[PATCH v2 02/17] arm64: Detect the ARMv8.4 TTL feature

Marc Zyngier
2020-06-15T13:27:42Z

In order to reduce the cost of TLB invalidation, the ARMv8.4 TTL
feature allows TLBs to be issued with a level allowing for quicker
invalidation.

Let's detect the feature for now. Further patches will implement
its actual usage.

Reviewed-by : Suzuki K Polose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 11 +++++++++++
3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index d7b3bb0cb180..d44ba903d11d 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -62,7 +62,8 @@
#define ARM64_HAS_GENERIC_AUTH 52
#define ARM64_HAS_32BIT_EL1 53
#define ARM64_BTI 54
+#define ARM64_HAS_ARMv8_4_TTL 55

-#define ARM64_NCAPS 55
+#define ARM64_NCAPS 56

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 463175f80341..8c209aa17273 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -746,6 +746,7 @@

/* id_aa64mmfr2 */
#define ID_AA64MMFR2_E0PD_SHIFT 60
+#define ID_AA64MMFR2_TTL_SHIFT 48
#define ID_AA64MMFR2_FWB_SHIFT 40
#define ID_AA64MMFR2_AT_SHIFT 32
#define ID_AA64MMFR2_LVA_SHIFT 16
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4ae41670c2e6..bda002078ec5 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -323,6 +323,7 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr1[] = {

static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_E0PD_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_TTL_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_FWB_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_AT_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LVA_SHIFT, 4, 0),
@@ -1880,6 +1881,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = has_cpuid_feature,
.cpu_enable = cpu_has_fwb,
},
+ {
+ .desc = "ARMv8.4 Translation Table Level",
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .capability = ARM64_HAS_ARMv8_4_TTL,
+ .sys_reg = SYS_ID_AA64MMFR2_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64MMFR2_TTL_SHIFT,
+ .min_field_value = 1,
+ .matches = has_cpuid_feature,
+ },
#ifdef CONFIG_ARM64_HW_AFDBM
{
/*
--
2.27.0