[PATCH v2 08/11] arm64: Convert CONFIG_ARM64_MTE to FTR_CONFIG()

[Fuad Tabba]

Hi Marc,

On Mon, 2 Mar 2026 at 11:57, Marc Zyngier <maz at kernel.org> wrote:
>
> While CONFIG_ARM64_MTE=n prevents userspace from using MTE,
> the sanitised ID registers still advertise the feature.
>
> Make it clear that nothing in the kernel should rely on this by
> marking the feature as hidden for all when CONFIG_ARM64_MTE=n.
>
> This is functionnaly equivalent to using arm64.nomte on the kernel
> command-line.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kernel/cpufeature.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index ab0a7d72608d4..a56d242fe1489 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -315,7 +315,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
>                        FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_SME_SHIFT, 4, 0),
>         ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_MPAM_frac_SHIFT, 4, 0),
>         ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_RAS_frac_SHIFT, 4, 0),
> -       ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_MTE),
> +       ARM64_FTR_BITS(FTR_CONFIG(CONFIG_ARM64_MTE, VISIBLE, ALL_HIDDEN),
>                        FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_MTE_SHIFT, 4, ID_AA64PFR1_EL1_MTE_NI),
>         ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_SSBS_SHIFT, 4, ID_AA64PFR1_EL1_SSBS_NI),
>         ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_BTI),

Although it wouldn't really be for the scope of this patch, but what
about gating the other MTE fields? e.g., MTE_frac here,
ID_AA64PFR2_EL1.MTEFAR and MTESTOREONLY?

Cheers,
/fuad

> --
> 2.47.3
>
>