Merge tag 'for-linus-4.13b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:
 "Some fixes and cleanups for running under Xen"

* tag 'for-linus-4.13b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: don't online new memory initially
  xen/x86: fix cpu hotplug
  xen/grant-table: log the lack of grants
  xen/x86: Don't BUG on CPU0 offlining

Author: torvalds

arch/x86/xen/smp_pv.c

@@ -19,6 +19,7 @@
 #include <linux/irq_work.h>
 #include <linux/tick.h>
 #include <linux/nmi.h>
+#include <linux/cpuhotplug.h>
 
 #include <asm/paravirt.h>
 #include <asm/desc.h>
@@ -413,7 +414,7 @@ static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
 	 */
 	tick_nohz_idle_enter();
 
-	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+	cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
 }
 
 #else /* !CONFIG_HOTPLUG_CPU */

arch/x86/xen/time.c

@@ -309,7 +309,6 @@ static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
 void xen_teardown_timer(int cpu)
 {
 	struct clock_event_device *evt;
-	BUG_ON(cpu == 0);
 	evt = &per_cpu(xen_clock_events, cpu).evt;
 
 	if (evt->irq >= 0) {

drivers/xen/balloon.c

@@ -780,6 +780,9 @@ static int __init balloon_init(void)
 	}
 #endif
 
+	/* Init the xen-balloon driver. */
+	xen_balloon_init();
+
 	return 0;
 }
 subsys_initcall(balloon_init);

drivers/xen/grant-table.c

@@ -42,6 +42,7 @@
 #include <linux/delay.h>
 #include <linux/hardirq.h>
 #include <linux/workqueue.h>
+#include <linux/ratelimit.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
@@ -1072,8 +1073,14 @@ static int gnttab_expand(unsigned int req_entries)
 	cur = nr_grant_frames;
 	extra = ((req_entries + (grefs_per_grant_frame-1)) /
 		 grefs_per_grant_frame);
-	if (cur + extra > gnttab_max_grant_frames())
+	if (cur + extra > gnttab_max_grant_frames()) {
+		pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
+				    " cur=%u extra=%u limit=%u"
+				    " gnttab_free_count=%u req_entries=%u\n",
+				    cur, extra, gnttab_max_grant_frames(),
+				    gnttab_free_count, req_entries);
 		return -ENOSPC;
+	}
 
 	rc = gnttab_map(cur, cur + extra - 1);
 	if (rc == 0)

drivers/xen/xen-balloon.c

@@ -59,6 +59,8 @@ static void watch_target(struct xenbus_watch *watch,
 {
 	unsigned long long new_target;
 	int err;
+	static bool watch_fired;
+	static long target_diff;
 
 	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
 	if (err != 1) {
@@ -69,7 +71,14 @@ static void watch_target(struct xenbus_watch *watch,
 	/* The given memory/target value is in KiB, so it needs converting to
 	 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
 	 */
-	balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
+	new_target >>= PAGE_SHIFT - 10;
+	if (watch_fired) {
+		balloon_set_new_target(new_target - target_diff);
+		return;
+	}
+
+	watch_fired = true;
+	target_diff = new_target - balloon_stats.target_pages;
 }
 static struct xenbus_watch target_watch = {
 	.node = "memory/target",
@@ -94,22 +103,15 @@ static struct notifier_block xenstore_notifier = {
 	.notifier_call = balloon_init_watcher,
 };
 
-static int __init balloon_init(void)
+void xen_balloon_init(void)
 {
-	if (!xen_domain())
-		return -ENODEV;
-
-	pr_info("Initialising balloon driver\n");
-
 	register_balloon(&balloon_dev);
 
 	register_xen_selfballooning(&balloon_dev);
 
 	register_xenstore_notifier(&xenstore_notifier);
-
-	return 0;
 }
-subsys_initcall(balloon_init);
+EXPORT_SYMBOL_GPL(xen_balloon_init);
 
 #define BALLOON_SHOW(name, format, args...)				\
 	static ssize_t show_##name(struct device *dev,			\

include/xen/balloon.h

@@ -35,3 +35,11 @@ static inline int register_xen_selfballooning(struct device *dev)
 	return -ENOSYS;
 }
 #endif
+
+#ifdef CONFIG_XEN_BALLOON
+void xen_balloon_init(void);
+#else
+static inline void xen_balloon_init(void)
+{
+}
+#endif