Re: [PATCH v8 0/8] xen: Support grant mappings

[Philippe Mathieu-Daudé]

+Anthony who wasn't Cc'ed.

On 29/5/24 16:07, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
>
> Hi,
>
> Grant mappings are a mechanism in Xen for guests to grant each other
> permissions to map and share pages. These grants can be temporary
> so both map and unmaps must be respected. See here for more info:
> https://github.com/xen-project/xen/blob/master/docs/misc/grant-tables.txt
>
> Currently, the primary use-case for grants in QEMU, is with VirtIO backends.
> Grant mappings will only work with models that use the address_space_map/unmap
> interfaces, any other access will fail with appropriate error messages.
>
> In response to feedback we got on v3, later version switch approach
> from adding new MemoryRegion types and map/unmap hooks to instead reusing
> the existing xen_map_cache() hooks (with extensions). Almost all of the
> changes are now contained to the Xen modules.
>
> This approach also refactors the mapcache to support multiple instances
> (one for existing foreign mappings and another for grant mappings).
>
> I've only enabled grants for the ARM PVH machine since that is what
> I can currently test on.

Anthony, I don't have an easy way to test patches 7 and 8.

I can merge patches 1-6 to reduce burden on Edgar (Stefano
reviewed this series), but if you are busy I can send a PR
for it.

Regards,

Phil.