Re: [Xen-devel] [PATCH v4 6/7] xen/arm: don't iomem_permit_access for reserved-memory regions

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

Hi Stefano,

Stefano Stabellini writes:

> Don't allow reserved-memory regions to be remapped into any guests,
> until reserved-memory regions are properly supported in Xen. For now,
> do not call iomem_permit_access for them.
>
> Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> ---
>
> Changes in v4:
> - compare the parent name with reserved-memory
> - use dt_node_cmp
>
> Changes in v3:
> - new patch
> ---
>  xen/arch/arm/domain_build.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 4c8404155a..267e0549e2 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1153,17 +1153,25 @@ static int __init map_range_to_domain(const struct 
> dt_device_node *dev,
>      struct map_range_data *mr_data = data;
>      struct domain *d = mr_data->d;
>      bool need_mapping = !dt_device_for_passthrough(dev);
> +    const struct dt_device_node *parent = dt_get_parent(dev);
>      int res;
>
> -    res = iomem_permit_access(d, paddr_to_pfn(addr),
> -                              paddr_to_pfn(PAGE_ALIGN(addr + len - 1)));
> -    if ( res )
> +    /*
> +     * Don't give iomem permissions for reserved-memory ranges until
> +     * reserved-memory support is complete.
> +     */
> +    if ( dt_node_cmp(dt_node_name(parent), "reserved-memory") == 0 )
Am I missing something, or you are permitting access only if it from a
"reserved-memory" node? This contradicts with patch description.

>      {
> -        printk(XENLOG_ERR "Unable to permit to dom%d access to"
> -               " 0x%"PRIx64" - 0x%"PRIx64"\n",
> -               d->domain_id,
> -               addr & PAGE_MASK, PAGE_ALIGN(addr + len) - 1);
> -        return res;
> +        res = iomem_permit_access(d, paddr_to_pfn(addr),
> +                                  paddr_to_pfn(PAGE_ALIGN(addr + len - 1)));
> +        if ( res )
> +        {
> +            printk(XENLOG_ERR "Unable to permit to dom%d access to"
> +                   " 0x%"PRIx64" - 0x%"PRIx64"\n",
> +                   d->domain_id,
> +                   addr & PAGE_MASK, PAGE_ALIGN(addr + len) - 1);
> +            return res;
> +        }
>      }
>
>      if ( need_mapping )
So, this region cold be mapped, but without the access?


--
Volodymyr Babchuk at EPAM
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