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

[Stefano Stabellini <sstabellini@kernel.org>]

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On Tue, 9 Jul 2019, Oleksandr wrote:
> 
> 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@xilinx.com>
> > ---
> > 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.

Yes, that is a mistake, thanks for spotting it. I should check the
parent node name instead.

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