[patch 72/96] x86, vmi: TSC going backwards check in vmi clocksource

Greg KH
2009-03-14T00:43:52Z

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

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

From: Alok N Kataria <akataria@vmware.com>

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@vmware.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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
@@ -280,10 +280,13 @@ 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 = {