On Wed, Jun 12, 2024 at 05:14:37PM +0200, Jan Beulich wrote: > On 12.06.2024 17:00, Roger Pau Monné wrote: > > I wonder if you should explicitly mention that if adding the > > mfn_valid() check was done to ensure all mappings to MMIO are created > > with effective UC caching attribute it won't be fully correct either. > > Xen could map those using a different effective caching attribute by > > virtue of host MTRRs being in effect plus Xen chosen PAT attributes. > > Well, the mfn_valid() can't have been there to cover _all_ MMIO. It was > maybe a flawed initial attempt at doing so, and then wasn't properly > adjusted / dropped. So overall - no, I don't think extending the > description with anything along the lines of the above would make a lot > of sense.
I realized myself when writing the paragraph that I wouldn't even know how to word it properly, neither it would be much helpful without knowing the exact intention the mfn_valid() check was added for. Thanks, Roger.
