diff mbox series

xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests

Message ID 1588976923-3667-1-git-send-email-boris.ostrovsky@oracle.com (mailing list archive)
State Accepted
Commit c54b071c192dfe8061336f650ceaf358e6386e0b
Headers show
Series xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests | expand

Commit Message

Boris Ostrovsky May 8, 2020, 10:28 p.m. UTC
Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with
device_online/offline()") replaced cpu_down() with device_offline()
call which requires that the CPU has been registered before. This
registration, however, happens later from topology_init() which
is called as subsys_initcall(). setup_vcpu_hotplug_event(), on the
other hand, is invoked earlier, during arch_initcall().

As result, booting a PV(H) guest with vcpus < maxvcpus causes a crash.

Move setup_vcpu_hotplug_event() (and therefore setup_cpu_watcher()) to
late_initcall(). In addition, instead of performing all offlining steps
in setup_cpu_watcher() simply call disable_hotplug_cpu().

Fixes: a926f81d2f6c (xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()"
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/cpu_hotplug.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

Comments

Jürgen Groß May 11, 2020, 8:16 a.m. UTC | #1
On 09.05.20 00:28, Boris Ostrovsky wrote:
> Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with
> device_online/offline()") replaced cpu_down() with device_offline()
> call which requires that the CPU has been registered before. This
> registration, however, happens later from topology_init() which
> is called as subsys_initcall(). setup_vcpu_hotplug_event(), on the
> other hand, is invoked earlier, during arch_initcall().
> 
> As result, booting a PV(H) guest with vcpus < maxvcpus causes a crash.
> 
> Move setup_vcpu_hotplug_event() (and therefore setup_cpu_watcher()) to
> late_initcall(). In addition, instead of performing all offlining steps
> in setup_cpu_watcher() simply call disable_hotplug_cpu().
> 
> Fixes: a926f81d2f6c (xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()"
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen
diff mbox series

Patch

diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
index ec975de..b96b11e 100644
--- a/drivers/xen/cpu_hotplug.c
+++ b/drivers/xen/cpu_hotplug.c
@@ -93,10 +93,8 @@  static int setup_cpu_watcher(struct notifier_block *notifier,
 	(void)register_xenbus_watch(&cpu_watch);
 
 	for_each_possible_cpu(cpu) {
-		if (vcpu_online(cpu) == 0) {
-			device_offline(get_cpu_device(cpu));
-			set_cpu_present(cpu, false);
-		}
+		if (vcpu_online(cpu) == 0)
+			disable_hotplug_cpu(cpu);
 	}
 
 	return NOTIFY_DONE;
@@ -119,5 +117,5 @@  static int __init setup_vcpu_hotplug_event(void)
 	return 0;
 }
 
-arch_initcall(setup_vcpu_hotplug_event);
+late_initcall(setup_vcpu_hotplug_event);