KVM: arm64: Advertise 0 event counters for IMPDEF PMU

oupton · jannau · commit 615ca25c62a1 · 2024-12-21T11:43:58.000+01:00
The programmable event counters on Apple M* parts are quite different
from what's available in PMUv3, as the event counters aren't fungible
(some events only work on specific counters) and the event ID space
doesn't match the architecture.

Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
@@ -942,6 +942,9 @@ u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)
 {
 	struct arm_pmu *arm_pmu = kvm->arch.arm_pmu;
 
+	if (cpus_have_final_cap(ARM64_WORKAROUND_PMUV3_IMPDEF_TRAPS))
+		return 0;
+
 	/*
 	 * The arm_pmu->cntr_mask considers the fixed counter(s) as well.
 	 * Ignore those and return only the general-purpose counters.

Original file line number	Diff line number	Diff line change
`@@ -942,6 +942,9 @@ u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)`
`942`	`942`	`{`
`943`	`943`	`struct arm_pmu *arm_pmu = kvm->arch.arm_pmu;`
`944`	`944`
	`945`	`+ if (cpus_have_final_cap(ARM64_WORKAROUND_PMUV3_IMPDEF_TRAPS))`
	`946`	`+ return 0;`
	`947`	`+`
`945`	`948`	`/*`
`946`	`949`	`* The arm_pmu->cntr_mask considers the fixed counter(s) as well.`
`947`	`950`	`* Ignore those and return only the general-purpose counters.`