[patch V2 25/36] PCI/MSI: Provide MSI_FLAG_MSIX_CONTIGUOUS

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

Provide a domain info flag which makes the core code check for a contiguous
MSI-X index on allocation. That's simpler than checking it at some other
domain callback in architecture code.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
 drivers/pci/msi/irqdomain.c |   16 ++++++++++++++--
 include/linux/msi.h         |    2 ++
 2 files changed, 16 insertions(+), 2 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -89,9 +89,21 @@ static int pci_msi_domain_check_cap(stru
        if (pci_msi_desc_is_multi_msi(desc) &&
            !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
                return 1;
-       else if (desc->pci.msi_attrib.is_msix && !(info->flags & 
MSI_FLAG_PCI_MSIX))
-               return -ENOTSUPP;
 
+       if (desc->pci.msi_attrib.is_msix) {
+               if (!(info->flags & MSI_FLAG_PCI_MSIX))
+                       return -ENOTSUPP;
+
+               if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
+                       unsigned int idx = 0;
+
+                       /* Check for gaps in the entry indices */
+                       for_each_msi_entry(desc, dev) {
+                               if (desc->msi_index != idx++)
+                                       return -ENOTSUPP;
+                       }
+               }
+       }
        return 0;
 }
 
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -376,6 +376,8 @@ enum {
        MSI_FLAG_LEVEL_CAPABLE          = (1 << 6),
        /* Populate sysfs on alloc() and destroy it on free() */
        MSI_FLAG_DEV_SYSFS              = (1 << 7),
+       /* MSI-X entries must be contiguous */
+       MSI_FLAG_MSIX_CONTIGUOUS        = (1 << 8),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,