Commit 07ec5148 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Michael S. Tsirkin
Browse files

virtio_pci: use shared interrupts for virtqueues 



This lets IRQ layer handle dispatching IRQs to separate handlers for the
case where we don't have per-VQ MSI-X vectors, and allows us to greatly
simplify the code based on the assumption that we always have interrupt
vector 0 (legacy INTx or config interrupt for MSI-X) available, and
any other interrupt is request/freed throught the VQ, even if the
actual interrupt line might be shared in some cases.

This allows removing a great deal of variables keeping track of the
interrupt state in struct virtio_pci_device, as we can now simply walk the
list of VQs and deal with per-VQ interrupt handlers there, and only treat
vector 0 special.

Additionally clean up the VQ allocation code to properly unwind on error
instead of having a single global cleanup label, which is error prone,
and in this case also leads to more code.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 5c34d002

drivers/virtio/virtio_pci_common.c

+104 −131
Original line number Diff line number Diff line
@@ -33,10 +33,8 @@ void vp_synchronize_vectors(struct virtio_device *vdev) 
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	int i;



	if (vp_dev->intx_enabled)

		synchronize_irq(vp_dev->pci_dev->irq);



	for (i = 0; i < vp_dev->msix_vectors; ++i)

	synchronize_irq(pci_irq_vector(vp_dev->pci_dev, 0));

	for (i = 1; i < vp_dev->msix_vectors; i++)

		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));

}
@@ -99,77 +97,10 @@ static irqreturn_t vp_interrupt(int irq, void *opaque) 
	return vp_vring_interrupt(irq, opaque);

}



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);

	const char *name = dev_name(&vp_dev->vdev.dev);

	unsigned i, v;

	int err = -ENOMEM;



	vp_dev->msix_vectors = nvectors;



	vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,

				     GFP_KERNEL);

	if (!vp_dev->msix_names)

		goto error;

	vp_dev->msix_affinity_masks

		= kzalloc(nvectors * sizeof *vp_dev->msix_affinity_masks,

			  GFP_KERNEL);

	if (!vp_dev->msix_affinity_masks)

		goto error;

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

		if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],

					GFP_KERNEL))

			goto error;



	err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,

			PCI_IRQ_MSIX);

	if (err < 0)

		goto error;

	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(pci_irq_vector(vp_dev->pci_dev, v),

			  vp_config_changed, 0, vp_dev->msix_names[v],

			  vp_dev);

	if (err)

		goto error;

	++vp_dev->msix_used_vectors;



	v = vp_dev->config_vector(vp_dev, v);

	/* Verify we had enough resources to assign the vector */

	if (v == VIRTIO_MSI_NO_VECTOR) {

		err = -EBUSY;

		goto error;

	}



	if (!per_vq_vectors) {

		/* Shared vector for all VQs */

		v = vp_dev->msix_used_vectors;

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

			 "%s-virtqueues", name);

		err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),

				  vp_vring_interrupt, 0, vp_dev->msix_names[v],

				  vp_dev);

		if (err)

			goto error;

		++vp_dev->msix_used_vectors;

	}

	return 0;

error:

	return err;

}



/* the config->del_vqs() implementation */

void vp_del_vqs(struct virtio_device *vdev)

static void vp_remove_vqs(struct virtio_device *vdev)

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	struct virtqueue *vq, *n;

	int i;



	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {

		if (vp_dev->msix_vector_map) {
@@ -181,35 +112,33 @@ void vp_del_vqs(struct virtio_device *vdev) 
		}

		vp_dev->del_vq(vq);

	}



	if (vp_dev->intx_enabled) {

		free_irq(vp_dev->pci_dev->irq, vp_dev);

		vp_dev->intx_enabled = 0;

}



	for (i = 0; i < vp_dev->msix_used_vectors; ++i)

		free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);

/* the config->del_vqs() implementation */

void vp_del_vqs(struct virtio_device *vdev)

