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Subject[PATCH 08/13] pci: spread interrupt vectors in pci_alloc_irq_vectors
Date
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. Add a new helper __pci_enable_msi_range which is
similar to __pci_enable_msix_range introduced in the last patch so that
we can allocate the affinity mask in a self-contained fashion and for the
right number of vectors.

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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
Documentation/PCI/MSI-HOWTO.txt | 3 +-
drivers/pci/msi.c | 72 ++++++++++++++++++++++++++++++++++++++---
include/linux/pci.h | 2 ++
3 files changed, 72 insertions(+), 5 deletions(-)

diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 35d1326..dcd3f6d 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -95,7 +95,8 @@ argument set to this limit, and the PCI core will return -ENOSPC if it can't
meet the minimum number of vectors.
The flags argument should normally be set to 0, but can be used to
pass the PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims
-to support MSI or MSI-X, but the support is broken.
+to support MSI or MSI-X, but the support is broken, or to PCI_IRQ_NOAFFINITY
+if the driver does not wish to use the automatic affinity assignment feature.

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 6b0834d..7f38e07 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -568,6 +568,7 @@ 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;
@@ -679,10 +680,18 @@ 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)
@@ -699,6 +708,7 @@ 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));
}
@@ -1121,8 +1131,53 @@ int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
}
EXPORT_SYMBOL(pci_enable_msix_range);

+static int __pci_enable_msi_range(struct pci_dev *dev, int min_vecs, int max_vecs,
+ unsigned int flags)
+{
+ int vecs, ret;
+
+ if (!pci_msi_supported(dev, min_vecs))
+ return -EINVAL;
+
+ vecs = pci_msi_vec_count(dev);
+ if (vecs < 0)
+ return vecs;
+ if (vecs < min_vecs)
+ return -EINVAL;
+ if (vecs > max_vecs)
+ vecs = max_vecs;
+
+retry:
+ if (vecs < min_vecs)
+ return -ENOSPC;
+
+ if (!(flags & PCI_IRQ_NOAFFINITY)) {
+ dev->irq_affinity = irq_create_affinity_mask(&vecs);
+ if (vecs < min_vecs) {
+ ret = -ERANGE;
+ goto out_fail;
+ }
+ }
+
+ ret = msi_capability_init(dev, vecs);
+ if (ret)
+ goto out_fail;
+
+ return vecs;
+
+out_fail:
+ kfree(dev->irq_affinity);
+ if (ret >= 0) {
+ /* retry with the actually supported number of vectors */
+ vecs = ret;
+ goto retry;
+ }
+
+ return ret;
+}
+
static int __pci_enable_msix_range(struct pci_dev *dev, unsigned int min_vecs,
- unsigned int max_vecs)
+ unsigned int max_vecs, unsigned int flags)
{
int vecs = max_vecs, ret, i;

@@ -1138,6 +1193,13 @@ retry:
for (i = 0; i < vecs; i++)
dev->msix_vectors[i].entry = i;

+ if (!(flags & PCI_IRQ_NOAFFINITY)) {
+ dev->irq_affinity = irq_create_affinity_mask(&vecs);
+ ret = -ENOSPC;
+ if (vecs < min_vecs)
+ goto out_fail;
+ }
+
ret = pci_enable_msix(dev, dev->msix_vectors, vecs);
if (ret)
goto out_fail;
@@ -1147,6 +1209,8 @@ retry:
out_fail:
kfree(dev->msix_vectors);
dev->msix_vectors = NULL;
+ kfree(dev->irq_affinity);
+ dev->irq_affinity = NULL;

if (ret >= 0) {
/* retry with the actually supported number of vectors */
@@ -1180,13 +1244,13 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
int vecs;

if (!(flags & PCI_IRQ_NOMSIX)) {
- vecs = __pci_enable_msix_range(dev, min_vecs, max_vecs);
+ vecs = __pci_enable_msix_range(dev, 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 129871f..6a64c54 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -321,6 +321,7 @@ struct pci_dev {
*/
unsigned int irq;
struct msix_entry *msix_vectors;
+ 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_NOMSI (1 << 0) /* don't try to use MSI interrupts */
#define PCI_IRQ_NOMSIX (1 << 1) /* don't try to use MSI-X interrupts */
+#define PCI_IRQ_NOAFFINITY (1 << 2) /* don't auto-assign affinity */

/* kmem_cache style wrapper around pci_alloc_consistent() */

--
2.1.4
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