On 3/29/23 18:43, Christian König wrote:
3) other uses of kmap() must switch to MMU-notifier protection.
I would rather suggest to return the page additionally to the pfn from
hva_to_pfn() when the function was able to grab a reference to it.
When the page is then not available you can't call kmap() on that either.
If the DRM people are okay with SetPageReserved() as a temporary hack,
we can change or remove the WARN in kvm_is_zone_device_page(), since
that is what you are referring to in the commit message.
Adding Daniel for additional comments on this, but essentially we have
changed quite some infrastructure to make sure that everybody uses
VM_PFNMAP to prevent stuff like this from happening.
I would really prefer a proper solution in KVM instead.
Hmm... Now that I think about it that would be
https://lore.kernel.org/kvm/Yc4H+dGfK83BaGpC@xxxxxxxxxx/t/
Time to resurrect that work.
Paolo
