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

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Feb 25, 2010 at 01:30:40PM -0600, Anthony Liguori wrote:
> 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


Hmm. Note that on qemu-kvm we also have interrupts using notifiers.
Possibly it's best to merge this, merge irqchip from qemu-kvm,
then think about the best API.

-- 
MST