xen: implement CPU hotplugging

Note the changes from 2.6.18-xen CPU hotplugging:

A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.

A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.

Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index b6c2b8f16bee..c3290bc186a0 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -360,6 +360,10 @@ static void unbind_from_irq(unsigned int irq)
                         per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
                                 [index_from_irq(irq)] = -1;
                         break;
+                case IRQT_IPI:
+                        per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn))
+                                [index_from_irq(irq)] = -1;
+                        break;
                 default:
                         break;
                 }