Re: [PATCH v2 3/8] xen/arm: Add SCMI over SMC calls handling layer

[Julien Grall <julien@xxxxxxx>]

Hi Andrei,

On 30/09/2024 12:47, Andrei Cherechesu (OSS) wrote:
> +/*
> + * Generic handler for SCMI-SMC requests, currently only forwarding the
> + * request to FW running at EL3 if it came from Dom0. Is called from the vSMC
> + * layer for SiP SMCs, since SCMI calls are usually provided this way.
> + * Can also be called from `platform_smc()` plat-specific callback.
> + *
> + * Returns true if SMC was handled (regardless of response), false otherwise.
> + */
> +bool scmi_handle_smc(struct cpu_user_regs *regs)
> +{
> +    struct arm_smccc_res res;
> +
> +    /* Only the hardware domain should use SCMI calls */
> +    if ( !is_hardware_domain(current->domain) )
> +    {
> +        gprintk(XENLOG_ERR, "SCMI: Unprivileged d%d cannot use SCMI.\n",
> +                current->domain->domain_id);
> +        return false;
> +    }
> +
> +    /* For the moment, forward the SCMI Request to FW running at EL3 */
> +    arm_smccc_1_1_smc(scmi_smc_id,
Actually, shouldn't this be get_user_reg(regs, 0) so we don't rely on 
scmi_handle_smc() to be called only when this is equal to scmi_smc_id?
The other option is to move the check for scmi_smc_id in this function.

Cheers,

--
Julien Grall