From 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Mon, 10 Jul 2017 10:10:45 +0200 Subject: [PATCH] xen/balloon: don't online new memory initially When setting up the Xenstore watch for the memory target size the new watch will fire at once. Don't try to reach the configured target size by onlining new memory in this case, as the current memory size will be smaller in almost all cases due to e.g. BIOS reserved pages. Onlining new memory will lead to more problems e.g. undesired conflicts with NVMe devices meant to be operated as block devices. Instead remember the difference between target size and current size when the watch fires for the first time and apply it to any further size changes, too. In order to avoid races between balloon.c and xen-balloon.c init calls do the xen-balloon.c initialization from balloon.c. Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Signed-off-by: Juergen Gross --- drivers/xen/balloon.c | 3 +++ drivers/xen/xen-balloon.c | 22 ++++++++++++---------- include/xen/balloon.h | 8 ++++++++ 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 50dcb68d8070..ab609255a0f3 100644 --- a/drivers/xen/balloon.c +++ b/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); diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c index e7715cb62eef..e89136ab851e 100644 --- a/drivers/xen/xen-balloon.c +++ b/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, \ diff --git a/include/xen/balloon.h b/include/xen/balloon.h index d1767dfb0d95..8906361bb50c 100644 --- a/include/xen/balloon.h +++ b/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