1 files changed, 43 insertions, 16 deletions

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index bcdf978c0d1d..f9da2fad9bd6 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1067,25 +1067,43 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 {
 	pmd_t *pmd, old_pmd;
 
+retry:
 	pmd = stage2_get_pmd(kvm, cache, addr);
 	VM_BUG_ON(!pmd);
 
 	old_pmd = *pmd;
+	/*
+	 * Multiple vcpus faulting on the same PMD entry, can
+	 * lead to them sequentially updating the PMD with the
+	 * same value. Following the break-before-make
+	 * (pmd_clear() followed by tlb_flush()) process can
+	 * hinder forward progress due to refaults generated
+	 * on missing translations.
+	 *
+	 * Skip updating the page table if the entry is
+	 * unchanged.
+	 */
+	if (pmd_val(old_pmd) == pmd_val(*new_pmd))
+		return 0;
+
 	if (pmd_present(old_pmd)) {
 		/*
-		 * Multiple vcpus faulting on the same PMD entry, can
-		 * lead to them sequentially updating the PMD with the
-		 * same value. Following the break-before-make
-		 * (pmd_clear() followed by tlb_flush()) process can
-		 * hinder forward progress due to refaults generated
-		 * on missing translations.
+		 * If we already have PTE level mapping for this block,
+		 * we must unmap it to avoid inconsistent TLB state and
+		 * leaking the table page. We could end up in this situation
+		 * if the memory slot was marked for dirty logging and was
+		 * reverted, leaving PTE level mappings for the pages accessed
+		 * during the period. So, unmap the PTE level mapping for this
+		 * block and retry, as we could have released the upper level
+		 * table in the process.
 		 *
-		 * Skip updating the page table if the entry is
-		 * unchanged.
+		 * Normal THP split/merge follows mmu_notifier callbacks and do
+		 * get handled accordingly.
 		 */
-		if (pmd_val(old_pmd) == pmd_val(*new_pmd))
-			return 0;
-
+		if (!pmd_thp_or_huge(old_pmd)) {
+			unmap_stage2_range(kvm, addr & S2_PMD_MASK, S2_PMD_SIZE);
+			goto retry;
+		}
 		/*
 		 * Mapping in huge pages should only happen through a
 		 * fault.  If a page is merged into a transparent huge
@@ -1097,8 +1115,7 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 		 * should become splitting first, unmapped, merged,
 		 * and mapped back in on-demand.
 		 */
-		VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));
-
+		WARN_ON_ONCE(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));
 		pmd_clear(pmd);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {
@@ -1114,6 +1131,7 @@ static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cac
 {
 	pud_t *pudp, old_pud;
 
+retry:
 	pudp = stage2_get_pud(kvm, cache, addr);
 	VM_BUG_ON(!pudp);
 
@@ -1121,14 +1139,23 @@ static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cac
 
 	/*
 	 * A large number of vcpus faulting on the same stage 2 entry,
-	 * can lead to a refault due to the
-	 * stage2_pud_clear()/tlb_flush(). Skip updating the page
-	 * tables if there is no change.
+	 * can lead to a refault due to the stage2_pud_clear()/tlb_flush().
+	 * Skip updating the page tables if there is no change.
 	 */
 	if (pud_val(old_pud) == pud_val(*new_pudp))
 		return 0;
 
 	if (stage2_pud_present(kvm, old_pud)) {
+		/*
+		 * If we already have table level mapping for this block, unmap
+		 * the range for this block and retry.
+		 */
+		if (!stage2_pud_huge(kvm, old_pud)) {
+			unmap_stage2_range(kvm, addr & S2_PUD_MASK, S2_PUD_SIZE);
+			goto retry;
+		}
+
+		WARN_ON_ONCE(kvm_pud_pfn(old_pud) != kvm_pud_pfn(*new_pudp));
 		stage2_pud_clear(kvm, pudp);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {