Re: [Xen-devel] [PATCH v8 5/8] xen/arm: assign devices to boot domains

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

A couple of comments below, mostly because I wasn't clear enough on the previous 
version. I am not sure if it is worth resending the series, maybe just resending 
this one would be sufficient?
On 03/10/2019 02:35, Stefano Stabellini wrote:
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 84b65b8f25..b90902ad97 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1714,6 +1714,88 @@ static int __init make_vpl011_uart_node(struct 
> kernel_info *kinfo)
>   }
>   #endif
>   
> +/*
> + * Scan device tree properties for passthrough specific information.
> + * Returns < 0 on error
> + *         0 on success
> + */
> +static int __init handle_passthrough_prop(struct kernel_info *kinfo,
> +                                          const struct fdt_property *xen_reg,
> +                                          const struct fdt_property *xen_path,
> +                                          bool xen_force,
> +                                          uint32_t address_cells, uint32_t 
> size_cells)
> +{
> +    const __be32 *cell;
> +    unsigned int i, len;
> +    struct dt_device_node *node;
> +    int res;
> +    paddr_t mstart, size, gstart;
> +
> +    /* xen,reg specifies where to map the MMIO region */
> +    cell = (const __be32 *)xen_reg->data;
> +    len = fdt32_to_cpu(xen_reg->len) / ((address_cells * 2 + size_cells) *
> +                                        sizeof(uint32_t));
Apologies for this, I misread you previous code. I am happy with this version or 
the previous one.
[...]

> +    /*
> +     * Only handle passthrough properties if both xen,reg and xen,path
> +     * are present, or if xen,force-assign-without-iommu is specified.
> +     */
> +    if ( xen_reg != NULL && (xen_path != NULL || xen_force) )
> +    {
> +        res = handle_passthrough_prop(kinfo, xen_reg, xen_path, xen_force,
> +                                      address_cells, size_cells);
> +        if ( res < 0 )
> +        {
> +            printk(XENLOG_ERR "Failed to assign device to %pd\n", kinfo->d);
This is not the error path I meant.

The one I was referring is the case where xen,path is present but not xen,reg. 
At the moment you will continue without telling the user. We should at least 
print a warning and probably return an error as someone specifying "xen,path" 
may expect to assign the device.
Cheers,


--
Julien Grall

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