From 0e4d394fe50308f69eb061eb89de78279df1e9dc Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Mon, 26 Jun 2017 18:39:30 +0200 Subject: [PATCH 1/4] xen/x86: Don't BUG on CPU0 offlining CONFIG_BOOTPARAM_HOTPLUG_CPU0 allows to offline CPU0 but Xen HVM guests BUG() in xen_teardown_timer(). Remove the BUG_ON(), this is probably a leftover from ancient times when CPU0 hotplug was impossible, it works just fine for HVM. Signed-off-by: Vitaly Kuznetsov Acked-by: Juergen Gross Signed-off-by: Juergen Gross --- arch/x86/xen/time.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index a1895a8e85c1..1ecb05db3632 100644 --- a/arch/x86/xen/time.c +++ b/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) { From 29d11cfd8698038b87458ba4d1329b9da81150a5 Mon Sep 17 00:00:00 2001 From: Wengang Wang Date: Tue, 18 Jul 2017 09:40:35 +0200 Subject: [PATCH 2/4] xen/grant-table: log the lack of grants log a message when we enter this situation: 1) we already allocated the max number of available grants from hypervisor and 2) we still need more (but the request fails because of 1)). Sometimes the lack of grants causes IO hangs in xen_blkfront devices. Adding this log would help debuging. Signed-off-by: Wengang Wang Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Junxiao Bi Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- drivers/xen/grant-table.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index d6786b87e13b..2c6a9114d332 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -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) From c185ddec54657c145a0c2055e4b87918da24974f Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 5 Jul 2017 16:05:20 +0200 Subject: [PATCH 3/4] xen/x86: fix cpu hotplug Commit dc6416f1d711eb4c1726e845d653235dcaae12e1 ("xen/x86: Call cpu_startup_entry(CPUHP_AP_ONLINE_IDLE) from xen_play_dead()") introduced an error leading to a stack overflow of the idle task when a cpu was brought offline/online many times: by calling cpu_startup_entry() instead of returning at the end of xen_play_dead() do_idle() would be entered again and again. Don't use cpu_startup_entry(), but cpuhp_online_idle() instead allowing to return from xen_play_dead(). Cc: # 4.12 Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Signed-off-by: Juergen Gross --- arch/x86/xen/smp_pv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 1ea598e5f030..51471408fdd1 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -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 */ From 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Mon, 10 Jul 2017 10:10:45 +0200 Subject: [PATCH 4/4] 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