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yaml --- r: 343536 b: refs/heads/master c: 189e117 h: refs/heads/master v: v3
git-mirror · Nov 28, 2012 · 8f1981d · 8f1981d
1 parent 01139a7
commit 8f1981d
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2697902be89d7f38e9736dfe946cd0e5d4f47b80
+refs/heads/master: 189e11731aa858597095fbe1e6d243bad26bd96b
diff --git a/trunk/arch/x86/include/asm/pvclock.h b/trunk/arch/x86/include/asm/pvclock.h
@@ -74,6 +74,12 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
 	u8 ret_flags;
 
 	version = src->version;
+	/* Note: emulated platforms which do not advertise SSE2 support
+	 * result in kvmclock not using the necessary RDTSC barriers.
+	 * Without barriers, it is possible that RDTSC instruction reads from
+	 * the time stamp counter outside rdtsc_barrier protected section
+	 * below, resulting in violation of monotonicity.
+	 */
 	rdtsc_barrier();
 	offset = pvclock_get_nsec_offset(src);
 	ret = src->system_time + offset;