[PATCH v3 10/47] arm64: mpam: Initialise and context switch the MPAMSM_EL1 register

[Catalin Marinas]

On Mon, Jan 12, 2026 at 04:58:37PM +0000, Ben Horgan wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 0cdfb3728f43..2ede543b3eeb 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -2491,6 +2491,8 @@ cpu_enable_mpam(const struct arm64_cpu_capabilities *entry)
>  		regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu));
>  
>  	write_sysreg_s(regval, SYS_MPAM1_EL1);
> +	if (system_supports_sme())
> +		write_sysreg_s(regval & (MPAMSM_EL1_PARTID_D | MPAMSM_EL1_PMG_D), SYS_MPAMSM_EL1);
>  	isb();

Do we know for sure that system_supports_sme() returns true at this
point (if SME supported)? Digging into the code, system_supports_sme()
uses alternative_has_cap_unlikely() which relies on instruction
patching. setup_system_capabilities(), IIUC, patches the alternatives
after enable_cpu_capabilities(). I think you better use cpus_have_cap().

-- 
Catalin