arm64: KVM: Add access handler for PMSELR register

Since the reset value of PMSELR_EL0 is UNKNOWN, use reset_unknown for
its reset handler. When reading PMSELR, return the PMSELR.SEL field to
guest.
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm64/include/asm/kvm_host.h

@@ -119,6 +119,7 @@ enum vcpu_sysreg {
 
 	/* Performance Monitors Registers */
 	PMCR_EL0,	/* Control Register */
+	PMSELR_EL0,	/* Event Counter Selection Register */
 
 	/* 32bit specific registers. Keep them at the end of the range */
 	DACR32_EL2,	/* Domain Access Control Register */

arch/arm64/kvm/sys_regs.c

@@ -477,6 +477,22 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	return true;
 }
 
+static bool access_pmselr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			  const struct sys_reg_desc *r)
+{
+	if (!kvm_arm_pmu_v3_ready(vcpu))
+		return trap_raz_wi(vcpu, p, r);
+
+	if (p->is_write)
+		vcpu_sys_reg(vcpu, PMSELR_EL0) = p->regval;
+	else
+		/* return PMSELR.SEL field */
+		p->regval = vcpu_sys_reg(vcpu, PMSELR_EL0)
+			    & ARMV8_PMU_COUNTER_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 */						\
@@ -676,7 +692,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	  trap_raz_wi },
 	/* PMSELR_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b101),
-	  trap_raz_wi },
+	  access_pmselr, reset_unknown, PMSELR_EL0 },
 	/* PMCEID0_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1001), CRm(0b1100), Op2(0b110),
 	  trap_raz_wi },
@@ -927,7 +943,7 @@ static const struct sys_reg_desc cp15_regs[] = {
 	{ 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( 3), trap_raz_wi },
-	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), trap_raz_wi },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), access_pmselr },
 	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), trap_raz_wi },
 	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), trap_raz_wi },
 	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), trap_raz_wi },