Commit 4ef33685 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Bjorn Helgaas
Browse files

PCI: Spread interrupt vectors in pci_alloc_irq_vectors() 



Set the affinity_mask in the PCI device before allocating vectors so that
the affinity can be propagated through the MSI descriptor structures to the
core IRQ code.  To facilitate this, new __pci_enable_msi_range() and
__pci_enable_msix_range() helpers are factored out of their not prefixed
variants which assigning the new IRQ affinity mask in the PCI device so
that the low-level interrupt code can perform the interrupt affinity
assignment and do node-local allocations.

A new PCI_IRQ_NOAFFINITY flag is added to pci_alloc_irq_vectors() so that
this function can also be used by drivers that don't wish to use the
automatic affinity assignment.

[bhelgaas: omit "else" after "return" consistently]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarAlexander Gordeev <agordeev@redhat.com>
parent aff17164

Documentation/PCI/MSI-HOWTO.txt

+4 −0
Original line number Diff line number Diff line
@@ -99,6 +99,10 @@ PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims to support 
MSI or MSI-X, but the support is broken, or to pass PCI_IRQ_NOLEGACY in

case the device does not support legacy interrupt lines.



By default this function will spread the interrupts around the available

CPUs, but this feature can be disabled by passing the PCI_IRQ_NOAFFINITY

flag.



To get the Linux IRQ numbers passed to request_irq() and free_irq() and the

vectors, use the following function:

drivers/pci/msi.c

+89 −45
Original line number Diff line number Diff line
@@ -569,6 +569,7 @@ static struct msi_desc *msi_setup_entry(struct pci_dev *dev, int nvec) 
	entry->msi_attrib.multi_cap	= (control & PCI_MSI_FLAGS_QMASK) >> 1;

	entry->msi_attrib.multiple	= ilog2(__roundup_pow_of_two(nvec));

	entry->nvec_used		= nvec;

	entry->affinity			= dev->irq_affinity;



	if (control & PCI_MSI_FLAGS_64BIT)

		entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
@@ -680,10 +681,18 @@ static void __iomem *msix_map_region(struct pci_dev *dev, unsigned nr_entries) 
static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,

			      struct msix_entry *entries, int nvec)

{

	const struct cpumask *mask = NULL;

	struct msi_desc *entry;

	int i;

	int cpu = -1, i;



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

		if (dev->irq_affinity) {

			cpu = cpumask_next(cpu, dev->irq_affinity);

			if (cpu >= nr_cpu_ids)

				cpu = cpumask_first(dev->irq_affinity);

			mask = cpumask_of(cpu);

		}



		entry = alloc_msi_entry(&dev->dev);

		if (!entry) {

			if (!i)
@@ -703,6 +712,7 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base, 
		entry->msi_attrib.default_irq	= dev->irq;

		entry->mask_base		= base;

		entry->nvec_used		= 1;

		entry->affinity			= mask;



		list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));

	}
@@ -1028,19 +1038,8 @@ int pci_msi_enabled(void) 
}

EXPORT_SYMBOL(pci_msi_enabled);



/**

 * pci_enable_msi_range - configure device's MSI capability structure

 * @dev: device to configure

 * @minvec: minimal number of interrupts to configure

 * @maxvec: maximum number of interrupts to configure

 *

 * This function tries to allocate a maximum possible number of interrupts in a

 * range between @minvec and @maxvec. It returns a negative errno if an error

 * occurs. If it succeeds, it returns the actual number of interrupts allocated

 * and updates the @dev's irq member to the lowest new interrupt number;

 * the other interrupt numbers allocated to this device are consecutive.

 **/

int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec)

static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,

		unsigned int flags)

{

	int nvec;

	int rc;
@@ -1063,26 +1062,86 @@ int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec) 
	nvec = pci_msi_vec_count(dev);

	if (nvec < 0)

		return nvec;

	else if (nvec < minvec)

	if (nvec < minvec)

		return -EINVAL;

	else if (nvec > maxvec)



	if (nvec > maxvec)

		nvec = maxvec;



	do {

	for (;;) {

		if (!(flags & PCI_IRQ_NOAFFINITY)) {

			dev->irq_affinity = irq_create_affinity_mask(&nvec);

			if (nvec < minvec)

				return -ENOSPC;

