[PATCH v2 3/3] KVM: arm64: Advertise STALL_SLOT* in PMCEID1 under strict PMUv3 UAPI

[Congkai Tan]

Skip masking STALL_SLOT, STALL_SLOT_FRONTEND and STALL_SLOT_BACKEND out
of PMCEID1 when KVM_ARM_VCPU_PMU_V3_STRICT is set, because this is when
PMMIR_EL1.SLOTS is exposed to guests, making these events meaningful for
collection.

Change the parameter of compute_pmceid1() from arm_pmu to kvm_vcpu, to
check if KVM_ARM_VCPU_PMU_V3_STRICT is set. Also updated the signature of
compute_pmceid0() for consistency.

Signed-off-by: Congkai Tan <congkai at amazon.com>
Reviewed-by: Geoff Blake <blakgeof at amazon.com>
Reviewed-by: Haris Okanovic <harisokn at amazon.com>
Reviewed-by: Stanislav Spassov <stanspas at amazon.de>
---
 arch/arm64/kvm/pmu-emul.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 9595bce6519f..89eec5a1a499 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -851,9 +851,9 @@ static u64 __compute_pmceid(struct arm_pmu *pmu, bool pmceid1)
 	return ((u64)hi[pmceid1] << 32) | lo[pmceid1];
 }
 
-static u64 compute_pmceid0(struct arm_pmu *pmu)
+static u64 compute_pmceid0(struct kvm_vcpu *vcpu)
 {
-	u64 val = __compute_pmceid(pmu, 0);
+	u64 val = __compute_pmceid(vcpu->kvm->arch.arm_pmu, 0);
 
 	/* always support SW_INCR */
 	val |= BIT(ARMV8_PMUV3_PERFCTR_SW_INCR);
@@ -862,32 +862,33 @@ static u64 compute_pmceid0(struct arm_pmu *pmu)
 	return val;
 }
 
-static u64 compute_pmceid1(struct arm_pmu *pmu)
+static u64 compute_pmceid1(struct kvm_vcpu *vcpu)
 {
-	u64 val = __compute_pmceid(pmu, 1);
+	u64 val = __compute_pmceid(vcpu->kvm->arch.arm_pmu, 1);
 
 	/*
-	 * Don't advertise STALL_SLOT*, as PMMIR_EL0 is handled
-	 * as RAZ
+	 * If KVM_ARM_VCPU_PMU_V3_STRICT is not set, PMMIR_EL1 is
+	 * unconditionally RAZ, so don't advertise STALL_SLOT* events.
 	 */
-	val &= ~(BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT - 32) |
-		 BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT_FRONTEND - 32) |
-		 BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT_BACKEND - 32));
+	if (!kvm_vcpu_has_pmuv3_strict(vcpu))
+		val &= ~(BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT - 32) |
+			 BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT_FRONTEND - 32) |
+			 BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT_BACKEND - 32));
+
 	return val;
 }
 
 u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
 {
-	struct arm_pmu *cpu_pmu = vcpu->kvm->arch.arm_pmu;
 	unsigned long *bmap = vcpu->kvm->arch.pmu_filter;
 	u64 val, mask = 0;
 	int base, i, nr_events;
 
 	if (!pmceid1) {
-		val = compute_pmceid0(cpu_pmu);
+		val = compute_pmceid0(vcpu);
 		base = 0;
 	} else {
-		val = compute_pmceid1(cpu_pmu);
+		val = compute_pmceid1(vcpu);
 		base = 32;
 	}
 
-- 
2.50.1