Re: [RFC PATCH v3 1/2] arm64: tlb: Detect the ARMv8.4 TLBI RANGE feature

Mark Rutland
2020-05-05T10:14:17Z

On Tue, Apr 14, 2020 at 07:28:34PM +0800, Zhenyu Ye wrote:
> ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a
> range of input addresses. This patch detect this feature.
>
> Signed-off-by: Zhenyu Ye <yezhenyu2@huawei.com>
> ---
> arch/arm64/include/asm/cpucaps.h | 3 ++-
> arch/arm64/include/asm/sysreg.h | 4 ++++
> arch/arm64/kernel/cpufeature.c | 11 +++++++++++
> 3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
> index 8eb5a088ae65..950095a72617 100644
> --- a/arch/arm64/include/asm/cpucaps.h
> +++ b/arch/arm64/include/asm/cpucaps.h
> @@ -61,7 +61,8 @@
> #define ARM64_HAS_AMU_EXTN 51
> #define ARM64_HAS_ADDRESS_AUTH 52
> #define ARM64_HAS_GENERIC_AUTH 53
> +#define ARM64_HAS_TLBI_RANGE 54
>
> -#define ARM64_NCAPS 54
> +#define ARM64_NCAPS 55
>
> #endif /* __ASM_CPUCAPS_H */
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index ebc622432831..ac1b98650234 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -592,6 +592,7 @@
>
> /* id_aa64isar0 */
> #define ID_AA64ISAR0_RNDR_SHIFT 60
> +#define ID_AA64ISAR0_TLBI_RANGE_SHIFT 56
> #define ID_AA64ISAR0_TS_SHIFT 52
> #define ID_AA64ISAR0_FHM_SHIFT 48
> #define ID_AA64ISAR0_DP_SHIFT 44
> @@ -605,6 +606,9 @@
> #define ID_AA64ISAR0_SHA1_SHIFT 8
> #define ID_AA64ISAR0_AES_SHIFT 4
>
> +#define ID_AA64ISAR0_TLBI_RANGE_NI 0x0
> +#define ID_AA64ISAR0_TLBI_RANGE 0x2
> +
> /* id_aa64isar1 */
> #define ID_AA64ISAR1_I8MM_SHIFT 52
> #define ID_AA64ISAR1_DGH_SHIFT 48
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 9fac745aa7bb..31bcfd0722b5 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -124,6 +124,7 @@ static bool __system_matches_cap(unsigned int n);
> */
> static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RNDR_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TLBI_RANGE_SHIFT, 4, 0),

This should be FTR_HIDDEN as userspace has no reason to see this.

Otherwise this all seems to match the ARM ARM.

Mark.

> ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0),
> @@ -1779,6 +1780,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
> .min_field_value = 1,
> },
> #endif
> + {
> + .desc = "TLB range maintenance instruction",
> + .capability = ARM64_HAS_TLBI_RANGE,
> + .type = ARM64_CPUCAP_SYSTEM_FEATURE,
> + .matches = has_cpuid_feature,
> + .sys_reg = SYS_ID_AA64ISAR0_EL1,
> + .field_pos = ID_AA64ISAR0_TLBI_RANGE_SHIFT,
> + .sign = FTR_UNSIGNED,
> + .min_field_value = ID_AA64ISAR0_TLBI_RANGE,
> + },
> {},
> };
>
> --
> 2.19.1
>
>
>
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