		}



		rc = msi_capability_init(dev, nvec);

		if (rc < 0) {

		if (rc == 0)

			return nvec;



		kfree(dev->irq_affinity);

		dev->irq_affinity = NULL;



		if (rc < 0)

			return rc;

		} else if (rc > 0) {

		if (rc < minvec)

			return -ENOSPC;



		nvec = rc;

	}

	} while (rc);

}



	return nvec;

/**

 * pci_enable_msi_range - configure device's MSI capability structure

 * @dev: device to configure

 * @minvec: minimal number of interrupts to configure

 * @maxvec: maximum number of interrupts to configure

 *

 * This function tries to allocate a maximum possible number of interrupts in a

 * range between @minvec and @maxvec. It returns a negative errno if an error

 * occurs. If it succeeds, it returns the actual number of interrupts allocated

 * and updates the @dev's irq member to the lowest new interrupt number;

 * the other interrupt numbers allocated to this device are consecutive.

 **/

int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec)

{

	return __pci_enable_msi_range(dev, minvec, maxvec, PCI_IRQ_NOAFFINITY);

}

EXPORT_SYMBOL(pci_enable_msi_range);



static int __pci_enable_msix_range(struct pci_dev *dev,

		struct msix_entry *entries, int minvec, int maxvec,

		unsigned int flags)

{

	int nvec = maxvec;

	int rc;



	if (maxvec < minvec)

		return -ERANGE;



	for (;;) {

		if (!(flags & PCI_IRQ_NOAFFINITY)) {

			dev->irq_affinity = irq_create_affinity_mask(&nvec);

			if (nvec < minvec)

				return -ENOSPC;

		}



		rc = pci_enable_msix(dev, entries, nvec);

		if (rc == 0)

			return nvec;



		kfree(dev->irq_affinity);

		dev->irq_affinity = NULL;



		if (rc < 0)

			return rc;

		if (rc < minvec)

			return -ENOSPC;



		nvec = rc;

	}

}



/**

 * pci_enable_msix_range - configure device's MSI-X capability structure

 * @dev: pointer to the pci_dev data structure of MSI-X device function
@@ -1101,24 +1160,8 @@ EXPORT_SYMBOL(pci_enable_msi_range); 
int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,

		int minvec, int maxvec)

{

	int nvec = maxvec;

	int rc;



	if (maxvec < minvec)

		return -ERANGE;



	do {

		rc = pci_enable_msix(dev, entries, nvec);

		if (rc < 0) {

			return rc;

		} else if (rc > 0) {

			if (rc < minvec)

				return -ENOSPC;

			nvec = rc;

		}

	} while (rc);



	return nvec;

	return __pci_enable_msix_range(dev, entries, minvec, maxvec,

			PCI_IRQ_NOAFFINITY);

}

EXPORT_SYMBOL(pci_enable_msix_range);
@@ -1145,13 +1188,14 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, 
	int vecs = -ENOSPC;



	if (!(flags & PCI_IRQ_NOMSIX)) {

		vecs = pci_enable_msix_range(dev, NULL, min_vecs, max_vecs);

		vecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs,

				flags);

		if (vecs > 0)

			return vecs;

	}



	if (!(flags & PCI_IRQ_NOMSI)) {

		vecs = pci_enable_msi_range(dev, min_vecs, max_vecs);

		vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, flags);

		if (vecs > 0)

			return vecs;

	}

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -320,6 +320,7 @@ struct pci_dev { 
	 * directly, use the values stored here. They might be different!

	 */

	unsigned int	irq;

	struct cpumask	*irq_affinity;

	struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */



	bool match_driver;		/* Skip attaching driver */
@@ -1240,6 +1241,7 @@ int pci_set_vga_state(struct pci_dev *pdev, bool decode, 
#define PCI_IRQ_NOLEGACY	(1 << 0) /* don't use legacy interrupts */

#define PCI_IRQ_NOMSI		(1 << 1) /* don't use MSI interrupts */

#define PCI_IRQ_NOMSIX		(1 << 2) /* don't use MSI-X interrupts */

#define PCI_IRQ_NOAFFINITY	(1 << 3) /* don't auto-assign affinity */



/* kmem_cache style wrapper around pci_alloc_consistent() */

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