On (Tue) Jul 21 2009 [19:54:00], Michael S. Tsirkin wrote:
> On Fri, Jul 17, 2009 at 06:34:40PM +0530, Amit Shah wrote:
> > Hello,
> >
> > Using recent qemu-kvm userspace with a slightly older kernel module I
> > get this when using the virtio-net device:
I was getting this with a very recent kernel in the guest with an older
host kernel.
2.6.31-rc3 in the guest and 2.6.29 (F11) kernel in the host.
> > kvm_msix_add: kvm_get_irq_route_gsi failed: No space left on device
> >
> > ... and the guest doesn't use the net device.
> >
> > This goes away when using a newer kvm module.
> >
> > Amit
>
> Could you verify if the following helps please?
This worked for me with your other patches:
guest kernel (on top of Avi's kvm/master):
1. [PATCH 1/2] virtio: Fix memory leak on device removal
2. [PATCH 2/2] virtio: fix double free_irq]
qemu-kvm (on top of Avi's qemu-kvm/master):
1. [PATCHv2] qemu-kvm: routing table update thinko fix
2. [PATCH 2/2] qemu-kvm: broken MSI routing work-around
3. [PATCH] qemu-kvm: fix error handling in msix vector add
Tested-by: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
>
> virtio: retry on vector assignment failure
>
> 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 disabling msi on
> such failures and falling back on regular interrupts.
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> index 9dcc368..567c972 100644
> --- a/drivers/virtio/virtio_pci.c
> +++ b/drivers/virtio/virtio_pci.c
> @@ -273,26 +273,35 @@ static void vp_free_vectors(struct virtio_device *vdev)
> }
>
> static int vp_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
> - int *options, int noptions)
> + int nvectors)
> {
> - int i;
> - for (i = 0; i < noptions; ++i)
> - if (!pci_enable_msix(dev, entries, options[i]))
> - return options[i];
> - return -EBUSY;
> + int err = pci_enable_msix(dev, entries, nvectors);
> + if (err > 0)
> + err = -ENOSPC;
> + return err;
> }
>
> -static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
> +static int vp_request_irq(struct virtio_device *vdev)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + int err;
> + /* 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, dev_name(&vp_dev->vdev.dev), vp_dev);
> + if (err)
> + return err;
> + vp_dev->intx_enabled = 1;
> + return 0;
> +}
> +
> +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]);
>
> vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
> GFP_KERNEL);
> @@ -307,37 +316,29 @@ static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
> 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_irq;
> - 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_irq;
> - ++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_irq;
> - }
> + nvectors);
> + if (err)
> + goto error_enable;
> + 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_irq;
> + ++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_irq;
> }
>
> if (vp_dev->msix_vectors && vp_dev->msix_vectors != max_vqs + 1) {
> @@ -355,9 +356,12 @@ static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
> return 0;
> error_irq:
> vp_free_vectors(vdev);
> +error_enable:
> kfree(vp_dev->msix_names);
> + vp_dev->msix_names = NULL;
> error_names:
> kfree(vp_dev->msix_entries);
> + vp_dev->msix_entries = NULL;
> error_entries:
> return err;
> }
> @@ -499,24 +503,24 @@ static void vp_del_vqs(struct virtio_device *vdev)
>
> vp_free_vectors(vdev);
> kfree(vp_dev->msix_names);
> + vp_dev->msix_names = NULL;
> kfree(vp_dev->msix_entries);
> + vp_dev->msix_entries = NULL;
> }
>
> -/* 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_vectors,
> + int nvectors)
> {
> - int vectors = 0;
> int i, err;
>
> - /* How many vectors would we like? */
> - for (i = 0; i < nvqs; ++i)
> - if (callbacks[i])
> - ++vectors;
> -
> - err = vp_request_vectors(vdev, vectors);
> + if (nvectors)
> + err = vp_request_vectors(vdev, max_vectors, nvectors);
> + else
> + err = vp_request_irq(vdev);
> if (err)
> goto error_request;
>
> @@ -534,6 +538,34 @@ 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,
Amit
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