Re: [PATCH v19 2/7] firmware: arm_rmm: Check for RMI support at init

[Catalin Marinas <catalin.marinas@arm.com>]

On Thu, Sep 24, 2026 at 02:51:56PM +0100, Suzuki K Poulose wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 32102c3912fa7..e8b29983b0021 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -293,6 +293,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar3[] = {
>  static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
>  	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV3_SHIFT, 4, 0),
>  	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV2_SHIFT, 4, 0),
> +	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_RME_SHIFT, 4, 0),

I think we end up exposing this to (any) guest unless we mask it out in
sanitise_id_aa64dfr0_el1(). Do the guests care about the RME version? I
don't think they should, especially the non-realm ones. For nested it's
masked away already (limit_nv_id_reg()).

-- 
Catalin