Xen devel - Oct 2011 - [PATCH] linux-2.6.18/MSI-X: Avoid unconditional BUG() in DomU

msi_remove_pci_irq_vectors() unconditionally (i.e. even in a DomU)
calling msi_unmap_pirq() is guaranteed to BUG() in msi_get_dev_owner().
Adjust the function to call evtchn_map_pirq() instead in a DomU (just
like pci_disable_msix() is doing).

While looking into this I also realized that the
CONFIG_XEN_PCIDEV_FRONTEND conditionals are misplaced - since on x86-64
it is possible to build with this disabled, execution would flow into
Dom0 code even on a DomU in this case. Hence adjust their placement at
once.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/drivers/pci/msi-xen.c
+++ b/drivers/pci/msi-xen.c
@@ -547,9 +547,8 @@ int pci_enable_msi(struct pci_dev* dev
 	if (status < 0)
 		return status;
 
+	if (!is_initial_xendomain()) {
 #ifdef CONFIG_XEN_PCIDEV_FRONTEND
-	if (!is_initial_xendomain())
-	{
 		int ret;
 
 		temp = dev->irq;
@@ -563,8 +562,10 @@ int pci_enable_msi(struct pci_dev* dev
 		msi_dev_entry->default_irq = temp;
 
 		return ret;
-	}
+#else
+		return -EOPNOTSUPP;
 #endif
+	}
 
 	temp = dev->irq;
 
@@ -592,8 +593,8 @@ void pci_disable_msi(struct pci_dev* dev
 	if (!dev)
 		return;
 
-#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 	if (!is_initial_xendomain()) {
+#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 		if (!(dev->msi_enabled)) {
 			printk(KERN_INFO "PCI: %s: Device did not enabled MSI.\n",
 			       pci_name(dev));
@@ -603,9 +604,9 @@ void pci_disable_msi(struct pci_dev* dev
 		pci_frontend_disable_msi(dev);
 		dev->irq = msi_dev_entry->default_irq;
 		dev->msi_enabled = 0;
+#endif
 		return;
 	}
-#endif
 
 	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
 	if (!pos)
@@ -663,8 +664,8 @@ void pci_disable_msix(struct pci_dev *de
 		if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)
 			return -EINVAL;
 
-#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 	if (!is_initial_xendomain()) {
+#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 		struct msi_pirq_entry *pirq_entry;
 		int ret, irq;
 
@@ -696,9 +697,11 @@ int pci_enable_msix(struct pci_dev* dev,
 			attach_pirq_entry(irq, entries[i].entry, msi_dev_entry);
 			entries[i].vector = irq;
 		}
-        return 0;
-	}
+		return 0;
+#else
+		return -EOPNOTSUPP;
 #endif
+	}
 
 	status = msi_init();
 	if (status < 0)
@@ -741,8 +744,8 @@ void pci_disable_msix(struct pci_dev *de
 		return;
 	}
 
-#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 	if (!is_initial_xendomain()) {
+#ifdef CONFIG_XEN_PCIDEV_FRONTEND
 		struct msi_dev_list *msi_dev_entry;
 		struct msi_pirq_entry *pirq_entry, *tmp;

@@ -758,9 +761,9 @@ void pci_msix_shutdown(struct pci_dev *d

		dev->irq = msi_dev_entry->default_irq;
		dev->msix_enabled = 0;
+#endif
 		return;
 	}
-#endif
 
 	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
 	if (!pos)
@@ -800,7 +791,10 @@ void msi_remove_pci_irq_vectors(struct p
 	if (!list_empty(&msi_dev_entry->pirq_list_head))
 		list_for_each_entry_safe(pirq_entry, tmp,
 		                         &msi_dev_entry->pirq_list_head, list) {
-			msi_unmap_pirq(dev, pirq_entry->pirq);
+			if (is_initial_xendomain())
+				msi_unmap_pirq(dev, pirq_entry->pirq);
+			else
+				evtchn_map_pirq(pirq_entry->pirq, 0);
 			list_del(&pirq_entry->list);
 			kfree(pirq_entry);
 		}




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