[PATCH 02/16] arm64: Add HAS_ECV_CNTPOFF capability

[Marc Zyngier]

Add the probing code for the FEAT_ECV variant that implements CNTPOFF_EL2.
Why is it optional is a mystery, but let's try and detect it.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kernel/cpufeature.c | 11 +++++++++++
 arch/arm64/tools/cpucaps       |  1 +
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 23bd2a926b74..36852f96898d 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -2186,6 +2186,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.sign = FTR_UNSIGNED,
 		.min_field_value = 1,
 	},
+	{
+		.desc = "Enhanced Counter Virtualization (CNTPOFF)",
+		.capability = ARM64_HAS_ECV_CNTPOFF,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64MMFR0_EL1,
+		.field_pos = ID_AA64MMFR0_EL1_ECV_SHIFT,
+		.field_width = 4,
+		.sign = FTR_UNSIGNED,
+		.min_field_value = 2,
+	},
 #ifdef CONFIG_ARM64_PAN
 	{
 		.desc = "Privileged Access Never",
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 82c7e579a8ba..6a26a4678406 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -23,6 +23,7 @@ HAS_DCPOP
 HAS_DIT
 HAS_E0PD
 HAS_ECV
+HAS_ECV_CNTPOFF
 HAS_EPAN
 HAS_GENERIC_AUTH
 HAS_GENERIC_AUTH_ARCH_QARMA3
-- 
2.34.1