vcpu_sys_reg(vcpu, PMSELR_EL0);
 			kvm_pmu_set_counter_event_type(vcpu,
@@ -519,6 +529,12 @@ static bool access_pmu_regs(struct kvm_vcpu *vcpu,
 		}
 	} else {
 		switch (r->reg) {
+		case PMXEVCNTR_EL0: {
+			val = kvm_pmu_get_counter_value(vcpu,
+						vcpu_sys_reg(vcpu, PMSELR_EL0));
+			*vcpu_reg(vcpu, p->Rt) = val;
+			break;
+		}
 		case PMCR_EL0: {
 			/* PMCR.P & PMCR.C are RAZ */
 			val = vcpu_sys_reg(vcpu, r->reg)
@@ -749,7 +765,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  access_pmu_regs, reset_unknown, PMXEVTYPER_EL0 },
 	/* PMXEVCNTR_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1101), Op2(0b010),
-	  trap_raz_wi },
+	  access_pmu_regs, reset_unknown, PMXEVCNTR_EL0 },
 	/* PMUSERENR_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1110), Op2(0b000),
 	  trap_raz_wi },
@@ -962,6 +978,15 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
 
 	if (p->is_write) {
 		switch (r->reg) {
+		case c9_PMXEVCNTR: {
+			int index = c14_PMEVCNTR0 + vcpu_cp15(vcpu, c9_PMSELR);
+
+			val = kvm_pmu_get_counter_value(vcpu,
+						    vcpu_cp15(vcpu, c9_PMSELR));
+			vcpu_cp15(vcpu, index) += (s64)*vcpu_reg(vcpu, p->Rt)
+						  - val;
+			break;
+		}
 		case c9_PMXEVTYPER: {
 			val = vcpu_cp15(vcpu, c9_PMSELR);
 			kvm_pmu_set_counter_event_type(vcpu,
@@ -989,6 +1014,12 @@ static bool access_pmu_cp15_regs(struct kvm_vcpu *vcpu,
 		}
 	} else {
 		switch (r->reg) {
+		case c9_PMXEVCNTR: {
+			val = kvm_pmu_get_counter_value(vcpu,
+						    vcpu_cp15(vcpu, c9_PMSELR));
+			*vcpu_reg(vcpu, p->Rt) = val;
+			break;
+		}
 		case c9_PMCR: {
 			/* PMCR.P & PMCR.C are RAZ */
 			val = vcpu_cp15(vcpu, r->reg)
@@ -1047,7 +1078,8 @@ static const struct sys_reg_desc cp15_regs[] = {
 	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), trap_raz_wi },
 	{ Op1( 0), CRn( 9), CRm(13), Op2( 1), access_pmu_cp15_regs,
 	  reset_unknown_cp15, c9_PMXEVTYPER },
-	{ Op1( 0), CRn( 9), CRm(13), Op2( 2), trap_raz_wi },
+	{ Op1( 0), CRn( 9), CRm(13), Op2( 2), access_pmu_cp15_regs,
+	  reset_unknown_cp15, c9_PMXEVCNTR },
 	{ Op1( 0), CRn( 9), CRm(14), Op2( 0), trap_raz_wi },
 	{ Op1( 0), CRn( 9), CRm(14), Op2( 1), trap_raz_wi },
 	{ Op1( 0), CRn( 9), CRm(14), Op2( 2), trap_raz_wi },
-- 
2.0.4