Re: [PATCH v8 13/14] tools/libxl: explicitly grant access to needed I/O-memory ranges

[Julien Grall <julien.grall@linaro.org>]

Hi Arianna,

On 25/05/14 11:51, Arianna Avanzini wrote:
> +
> +        /*
> +         * If VGA passthru is enabled by domain config, be sure that the
> +         * domain can access VGA-related iomem regions.
> +         */
> +        if (d_config->b_info.u.hvm.gfx_passthru.val) {
> +            uint64_t vga_iomem_start = 0xa0000 >> XC_PAGE_SHIFT;
> +            ret = xc_domain_iomem_permission(CTX->xch, domid,
> +                                             vga_iomem_start, 0x20, 1);
> +            if (ret < 0) {
> +                LOGE(ERROR,
> +                     "failed to give dom%d access to iomem range "
> +                     "%"PRIx64"-%"PRIx64" for VGA passthru",
> +                     domid, vga_iomem_start, (vga_iomem_start + 0x20 - 1));
> +                goto error_out;
> +            }
> +        }

IHMO, the guest doesn't need to have permission to this region. When 
QEMU ask to map this region to the guest, the hypercall will only check 
the permission on the domain where QEMU is running. Therefore, the 
permission should be given to the stubdomain.

Regards,

-- 
Julien Grall