Re: [Xen-devel] [PATCH v3 5/6] xen/arm: don't iomem_permit_access for reserved-memory regions

[Oleksandr <olekstysh@xxxxxxxxx>]

On 22.06.19 02:56, Stefano Stabellini wrote:

Hi, Stefano

> 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:
> - new patch
> ---
>   xen/arch/arm/domain_build.c | 23 +++++++++++++++--------
>   1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index d9836779d1..76dd4bf6f9 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -1158,15 +1158,22 @@ static int __init map_range_to_domain(const struct 
> dt_device_node *dev,
>       bool need_mapping = !dt_device_for_passthrough(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 ( strcmp(dt_node_name(dev), "reserved-memory") )
This filter doesn't catch child nodes if the "reserved-memory" node has 
ones.
Here is my "reserved-memory" node:

reserved-memory {
        #address-cells = <2>;
        #size-cells = <2>;
        ranges;

        /* device specific region for Lossy Decompression */
        lossy_decompress: linux,lossy_decompress@54000000 {
            no-map;
            reg = <0x00000000 0x54000000 0x0 0x03000000>;
        };

        /* For Audio DSP */
        adsp_reserved: linux,adsp@57000000 {
            compatible = "shared-dma-pool";
            reusable;
            reg = <0x00000000 0x57000000 0x0 0x01000000>;
        };

        /* global autoconfigured region for contiguous allocations */
        linux,cma@58000000 {
            compatible = "shared-dma-pool";
            reusable;
            reg = <0x00000000 0x58000000 0x0 0x18000000>;
            linux,cma-default;
        };

        /* device specific region for contiguous allocations */
        mmp_reserved: linux,multimedia@70000000 {
            compatible = "shared-dma-pool";
            reusable;
            reg = <0x00000000 0x70000000 0x0 0x10000000>;
        };
    };


So, the dt_node_name(dev) for child nodes are:

- linux,lossy_decompress
- linux,adsp
- linux,cma
- linux,multimedia


Probably, we should check whether the parent node is "reserved-memory" 
as well.

--
Regards,

Oleksandr Tyshchenko


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