Re: [XEN PATCH v10 09/24] xen/arm: ffa: add support for FFA_ID_GET

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Jens,

> On 17 Jul 2023, at 09:20, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
> 
> Adds support for the FF-A function FFA_ID_GET to return the ID of the
> calling client.
> 
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

Cheers
Bertrand

> ---
> xen/arch/arm/tee/ffa.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
> 
> diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> index f0a2715d4bbf..e157ed20ad8b 100644
> --- a/xen/arch/arm/tee/ffa.c
> +++ b/xen/arch/arm/tee/ffa.c
> @@ -181,6 +181,12 @@ static bool ffa_get_version(uint32_t *vers)
>     return true;
> }
> 
> +static uint16_t get_vm_id(const struct domain *d)
> +{
> +    /* +1 since 0 is reserved for the hypervisor in FF-A */
> +    return d->domain_id + 1;
> +}
> +
> static void set_regs(struct cpu_user_regs *regs, register_t v0, register_t v1,
>                      register_t v2, register_t v3, register_t v4, register_t 
> v5,
>                      register_t v6, register_t v7)
> @@ -195,6 +201,12 @@ static void set_regs(struct cpu_user_regs *regs, 
> register_t v0, register_t v1,
>         set_user_reg(regs, 7, v7);
> }
> 
> +static void set_regs_success(struct cpu_user_regs *regs, uint32_t w2,
> +                             uint32_t w3)
> +{
> +    set_regs(regs, FFA_SUCCESS_32, 0, w2, w3, 0, 0, 0, 0);
> +}
> +
> static void handle_version(struct cpu_user_regs *regs)
> {
>     struct domain *d = current->domain;
> @@ -224,6 +236,9 @@ static bool ffa_handle_call(struct cpu_user_regs *regs)
>     case FFA_VERSION:
>         handle_version(regs);
>         return true;
> +    case FFA_ID_GET:
> +        set_regs_success(regs, get_vm_id(d), 0);
> +        return true;
> 
>     default:
>         gprintk(XENLOG_ERR, "ffa: unhandled fid 0x%x\n", fid);
> @@ -237,6 +252,12 @@ static int ffa_domain_init(struct domain *d)
> 
>     if ( !ffa_version )
>         return -ENODEV;
> +     /*
> +      * We can't use that last possible domain ID or get_vm_id() would cause
> +      * an overflow.
> +      */
> +    if ( d->domain_id >= UINT16_MAX)
> +        return -ERANGE;
> 
>     ctx = xzalloc(struct ffa_ctx);
>     if ( !ctx )
> -- 
> 2.34.1
>