diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 56ab749..94e7662 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -162,6 +162,9 @@
 	struct msi_desc *msidesc;
 	int *v;
 
+	if (type == PCI_CAP_ID_MSI && nvec > 1)
+		return 1;
+
 	v = kzalloc(sizeof(int) * max(1, nvec), GFP_KERNEL);
 	if (!v)
 		return -ENOMEM;
@@ -220,6 +223,9 @@
 	struct msi_desc *msidesc;
 	struct msi_msg msg;
 
+	if (type == PCI_CAP_ID_MSI && nvec > 1)
+		return 1;
+
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
 		__read_msi_msg(msidesc, &msg);
 		pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
@@ -263,6 +269,9 @@
 	int ret = 0;
 	struct msi_desc *msidesc;
 
+	if (type == PCI_CAP_ID_MSI && nvec > 1)
+		return 1;
+
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
 		struct physdev_map_pirq map_irq;
 		domid_t domid;
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 39928d1..c8e1c7b 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -67,6 +67,7 @@
 #include <asm/hypervisor.h>
 #include <asm/mwait.h>
 #include <asm/pci_x86.h>
+#include <asm/pat.h>
 
 #ifdef CONFIG_ACPI
 #include <linux/acpi.h>
@@ -1417,7 +1418,14 @@
 	 */
 	acpi_numa = -1;
 #endif
-
+#ifdef CONFIG_X86_PAT
+	/*
+	 * For right now disable the PAT. We should remove this once
+	 * git commit 8eaffa67b43e99ae581622c5133e20b0f48bcef1
+	 * (xen/pat: Disable PAT support for now) is reverted.
+	 */
+	pat_enabled = 0;
+#endif
 	/* Don't do the full vcpu_info placement stuff until we have a
 	   possible map and a non-dummy shared_info. */
 	per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
diff --git a/drivers/xen/xen-acpi-cpuhotplug.c b/drivers/xen/xen-acpi-cpuhotplug.c
index 7578279..18c742b 100644
--- a/drivers/xen/xen-acpi-cpuhotplug.c
+++ b/drivers/xen/xen-acpi-cpuhotplug.c
@@ -239,24 +239,6 @@
 	return AE_OK;
 }
 
-static
-int acpi_processor_device_add(acpi_handle handle, struct acpi_device **device)
-{
-	acpi_handle phandle;
-	struct acpi_device *pdev;
-
-	if (acpi_get_parent(handle, &phandle))
-		return -ENODEV;
-
-	if (acpi_bus_get_device(phandle, &pdev))
-		return -ENODEV;
-
-	if (acpi_bus_scan(handle))
-		return -ENODEV;
-
-	return 0;
-}
-
 static int acpi_processor_device_remove(struct acpi_device *device)
 {
 	pr_debug(PREFIX "Xen does not support CPU hotremove\n");
@@ -272,6 +254,8 @@
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
 	int result;
 
+	acpi_scan_lock_acquire();
+
 	switch (event) {
 	case ACPI_NOTIFY_BUS_CHECK:
 	case ACPI_NOTIFY_DEVICE_CHECK:
@@ -286,12 +270,16 @@
 		if (!acpi_bus_get_device(handle, &device))
 			break;
 
-		result = acpi_processor_device_add(handle, &device);
+		result = acpi_bus_scan(handle);
 		if (result) {
 			pr_err(PREFIX "Unable to add the device\n");
 			break;
 		}
-
+		result = acpi_bus_get_device(handle, &device);
+		if (result) {
+			pr_err(PREFIX "Missing device object\n");
+			break;
+		}
 		ost_code = ACPI_OST_SC_SUCCESS;
 		break;
 
@@ -321,11 +309,13 @@
 				  "Unsupported event [0x%x]\n", event));
 
 		/* non-hotplug event; possibly handled by other handler */
-		return;
+		goto out;
 	}
 
 	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
-	return;
+
+out:
+	acpi_scan_lock_release();
 }
 
 static acpi_status is_processor_device(acpi_handle handle)
diff --git a/drivers/xen/xen-acpi-memhotplug.c b/drivers/xen/xen-acpi-memhotplug.c
index 853b12d..faef5b3 100644
--- a/drivers/xen/xen-acpi-memhotplug.c
+++ b/drivers/xen/xen-acpi-memhotplug.c
@@ -158,50 +158,46 @@
 	return 0;
 }
 
-static int
-acpi_memory_get_device(acpi_handle handle,
-		       struct acpi_memory_device **mem_device)
+static int acpi_memory_get_device(acpi_handle handle,
+				  struct acpi_memory_device **mem_device)
 {
-	acpi_status status;
-	acpi_handle phandle;
 	struct acpi_device *device = NULL;
-	struct acpi_device *pdevice = NULL;
-	int result;
+	int result = 0;
 
-	if (!acpi_bus_get_device(handle, &device) && device)
+	acpi_scan_lock_acquire();
+
+	acpi_bus_get_device(handle, &device);
+	if (device)
 		goto end;
 
-	status = acpi_get_parent(handle, &phandle);
-	if (ACPI_FAILURE(status)) {
-		pr_warn(PREFIX "Cannot find acpi parent\n");
-		return -EINVAL;
-	}
-
-	/* Get the parent device */
-	result = acpi_bus_get_device(phandle, &pdevice);
-	if (result) {
-		pr_warn(PREFIX "Cannot get acpi bus device\n");
-		return -EINVAL;
-	}
-
 	/*
 	 * Now add the notified device.  This creates the acpi_device
 	 * and invokes .add function
 	 */
 	result = acpi_bus_scan(handle);
 	if (result) {
-		pr_warn(PREFIX "Cannot add acpi bus\n");
-		return -EINVAL;
+		pr_warn(PREFIX "ACPI namespace scan failed\n");
+		result = -EINVAL;
+		goto out;
+	}
+	result = acpi_bus_get_device(handle, &device);
+	if (result) {
+		pr_warn(PREFIX "Missing device object\n");
+		result = -EINVAL;
+		goto out;
 	}
 
 end:
 	*mem_device = acpi_driver_data(device);
 	if (!(*mem_device)) {
-		pr_err(PREFIX "Driver data not found\n");
-		return -ENODEV;
+		pr_err(PREFIX "driver data not found\n");
+		result = -ENODEV;
+		goto out;
 	}
 
-	return 0;
+out:
+	acpi_scan_lock_release();
+	return result;
 }
 
 static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
@@ -259,12 +255,15 @@
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 			"\nReceived EJECT REQUEST notification for device\n"));
 
+		acpi_scan_lock_acquire();
 		if (acpi_bus_get_device(handle, &device)) {
+			acpi_scan_lock_release();
 			pr_err(PREFIX "Device doesn't exist\n");
 			break;
 		}
 		mem_device = acpi_driver_data(device);
 		if (!mem_device) {
+			acpi_scan_lock_release();
 			pr_err(PREFIX "Driver Data is NULL\n");
 			break;
 		}
@@ -274,6 +273,7 @@
 		 * acpi_bus_remove if Xen support hotremove in the future
 		 */
 		acpi_memory_disable_device(mem_device);
+		acpi_scan_lock_release();
 		break;
 
 	default:
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index bcf3ba4..61786be 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -30,6 +30,7 @@
  * IN THE SOFTWARE.
  */
 
+#include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/spinlock.h>