diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 5b6a40dd5556..3aa37669ff8c 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -355,11 +355,17 @@ config HARDWALL
 config KERNEL_PL
 	int "Processor protection level for kernel"
 	range 1 2
-	default "1"
+	default 2 if TILEGX
+	default 1 if !TILEGX
 	---help---
-	  This setting determines the processor protection level the
-	  kernel will be built to run at.  Generally you should use
-	  the default value here.
+	  Since MDE 4.2, the Tilera hypervisor runs the kernel
+	  at PL2 by default.  If running under an older hypervisor,
+	  or as a KVM guest, you must run at PL1.  (The current
+	  hypervisor may also be recompiled with "make HV_PL=2" to
+	  allow it to run a kernel at PL1, but clients running at PL1
+	  are not expected to be supported indefinitely.)
+
+	  If you're not sure, don't change the default.
 
 source "arch/tile/gxio/Kconfig"
 
diff --git a/arch/tile/include/hv/hypervisor.h b/arch/tile/include/hv/hypervisor.h
index ccd847e2347f..837dca5328c2 100644
--- a/arch/tile/include/hv/hypervisor.h
+++ b/arch/tile/include/hv/hypervisor.h
@@ -107,7 +107,22 @@
 #define HV_DISPATCH_ENTRY_SIZE 32
 
 /** Version of the hypervisor interface defined by this file */
-#define _HV_VERSION 11
+#define _HV_VERSION 13
+
+/** Last version of the hypervisor interface with old hv_init() ABI.
+ *
+ * The change from version 12 to version 13 corresponds to launching
+ * the client by default at PL2 instead of PL1 (corresponding to the
+ * hv itself running at PL3 instead of PL2).  To make this explicit,
+ * the hv_init() API was also extended so the client can report its
+ * desired PL, resulting in a more helpful failure diagnostic.  If you
+ * call hv_init() with _HV_VERSION_OLD_HV_INIT and omit the client_pl
+ * argument, the hypervisor will assume client_pl = 1.
+ *
+ * Note that this is a deprecated solution and we do not expect to
+ * support clients of the Tilera hypervisor running at PL1 indefinitely.
+ */
+#define _HV_VERSION_OLD_HV_INIT 12
 
 /* Index into hypervisor interface dispatch code blocks.
  *
@@ -377,7 +392,11 @@ typedef int HV_Errno;
 #ifndef __ASSEMBLER__
 
 /** Pass HV_VERSION to hv_init to request this version of the interface. */
-typedef enum { HV_VERSION = _HV_VERSION } HV_VersionNumber;
+typedef enum {
+  HV_VERSION = _HV_VERSION,
+  HV_VERSION_OLD_HV_INIT = _HV_VERSION_OLD_HV_INIT,
+
+} HV_VersionNumber;
 
 /** Initializes the hypervisor.
  *
@@ -385,9 +404,11 @@ typedef enum { HV_VERSION = _HV_VERSION } HV_VersionNumber;
  * that this program expects, typically HV_VERSION.
  * @param chip_num Architecture number of the chip the client was built for.
  * @param chip_rev_num Revision number of the chip the client was built for.
+ * @param client_pl Privilege level the client is built for
+ *   (not required if interface_version_number == HV_VERSION_OLD_HV_INIT).
  */
 void hv_init(HV_VersionNumber interface_version_number,
-             int chip_num, int chip_rev_num);
+             int chip_num, int chip_rev_num, int client_pl);
 
