arm64: cpufeature: Add scope for capability check

Add scope parameter to the arm64_cpu_capabilities::matches(), so that
this can be reused for checking the capability on a given CPU vs the
system wide. The system uses the default scope associated with the
capability for initialising the CPU_HWCAPs and ELF_HWCAPs.

Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/cpufeature.h

@@ -78,10 +78,17 @@ struct arm64_ftr_reg {
 	struct arm64_ftr_bits	*ftr_bits;
 };
 
+/* scope of capability check */
+enum {
+	SCOPE_SYSTEM,
+	SCOPE_LOCAL_CPU,
+};
+
 struct arm64_cpu_capabilities {
 	const char *desc;
 	u16 capability;
-	bool (*matches)(const struct arm64_cpu_capabilities *);
+	int def_scope;			/* default scope */
+	bool (*matches)(const struct arm64_cpu_capabilities *caps, int scope);
 	void (*enable)(void *);		/* Called on all active CPUs */
 	union {
 		struct {	/* To be used for erratum handling only */

arch/arm64/kernel/cpu_errata.c

@@ -22,14 +22,16 @@
 #include <asm/cpufeature.h>
 
 static bool __maybe_unused
-is_affected_midr_range(const struct arm64_cpu_capabilities *entry)
+is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
 {
+	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
 	return MIDR_IS_CPU_MODEL_RANGE(read_cpuid_id(), entry->midr_model,
 				       entry->midr_range_min,
 				       entry->midr_range_max);
 }
 
 #define MIDR_RANGE(model, min, max) \
+	.def_scope = SCOPE_LOCAL_CPU, \
 	.matches = is_affected_midr_range, \
 	.midr_model = model, \
 	.midr_range_min = min, \