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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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
zero-colors
Christoph Hellwig 2017-02-05 18:15:21 +01:00 committed by Michael S. Tsirkin
parent 53a020c661
commit 52a6151612
1 changed files with 18 additions and 17 deletions
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35
drivers/virtio/virtio_pci_common.c
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@ -142,14 +142,13 @@ void vp_del_vqs(struct virtio_device *vdev)
}
static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
const char * const names[],
bool per_vq_vectors)
struct virtqueue *vqs[], vq_callback_t *callbacks[],
const char * const names[])
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
const char *name = dev_name(&vp_dev->vdev.dev);
int i, err = -ENOMEM, allocated_vectors, nvectors;
bool shared = false;
u16 msix_vec;
nvectors = 1;
@ -157,12 +156,16 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
if (callbacks[i])
nvectors++;
if (per_vq_vectors) {
err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,
PCI_IRQ_MSIX);
} else {
/* Try one vector per queue first. */
err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,
PCI_IRQ_MSIX);
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,
PCI_IRQ_MSIX);
if (err < 0)
return err;
}
if (err < 0)
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,
0, vp_dev->msix_names[0], vp_dev);
if (err)
goto out_free_irq_vectors;
goto out_free_msix_affinity_masks;
/* Verify we had enough resources to assign the 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;
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++;
}
@ -307,15 +314,9 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
{
int err;
/* Try MSI-X with one vector per queue. */
err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true);
err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names);
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)
return 0;
/* Finally fall back to regular interrupts. */
return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names);
}