On Fri, 2022-08-05 at 19:41 +0000, Sean Christopherson wrote: > Add compile-time and init-time sanity checks to ensure that the MMIO SPTE > mask doesn't overlap the MMIO SPTE generation or the MMU-present bit. > The generation currently avoids using bit 63, but that's as much > coincidence as it is strictly necessarly. That will change in the future, > as TDX support will require setting bit 63 (SUPPRESS_VE) in the mask. > > Explicitly carve out the bits that are allowed in the mask so that any > future shuffling of SPTE bits doesn't silently break MMIO caching (KVM > has broken MMIO caching more than once due to overlapping the generation > with other things). > > Suggested-by: Kai Huang <kai.huang@xxxxxxxxx> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > --- > > Kai, I didn't included your review since I pretty much rewrote the entire > comment. > > v2: Prevent overlap with SPTE_MMU_PRESENT_MASK > v1: https://lore.kernel.org/all/20220803213354.951376-1-seanjc@xxxxxxxxxx Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> -- Thanks, -Kai
