Re: [PATCH v21 8/9] firmware: arm_rmm: Add wrappers for Realm related RMI commands

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

On Thu, Oct 01, 2026 at 09:45:54AM +0100, Suzuki K Poulose wrote:
> diff --git a/include/linux/arm-rmi-cmds.h b/include/linux/arm-rmi-cmds.h
> index 5d005054f3c6c..e3503aba646e2 100644
> --- a/include/linux/arm-rmi-cmds.h
> +++ b/include/linux/arm-rmi-cmds.h
> @@ -53,6 +53,17 @@ static inline void rmi_smccc_invoke(struct arm_smccc_1_2_regs *regs)
>  	}
>  }
>  
> +/*
> + * rmi_smccc_invoke_once: Invoke the RMI call and return the results. Do not
> + * retry the command. Let the caller deal with RMI_BUSY or RMI_BLOCKED.
> + */
> +static inline void rmi_smccc_invoke_once(struct arm_smccc_1_2_regs *regs)
> +{
> +	struct arm_smccc_1_2_regs args = *regs;
> +
> +	arm_smccc_1_2_invoke(&args, regs);
> +}

Nit: I don't think we need to copy to args since there's no retry here.

That said, the SMCCC call clobbers regs->a0. We should write a comment
in case the caller thinks it can just retry with the same regs.
Alternatively, we could pass args and res structures separately.

> +/**
> + * rmi_rec_destroy() - Destroy a REC
> + * @rec: PA of the target REC
> + * @sro: Allocated SRO context to be used
> + *
> + * Destroys a REC. The REC must not be running.
> + *
> + * Return: 0 on success, positive RMI result code or negative Linux error code
> + */
> +static inline long rmi_rec_destroy(unsigned long rec,
> +				   struct rmi_sro_state *sro)
> +{
> +	return rmi_sro_memxfer_cmd(sro, GFP_KERNEL, SMC_RMI_REC_DESTROY, rec);
> +}
> +
> +/**
> + * rmi_rec_enter() - Enter a REC
> + * @rec: PA of the target REC
> + * @run_ptr: PA of RecRun structure
> + *
> + * Starts (or continues) execution within a REC.
> + *
> + * Return: RMI return code
> + */
> +static inline long rmi_rec_enter(unsigned long rec, unsigned long run_ptr)

Nit: should probably be __always_inline. rmi_rec_destroy() and
rmi_smccc_invoke_once() as well.

Not for this series but something claude spotted in the integration
branch - kvm_rec_enter() is noinstr. On this path, we end up in
arm_smccc_1_1_get_conduit() which is not noinstr (again, that's for the
other series; here just __always_inline should suffice).

> +{
> +	struct arm_smccc_1_2_regs regs = {
> +		SMC_RMI_REC_ENTER, rec, run_ptr,
> +	};
> +
> +	rmi_smccc_invoke_once(&regs);
> +	return regs.a0;

Should this use RMI_RESULT_STATUS(regs.a0)?

The rest looks fine to me.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>