Look for a !leaf=>leaf conversion instead of a PFN change when checking if a SPTE change removed a TDP MMU shadow page. Convert the PFN check into a WARN, as KVM should never change the PFN of a shadow page (except when its being zapped or replaced). >From a purely theoretical perspective, it's not illegal to replace a SP with a hugepage pointing at the same PFN. In practice, it's impossible as that would require mapping guest memory overtop a kernel-allocated SP. Either way, the check is odd. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/mmu/tdp_mmu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 138c7dc41d2c..8e446ef03022 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -489,9 +489,12 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, /* * Recursively handle child PTs if the change removed a subtree from - * the paging structure. + * the paging structure. Note the WARN on the PFN changing without the + * SPTE being converted to a hugepage (leaf) or being zapped. Shadow + * pages are kernel allocations and should never be migrated. */ - if (was_present && !was_leaf && (pfn_changed || !is_present)) + if (was_present && !was_leaf && + (is_leaf || !is_present || WARN_ON_ONCE(pfn_changed))) handle_removed_tdp_mmu_page(kvm, spte_to_child_pt(old_spte, level), shared); } -- 2.34.0.rc2.393.gf8c9666880-goog
