Re: [Xen-devel] [PATCH V13 3/7] xen/arm: Allow hypervisor access to mem_access protected pages

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Thu, Mar 12, 2015 at 2:43 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> On 12/03/15 13:38, Tamas K Lengyel wrote:
>>     > +    if ( flag == GV2M_WRITE )
>>     > +    {
>>     > +        switch ( t )
>>     > +        {
>>     > +        case p2m_ram_rw:
>>
>>     > +        case p2m_iommu_map_rw:
>>     > +        case p2m_map_foreign:
>>     > +        case p2m_grant_map_rw:
>>     > +        case p2m_mmio_direct:
>>
>>     We disallow guest copy from the above 4 types via get_page_from_gva. So
>>     I'm not sure if it's worth to check them here.
>>
>>
>> You mean get_page_from_gva only works for p2m_ram_rw type? Is this the
>> case for GV2M_READ as well?
>
> Yes, currently p2m_ram_rw is the only type bound to a struct page.

That makes the white-list quite simple, t has to be p2m_ram_rw
regardless of the flag, otherwise fault.

>
> --
> Julien Grall
>

Thanks,
Tamas

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