patch-0003-xen-add-new-cpu-notifier-action-CPU_RESUME_FAILED.patch

From b14779c4ada96c52d0c1964fcf6ef20416012478 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Tue, 2 Apr 2019 07:34:54 +0200
Subject: [PATCH 3/9] xen: add new cpu notifier action CPU_RESUME_FAILED

Add a new cpu notifier action CPU_RESUME_FAILED which is called for all
cpus which failed to come up at resume. The calls will be done after
all other cpus are already up in order to know which resources are
available then.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
(cherry picked from commit 51c79e943fb3f9a746181f8b8415cf2baa5d26bd)
---
 xen/common/cpu.c      |  5 +++++
 xen/include/xen/cpu.h | 29 ++++++++++++++++++-----------
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/xen/common/cpu.c b/xen/common/cpu.c
index ccf62b5e013e..8dca74cbb0bd 100644
--- a/xen/common/cpu.c
+++ b/xen/common/cpu.c
@@ -215,7 +215,12 @@ void enable_nonboot_cpus(void)
             printk("Error bringing CPU%d up: %d\n", cpu, error);
             BUG_ON(error == -EBUSY);
         }
+        else
+            __cpumask_clear_cpu(cpu, &frozen_cpus);
     }
 
+    for_each_cpu ( cpu, &frozen_cpus )
+        cpu_notifier_call_chain(cpu, CPU_RESUME_FAILED, NULL, true);
+
     cpumask_clear(&frozen_cpus);
 }
diff --git a/xen/include/xen/cpu.h b/xen/include/xen/cpu.h
index 2fe3ec05d851..4638c509e271 100644
--- a/xen/include/xen/cpu.h
+++ b/xen/include/xen/cpu.h
@@ -22,33 +22,40 @@ void register_cpu_notifier(struct notifier_block *nb);
  *  CPU_UP_PREPARE -> CPU_STARTING -> CPU_ONLINE -- successful CPU up
  *  CPU_DOWN_PREPARE -> CPU_DOWN_FAILED          -- failed CPU down
  *  CPU_DOWN_PREPARE -> CPU_DYING -> CPU_DEAD    -- successful CPU down
- * 
+ * in the resume case we have additionally:
+ *  CPU_UP_PREPARE -> CPU_UP_CANCELLED -> CPU_RESUME_FAILED -- CPU not resumed
+ *  with the CPU_RESUME_FAILED handler called only after all CPUs have been
+ *  tried to put online again in order to know which CPUs did restart
+ *  successfully.
+ *
  * Hence note that only CPU_*_PREPARE handlers are allowed to fail. Also note
  * that once CPU_DYING is delivered, an offline action can no longer fail.
- * 
+ *
  * Notifiers are called highest-priority-first when:
  *  (a) A CPU is coming up; or (b) CPU_DOWN_FAILED
  * Notifiers are called lowest-priority-first when:
  *  (a) A CPU is going down; or (b) CPU_UP_CANCELED
  */
 /* CPU_UP_PREPARE: Preparing to bring CPU online. */
-#define CPU_UP_PREPARE   (0x0001 | NOTIFY_FORWARD)
+#define CPU_UP_PREPARE    (0x0001 | NOTIFY_FORWARD)
 /* CPU_UP_CANCELED: CPU is no longer being brought online. */
-#define CPU_UP_CANCELED  (0x0002 | NOTIFY_REVERSE)
+#define CPU_UP_CANCELED   (0x0002 | NOTIFY_REVERSE)
 /* CPU_STARTING: CPU nearly online. Runs on new CPU, irqs still disabled. */
-#define CPU_STARTING     (0x0003 | NOTIFY_FORWARD)
+#define CPU_STARTING      (0x0003 | NOTIFY_FORWARD)
 /* CPU_ONLINE: CPU is up. */
-#define CPU_ONLINE       (0x0004 | NOTIFY_FORWARD)
+#define CPU_ONLINE        (0x0004 | NOTIFY_FORWARD)
 /* CPU_DOWN_PREPARE: CPU is going down. */
-#define CPU_DOWN_PREPARE (0x0005 | NOTIFY_REVERSE)
+#define CPU_DOWN_PREPARE  (0x0005 | NOTIFY_REVERSE)
 /* CPU_DOWN_FAILED: CPU is no longer going down. */
-#define CPU_DOWN_FAILED  (0x0006 | NOTIFY_FORWARD)
+#define CPU_DOWN_FAILED   (0x0006 | NOTIFY_FORWARD)
 /* CPU_DYING: CPU is nearly dead (in stop_machine context). */
-#define CPU_DYING        (0x0007 | NOTIFY_REVERSE)
+#define CPU_DYING         (0x0007 | NOTIFY_REVERSE)
 /* CPU_DEAD: CPU is dead. */
-#define CPU_DEAD         (0x0008 | NOTIFY_REVERSE)
+#define CPU_DEAD          (0x0008 | NOTIFY_REVERSE)
 /* CPU_REMOVE: CPU was removed. */
-#define CPU_REMOVE       (0x0009 | NOTIFY_REVERSE)
+#define CPU_REMOVE        (0x0009 | NOTIFY_REVERSE)
+/* CPU_RESUME_FAILED: CPU failed to come up in resume, all other CPUs up. */
+#define CPU_RESUME_FAILED (0x000a | NOTIFY_REVERSE)
 
 /* Perform CPU hotplug. May return -EAGAIN. */
 int cpu_down(unsigned int cpu);
-- 
2.26.2