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>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 665a260c7e09948fa3b5e3516efca2890edef840..ba9fb4a9762d69f754b1bb2c65047714c6633f2c 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -68,10 +68,11 @@ struct kvm_io_range {
        struct kvm_io_device *dev;
 };
 
+#define NR_IOBUS_DEVS 300
+
 struct kvm_io_bus {
        int                   dev_count;
-#define NR_IOBUS_DEVS 300
-       struct kvm_io_range range[NR_IOBUS_DEVS];
+       struct kvm_io_range range[];
 };
 
 enum kvm_bus {

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42b73930a6de6b2210708aca55903f87a9bab459..a9565e240636d11ed35dd1570f06cfd88be71016 100644 (file)
--- 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);