Commit f68d2408 authored by Rusty Russell's avatar Rusty Russell
Browse files

virtio_pci: minor MSI-X cleanups 



1) Rename vp_request_vectors to vp_request_msix_vectors, and take
   non-MSI-X case out to caller.
2) Comment weird pci_enable_msix API
3) Rename vp_find_vq to setup_vq.
4) Fix spaces to tabs
5) Make nvectors calc internal to vp_try_to_find_vqs()
6) Rename vector to msix_vector for more clarity.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
parent ebc79c4f

drivers/virtio/virtio_pci.c

+70 −55
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ struct virtio_pci_vq_info 
	struct list_head node;



	/* MSI-X vector (or none) */

	unsigned vector;

	unsigned msix_vector;

};



/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
@@ -280,7 +280,7 @@ static void vp_free_vectors(struct virtio_device *vdev) 
	vp_dev->msix_entries = NULL;

}



static int vp_request_vectors(struct virtio_device *vdev, int nvectors,

static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,

				   bool per_vq_vectors)

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -288,17 +288,6 @@ static int vp_request_vectors(struct virtio_device *vdev, int nvectors, 
	unsigned i, v;

	int err = -ENOMEM;



	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);

	if (!vp_dev->msix_entries)
@@ -311,6 +300,7 @@ static int vp_request_vectors(struct virtio_device *vdev, int nvectors, 
	for (i = 0; i < nvectors; ++i)

		vp_dev->msix_entries[i].entry = i;



	/* pci_enable_msix returns positive if we can't get this many. */

	err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);

	if (err > 0)

		err = -ENOSPC;
@@ -356,10 +346,22 @@ error: 
	return err;

}



static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,

static int vp_request_intx(struct virtio_device *vdev)

{

	int err;

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);



	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,

			  IRQF_SHARED, dev_name(&vdev->dev), vp_dev);

	if (!err)

		vp_dev->intx_enabled = 1;

	return err;

}



static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,

				  void (*callback)(struct virtqueue *vq),

				  const char *name,

				    u16 vector)

				  u16 msix_vec)

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	struct virtio_pci_vq_info *info;
@@ -384,7 +386,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index, 


	info->queue_index = index;

	info->num = num;

	info->vector = vector;

	info->msix_vector = msix_vec;



	size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));

	info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
@@ -408,10 +410,10 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index, 
	vq->priv = info;

	info->vq = vq;



	 if (vector != VIRTIO_MSI_NO_VECTOR) {

		iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);

		vector = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);

		if (vector == VIRTIO_MSI_NO_VECTOR) {

	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {

		iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);

		msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);

		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {

			err = -EBUSY;

			goto out_assign;

		}
@@ -472,7 +474,8 @@ static void vp_del_vqs(struct virtio_device *vdev) 
	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {

		info = vq->priv;

		if (vp_dev->per_vq_vectors)

			free_irq(vp_dev->msix_entries[info->vector].vector, vq);

			free_irq(vp_dev->msix_entries[info->msix_vector].vector,

				 vq);

		vp_del_vq(vq);

	}

	vp_dev->per_vq_vectors = false;
@@ -484,38 +487,58 @@ static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs, 
			      struct virtqueue *vqs[],

			      vq_callback_t *callbacks[],

			      const char *names[],

			      int nvectors,

			      bool use_msix,

			      bool per_vq_vectors)

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	u16 vector;

	int i, err, allocated_vectors;

	u16 msix_vec;

	int i, err, nvectors, allocated_vectors;



	if (!use_msix) {

		/* Old style: one normal interrupt for change and all vqs. */

		err = vp_request_intx(vdev);

		if (err)

			goto error_request;

	} else {

		if (per_vq_vectors) {

			/* Best option: one for change interrupt, one per vq. */

			nvectors = 1;

			for (i = 0; i < nvqs; ++i)

				if (callbacks[i])

					++nvectors;

		} else {

			/* Second best: one for change, shared for all vqs. */

			nvectors = 2;

		}



	err = vp_request_vectors(vdev, nvectors, per_vq_vectors);

		err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);

		if (err)

			goto error_request;

	}



	vp_dev->per_vq_vectors = per_vq_vectors;

	allocated_vectors = vp_dev->msix_used_vectors;

	for (i = 0; i < nvqs; ++i) {

		if (!callbacks[i] || !vp_dev->msix_enabled)

			vector = VIRTIO_MSI_NO_VECTOR;

			msix_vec = VIRTIO_MSI_NO_VECTOR;

		else if (vp_dev->per_vq_vectors)

			vector = allocated_vectors++;

			msix_vec = allocated_vectors++;

		else

			vector = VP_MSIX_VQ_VECTOR;

		vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i], vector);

			msix_vec = VP_MSIX_VQ_VECTOR;

		vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], msix_vec);

		if (IS_ERR(vqs[i])) {

			err = PTR_ERR(vqs[i]);

			goto error_find;

		}

		/* allocate per-vq irq if available and necessary */

		if (vp_dev->per_vq_vectors && vector != VIRTIO_MSI_NO_VECTOR) {

			snprintf(vp_dev->msix_names[vector], sizeof *vp_dev->msix_names,

				 "%s-%s", dev_name(&vp_dev->vdev.dev), names[i]);

			err = request_irq(vp_dev->msix_entries[vector].vector,

					  vring_interrupt, 0,

					  vp_dev->msix_names[vector], vqs[i]);

		if (vp_dev->per_vq_vectors) {

			snprintf(vp_dev->msix_names[msix_vec],

				 sizeof *vp_dev->msix_names,

				 "%s-%s",

				 dev_name(&vp_dev->vdev.dev), names[i]);

			err = request_irq(msix_vec, vring_interrupt, 0,

					  vp_dev->msix_names[msix_vec],

					  vqs[i]);

			if (err) {

				vp_del_vq(vqs[i]);

				goto error_find;
@@ -537,28 +560,20 @@ static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs, 
		       vq_callback_t *callbacks[],

		       const char *names[])

{

	int vectors = 0;

	int i, uninitialized_var(err);



	/* How many vectors would we like? */

	for (i = 0; i < nvqs; ++i)

		if (callbacks[i])

			++vectors;

	int err;



	/* We want at most one vector per queue and one for config changes. */

	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,

				 vectors + 1, true);

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

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

	if (!err)

		return 0;

	/* Fallback to separate vectors for config and a shared for queues. */

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

	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,

				 2, false);

				 true, false);

	if (!err)

		return 0;

	/* Finally fall back to regular interrupts. */

	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,

				 0, false);

	return err;

	return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,

				  false, false);

}



static struct virtio_config_ops virtio_pci_config_ops = {

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