[patch 044/114] x86, vmi: TSC going backwards check in vmi clocksource

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Alok N Kataria <akataria@xxxxxxxxxx>

commit 48ffc70b675aa7798a52a2e92e20f6cce9140b3d upstream.

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@xxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/x86/kernel/vmiclock_32.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/vmiclock_32.c
+++ b/arch/x86/kernel/vmiclock_32.c
@@ -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 = {


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