x86, vmi: TSC going backwards check in vmi clocksource
authorAlok N Kataria <akataria@vmware.com>
Wed, 18 Feb 2009 20:33:55 +0000 (12:33 -0800)
committerIngo Molnar <mingo@elte.hu>
Fri, 20 Feb 2009 06:53:08 +0000 (07:53 +0100)
Impact: fix time warps under vmware

Similar to the check for TSC going backwards in the TSC clocksource,
we also need this check for VMI clocksource.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
arch/x86/kernel/vmiclock_32.c

index c4c1f9e094027089373189f7e57cb7ede8149be9..bde106cae0a98c600498378db8420a9daafdc60f 100644 (file)
@@ -283,10 +283,13 @@ void __devinit vmi_time_ap_init(void)
 #endif
 
 /** vmi clocksource */
+static struct clocksource clocksource_vmi;
 
 static cycle_t read_real_cycles(void)
 {
-       return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
+       cycle_t ret = (cycle_t)vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
+       return ret >= clocksource_vmi.cycle_last ?
+               ret : clocksource_vmi.cycle_last;
 }
 
 static struct clocksource clocksource_vmi = {