[PATCH 1/4] xen: disable non-boot VCPUs during suspend

[David Vrabel <david.vrabel@citrix.com>]

From: David Vrabel <david.vrabel@citrix.com>

syscore_suspend() and syscore_resume() expect there to be only one
online CPU.  e.g., hrtimers_resume() only triggers events for the
current CPU.  Xen's suspend path was leaving all VCPUs online and then
attempting to fixup problems afterwards (e.g., with an explicit call
to clock_was_set() to trigger pending high resolution timers).

Instead, disable non-boot CPUs before calling stop_machine() and
reenable them afterwards.

This is then similar to what the kexec code does before and after a
kexec jump (see kernel_kexec() in kernel/kexec.c).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/manage.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 412b96c..596e55a 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -148,8 +148,19 @@ static void do_suspend(void)
 		si.post = &xen_post_suspend;
 	}
 
+	/*
+	 * syscore_suspend() and syscore_resume() called in
+	 * xen_suspend() above, assume that only the boot CPU is
+	 * online.
+	 */
+	err = disable_nonboot_cpus();
+	if (err)
+		goto out_resume;
+
 	err = stop_machine(xen_suspend, &si, cpumask_of(0));
 
+	enable_nonboot_cpus();
+
 	dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
 
 	if (err) {
@@ -166,9 +177,6 @@ out_resume:
 
 	dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
 
-	/* Make sure timer events get retriggered on all CPUs */
-	clock_was_set();
-
 out_thaw:
 #ifdef CONFIG_PREEMPT
 	thaw_processes();
-- 
1.7.2.5