On 17.10.24 01:49, Peter Xu wrote:
On Wed, Oct 16, 2024 at 07:51:57PM -0300, Jason Gunthorpe wrote:
On Wed, Oct 16, 2024 at 04:16:17PM -0400, Peter Xu wrote:
Is there chance that when !CoCo will be supported, then external modules
(e.g. VFIO) can reuse the old user mappings, just like before gmemfd?
To support CoCo, I understand gmem+offset is required all over the places.
However in a non-CoCo context, I wonder whether the other modules are
required to stick with gmem+offset, or they can reuse the old VA ways,
because how it works can fundamentally be the same as before, except that
the folios now will be managed by gmemfd.
My intention with iommufd was to see fd + offest as the "new" way
to refer to all guest memory and discourage people from using VMA
handles.
Does it mean anonymous memory guests will not be supported at all for
iommufd?
Indeed it's very rare now, lose quite some flexibility (v.s. fd based), and
I can't think of a lot besides some default configs or KSM users (which I
would expect rare), but still I wonder there're other use cases that people
would still need to stick with anon, hence fd isn't around.
Not sure I completely understand the question, but for most VMs out
there I expect an anonymous memory to remain the default memory backing.
Regarding users of iommufd, I have absolutely no clue :)
--
Cheers,
David / dhildenb
