arm64: Add a capability for FEAT_ECV

Add a new capability to detect the Enhanced Counter Virtualization
feature (FEAT_ECV).

Reviewed-by: Oliver Upton <oupton@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-15-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: hongrongxuan <hongrongxuan@huawei.com>

 Conflicts:
	arch/arm64/tools/cpucaps

arch/arm64/include/asm/cpucaps.h

@@ -60,6 +60,7 @@
 #define ARM64_HAS_ARMv8_4_TTL			50
 #define ARM64_HAS_TLB_RANGE			51
 #define ARM64_WORKAROUND_AMPERE_AC03_XXXXXX	52
+#define ARM64_HAS_ECV				53
 
 #define ARM64_NCAPS				80
 

arch/arm64/kernel/cpufeature.c

@@ -1305,6 +1305,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.sign = FTR_UNSIGNED,
 		.min_field_value = 1,
 	},
+	{
+		.desc = "Enhanced Counter Virtualization",
+		.capability = ARM64_HAS_ECV,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64MMFR0_EL1,
+		.field_pos = ID_AA64MMFR0_ECV_SHIFT,
+		.sign = FTR_UNSIGNED,
+		.min_field_value = 1,
+	},
 #ifdef CONFIG_ARM64_PAN
 	{
 		.desc = "Privileged Access Never",