Fix the wrong wall clock of Dom0 after it resumes from S3.
 - In the GMT+08:00 time zone, if disable UTC, when Dom0 resumes from S3, its
   wallclock will increase by 8 hours wrongly; this is because: time_resume()
   treats the CMOS time as UTC time, and assigns it to the global variable
   wc_sec; this patch fixes the issue by remembering the difference between
   them before S3, and making adjustment accordingly after S3.

Signed-off-by: Xu Dongxiao <dongxiao.xu@intel.com>

diff -r 2491691e3e69 xen/arch/x86/time.c
--- a/xen/arch/x86/time.c	Sat Dec 29 17:57:47 2007 +0000
+++ b/xen/arch/x86/time.c	Fri Jan 04 16:16:11 2008 +0800
@@ -971,8 +971,13 @@ unsigned long get_localtime(struct domai
         + d->time_offset_seconds;
 }
 
+/* "clock_cmos_diff" means the difference between UTC time and CMOS time. */
+static long clock_cmos_diff;
+
 int time_suspend(void)
 {
+    clock_cmos_diff = (wc_sec + (wc_nsec + NOW()) / 1000000000ULL)
+        - get_cmos_time();
     /* Better to cancel calibration timer for accuracy. */
     kill_timer(&this_cpu(cpu_time).calibration_timer);
 
@@ -986,7 +991,8 @@ int time_resume(void)
     set_time_scale(&this_cpu(cpu_time).tsc_scale, tmp);
 
     resume_platform_timer();
-    do_settime(get_cmos_time(), 0, read_platform_stime());
+
+    do_settime(get_cmos_time() + clock_cmos_diff, 0, read_platform_stime());
 
     init_percpu_time();