[Xen-changelog] [xen-unstable] xen: Move tsc reliability check until after CPUs have booted

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User George Dunlap <george.dunlap@xxxxxxxxxxxxx>
# Date 1316272974 -3600
# Node ID bf2aaf21e8e72fdd033c603b55792e9efd471dfa
# Parent  17b754cab7b09c3fc76841366a378eb64007d091
xen: Move tsc reliability check until after CPUs have booted

AMD CPUs by default enable X86_FEATURE_TSC_RELIABLE, and depend upon a
later check to disable this feature if TSC drift is detected.
Unfortunately, this check is done in time.c:init_xen_time(), which is
done before any secondary CPUs are brought up, and is thus guaranteed
to succed.

This patch moves the check into its own function, and calls it after
cpus are brought up.

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---


diff -r 17b754cab7b0 -r bf2aaf21e8e7 xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      Sat Sep 17 16:22:13 2011 +0100
+++ b/xen/arch/x86/setup.c      Sat Sep 17 16:22:54 2011 +0100
@@ -1292,8 +1292,11 @@
     printk("Brought up %ld CPUs\n", (long)num_online_cpus());
     smp_cpus_done();
 
+    verify_tsc_reliability();
+
     do_initcalls();
 
+
     if ( opt_watchdog ) 
         watchdog_setup();
 
diff -r 17b754cab7b0 -r bf2aaf21e8e7 xen/arch/x86/time.c
--- a/xen/arch/x86/time.c       Sat Sep 17 16:22:13 2011 +0100
+++ b/xen/arch/x86/time.c       Sat Sep 17 16:22:54 2011 +0100
@@ -1450,8 +1450,8 @@
     disable_tsc_sync = 1;
 }
 
-/* Late init function (after interrupts are enabled). */
-int __init init_xen_time(void)
+/* Late init function, after all cpus have booted */
+void __init verify_tsc_reliability(void)
 {
     if ( boot_cpu_has(X86_FEATURE_TSC_RELIABLE) )
     {
@@ -1463,9 +1463,17 @@
          */
         tsc_check_reliability();
         if ( tsc_max_warp )
+        {
+            printk("%s: TSC warp detected, disabling TSC_RELIABLE\n",
+                   __func__);
             setup_clear_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+        }
     }
+}
 
+/* Late init function (after interrupts are enabled). */
+int __init init_xen_time(void)
+{
     tsc_check_writability();
 
     /* If we have constant-rate TSCs then scale factor can be shared. */
diff -r 17b754cab7b0 -r bf2aaf21e8e7 xen/include/xen/time.h
--- a/xen/include/xen/time.h    Sat Sep 17 16:22:13 2011 +0100
+++ b/xen/include/xen/time.h    Sat Sep 17 16:22:54 2011 +0100
@@ -11,6 +11,7 @@
 #include <xen/types.h>
 #include <public/xen.h>
 
+extern void verify_tsc_reliability(void);
 extern int init_xen_time(void);
 extern void cstate_restore_tsc(void);
 

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