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arm64: Detect the ARMv8.4 TTL feature

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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>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2018-12-22 12:00:10 +00:00
parent 9ebcfadb06
commit 552ae76fac
3 changed files with 14 additions and 1 deletions
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3
arch/arm64/include/asm/cpucaps.h
View File

@ -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 */

1
arch/arm64/include/asm/sysreg.h
View File

@ -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

11
arch/arm64/kernel/cpufeature.c
View File

@ -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),
@ -1882,6 +1883,16 @@ 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
{
/*