Re: [XEN PATCH v2 5/5] xen/arm: ffa: support notification

[Julien Grall <julien@xxxxxxx>]

Hi Jens,

This is not a full review of the code. I will let Bertrand doing it.

On 22/04/2024 08:37, Jens Wiklander wrote:
> +void ffa_notif_init(void)
> +{
> +    const struct arm_smccc_1_2_regs arg = {
> +        .a0 = FFA_FEATURES,
> +        .a1 = FFA_FEATURE_SCHEDULE_RECV_INTR,
> +    };
> +    struct arm_smccc_1_2_regs resp;
> +    unsigned int irq;
> +    int ret;
> +
> +    arm_smccc_1_2_smc(&arg, &resp);
> +    if ( resp.a0 != FFA_SUCCESS_32 )
> +        return;
> +
> +    irq = resp.a2;
> +    if ( irq >= NR_GIC_SGI )
> +        irq_set_type(irq, IRQ_TYPE_EDGE_RISING);
> +    ret = request_irq(irq, 0, notif_irq_handler, "FF-A notif", NULL);
If I am not mistaken, ffa_notif_init() is only called once on the boot 
CPU. However, request_irq() needs to be called on every CPU so the 
callback is registered every where and the interrupt enabled.
I know the name of the function is rather confusing. So can you confirm 
this is what you expected?
[...]

> diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
> index 98236cbf14a3..ef8ffd4526bd 100644
> --- a/xen/arch/arm/tee/ffa_private.h
> +++ b/xen/arch/arm/tee/ffa_private.h
> @@ -25,6 +25,7 @@
>   #define FFA_RET_DENIED                  -6
>   #define FFA_RET_RETRY                   -7
>   #define FFA_RET_ABORTED                 -8
> +#define FFA_RET_NO_DATA                 -9
>   
>   /* FFA_VERSION helpers */
>   #define FFA_VERSION_MAJOR_SHIFT         16U
> @@ -97,6 +98,18 @@
>    */
>   #define FFA_MAX_SHM_COUNT               32
>   
> +/*
> + * TODO How to manage the available SGIs? SGI 8-15 seem to be entirely
> + * unused, but that may change.
Are the value below intended for the guests? If so, can they be moved in 
public/arch-arm.h along with the others guest interrupts?
> + *
> + * SGI is the preferred delivery mechanism. SGIs 8-15 are normally not used
> + * by a guest as they in a non-virtualized system typically are assigned to
> + * the secure world. Here we're free to use SGI 8-15 since they are virtual
> + * and have nothing to do with the secure world.
Do you have a pointer to the specification?

[...]

Cheers,

--
Julien Grall