From 52a61516125fa9a21b3bdf4f90928308e2e5573f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 5 Feb 2017 18:15:21 +0100 Subject: [PATCH] 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 Reviewed-by: Jason Wang Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_pci_common.c | 35 +++++++++++++++--------------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index b83053082875..822f8e5dcee4 100644 --- a/drivers/virtio/virtio_pci_common.c +++ b/drivers/virtio/virtio_pci_common.c @@ -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); - 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); + err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names); if (!err) return 0; - /* Finally fall back to regular interrupts. */ return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names); } -- 2.20.1