diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 8634e1b49c039fad57cb149e69e9a7b27116a50a..8c4085a95ef153354aa7b58ddd4b48a588de5e53 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -20,7 +20,8 @@
 #include <asm/xen/pci.h>
 
 #ifdef CONFIG_ACPI
-static int xen_hvm_register_pirq(u32 gsi, int triggering)
+static int acpi_register_gsi_xen_hvm(struct device *dev, u32 gsi,
+				 int trigger, int polarity)
 {
 	int rc, irq;
 	struct physdev_map_pirq map_irq;
@@ -41,7 +42,7 @@ static int xen_hvm_register_pirq(u32 gsi, int triggering)
 		return -1;
 	}
 
-	if (triggering == ACPI_EDGE_SENSITIVE) {
+	if (trigger == ACPI_EDGE_SENSITIVE) {
 		shareable = 0;
 		name = "ioapic-edge";
 	} else {
@@ -55,12 +56,6 @@ static int xen_hvm_register_pirq(u32 gsi, int triggering)
 
 	return irq;
 }
-
-static int acpi_register_gsi_xen_hvm(struct device *dev, u32 gsi,
-				 int trigger, int polarity)
-{
-	return xen_hvm_register_pirq(gsi, trigger);
-}
 #endif
 
 #if defined(CONFIG_PCI_MSI)
@@ -91,7 +86,7 @@ static void xen_msi_compose_msg(struct pci_dev *pdev, unsigned int pirq,
 
 static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 {
-	int irq, pirq, ret = 0;
+	int irq, pirq;
 	struct msi_desc *msidesc;
 	struct msi_msg msg;
 
@@ -99,39 +94,32 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 		__read_msi_msg(msidesc, &msg);
 		pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
 			((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
-		if (xen_irq_from_pirq(pirq) >= 0 && msg.data == XEN_PIRQ_MSI_DATA) {
-			xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
-					"msi-x" : "msi", &irq, &pirq, XEN_ALLOC_IRQ);
-			if (irq < 0)
+		if (msg.data != XEN_PIRQ_MSI_DATA ||
+		    xen_irq_from_pirq(pirq) < 0) {
+			pirq = xen_allocate_pirq_msi(dev, msidesc);
+			if (pirq < 0)
 				goto error;
-			ret = set_irq_msi(irq, msidesc);
-			if (ret < 0)
-				goto error_while;
-			printk(KERN_DEBUG "xen: msi already setup: msi --> irq=%d"
-					" pirq=%d\n", irq, pirq);
-			return 0;
+			xen_msi_compose_msg(dev, pirq, &msg);
+			__write_msi_msg(msidesc, &msg);
+			dev_dbg(&dev->dev, "xen: msi bound to pirq=%d\n", pirq);
+		} else {
+			dev_dbg(&dev->dev,
+				"xen: msi already bound to pirq=%d\n", pirq);
 		}
-		xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
-				"msi-x" : "msi", &irq, &pirq, (XEN_ALLOC_IRQ | XEN_ALLOC_PIRQ));
-		if (irq < 0 || pirq < 0)
+		irq = xen_bind_pirq_msi_to_irq(dev, msidesc, pirq, 0,
+					       (type == PCI_CAP_ID_MSIX) ?
+					       "msi-x" : "msi");
+		if (irq < 0)
 			goto error;
-		printk(KERN_DEBUG "xen: msi --> irq=%d, pirq=%d\n", irq, pirq);
-		xen_msi_compose_msg(dev, pirq, &msg);
-		ret = set_irq_msi(irq, msidesc);
-		if (ret < 0)
-			goto error_while;
-		write_msi_msg(irq, &msg);
+		dev_dbg(&dev->dev,
+			"xen: msi --> pirq=%d --> irq=%d\n", pirq, irq);
 	}
 	return 0;
 
-error_while:
-	unbind_from_irqhandler(irq, NULL);
 error:
-	if (ret == -ENODEV)
-		dev_err(&dev->dev, "Xen PCI frontend has not registered" \
-				" MSI/MSI-X support!\n");
-
-	return ret;
+	dev_err(&dev->dev,
+		"Xen PCI frontend has not registered MSI/MSI-X support!\n");
+	return -ENODEV;
 }
 
