Re: [Qemu-devel] [PATCH v2 3/5] KVM: s390: adapter interrupt sources

[Christian Borntraeger]

On 17/03/14 19:11, Cornelia Huck wrote:
> Add a new interface to register/deregister sources of adapter interrupts
> identified by an unique id via the flic. Adapters may also be maskable
> and carry a list of pinned pages.
> 
> These adapters will be used by irq routing later.
> 
> Signed-off-by: Cornelia Huck <address@hidden>

[...]

> +static int kvm_s390_adapter_map(struct kvm *kvm, unsigned int id, __u64 addr)
> +{
> +     struct s390_io_adapter *adapter = get_io_adapter(kvm, id);
> +     struct s390_map_info *map;
> +     int ret;
> +
> +     if (!adapter || !addr)
> +             return -EINVAL;
> +
> +     map = kzalloc(sizeof(*map), GFP_KERNEL);
> +     if (!map) {
> +             ret = -ENOMEM;
> +             goto out;
> +     }
> +     INIT_LIST_HEAD(&map->list);
> +     map->addr = addr;
> +     ret = get_user_pages_fast(addr, 1, 1, &map->page);
> +     if (ret < 0)
> +             goto out;
> +     BUG_ON(ret != 1);
> +     down_write(&adapter->maps_lock);
> +     list_add_tail(&map->list, &adapter->maps);
> +     up_write(&adapter->maps_lock);
> +     ret = 0;

Can you limit the amount of pinned pages to something sane, e.g. 1MB?
As far as I can see, QEMU will fall back to non-irqfd if the mapping fails.

Otherwise looks good.

Acked-by: Christian Borntraeger <address@hidden>