Re: [Qemu-devel] [Bug 1771042] Re: dataplane interrupt handler doesn't support msi

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, May 14, 2018 at 03:00:44AM -0000, eric hoffman wrote:
> diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
> index 101f32c..31d9eb8 100644
> --- a/hw/block/dataplane/virtio-blk.c
> +++ b/hw/block/dataplane/virtio-blk.c
> @@ -73,7 +73,7 @@ static void notify_guest_bh(void *opaque)
>              unsigned i = j + ctzl(bits);
>              VirtQueue *vq = virtio_get_queue(s->vdev, i);
> 
> -            virtio_notify_irqfd(s->vdev, vq);
> +            virtio_notify(s->vdev, vq);
> 
>              bits &= bits - 1; /* clear right-most bit */
>          }

Please send patches to qemu-devel@nongnu.org.  Guidelines for submitting
patches are here:
https://wiki.qemu.org/Contribute/SubmitAPatch

The issue with this approach is that hw/pci/msi.c:msi_send_message()
invokes device emulation outside the QEMU global mutex (it calls into
the APIC to send MSIs).  I've CCed Paolo Bonzini to check whether doing
this is thread-safe.

Stefan

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