Re: [Xen-devel] [PATCH V4 2/8] iommu/arm: Add ability to handle deferred probing request

[Julien Grall <julien.grall@xxxxxxx>]

Hi Oleksandr,

On 13/09/2019 16:35, Oleksandr Tyshchenko wrote:
> diff --git a/xen/drivers/passthrough/arm/iommu.c 
> b/xen/drivers/passthrough/arm/iommu.c
> index f219de9..555acfc 100644
> --- a/xen/drivers/passthrough/arm/iommu.c
> +++ b/xen/drivers/passthrough/arm/iommu.c
> @@ -20,6 +20,12 @@
>   #include <xen/device_tree.h>
>   #include <asm/device.h>
>   
> +/*
> + * Deferred probe list is used to keep track of devices for which driver
> + * requested deferred probing (returned -EAGAIN).
> + */
> +static __initdata LIST_HEAD(deferred_probe_list);
> +
>   static const struct iommu_ops *iommu_ops;
>   
>   const struct iommu_ops *iommu_get_ops(void)
> @@ -42,7 +48,7 @@ void __init iommu_set_ops(const struct iommu_ops *ops)
>   
>   int __init iommu_hardware_setup(void)
>   {
> -    struct dt_device_node *np;
> +    struct dt_device_node *np, *tmp;
>       int rc;
>       unsigned int num_iommus = 0;
>   
> @@ -51,6 +57,21 @@ int __init iommu_hardware_setup(void)
>           rc = device_init(np, DEVICE_IOMMU, NULL);
>           if ( !rc )
>               num_iommus++;
> +        else if ( rc == -EAGAIN )
> +        {
> +            /*
> +             * We expect nobody uses device's domain_list at such early stage,
NIT: s/We expect nobody uses/Nobody should use/

> +             * so we can re-use it to link the device in the deferred list to
> +             * avoid introducing extra list_head field in struct 
> dt_device_node.
> +             */
> +            ASSERT(list_empty(&np->domain_list));
[...]

>   void __hwdom_init arch_iommu_check_autotranslated_hwdom(struct domain *d)
> diff --git a/xen/include/asm-arm/device.h b/xen/include/asm-arm/device.h
> index 63a0f36..ee1c3bc 100644
> --- a/xen/include/asm-arm/device.h
> +++ b/xen/include/asm-arm/device.h
> @@ -44,7 +44,11 @@ struct device_desc {
>       enum device_class class;
>       /* List of devices supported by this driver */
>       const struct dt_device_match *dt_match;
> -    /* Device initialization */
> +    /*
> +     * Device initialization.
> +     *
> +     * -EAGAIN is used to indicate that device probing is deferred.
> +     */
>       int (*init)(struct dt_device_node *dev, const void *data);
>   };
>   
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index 9a7a8f2..3702e9b 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -92,6 +92,13 @@ struct dt_device_node {
>   
>       /* IOMMU specific fields */
>       bool is_protected;
> +    /*
> +     * The main purpose of this list node is to link the structure in the list
s/node//?

> +     * of devices assigned to domain.
> +     *
> +     * Boot code (iommu_hardware_setup) re-uses this list to link the structure
> +     * in the list of devices for which driver requested deferred probing.
> +     */
>       struct list_head domain_list;
>   
>       struct device dev;
With the two above addressed and pending the patch it depends on [1] is acked:

Reviewed-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

[1] https://lists.xenproject.org/archives/html/xen-devel/2019-08/msg01924.html

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel