[PATCH v8 04/11] arm64: errata: Require Apple IMPDEF PMUv3 traps on all CPUs

[Akihiko Odaki]

KVM relies on ARM64_WORKAROUND_PMUV3_IMPDEF_TRAPS as a system-wide
precondition for PMUv3 emulation on affected Apple CPUs. A local CPU
erratum is too weak for that: once the workaround is enabled, a late CPU
that misses it may still be onlined.

Make the workaround an all-early-CPU capability instead. The matcher is
still local because it depends on MIDR_EL1, but the capability is only
advertised if all early CPUs match, and late CPUs that miss it are
rejected once the capability is enabled.

Assisted-by: Codex:gpt-5.5
Signed-off-by: Akihiko Odaki <odaki at rsg.ci.i.u-tokyo.ac.jp>
---
 arch/arm64/kernel/cpu_errata.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 476a37c82108..14ce49d693c4 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -964,7 +964,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 	{
 		.desc = "Apple IMPDEF PMUv3 Traps",
 		.capability = ARM64_WORKAROUND_PMUV3_IMPDEF_TRAPS,
-		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
+		.type = ARM64_CPUCAP_EARLY_LOCAL_CPU_FEATURE,
 		.matches = has_impdef_pmuv3,
 		.cpu_enable = cpu_enable_impdef_pmuv3_traps,
 	},

-- 
2.55.0