On Fri, Feb 07, 2025 at 07:07:06AM -0800, Sean Christopherson wrote: > On Fri, Feb 07, 2025, Yan Zhao wrote: > > Make sure pfn is not changed for a spurious fault by warning in the TDP > > MMU. For shadow path, only treat a prefetch fault as spurious when pfn is > > not changed, since the rmap removal and add are required when pfn is > > changed. > > I like sanity checks, but I don't like special casing "prefetch" faults like this. > KVM should _never_ change the PFN of a shadow-present SPTE. The TDP MMU already > BUG()s on this, and mmu_spte_update() WARNs on the transition. However, both TDP MMU and mmu_set_spte() return RET_PF_SPURIOUS directly before the BUG() in TDP MMU or mmu_spte_update() could be hit.
