[Xen-changelog] [xen-unstable] CPUIDLE: Avoid remnant LAPIC timer intr while force hpetbroadcast

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1221041786 -3600
# Node ID 020b8340e83938b1b7693bffbd445f616063ea22
# Parent  9ee24da5a488c2899026df0ad4172fe497f631fb
CPUIDLE: Avoid remnant LAPIC timer intr while force hpetbroadcast

LAPIC will stop during C3, and resume to work after exit from
C3. Considering below case:
The LAPIC timer was programmed to expire after 1000us, but CPU enter
C3 after 100us and exit C3 at 9xxus.

   0us: reprogram_timer(1000us)
 100us: entry C3, LAPIC timer stop
 9xxus: exit C3 due to unexpected event, LAPIC timer continue running
10xxus: reprogram_timer(1000us), fail due to the past expiring time.
......: no timer softirq raised, no change to LAPIC timer.
......: if entry C3 again, HPET will be forced reprogramed to
 now+small_slop.
......: if entry C2, no change to LAPIC.
18xxus: LAPIC timer expires unexpectedly if no C3 entries after
 10xxus.

Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>
---
 xen/arch/x86/hpet.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletion(-)

diff -r 9ee24da5a488 -r 020b8340e839 xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c       Wed Sep 10 11:09:08 2008 +0100
+++ b/xen/arch/x86/hpet.c       Wed Sep 10 11:16:26 2008 +0100
@@ -233,7 +233,15 @@ void hpet_broadcast_exit(void)
 
     if ( cpu_test_and_clear(cpu, ch->cpumask) )
     {
-        reprogram_timer(per_cpu(timer_deadline, cpu));
+        if ( !reprogram_timer(per_cpu(timer_deadline, cpu)) )
+        {
+            /*
+             * The deadline must have passed -- trigger timer work now.
+             * Also cancel any outstanding LAPIC event.
+             */
+            reprogram_timer(0);
+            raise_softirq(TIMER_SOFTIRQ);
+        }
 
         if ( cpus_empty(ch->cpumask) && ch->next_event != STIME_MAX )
             reprogram_hpet_evt_channel(ch, STIME_MAX, 0, 0);

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog