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Diffstat (limited to 'virt/kvm/arm/mmu.c')
-rw-r--r--virt/kvm/arm/mmu.c59
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 {