On Thu, Jul 22, 2021 at 09:45:36PM +0530, Praveen Kumar wrote: > > > > I think about this a bit more, the NULL check for *hvp in hv_cpu_init in > > the original code is perhaps due to the code has opted to not free the > > page when disabling the VP assist page. When the CPU is brought back > > online, it does not want to allocate another page, but to use the one > > that's already allocated. > > > > So, since you listened to my suggestion to add a similar check, you need > > to reset hv_vp_assist_page to NULL here. Alternatively the check for > > *hvp can be dropped for the root path. Either way, the difference > > between root and non-root should be documented. > > > > I would make it as NULL post memunmap as you suggested, so that we > don't end up reusing the old/cached value. Before doing that, is there > any use-case where hypervisor can allocate or change the VP assist > page that can impact root kernel execution ? I don't think a sane hypervisor will change the page in such a way. Wei.
