On 11/16/2022 1:09 PM, Borislav Petkov wrote:

On Wed, Nov 16, 2022 at 12:53:36PM -0600, Kalra, Ashish wrote:

quoted

Actually, these host allocated pages would have already been removed from
the kernel direct map,

And, as I said above, it would be a lot easier to handle any potential
faults resulting from the host touching them by having it raise a *RMP*
fault instead of normal *PF* fault where the latter code is a crazy mess.

Just to reiterate here, we won't be getting a *RMP* fault but will 
instead get a normal (not-present) #PF fault when the host touches these 
pages.

Sorry for any confusion about the fault signaled, earlier i mentioned we 
will get a RMP violation #PF, but actually as these pages are also 
removed from the kernel direct-map, therefore, we will get the 
not-present #PF and not the RMP #PF (core will check and signal 
not-present #PF before it performs the RMP checks).

Thanks,
Ashish