{

	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	int i;



	if (WARN_ON_ONCE(list_empty_careful(&vdev->vqs)))

		return;



	vp_remove_vqs(vdev);



	if (vp_dev->msix_enabled) {

		for (i = 0; i < vp_dev->msix_vectors; i++)

		if (vp_dev->msix_affinity_masks[i])

			free_cpumask_var(vp_dev->msix_affinity_masks[i]);



	if (vp_dev->msix_enabled) {

		/* Disable the vector used for configuration */

		vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);



		pci_free_irq_vectors(vp_dev->pci_dev);

		vp_dev->msix_enabled = 0;

	}



	vp_dev->msix_vectors = 0;

	vp_dev->msix_used_vectors = 0;

	kfree(vp_dev->msix_names);

	vp_dev->msix_names = NULL;

		kfree(vp_dev->msix_affinity_masks);

	vp_dev->msix_affinity_masks = NULL;

		kfree(vp_dev->msix_names);

		kfree(vp_dev->msix_vector_map);

	vp_dev->msix_vector_map = NULL;

	}



	free_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_dev);

	pci_free_irq_vectors(vp_dev->pci_dev);

}



static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
@@ -219,79 +148,122 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs, 
			      bool per_vq_vectors)

{

	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;

	u16 msix_vec;

	int i, err, nvectors, allocated_vectors;



	if (per_vq_vectors) {

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

	nvectors = 1;

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

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

		if (callbacks[i])

				++nvectors;

			nvectors++;



	if (per_vq_vectors) {

		err = pci_alloc_irq_vectors(vp_dev->pci_dev, nvectors, nvectors,

				PCI_IRQ_MSIX);

	} else {

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

		nvectors = 2;

		err = pci_alloc_irq_vectors(vp_dev->pci_dev, 2, 2,

				PCI_IRQ_MSIX);

	}

	if (err < 0)

		return err;



	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);

	vp_dev->msix_vectors = nvectors;

	vp_dev->msix_names = kmalloc_array(nvectors,

			sizeof(*vp_dev->msix_names), GFP_KERNEL);

	if (!vp_dev->msix_names)

		goto out_free_irq_vectors;



	vp_dev->msix_affinity_masks = kcalloc(nvectors,

			sizeof(*vp_dev->msix_affinity_masks), GFP_KERNEL);

	if (!vp_dev->msix_affinity_masks)

		goto out_free_msix_names;



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

		if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],

				GFP_KERNEL))

			goto out_free_msix_affinity_masks;

	}



	/* Set the vector used for configuration */

	snprintf(vp_dev->msix_names[0], sizeof(*vp_dev->msix_names),

		 "%s-config", name);

	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 error_find;

		goto out_free_irq_vectors;



	/* Verify we had enough resources to assign the vector */

	if (vp_dev->config_vector(vp_dev, 0) == VIRTIO_MSI_NO_VECTOR) {

		err = -EBUSY;

		goto out_free_config_irq;

	}



	if (per_vq_vectors) {

	vp_dev->msix_vector_map = kmalloc_array(nvqs,

			sizeof(*vp_dev->msix_vector_map), GFP_KERNEL);

	if (!vp_dev->msix_vector_map)

			goto error_find;

	}

		goto out_disable_config_irq;



	allocated_vectors = vp_dev->msix_used_vectors;

	allocated_vectors = 1; /* vector 0 is the config interrupt */

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

		if (!names[i]) {

			vqs[i] = NULL;

			continue;

		}



		if (!callbacks[i])

			msix_vec = VIRTIO_MSI_NO_VECTOR;

		else if (per_vq_vectors)

			msix_vec = allocated_vectors++;

		if (callbacks[i])

			msix_vec = allocated_vectors;

		else

			msix_vec = VP_MSIX_VQ_VECTOR;

			msix_vec = VIRTIO_MSI_NO_VECTOR;



		vqs[i] = vp_dev->setup_vq(vp_dev, i, callbacks[i], names[i],

				msix_vec);

		if (IS_ERR(vqs[i])) {

			err = PTR_ERR(vqs[i]);

			goto error_find;

			goto out_remove_vqs;

