vp_vdpa: add vq irq offloading support

This patch implements the get_vq_irq() callback for virtio pci devices
to allow irq offloading.
Signed-off-by: Wu Zongyong <wuzongyong@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/bb091e5505db704dd620f8854a7aebc921d2a752.1635493219.git.wuzongyong@linux.alibaba.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/virtio_pci/vp_vdpa.c

@@ -76,6 +76,17 @@ static u8 vp_vdpa_get_status(struct vdpa_device *vdpa)
 	return vp_modern_get_status(mdev);
 }
 
+static int vp_vdpa_get_vq_irq(struct vdpa_device *vdpa, u16 idx)
+{
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
+	int irq = vp_vdpa->vring[idx].irq;
+
+	if (irq == VIRTIO_MSI_NO_VECTOR)
+		return -EINVAL;
+
+	return irq;
+}
+
 static void vp_vdpa_free_irq(struct vp_vdpa *vp_vdpa)
 {
 	struct virtio_pci_modern_device *mdev = &vp_vdpa->mdev;
@@ -427,6 +438,7 @@ static const struct vdpa_config_ops vp_vdpa_ops = {
 	.get_config	= vp_vdpa_get_config,
 	.set_config	= vp_vdpa_set_config,
 	.set_config_cb  = vp_vdpa_set_config_cb,
+	.get_vq_irq	= vp_vdpa_get_vq_irq,
 };
 
 static void vp_vdpa_free_irq_vectors(void *data)