On 03/01/2012 09:01 AM, Amos Kong wrote:
> kvm_io_bus devices are used for ioevent, pit, pic, ioapic,
> coalesced_mmio.
>
> Currently Qemu only emulates one PCI bus, it contains 32 slots,
> one slot contains 8 functions, maximum of supported PCI devices:
> 1 * 32 * 8 = 256. One virtio-blk takes one iobus device,
> one virtio-net(vhost=on) takes two iobus devices.
> The maximum of coalesced mmio zone is 100, each zone
> has an iobus devices. So 300 io_bus devices are not enough.
>
> This patch makes the kvm_io_range array can be resized dynamically.
> Set an upper bounds for kvm_io_range to limit userspace.
> 1000 is a very large limit and not bloat the typical user.
>
Please separate the change to 1000 devs to a new patch.
>
> +#define NR_IOBUS_DEVS 1000
> +
> 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 e4431ad..1baed68 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2389,9 +2389,6 @@ 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,
> @@ -2491,10 +2488,14 @@ 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)
> + memcpy(new_bus, bus, sizeof(*bus) + (bus->dev_count *
> + sizeof(struct kvm_io_range)));
This will be cleaner if you move the memcmp() after the check just below.
> if (!new_bus)
> return -ENOMEM;
> kvm_io_bus_insert_dev(new_bus, dev, addr, len);
> @@ -2513,26 +2514,28 @@ 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 = kmemdup(bus, sizeof(*bus) + ((bus->dev_count - 1) *
> + sizeof(struct kvm_io_range)), GFP_KERNEL);
> + if (!new_bus)
> + return -ENOMEM;
> +
> + new_bus->dev_count--;
> + /* copy last entry of bus->range to deleted entry spot if
> + deleted entry isn't the last entry of bus->range */
> + if (i != bus->dev_count - 1) {
The check is unneeded - if they compare equal, the copy is a no-op.
> + new_bus->range[i] = bus->range[bus->dev_count - 1];
> + sort(new_bus->range, new_bus->dev_count,
> + sizeof(struct kvm_io_range), kvm_io_bus_sort_cmp, NULL);
> }
>
> rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
>
--
error compiling committee.c: too many arguments to function
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