Merge branch 'master' into for-next

Sync up with Linus' tree to be able to apply Cesar's patch
against newer version of the code.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 25 insertions, 1 deletions

diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index bce15cf4a8df..acedeabe589c 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -44,9 +44,11 @@
 #include <linux/rwsem.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <asm/xen/hypervisor.h>
 #include <xen/xenbus.h>
 #include <xen/xen.h>
 #include "xenbus_comms.h"
+#include <asm/xen/hypervisor.h>
 
 struct xs_stored_msg {
 	struct list_head list;
@@ -617,12 +619,34 @@ static struct xenbus_watch *find_watch(const char *token)
 
 	return NULL;
 }
+/*
+ * Certain older XenBus toolstack cannot handle reading values that are
+ * not populated. Some Xen 3.4 installation are incapable of doing this
+ * so if we are running on anything older than 4 do not attempt to read
+ * control/platform-feature-xs_reset_watches.
+ */
+static bool xen_strict_xenbus_quirk(void)
+{
+#ifdef CONFIG_X86
+	uint32_t eax, ebx, ecx, edx, base;
+
+	base = xen_cpuid_base();
+	cpuid(base + 1, &eax, &ebx, &ecx, &edx);
 
+	if ((eax >> 16) < 4)
+		return true;
+#endif
+	return false;
+
+}
 static void xs_reset_watches(void)
 {
 	int err, supported = 0;
 
-	if (!xen_hvm_domain())
+	if (!xen_hvm_domain() || xen_initial_domain())
+		return;
+
+	if (xen_strict_xenbus_quirk())
 		return;
 
 	err = xenbus_scanf(XBT_NIL, "control",