arm: perf/kvm: Use GENMASK for ARMV8_PMU_PMCR_N

This is so that FIELD_GET and FIELD_PREP can be used and that the fields
are in a consistent format to arm64/tools/sysreg
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20231211161331.1277825-3-james.clark@arm.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/kvm/pmu-emul.c

@@ -267,9 +267,8 @@ void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu)
 
 u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
 {
-	u64 val = kvm_vcpu_read_pmcr(vcpu) >> ARMV8_PMU_PMCR_N_SHIFT;
+	u64 val = FIELD_GET(ARMV8_PMU_PMCR_N, kvm_vcpu_read_pmcr(vcpu));
 
-	val &= ARMV8_PMU_PMCR_N_MASK;
 	if (val == 0)
 		return BIT(ARMV8_PMU_CYCLE_IDX);
 	else
@@ -1136,8 +1135,7 @@ u8 kvm_arm_pmu_get_pmuver_limit(void)
  */
 u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
 {
-	u64 pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0) &
-			~(ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
+	u64 pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
 
-	return pmcr | ((u64)vcpu->kvm->arch.pmcr_n << ARMV8_PMU_PMCR_N_SHIFT);
+	return u64_replace_bits(pmcr, vcpu->kvm->arch.pmcr_n, ARMV8_PMU_PMCR_N);
 }

arch/arm64/kvm/sys_regs.c

@@ -877,7 +877,7 @@ static bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
 	u64 pmcr, val;
 
 	pmcr = kvm_vcpu_read_pmcr(vcpu);
-	val = (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
+	val = FIELD_GET(ARMV8_PMU_PMCR_N, pmcr);
 	if (idx >= val && idx != ARMV8_PMU_CYCLE_IDX) {
 		kvm_inject_undefined(vcpu);
 		return false;
@@ -1143,7 +1143,7 @@ static int get_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
 static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
 		    u64 val)
 {
-	u8 new_n = (val >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
+	u8 new_n = FIELD_GET(ARMV8_PMU_PMCR_N, val);
 	struct kvm *kvm = vcpu->kvm;
 
 	mutex_lock(&kvm->arch.config_lock);

drivers/perf/arm_pmuv3.c

@@ -15,6 +15,7 @@
 #include <clocksource/arm_arch_timer.h>
 
 #include <linux/acpi.h>
+#include <linux/bitfield.h>
 #include <linux/clocksource.h>
 #include <linux/of.h>
 #include <linux/perf/arm_pmu.h>
@@ -1111,8 +1112,7 @@ static void __armv8pmu_probe_pmu(void *info)
 	probe->present = true;
 
 	/* Read the nb of CNTx counters supported from PMNC */
-	cpu_pmu->num_events = (armv8pmu_pmcr_read() >> ARMV8_PMU_PMCR_N_SHIFT)
-		& ARMV8_PMU_PMCR_N_MASK;
+	cpu_pmu->num_events = FIELD_GET(ARMV8_PMU_PMCR_N, armv8pmu_pmcr_read());
 
 	/* Add the CPU cycles counter */
 	cpu_pmu->num_events += 1;

include/linux/perf/arm_pmuv3.h

@@ -215,8 +215,7 @@
 #define ARMV8_PMU_PMCR_DP	(1 << 5) /* Disable CCNT if non-invasive debug*/
 #define ARMV8_PMU_PMCR_LC	(1 << 6) /* Overflow on 64 bit cycle counter */
 #define ARMV8_PMU_PMCR_LP	(1 << 7) /* Long event counter enable */
-#define ARMV8_PMU_PMCR_N_SHIFT	11  /* Number of counters supported */
-#define ARMV8_PMU_PMCR_N_MASK	0x1f
+#define ARMV8_PMU_PMCR_N	GENMASK(15, 11) /* Number of counters supported */
 #define ARMV8_PMU_PMCR_MASK	0xff    /* Mask for writable bits */
 
 /*