Re: [PATCH v19 5/7] firmware: arm_rmm: Activate the RMM

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

On Thu, Sep 24, 2026 at 02:51:59PM +0100, Suzuki K Poulose wrote:
> From: Steven Price <steven.price@arm.com>
> 
> Activate the RMM after the basic configuration. This is a memory
> transferring stateful operation.
> 
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
> Signed-off-by: Steven Price <steven.price@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> Changes since v17:
>  * Inline RMM_ACTIVATE command and remove the definitions from arm-rmi-cmds.h
>  * Use scope-based cleanup to free sro object
> Changes since v16:
>  * Split into a new patch
> ---
>  drivers/firmware/arm_rmm/rmi.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/arm_rmm/rmi.c
> index 035f21d3f26b6..0859f256e192b 100644
> --- a/drivers/firmware/arm_rmm/rmi.c
> +++ b/drivers/firmware/arm_rmm/rmi.c
> @@ -834,7 +834,18 @@ static int __init arm64_init_rmi(void)
>  	if (ret)
>  		return ret;
>  
> -	return 0;
> +	/* Activate the RMM */
> +	struct rmi_sro_state *sro __free(kfree) = kmalloc_obj(*sro);
> +	if (!sro)
> +		return -ENOMEM;
> +
> +	ret = rmi_sro_memxfer_cmd(sro, GFP_KERNEL, SMC_RMI_RMM_ACTIVATE);
> +	if (ret) {
> +		pr_err("RMM activate failed (%d)\n", ret);
> +		ret = ret < 0 ? ret : -ENXIO;
> +	}
> +
> +	return ret;

It was raised earlier this year [1] but I'm not sure it concluded. How
do we handle kexec and kdump? I think RMI_RMM_DEACTIVATE only succeeds
if nothing is delegated, so it would need all realms torn down first. If
that's not feasible, we could at least block (non-crash) kexec like pKVM
does.

Kdump gets even more interesting if it starts accessing delegated pages
and getting GPF.

[1] https://lore.kernel.org/r/CABpDEukEO4Y_fg8fv5Nr1_Pw_qOK=2UmioXk=WyPEzoEprPcGA@mail.gmail.com

-- 
Catalin