x86, paravirt: don't compute pvclock adjustments if we trust the tsc
If the HV told us we can fully trust the TSC, skip any
correction
Signed-off-by: Glauber Costa <glommer@redhat.com>
Acked-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index f5bc40e..239427c 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -135,6 +135,10 @@
barrier();
} while (version != src->version);
+ if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&
+ (shadow.flags & PVCLOCK_TSC_STABLE_BIT))
+ return ret;
+
/*
* Assumption here is that last_value, a global accumulator, always goes
* forward. If we are less than that, we should not be much smaller.
