Re: [PATCH V3 02/16] arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register

[Will Deacon]

On Sat, May 02, 2020 at 07:03:51PM +0530, Anshuman Khandual wrote:
> ID_DFR0 based TraceFilt feature should not be exposed to guests. Hence lets
> drop it.
> 
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: James Morse <james.morse@xxxxxxx>
> Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> 
> Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---
>  arch/arm64/kernel/cpufeature.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 6d032fbe416f..51386dade423 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -435,7 +435,6 @@ static const struct arm64_ftr_bits ftr_id_pfr1[] = {
>  };
>  
>  static const struct arm64_ftr_bits ftr_id_dfr0[] = {
> -	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0),

Hmm, this still confuses me. Is this not now FTR_NONSTRICT? Why is that ok?

Will