 
 /** Queries we can make for hv_sysconf().
diff --git a/arch/tile/kernel/head_32.S b/arch/tile/kernel/head_32.S
index f71bfeeaf1a9..ac115307e5e4 100644
--- a/arch/tile/kernel/head_32.S
+++ b/arch/tile/kernel/head_32.S
@@ -38,7 +38,7 @@ ENTRY(_start)
 	  movei r2, TILE_CHIP_REV
 	}
 	{
-	  moveli r0, _HV_VERSION
+	  moveli r0, _HV_VERSION_OLD_HV_INIT
 	  jal hv_init
 	}
 	/* Get a reasonable default ASID in r0 */
diff --git a/arch/tile/kernel/head_64.S b/arch/tile/kernel/head_64.S
index f9a2734f7b82..6093964fa5c7 100644
--- a/arch/tile/kernel/head_64.S
+++ b/arch/tile/kernel/head_64.S
@@ -34,13 +34,19 @@
 ENTRY(_start)
 	/* Notify the hypervisor of what version of the API we want */
 	{
+#if KERNEL_PL == 1 && _HV_VERSION == 13
+	  /* Support older hypervisors by asking for API version 12. */
+	  movei r0, _HV_VERSION_OLD_HV_INIT
+#else
+	  movei r0, _HV_VERSION
+#endif
 	  movei r1, TILE_CHIP
-	  movei r2, TILE_CHIP_REV
 	}
 	{
-	  moveli r0, _HV_VERSION
-	  jal hv_init
+	  movei r2, TILE_CHIP_REV
+	  movei r3, KERNEL_PL
 	}
+	jal hv_init
 	/* Get a reasonable default ASID in r0 */
 	{
 	  move r0, zero
diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c
index b16ac49a968e..b34f79aada48 100644
--- a/arch/tile/lib/spinlock_32.c
+++ b/arch/tile/lib/spinlock_32.c
@@ -101,7 +101,7 @@ EXPORT_SYMBOL(arch_spin_unlock_wait);
  * preserve the semantic that the same read lock can be acquired in an
  * interrupt context.
  */
-inline int arch_read_trylock(arch_rwlock_t *rwlock)
+int arch_read_trylock(arch_rwlock_t *rwlock)
 {
 	u32 val;
 	__insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 1);
diff --git a/drivers/net/ethernet/tile/tilegx.c b/drivers/net/ethernet/tile/tilegx.c
index 66e025ad5df1..f3c2d034b32c 100644
--- a/drivers/net/ethernet/tile/tilegx.c
+++ b/drivers/net/ethernet/tile/tilegx.c
@@ -930,7 +930,7 @@ static int tile_net_setup_interrupts(struct net_device *dev)
 		if (info->has_iqueue) {
 			gxio_mpipe_request_notif_ring_interrupt(
 				&context, cpu_x(cpu), cpu_y(cpu),
-				1, ingress_irq, info->iqueue.ring);
+				KERNEL_PL, ingress_irq, info->iqueue.ring);
 		}
 	}
 
diff --git a/drivers/rtc/rtc-tile.c b/drivers/rtc/rtc-tile.c
index 249b6531f119..fc3dee95f166 100644
--- a/drivers/rtc/rtc-tile.c
+++ b/drivers/rtc/rtc-tile.c
@@ -146,6 +146,7 @@ exit_driver_unregister:
  */
 static void __exit tile_rtc_driver_exit(void)
 {
+	platform_device_unregister(tile_rtc_platform_device);
 	platform_driver_unregister(&tile_rtc_platform_driver);
 }
 
diff --git a/drivers/usb/host/ehci-tilegx.c b/drivers/usb/host/ehci-tilegx.c
index 1d215cdb9dea..b083a350eea3 100644
--- a/drivers/usb/host/ehci-tilegx.c
+++ b/drivers/usb/host/ehci-tilegx.c
@@ -118,8 +118,10 @@ static int ehci_hcd_tilegx_drv_probe(struct platform_device *pdev)
 
 	hcd = usb_create_hcd(&ehci_tilegx_hc_driver, &pdev->dev,
 			     dev_name(&pdev->dev));
-	if (!hcd)
-		return -ENOMEM;
+	if (!hcd) {
+          ret = -ENOMEM;
+          goto err_hcd;
+        }
 
 	/*
 	 * We don't use rsrc_start to map in our registers, but seems like
@@ -176,6 +178,7 @@ err_have_irq:
 err_no_irq:
 	tilegx_stop_ehc();
 	usb_put_hcd(hcd);
+err_hcd:
 	gxio_usb_host_destroy(&pdata->usb_ctx);
 	return ret;
 }
diff --git a/drivers/usb/host/ohci-tilegx.c b/drivers/usb/host/ohci-tilegx.c
index 1ae7b28a71c2..ea73009de623 100644
--- a/drivers/usb/host/ohci-tilegx.c
+++ b/drivers/usb/host/ohci-tilegx.c
@@ -112,8 +112,10 @@ static int ohci_hcd_tilegx_drv_probe(struct platform_device *pdev)
 
 	hcd = usb_create_hcd(&ohci_tilegx_hc_driver, &pdev->dev,
 			     dev_name(&pdev->dev));
-	if (!hcd)
-		return -ENOMEM;
+	if (!hcd) {
+		ret = -ENOMEM;
+		goto err_hcd;
+	}
 
 	/*
 	 * We don't use rsrc_start to map in our registers, but seems like
@@ -165,6 +167,7 @@ err_have_irq:
 err_no_irq:
 	tilegx_stop_ohc();
 	usb_put_hcd(hcd);
+err_hcd:
 	gxio_usb_host_destroy(&pdata->usb_ctx);
 	return ret;
 }