kvm_handle_hva, called by MMU notifiers, manipulates mmu data only with
the protection of mmu_lock.

Update kvm_mmu_change_mmu_pages callers to take mmu_lock, thus protecting
against kvm_handle_hva.

CC: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -2732,7 +2732,6 @@ void kvm_mmu_slot_remove_write_access(st
 {
 	struct kvm_mmu_page *sp;
 
-	spin_lock(&kvm->mmu_lock);
 	list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
 		int i;
 		u64 *pt;
@@ -2747,7 +2746,6 @@ void kvm_mmu_slot_remove_write_access(st
 				pt[i] &= ~PT_WRITABLE_MASK;
 	}
 	kvm_flush_remote_tlbs(kvm);
-	spin_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)
Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -1647,10 +1647,12 @@ static int kvm_vm_ioctl_set_nr_mmu_pages
 		return -EINVAL;
 
 	down_write(&kvm->slots_lock);
+	spin_lock(&kvm->mmu_lock);
 
 	kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);
 	kvm->arch.n_requested_mmu_pages = kvm_nr_mmu_pages;
 
+	spin_unlock(&kvm->mmu_lock);
 	up_write(&kvm->slots_lock);
 	return 0;
 }
@@ -1826,7 +1828,9 @@ int kvm_vm_ioctl_get_dirty_log(struct kv
 
 	/* If nothing is dirty, don't bother messing with page tables. */
 	if (is_dirty) {
+		spin_lock(&kvm->mmu_lock);
 		kvm_mmu_slot_remove_write_access(kvm, log->slot);
+		spin_unlock(&kvm->mmu_lock);
 		kvm_flush_remote_tlbs(kvm);
 		memslot = &kvm->memslots[log->slot];
 		n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
@@ -4510,12 +4514,14 @@ int kvm_arch_set_memory_region(struct kv
 		}
 	}
 
+	spin_lock(&kvm->mmu_lock);
 	if (!kvm->arch.n_requested_mmu_pages) {
 		unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
 		kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
 	}
 
 	kvm_mmu_slot_remove_write_access(kvm, mem->slot);
+	spin_unlock(&kvm->mmu_lock);
 	kvm_flush_remote_tlbs(kvm);
 
 	return 0;