KVM: resize kvm_io_range array dynamically

This patch makes the kvm_io_range array can be resized dynamically.

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

1 files changed, 18 insertions, 20 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42b73930a6de..a9565e240636 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2393,9 +2393,6 @@ int kvm_io_bus_sort_cmp(const void *p1, const void *p2)
 int kvm_io_bus_insert_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev,
                           gpa_t addr, int len)
 {
-        if (bus->dev_count == NR_IOBUS_DEVS)
-                return -ENOSPC;
-
         bus->range[bus->dev_count++] = (struct kvm_io_range) {
                 .addr = addr,
                 .len = len,
@@ -2495,12 +2492,15 @@ 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->dev_count > NR_IOBUS_DEVS-1)
+        if (bus->dev_count > NR_IOBUS_DEVS - 1)
                 return -ENOSPC;
 
-        new_bus = kmemdup(bus, sizeof(struct kvm_io_bus), GFP_KERNEL);
+        new_bus = kzalloc(sizeof(*bus) + ((bus->dev_count + 1) *
+                          sizeof(struct kvm_io_range)), GFP_KERNEL);
         if (!new_bus)
                 return -ENOMEM;
+        memcpy(new_bus, bus, sizeof(*bus) + (bus->dev_count *
+               sizeof(struct kvm_io_range)));
         kvm_io_bus_insert_dev(new_bus, dev, addr, len);
         rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
         synchronize_srcu_expedited(&kvm->srcu);
@@ -2517,27 +2517,25 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
         struct kvm_io_bus *new_bus, *bus;
 
         bus = kvm->buses[bus_idx];
-
-        new_bus = kmemdup(bus, sizeof(*bus), GFP_KERNEL);
-        if (!new_bus)
-                return -ENOMEM;
-
         r = -ENOENT;
-        for (i = 0; i < new_bus->dev_count; i++)
-                if (new_bus->range[i].dev == dev) {
+        for (i = 0; i < bus->dev_count; i++)
+                if (bus->range[i].dev == dev) {
                         r = 0;
-                        new_bus->dev_count--;
-                        new_bus->range[i] = new_bus->range[new_bus->dev_count];
-                        sort(new_bus->range, new_bus->dev_count,
-                             sizeof(struct kvm_io_range),
-                             kvm_io_bus_sort_cmp, NULL);
                         break;
                 }
 
-        if (r) {
-                kfree(new_bus);
+        if (r)
                 return r;
-        }
+
+        new_bus = kzalloc(sizeof(*bus) + ((bus->dev_count - 1) *
+                          sizeof(struct kvm_io_range)), GFP_KERNEL);
+        if (!new_bus)
+                return -ENOMEM;
+
+        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));
 
         rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
         synchronize_srcu_expedited(&kvm->srcu);