On Thu, 2023-09-14 at 08:49 +0000, Paul Durrant wrote: > From: Paul Durrant <pdurrant@xxxxxxxxxx> > > Currently we treat the shared_info page as guest memory and the VMM informs > KVM of its location using a GFN. However it is not guest memory as such; > it's an overlay page. So we pointlessly invalidate and re-cache a mapping > to the *same page* of memory every time the guest requests that shared_info > be mapped into its address space. Let's avoid doing that by modifying the > pfncache code to allow activation using a fixed userspace HVA as well as > a GPA. Looks sane to me in general; thanks. The changes to the pfncache ended up being a little bit more than I originally anticipated when I said you just needed to disable the GPA→uHVA lookup via memslots which was about 10 lines... but I think it's still true that it's worth using the pfncache to avoid reproducing the intricate mmu_notifier invalidations.
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