 /*
@@ -157,28 +145,19 @@ static int xen_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 		goto error;
 	i = 0;
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
-		xen_allocate_pirq_msi(
-			(type == PCI_CAP_ID_MSIX) ?
-			"pcifront-msi-x" : "pcifront-msi",
-			&irq, &v[i], XEN_ALLOC_IRQ);
-		if (irq < 0) {
-			ret = -1;
+		irq = xen_bind_pirq_msi_to_irq(dev, msidesc, v[i], 0,
+					       (type == PCI_CAP_ID_MSIX) ?
+					       "pcifront-msi-x" :
+					       "pcifront-msi");
+		if (irq < 0)
 			goto free;
-		}
-		ret = set_irq_msi(irq, msidesc);
-		if (ret)
-			goto error_while;
 		i++;
 	}
 	kfree(v);
 	return 0;
 
-error_while:
-	unbind_from_irqhandler(irq, NULL);
 error:
-	if (ret == -ENODEV)
-		dev_err(&dev->dev, "Xen PCI frontend has not registered" \
-			" MSI/MSI-X support!\n");
+	dev_err(&dev->dev, "Xen PCI frontend has not registered MSI/MSI-X support!\n");
 free:
 	kfree(v);
 	return ret;
@@ -203,27 +182,56 @@ static void xen_teardown_msi_irq(unsigned int irq)
 	xen_destroy_irq(irq);
 }
 
+#ifdef CONFIG_XEN_DOM0
 static int xen_initdom_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 {
-	int irq, ret;
+	int ret = 0;
 	struct msi_desc *msidesc;
 
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
-		irq = xen_create_msi_irq(dev, msidesc, type);
-		if (irq < 0)
-			return -1;
+		struct physdev_map_pirq map_irq;
 
-		ret = set_irq_msi(irq, msidesc);
-		if (ret)
-			goto error;
-	}
-	return 0;
+		memset(&map_irq, 0, sizeof(map_irq));
+		map_irq.domid = DOMID_SELF;
+		map_irq.type = MAP_PIRQ_TYPE_MSI;
+		map_irq.index = -1;
+		map_irq.pirq = -1;
+		map_irq.bus = dev->bus->number;
+		map_irq.devfn = dev->devfn;
 
-error:
-	xen_destroy_irq(irq);
+		if (type == PCI_CAP_ID_MSIX) {
+			int pos;
+			u32 table_offset, bir;
+
+			pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
+
+			pci_read_config_dword(dev, pos + PCI_MSIX_TABLE,
+					      &table_offset);
+			bir = (u8)(table_offset & PCI_MSIX_FLAGS_BIRMASK);
+
+			map_irq.table_base = pci_resource_start(dev, bir);
+			map_irq.entry_nr = msidesc->msi_attrib.entry_nr;
+		}
+
+		ret = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
+		if (ret) {
+			dev_warn(&dev->dev, "xen map irq failed %d\n", ret);
+			goto out;
+		}
+
+		ret = xen_bind_pirq_msi_to_irq(dev, msidesc,
+					       map_irq.pirq, map_irq.index,
+					       (type == PCI_CAP_ID_MSIX) ?
+					       "msi-x" : "msi");
+		if (ret < 0)
+			goto out;
+	}
+	ret = 0;
+out:
 	return ret;
 }
 #endif
+#endif
 
 static int xen_pcifront_enable_irq(struct pci_dev *dev)
 {
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 89987a7bf26fe57527370e2227ad09adc9c50594..6befe62271598b0b858185befce03211ef58d154 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -644,104 +644,46 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name)
 }
 
 #ifdef CONFIG_PCI_MSI
-#include <linux/msi.h>
-#include "../pci/msi.h"
-
-static int find_unbound_pirq(int type)
+int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc)
 {
-	int rc, i;
+	int rc;
 	struct physdev_get_free_pirq op_get_free_pirq;
-	op_get_free_pirq.type = type;
 
