From: Keir Fraser <keir.fraser@citrix.com>
Date: Sat, 26 Jan 2008 11:29:29 +0000 (+0000)
Subject: x86: When Xen is notified that CPU frequency has changed, do not trust
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14392
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=c22615b9ae644208997cccbf2f14dccfc2ecdfb3;p=xen.git

x86: When Xen is notified that CPU frequency has changed, do not trust
the current TSC-extrapolated time when we re-sync.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---

diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 3793c4bb2c..e079138b23 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -732,8 +732,10 @@ int cpu_frequency_change(u64 freq)
     local_irq_disable();
     rdtscll(curr_tsc);
     t->local_tsc_stamp = curr_tsc;
-    t->stime_local_stamp = get_s_time();
     t->stime_master_stamp = read_platform_stime();
+    /* TSC-extrapolated time may be bogus after frequency change. */
+    /*t->stime_local_stamp = get_s_time();*/
+    t->stime_local_stamp = t->stime_master_stamp;
     set_time_scale(&t->tsc_scale, freq);
     local_irq_enable();