1 files changed, 31 insertions, 13 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a17d78759727..88257b311cb5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -727,8 +727,11 @@ static void kvm_destroy_vm(struct kvm *kvm)
         list_del(&kvm->vm_list);
         spin_unlock(&kvm_lock);
         kvm_free_irq_routing(kvm);
-        for (i = 0; i < KVM_NR_BUSES; i++)
-                kvm_io_bus_destroy(kvm->buses[i]);
+        for (i = 0; i < KVM_NR_BUSES; i++) {
+                if (kvm->buses[i])
+                        kvm_io_bus_destroy(kvm->buses[i]);
+                kvm->buses[i] = NULL;
+        }
         kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
         mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
@@ -1062,7 +1065,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
          * changes) is disallowed above, so any other attribute changes getting
          * here can be skipped.
          */
-        if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
+        if (as_id == 0 && (change == KVM_MR_CREATE || change == KVM_MR_MOVE)) {
                 r = kvm_iommu_map_pages(kvm, &new);
                 return r;
         }
@@ -3474,6 +3477,8 @@ int kvm_io_bus_write(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
         };
 
         bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+        if (!bus)
+                return -ENOMEM;
         r = __kvm_io_bus_write(vcpu, bus, &range, val);
         return r < 0 ? r : 0;
 }
@@ -3491,6 +3496,8 @@ int kvm_io_bus_write_cookie(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx,
         };
 
         bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+        if (!bus)
+                return -ENOMEM;
 
         /* First try the device referenced by cookie. */
         if ((cookie >= 0) && (cookie < bus->dev_count) &&
@@ -3541,6 +3548,8 @@ int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
         };
 
         bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+        if (!bus)
+                return -ENOMEM;
         r = __kvm_io_bus_read(vcpu, bus, &range, val);
         return r < 0 ? r : 0;
 }
@@ -3553,6 +3562,9 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
         struct kvm_io_bus *new_bus, *bus;
 
         bus = kvm->buses[bus_idx];
+        if (!bus)
+                return -ENOMEM;
+
         /* exclude ioeventfd which is limited by maximum fd */
         if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1)
                 return -ENOSPC;
@@ -3572,37 +3584,41 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 }
 
 /* Caller must hold slots_lock. */
-int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
-                              struct kvm_io_device *dev)
+void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+                               struct kvm_io_device *dev)
 {
-        int i, r;
+        int i;
         struct kvm_io_bus *new_bus, *bus;
 
         bus = kvm->buses[bus_idx];
-        r = -ENOENT;
+        if (!bus)
+                return;
+
         for (i = 0; i < bus->dev_count; i++)
                 if (bus->range[i].dev == dev) {
-                        r = 0;
                         break;
                 }
 
-        if (r)
-                return r;
+        if (i == bus->dev_count)
+                return;
 
         new_bus = kmalloc(sizeof(*bus) + ((bus->dev_count - 1) *
                           sizeof(struct kvm_io_range)), GFP_KERNEL);
-        if (!new_bus)
-                return -ENOMEM;
+        if (!new_bus)  {
+                pr_err("kvm: failed to shrink bus, removing it completely\n");
+                goto broken;
+        }
 
         memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range));
         new_bus->dev_count--;
         memcpy(new_bus->range + i, bus->range + i + 1,
                (new_bus->dev_count - i) * sizeof(struct kvm_io_range));
 
+broken:
         rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
         synchronize_srcu_expedited(&kvm->srcu);
         kfree(bus);
-        return r;
+        return;
 }
 
 struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
@@ -3615,6 +3631,8 @@ struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
         srcu_idx = srcu_read_lock(&kvm->srcu);
 
         bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
+        if (!bus)
+                goto out_unlock;
 
         dev_idx = kvm_io_bus_get_first_dev(bus, addr, 1);
         if (dev_idx < 0)