arm64: cpufeature: Add GCS to cpucap_is_possible()

Since system_supports_gcs() ends up referring to cpucap_is_possible(),
teach the latter about GCS for consistency with similar features.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/416c7369fcdce4ebb2a8f12daae234507be27e38.1733406275.git.robin.murphy@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: rmurphy-arm

arch/arm64/include/asm/cpucaps.h

@@ -44,6 +44,8 @@ cpucap_is_possible(const unsigned int cap)
 		return IS_ENABLED(CONFIG_ARM64_TLB_RANGE);
 	case ARM64_HAS_S1POE:
 		return IS_ENABLED(CONFIG_ARM64_POE);
+	case ARM64_HAS_GCS:
+		return IS_ENABLED(CONFIG_ARM64_GCS);
 	case ARM64_UNMAP_KERNEL_AT_EL0:
 		return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0);
 	case ARM64_WORKAROUND_843419:

arch/arm64/include/asm/cpufeature.h

@@ -847,8 +847,7 @@ static inline bool system_supports_poe(void)
 
 static inline bool system_supports_gcs(void)
 {
-	return IS_ENABLED(CONFIG_ARM64_GCS) &&
-		alternative_has_cap_unlikely(ARM64_HAS_GCS);
+	return alternative_has_cap_unlikely(ARM64_HAS_GCS);
 }
 
 static inline bool system_supports_haft(void)