Revert "KVM: MMU: lazily drop large spte"

This reverts commit caf6900f2d8aaebe404c976753f6813ccd31d95e.

It is causing migration failures, reference
https://bugzilla.kernel.org/show_bug.cgi?id=54061.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 16 insertions, 7 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1cda1f332654..4ed3edbe06bd 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1105,7 +1105,8 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
 
 /*
  * Write-protect on the specified @sptep, @pt_protect indicates whether
- * spte write-protection is caused by protecting shadow page table.
+ * spte writ-protection is caused by protecting shadow page table.
+ * @flush indicates whether tlb need be flushed.
  *
  * Note: write protection is difference between drity logging and spte
  * protection:
@@ -1114,9 +1115,10 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
  * - for spte protection, the spte can be writable only after unsync-ing
  *   shadow page.
  *
- * Return true if tlb need be flushed.
+ * Return true if the spte is dropped.
  */
-static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool pt_protect)
+static bool
+spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush, bool pt_protect)
 {
         u64 spte = *sptep;
 
@@ -1126,11 +1128,17 @@ static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool pt_protect)
 
         rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
 
+        if (__drop_large_spte(kvm, sptep)) {
+                *flush |= true;
+                return true;
+        }
+
         if (pt_protect)
                 spte &= ~SPTE_MMU_WRITEABLE;
         spte = spte & ~PT_WRITABLE_MASK;
 
-        return mmu_spte_update(sptep, spte);
+        *flush |= mmu_spte_update(sptep, spte);
+        return false;
 }
 
 static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
@@ -1142,8 +1150,11 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
 
         for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
                 BUG_ON(!(*sptep & PT_PRESENT_MASK));
+                if (spte_write_protect(kvm, sptep, &flush, pt_protect)) {
+                        sptep = rmap_get_first(*rmapp, &iter);
+                        continue;
+                }
 
-                flush |= spte_write_protect(kvm, sptep, pt_protect);
                 sptep = rmap_get_next(&iter);
         }
 
@@ -2581,8 +2592,6 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
                         break;
                 }
 
-                drop_large_spte(vcpu, iterator.sptep);
-
                 if (!is_shadow_present_pte(*iterator.sptep)) {
                         u64 base_addr = iterator.addr;