1 files changed, 46 insertions, 8 deletions

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 733b32fda390..46b9441b36bd 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1129,31 +1129,69 @@ static int its_alloc_device_irq(struct its_device *dev, irq_hw_number_t *hwirq)
         return 0;
 }
 
+struct its_pci_alias {
+        struct pci_dev  *pdev;
+        u32             dev_id;
+        u32             count;
+};
+
+static int its_pci_msi_vec_count(struct pci_dev *pdev)
+{
+        int msi, msix;
+
+        msi = max(pci_msi_vec_count(pdev), 0);
+        msix = max(pci_msix_vec_count(pdev), 0);
+
+        return max(msi, msix);
+}
+
+static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
+{
+        struct its_pci_alias *dev_alias = data;
+
+        dev_alias->dev_id = alias;
+        if (pdev != dev_alias->pdev)
+                dev_alias->count += its_pci_msi_vec_count(dev_alias->pdev);
+
+        return 0;
+}
+
 static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
                            int nvec, msi_alloc_info_t *info)
 {
         struct pci_dev *pdev;
         struct its_node *its;
-        u32 dev_id;
         struct its_device *its_dev;
+        struct its_pci_alias dev_alias;
 
         if (!dev_is_pci(dev))
                 return -EINVAL;
 
         pdev = to_pci_dev(dev);
-        dev_id = PCI_DEVID(pdev->bus->number, pdev->devfn);
+        dev_alias.pdev = pdev;
+        dev_alias.count = nvec;
+
+        pci_for_each_dma_alias(pdev, its_get_pci_alias, &dev_alias);
         its = domain->parent->host_data;
 
-        its_dev = its_find_device(its, dev_id);
-        if (WARN_ON(its_dev))
-                return -EINVAL;
+        its_dev = its_find_device(its, dev_alias.dev_id);
+        if (its_dev) {
+                /*
+                 * We already have seen this ID, probably through
+                 * another alias (PCI bridge of some sort). No need to
+                 * create the device.
+                 */
+                dev_dbg(dev, "Reusing ITT for devID %x\n", dev_alias.dev_id);
+                goto out;
+        }
 
-        its_dev = its_create_device(its, dev_id, nvec);
+        its_dev = its_create_device(its, dev_alias.dev_id, dev_alias.count);
         if (!its_dev)
                 return -ENOMEM;
 
-        dev_dbg(&pdev->dev, "ITT %d entries, %d bits\n", nvec, ilog2(nvec));
-
+        dev_dbg(&pdev->dev, "ITT %d entries, %d bits\n",
+                dev_alias.count, ilog2(dev_alias.count));
+out:
         info->scratchpad[0].ptr = its_dev;
         info->scratchpad[1].ptr = dev;
         return 0;