On 09.04.2025 09:11, Jan Beulich wrote: > On 07.04.2025 11:10, Teddy Astie wrote: >> Aside exposing this flag to guests, Xen can also make use of it to reduce >> the cost of >> some TLB flushes. Enable this flag if supported by hardware. > > As said before: This needs to come with (perhaps a lot of) justification as > to it being safe for Xen to use without any adjustments anywhere else. This > exercise may not be left to the reviewer(s).
One case to consider in particular is a shadow guest (EFER.TCE clear as per patch 1) running with host EFER.TCE set. The TLB flushes we do may then simply be insufficient for the guest's expectations. Jan
