Re: [PATCH V3 09/16] arm64/cpufeature: Add remaining feature bits in ID_AA64ISAR0 register

[Suzuki K Poulose]

On 05/02/2020 02:33 PM, Anshuman Khandual wrote:
> Enable TLB features bit in ID_AA64ISAR0 register as per ARM DDI 0487F.a
> specification.
>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
>
> Suggested-by: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---
>   arch/arm64/include/asm/sysreg.h | 1 +
>   arch/arm64/kernel/cpufeature.c  | 1 +
>   2 files changed, 2 insertions(+)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 0f34927f52b9..40eaf89f1032 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -597,6 +597,7 @@
>   
>   /* id_aa64isar0 */
>   #define ID_AA64ISAR0_RNDR_SHIFT		60
> +#define ID_AA64ISAR0_TLB_SHIFT		56
>   #define ID_AA64ISAR0_TS_SHIFT		52
>   #define ID_AA64ISAR0_FHM_SHIFT		48
>   #define ID_AA64ISAR0_DP_SHIFT		44
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index f4e15e355aee..dbedcae28061 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -174,6 +174,7 @@ 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_TLB_SHIFT, 4, 0),

I don't see any reason why this should be VISIBLE to the userspace.

Suzuki