your mail

[Lorenzo Stoakes]

On Thu, Aug 21, 2025 at 11:30:43AM +0200, David Hildenbrand wrote:
> > I will add this xen/apply_to_page_range() thing to my TODOs, which atm
> > would invovle changing these drivers to use vmf_insert_pfn_prot() instead.
> >
>
> Busy today (want to reply to Christian) but
>
> a) Re: performance, we would want something like
>    vmf_insert_pfns_prot(), similar to vm_insert_pages(), to bulk-insert
>    multiple PFNs.
>
> b) Re: PAT, we'll have to figure out why PAT information is wrong here
>    (was there no previous PAT reservation from the driver?), but IF we
>    really have to override, we'd want a way to tell
>    vmf_insert_pfn_prot() to force the selected caching mode.
>

Ack, ok good that we have a feasible way forward.

FYI, spoke to Peter off-list and he mentioned he had a more general series
to get rid of this kind of [ab]use of apply_to_page_range() (see [0]), I
gather he hasn't the time to resurrect but perhaps one of us can at some
point?

Perhaps we need a shorter term fix to _this_ issue (which involves not
using this interface), and then follow it up with an adaptation of the
below?

Cheers, Lorenzo

[0]:https://lore.kernel.org/all/20210412080012.357146277@infradead.org/



> --
> Cheers
>
> David / dhildenb