virtio currently fails to find any vqs if the device supports msi-x but fails to assign it to a queue. Turns out, this actually happens for old host kernels which can't allocate a gsi for the vector. As a result guest does not use virtio net. Fix this by retrying with less vectors and finally disabling msi on such failures and falling back on regular interrupts.
Reported-by: Amit Shah <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]> --- A slightly bigger patch was tested by Amit Shah and reported working, this one has been made as small as possible for -rc inclusion. Let's pospone bigger refactorings for 2.6.32. drivers/virtio/virtio_pci.c | 130 +++++++++++++++++++++++------------------- 1 files changed, 71 insertions(+), 59 deletions(-) diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 4bff231..25c7995 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -278,27 +278,24 @@ static void vp_free_vectors(struct virtio_device *vdev) vp_dev->msix_entries = NULL; } -static int vp_enable_msix(struct pci_dev *dev, struct msix_entry *entries, - int *options, int noptions) -{ - int i; - for (i = 0; i < noptions; ++i) - if (!pci_enable_msix(dev, entries, options[i])) - return options[i]; - return -EBUSY; -} - -static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs) +static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs, + int nvectors) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); const char *name = dev_name(&vp_dev->vdev.dev); unsigned i, v; int err = -ENOMEM; - /* We want at most one vector per queue and one for config changes. - * Fallback to separate vectors for config and a shared for queues. - * Finally fall back to regular interrupts. */ - int options[] = { max_vqs + 1, 2 }; - int nvectors = max(options[0], options[1]); + + if (!nvectors) { + /* Can't allocate MSI-X vectors, use regular interrupt */ + vp_dev->msix_vectors = 0; + err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, + IRQF_SHARED, name, vp_dev); + if (err) + return err; + vp_dev->intx_enabled = 1; + return 0; + } vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries, GFP_KERNEL); @@ -312,38 +309,31 @@ static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs) for (i = 0; i < nvectors; ++i) vp_dev->msix_entries[i].entry = i; - err = vp_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, - options, ARRAY_SIZE(options)); - if (err < 0) { - /* Can't allocate enough MSI-X vectors, use regular interrupt */ - vp_dev->msix_vectors = 0; - err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, - IRQF_SHARED, name, vp_dev); - if (err) - goto error; - vp_dev->intx_enabled = 1; - } else { - vp_dev->msix_vectors = err; - vp_dev->msix_enabled = 1; - - /* Set the vector used for configuration */ - v = vp_dev->msix_used_vectors; - snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names, - "%s-config", name); - err = request_irq(vp_dev->msix_entries[v].vector, - vp_config_changed, 0, vp_dev->msix_names[v], - vp_dev); - if (err) - goto error; - ++vp_dev->msix_used_vectors; + err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors); + if (err > 0) + err = -ENOSPC; + if (err) + goto error; + vp_dev->msix_vectors = nvectors; + vp_dev->msix_enabled = 1; + + /* Set the vector used for configuration */ + v = vp_dev->msix_used_vectors; + snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names, + "%s-config", name); + err = request_irq(vp_dev->msix_entries[v].vector, + vp_config_changed, 0, vp_dev->msix_names[v], + vp_dev); + if (err) + goto error; + ++vp_dev->msix_used_vectors; - iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR); - /* Verify we had enough resources to assign the vector */ - v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR); - if (v == VIRTIO_MSI_NO_VECTOR) { - err = -EBUSY; - goto error; - } + iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR); + /* Verify we had enough resources to assign the vector */ + v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR); + if (v == VIRTIO_MSI_NO_VECTOR) { + err = -EBUSY; + goto error; } if (vp_dev->msix_vectors && vp_dev->msix_vectors != max_vqs + 1) { @@ -499,23 +489,17 @@ static void vp_del_vqs(struct virtio_device *vdev) vp_free_vectors(vdev); } -/* the config->find_vqs() implementation */ -static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, - struct virtqueue *vqs[], - vq_callback_t *callbacks[], - const char *names[]) +static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs, + struct virtqueue *vqs[], + vq_callback_t *callbacks[], + const char *names[], + int max_vqs, int nvectors) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); u16 vector, per_vq_vector; - int vectors = 0; int i, err, allocated_vectors; - /* How many vectors would we like? */ - for (i = 0; i < nvqs; ++i) - if (callbacks[i]) - ++vectors; - - err = vp_request_vectors(vdev, vectors); + err = vp_request_vectors(vdev, max_vqs, nvectors); if (err) goto error_request; @@ -543,6 +527,34 @@ error_request: return PTR_ERR(vqs[i]); } +/* the config->find_vqs() implementation */ +static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, + struct virtqueue *vqs[], + vq_callback_t *callbacks[], + const char *names[]) +{ + /* We want at most one vector per queue and one for config changes. + * Fallback to separate vectors for config and a shared for queues. + * Finally fall back to regular interrupts. */ + int options[] = { 1, 2, 0 }; + int vectors = 0; + int i, uninitialized_var(err); + + /* How many vectors would we like? */ + for (i = 0; i < nvqs; ++i) + if (callbacks[i]) + ++vectors; + options[0] = vectors + 1; + + for (i = 0; i < ARRAY_SIZE(options); ++i) { + err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, + vectors, options[i]); + if (!err) + break; + } + return err; +} + static struct virtio_config_ops virtio_pci_config_ops = { .get = vp_get, .set = vp_set, -- 1.6.2.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