+	op_get_free_pirq.type = MAP_PIRQ_TYPE_MSI;
 	rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);
-	if (!rc)
-		return op_get_free_pirq.pirq;
-
-	for (i = 0; i < nr_irqs; i++) {
-		if (pirq_to_irq[i] < 0)
-			return i;
-	}
-	return -1;
-}
-
-void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc)
-{
-	spin_lock(&irq_mapping_update_lock);
-
-	if (alloc & XEN_ALLOC_IRQ) {
-		*irq = xen_allocate_irq_dynamic();
-		if (*irq == -1)
-			goto out;
-	}
-
-	if (alloc & XEN_ALLOC_PIRQ) {
-		*pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
-		if (*pirq == -1)
-			goto out;
-	}
-
-	set_irq_chip_and_handler_name(*irq, &xen_pirq_chip,
-				      handle_level_irq, name);
 
-	irq_info[*irq] = mk_pirq_info(0, *pirq, 0, 0);
-	pirq_to_irq[*pirq] = *irq;
+	WARN_ONCE(rc == -ENOSYS,
+		  "hypervisor does not support the PHYSDEVOP_get_free_pirq interface\n");
 
-out:
-	spin_unlock(&irq_mapping_update_lock);
+	return rc ? -1 : op_get_free_pirq.pirq;
 }
 
-int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int type)
+int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
+			     int pirq, int vector, const char *name)
 {
-	int irq = -1;
-	struct physdev_map_pirq map_irq;
-	int rc;
-	int pos;
-	u32 table_offset, bir;
-
-	memset(&map_irq, 0, sizeof(map_irq));
-	map_irq.domid = DOMID_SELF;
-	map_irq.type = MAP_PIRQ_TYPE_MSI;
-	map_irq.index = -1;
-	map_irq.pirq = -1;
-	map_irq.bus = dev->bus->number;
-	map_irq.devfn = dev->devfn;
-
-	if (type == PCI_CAP_ID_MSIX) {
-		pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
-
-		pci_read_config_dword(dev, msix_table_offset_reg(pos),
-					&table_offset);
-		bir = (u8)(table_offset & PCI_MSIX_FLAGS_BIRMASK);
-
-		map_irq.table_base = pci_resource_start(dev, bir);
-		map_irq.entry_nr = msidesc->msi_attrib.entry_nr;
-	}
+	int irq, ret;
 
 	spin_lock(&irq_mapping_update_lock);
 
 	irq = xen_allocate_irq_dynamic();
-
 	if (irq == -1)
 		goto out;
 
-	rc = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
-	if (rc) {
-		printk(KERN_WARNING "xen map irq failed %d\n", rc);
-
-		xen_free_irq(irq);
-
-		irq = -1;
-		goto out;
-	}
-	irq_info[irq] = mk_pirq_info(0, map_irq.pirq, 0, map_irq.index);
-
 	set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
-			handle_level_irq,
-			(type == PCI_CAP_ID_MSIX) ? "msi-x":"msi");
+				      handle_level_irq, name);
 
+	irq_info[irq] = mk_pirq_info(0, pirq, 0, vector);
+	pirq_to_irq[pirq] = irq;
+	ret = set_irq_msi(irq, msidesc);
+	if (ret < 0)
+		goto error_irq;
 out:
 	spin_unlock(&irq_mapping_update_lock);
 	return irq;
+error_irq:
+	spin_unlock(&irq_mapping_update_lock);
+	xen_free_irq(irq);
+	return -1;
 }
 #endif
 
diff --git a/include/xen/events.h b/include/xen/events.h
index 00f53ddcc06284658d33ff80d66908e2b394d4ca..962da2ced5b4dc358e5980f1429f3fb659ddd054 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -75,11 +75,9 @@ int xen_allocate_pirq(unsigned gsi, int shareable, char *name);
 int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name);
 
 #ifdef CONFIG_PCI_MSI
-/* Allocate an irq and a pirq to be used with MSIs. */
-#define XEN_ALLOC_PIRQ (1 << 0)
-#define XEN_ALLOC_IRQ  (1 << 1)
-void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc_mask);
-int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int type);
+int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc);
+int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
+			     int pirq, int vector, const char *name);
 #endif
 
 /* De-allocates the above mentioned physical interrupt. */