		}



		if (!per_vq_vectors)

			continue;



		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {

			vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;

			continue;

		}



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

		snprintf(vp_dev->msix_names[msix_vec],

			 sizeof *vp_dev->msix_names,

			 "%s-%s",

		snprintf(vp_dev->msix_names[i + 1],

			 sizeof(*vp_dev->msix_names), "%s-%s",

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

		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),

				  vring_interrupt, 0,

				  vp_dev->msix_names[msix_vec],

				  vqs[i]);

				  vring_interrupt, IRQF_SHARED,

				  vp_dev->msix_names[i + 1], vqs[i]);

		if (err) {

			/* don't free this irq on error */

			vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;

			goto error_find;

			goto out_remove_vqs;

		}

		vp_dev->msix_vector_map[i] = msix_vec;



		if (per_vq_vectors)

			allocated_vectors++;

	}



	vp_dev->msix_enabled = 1;

	return 0;



error_find:

	vp_del_vqs(vdev);

out_remove_vqs:

	vp_remove_vqs(vdev);

	kfree(vp_dev->msix_vector_map);

out_disable_config_irq:

	vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);

out_free_config_irq:

	free_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_dev);

out_free_msix_affinity_masks:

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

		if (vp_dev->msix_affinity_masks[i])

			free_cpumask_var(vp_dev->msix_affinity_masks[i]);

	}

	kfree(vp_dev->msix_affinity_masks);

out_free_msix_names:

	kfree(vp_dev->msix_names);

out_free_irq_vectors:

	pci_free_irq_vectors(vp_dev->pci_dev);

	return err;

}
@@ -305,9 +277,8 @@ static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs, 
	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,

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

	if (err)

		goto out_del_vqs;

		return err;



	vp_dev->intx_enabled = 1;

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

		if (!names[i]) {

			vqs[i] = NULL;
@@ -317,13 +288,15 @@ static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs, 
				VIRTIO_MSI_NO_VECTOR);

		if (IS_ERR(vqs[i])) {

			err = PTR_ERR(vqs[i]);

			goto out_del_vqs;

			goto out_remove_vqs;

		}

	}



	return 0;

out_del_vqs:

	vp_del_vqs(vdev);



out_remove_vqs:

	vp_remove_vqs(vdev);

	free_irq(pci_irq_vector(vp_dev->pci_dev, 0), vp_dev);

	return err;

}

drivers/virtio/virtio_pci_common.h

+2 −14
Original line number Diff line number Diff line
@@ -66,16 +66,12 @@ struct virtio_pci_device { 


	/* MSI-X support */

	int msix_enabled;

	int intx_enabled;

	cpumask_var_t *msix_affinity_masks;

	/* Name strings for interrupts. This size should be enough,

	 * and I'm too lazy to allocate each name separately. */

	char (*msix_names)[256];

	/* Number of available vectors */

	unsigned msix_vectors;

	/* Vectors allocated, excluding per-vq vectors if any */

	unsigned msix_used_vectors;



	/* Total Number of MSI-X vectors (including per-VQ ones). */

	int msix_vectors;

	/* Map of per-VQ MSI-X vectors, may be NULL */

	unsigned *msix_vector_map;
@@ -89,14 +85,6 @@ struct virtio_pci_device { 
	u16 (*config_vector)(struct virtio_pci_device *vp_dev, u16 vector);

};



/* Constants for MSI-X */

/* Use first vector for configuration changes, second and the rest for

 * virtqueues Thus, we need at least 2 vectors for MSI. */

enum {

	VP_MSIX_CONFIG_VECTOR = 0,

	VP_MSIX_VQ_VECTOR = 1,

};



/* Convert a generic virtio device to our structure */

static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)

{

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