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Date: Wed, 19 Dec 2012 13:35:31 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20121219123531.GD6498@stefanha-thinkpad.redhat.com>
References: <cover.1355833220.git.mst@redhat.com>
	<a66ea256e5e977f94039e392e67039fa09c1c368.1355833220.git.mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/3] virtio-pci: don't poll masked vectors
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, kvm@vger.kernel.org, Jan Kiszka <jan.kiszka@siemens.com>, Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, Asias He <asias@redhat.com>

On Tue, Dec 18, 2012 at 02:39:19PM +0200, Michael S. Tsirkin wrote:
> -static int virtio_pci_set_guest_notifier(DeviceState *d, int n, bool assign)
> +static void kvm_virtio_pci_vector_poll(PCIDevice *dev,
> +                                       unsigned int vector_start,
> +                                       unsigned int vector_end)
> +{
> +    VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev);
> +    VirtIODevice *vdev = proxy->vdev;
> +    int queue_no;
> +    unsigned int vector;
> +    EventNotifier *notifier;
> +    VirtQueue *vq;
> +
> +    for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
> +        if (!virtio_queue_get_num(vdev, queue_no)) {
> +            break;
> +        }
> +        vector = virtio_queue_vector(vdev, queue_no);
> +        if (vector < vector_start || vector >= vector_end ||
> +            !msix_is_masked(dev, vector)) {
> +            continue;
> +        }
> +        vq = virtio_get_queue(vdev, queue_no);
> +        notifier = virtio_queue_get_guest_notifier(vq);
> +        if (event_notifier_test_and_clear(notifier)) {
> +            msix_set_pending(dev, vector);
> +        }

Small difference to virtio_queue_guest_notifier_read() here: we do not
set vq->vdev->isr |= 0x01.  I guess no guest drivers use isr with MSIX
but should we still set it or even just call
virtio_queue_guest_notifier_read() instead of duplicating that event
notifier read here?

Stefan