KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs

stable inclusion
from stable-5.10.15
commit dd7f10523b19c809b908be8b11da35c8e13e15f2
bugzilla: 48167

--------------------------------

commit 87aa9ec9 upstream.

There is a bug in the TDP MMU function to zap SPTEs which could be
replaced with a larger mapping which prevents the function from doing
anything. Fix this by correctly zapping the last level SPTEs.

Cc: stable@vger.kernel.org
Fixes: 14881998 ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
Signed-off-by: NBen Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-11-bgardon@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

arch/x86/kvm/mmu/tdp_mmu.c

@@ -1037,8 +1037,8 @@ bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot)
 }
 
 /*
- * Clear non-leaf entries (and free associated page tables) which could
- * be replaced by large mappings, for GFNs within the slot.
+ * Clear leaf entries which could be replaced by large mappings, for
+ * GFNs within the slot.
  */
 static void zap_collapsible_spte_range(struct kvm *kvm,
 				       struct kvm_mmu_page *root,
@@ -1050,7 +1050,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 
 	tdp_root_for_each_pte(iter, root, start, end) {
 		if (!is_shadow_present_pte(iter.old_spte) ||
-		    is_last_spte(iter.old_spte, iter.level))
+		    !is_last_spte(iter.old_spte, iter.level))
 			continue;
 
 		pfn = spte_to_pfn(iter.old_spte);