[Xen-changelog] [xen master] x86/time: use correct (local) time stamp in constant-TSC calibration fast path

[patchbot@xxxxxxx]

commit b64438c7c1495a7580d1bb9d8ba644f3705e1ffb
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jun 14 15:08:47 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jun 14 15:08:47 2016 +0200

    x86/time: use correct (local) time stamp in constant-TSC calibration fast 
path
    
    This looks like a copy and paste mistake in commit 1b6a99892d ("x86:
    Simpler time handling when TSC is constant across all power saving
    states"), responsible for occasional many-microsecond cross-CPU skew of
    what NOW() returns.
    
    Also improve the correlation between local TSC and stime stamps
    obtained at the end of the two calibration handlers: Compute the stime
    one from the TSC one, instead of doing another rdtsc() for that
    compuation.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/time.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 3928a5f..9707e76 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -998,7 +998,7 @@ static void local_time_calibration(void)
         /* Atomically read cpu_calibration struct and write cpu_time struct. */
         local_irq_disable();
         t->local_tsc_stamp    = c->local_tsc_stamp;
-        t->stime_local_stamp  = c->stime_master_stamp;
+        t->stime_local_stamp  = c->stime_local_stamp;
         t->stime_master_stamp = c->stime_master_stamp;
         local_irq_enable();
         update_vcpu_system_time(current);
@@ -1275,7 +1275,7 @@ static void time_calibration_tsc_rendezvous(void *_r)
     }
 
     c->local_tsc_stamp = rdtsc();
-    c->stime_local_stamp = get_s_time();
+    c->stime_local_stamp = get_s_time_fixed(c->local_tsc_stamp);
     c->stime_master_stamp = r->master_stime;
 
     raise_softirq(TIME_CALIBRATE_SOFTIRQ);
@@ -1305,7 +1305,7 @@ static void time_calibration_std_rendezvous(void *_r)
     }
 
     c->local_tsc_stamp = rdtsc();
-    c->stime_local_stamp = get_s_time();
+    c->stime_local_stamp = get_s_time_fixed(c->local_tsc_stamp);
     c->stime_master_stamp = r->master_stime;
 
     raise_softirq(TIME_CALIBRATE_SOFTIRQ);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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