[Qemu-devel] Re: [PATCHv2 08/12] virtio-pci: fill in notifier support

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/25/2010 12:28 PM, Michael S. Tsirkin wrote:
> Support host/guest notifiers in virtio-pci.
> The last one only with kvm, that's okay
> because vhost relies on kvm anyway.
>
> Note on kvm usage: kvm ioeventfd API
> is implemented on non-kvm systems as well,
> this is the reason we don't need if (kvm_enabled())
> around it.
>
> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> ---
>   hw/virtio-pci.c |   62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 62 insertions(+), 0 deletions(-)
>
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 006ff38..3f1214c 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -24,6 +24,7 @@
>   #include "net.h"
>   #include "block_int.h"
>   #include "loader.h"
> +#include "kvm.h"
>
>   /* from Linux's linux/virtio_pci.h */
>
> @@ -398,6 +399,65 @@ static unsigned virtio_pci_get_features(void *opaque)
>       return proxy->host_features;
>   }
>
> +static void virtio_pci_guest_notifier_read(void *opaque)
> +{
> +    VirtQueue *vq = opaque;
> +    EventNotifier *n = virtio_queue_guest_notifier(vq);
> +    if (event_notifier_test_and_clear(n)) {
> +        virtio_irq(vq);
> +    }
> +}
> +
> +static int virtio_pci_guest_notifier(void *opaque, int n, bool assign)
> +{
> +    VirtIOPCIProxy *proxy = opaque;
> +    VirtQueue *vq = virtio_queue(proxy->vdev, n);
> +    EventNotifier *notifier = virtio_queue_guest_notifier(vq);
> +
> +    if (assign) {
> +        int r = event_notifier_init(notifier, 0);
> +	if (r<  0)
> +		return r;
> +        qemu_set_fd_handler(event_notifier_get_fd(notifier),
> +                            virtio_pci_guest_notifier_read, NULL, vq);
>    

While not super important, it would be nice to have this a bit more 
common.  IOW:

     r = read_event_notifier_init(notifier, 
virtio_pci_guest_notifier_read, vq);

and:

     r = kvm_eventfd_notifier_init(notifier, proxy->addr + 
VIRTIO_PCI_QUEUE_NOTIFY, n, assign);

Regards,

Anthony Liguori