Re: [PATCH v2 4/8] xen/arm: vsmc: Enable handling SiP-owned SCMI SMC calls

[Julien Grall <julien@xxxxxxx>]

Hi,

On 30/09/2024 12:47, Andrei Cherechesu (OSS) wrote:
> From: Andrei Cherechesu <andrei.cherechesu@xxxxxxx>
>
> Change the handling of SiP SMC calls to be more generic,
> instead of directly relying on the `platform_smc()` callback
> implementation.
>
> Try to handle the SiP SMC first through the `platform_smc()`
> callback (if implemented). If not handled, check if the
> SCMI layer is available and that the SMC is a valid SCMI
> message. Handle it then within the SCMI layer which forwards
> it to EL3 FW, only if the SMC comes from Dom0.
NIT: I would remove the last sentence as this is implementation details. 
But if you want to keep it, then s/Dom0/Hardware domain/
> Signed-off-by: Andrei Cherechesu <andrei.cherechesu@xxxxxxx>
> ---
>   xen/arch/arm/vsmc.c | 19 ++++++++++++++++++-
>   1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
> index 7f2f5eb9ce..0de194a132 100644
> --- a/xen/arch/arm/vsmc.c
> +++ b/xen/arch/arm/vsmc.c
> @@ -14,6 +14,7 @@
>   #include <asm/cpufeature.h>
>   #include <asm/monitor.h>
>   #include <asm/regs.h>
> +#include <asm/scmi-smc.h>
>   #include <asm/smccc.h>
>   #include <asm/tee/ffa.h>
>   #include <asm/tee/tee.h>
> @@ -224,6 +225,22 @@ static bool handle_sssc(struct cpu_user_regs *regs)
>       }
>   }
>   
> +/* Secure Calls defined by the Silicon Provider (SiP) */
> +static bool handle_sip(struct cpu_user_regs *regs)
> +{
> +    uint32_t fid = (uint32_t)get_user_reg(regs, 0);
> +
> +    /* Firstly, let each platform define custom handling for these SMCs */
> +    if ( platform_smc(regs) )
> +        return true;
> +
> +    /* Otherwise, if valid SCMI SMC, forward the call to EL3 */
This comment is likely going to stale. This is up to smci_handle_smc() 
to decide what to do. So I would remove this comment.
With that:

Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall