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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexander Gordeev <agordeev@redhat.com>

diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 0ac612b..c55df29 100644 (file)
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -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:
 

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 5e5ab47..a02981e 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -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;
@@ -1063,25 +1062,85 @@ 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)
+               if (rc < minvec)
+                       return -ENOSPC;
+
+               nvec = rc;
+       }
+}
+
+/**
+ * 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;
-                       nvec = rc;
                }
-       } while (rc);
 
-       return nvec;
+               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;
+       }
 }
-EXPORT_SYMBOL(pci_enable_msi_range);
 
 /**
  * pci_enable_msix_range - configure device's MSI-X capability structure
@@ -1099,26 +1158,10 @@ EXPORT_SYMBOL(pci_enable_msi_range);
  * with new allocated MSI-X interrupts.
  **/
 int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
-                              int minvec, int maxvec)
+               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;
        }

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 52ecd49..f140661 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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() */