KVM: MMU: Don't flush shadow when enabling dirty tracking

Instead, drop large mappings, which were the reason we dropped shadow.

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

1 files changed, 8 insertions, 4 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f02b8edc3d44..ccacf0b1b540 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3538,14 +3538,18 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
                 if (!test_bit(slot, sp->slot_bitmap))
                         continue;
 
-                if (sp->role.level != PT_PAGE_TABLE_LEVEL)
-                        continue;
-
                 pt = sp->spt;
-                for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
+                for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+                        if (sp->role.level != PT_PAGE_TABLE_LEVEL
+                            && is_large_pte(pt[i])) {
+                                drop_spte(kvm, &pt[i],
+                                          shadow_trap_nonpresent_pte);
+                                --kvm->stat.lpages;
+                        }
                         /* avoid RMW */
                         if (is_writable_pte(pt[i]))
                                 update_spte(&pt[i], pt[i] & ~PT_WRITABLE_MASK);
+                }
         }
         kvm_flush_remote_tlbs(kvm);
 }