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Commit 52a61516 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Michael S. Tsirkin
Browse files

virtio_pci: simplify MSI-X setup 



Try to grab the MSI-X vectors early and fall back to the shared one
before doing lots of allocations.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 53a020c6

drivers/virtio/virtio_pci_common.c

+18 −17
Original line number Original line Diff line number Diff line
@@ -142,14 +142,13 @@ void vp_del_vqs(struct virtio_device *vdev) 
}

}





static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,

static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,

			      struct virtqueue *vqs[],

		struct virtqueue *vqs[], vq_callback_t *callbacks[],

			      vq_callback_t *callbacks[],

		const char * const names[])

			      const char * const names[],

			      bool per_vq_vectors)

{

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	const char *name = dev_name(&vp_dev->vdev.dev);

	const char *name = dev_name(&vp_dev->vdev.dev);

	int i, err = -ENOMEM, allocated_vectors, nvectors;

	int i, err = -ENOMEM, allocated_vectors, nvectors;

	bool shared = false;

	u16 msix_vec;

	u16 msix_vec;





	nvectors = 1;

	nvectors = 1;
@@ -157,12 +156,16 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, 
		if (callbacks[i])

		if (callbacks[i])

			nvectors++;

			nvectors++;





	if (per_vq_vectors) {

	/* Try one vector per queue first. */

	err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,

	err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,

			PCI_IRQ_MSIX);

			PCI_IRQ_MSIX);

	} else {

	if (err < 0) {

		/* Fallback to one vector for config, one shared for queues. */

		shared = true;

		err = pci_alloc_irq_vectors(vp_dev->pci_dev, 2, 2,

		err = pci_alloc_irq_vectors(vp_dev->pci_dev, 2, 2,

				PCI_IRQ_MSIX);

				PCI_IRQ_MSIX);

		if (err < 0)

			return err;

	}

	}

	if (err < 0)

	if (err < 0)

		return err;

		return err;
@@ -190,7 +193,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, 
	err = request_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_config_changed,

	err = request_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_config_changed,

			0, vp_dev->msix_names[0], vp_dev);

			0, vp_dev->msix_names[0], vp_dev);

	if (err)

	if (err)

		goto out_free_irq_vectors;

		goto out_free_msix_affinity_masks;





	/* Verify we had enough resources to assign the vector */

	/* Verify we had enough resources to assign the vector */

	if (vp_dev->config_vector(vp_dev, 0) == VIRTIO_MSI_NO_VECTOR) {

	if (vp_dev->config_vector(vp_dev, 0) == VIRTIO_MSI_NO_VECTOR) {
@@ -240,7 +243,11 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, 
		}

		}

		vp_dev->msix_vector_map[i] = msix_vec;

		vp_dev->msix_vector_map[i] = msix_vec;





		if (per_vq_vectors)

		/*

		 * Use a different vector for each queue if they are available,

		 * else share the same vector for all VQs.

		 */

		if (!shared)

			allocated_vectors++;

			allocated_vectors++;

	}

	}
@@ -307,15 +314,9 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, 
{

{

	int err;

	int err;





	/* Try MSI-X with one vector per queue. */

	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names);

	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true);

	if (!err)

		return 0;

	/* Fallback: MSI-X with one vector for config, one shared for queues. */

	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false);

	if (!err)

	if (!err)

		return 0;

		return 0;

	/* Finally fall back to regular interrupts. */

	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names);

	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names);

}

}