hvm: correct time offset update in RTC write emulation

mktime takes a month in 1..12 form while tm->tm_mon contains 0..11 so
we need to add 1. Without this fix setting the month back or forward a
month inside the guest would lead to the wrong number of days being
added/subtracted.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/xen/arch/x86/hvm/rtc.c b/xen/arch/x86/hvm/rtc.c
index 174a111535060ef072b37b2b49dfed3b70a44127..1eb48542764cf977b54652d5830a794cebe99604 100644 (file)
--- a/xen/arch/x86/hvm/rtc.c
+++ b/xen/arch/x86/hvm/rtc.c
@@ -165,7 +165,7 @@ static void rtc_set_time(RTCState *s)
       
     ASSERT(spin_is_locked(&s->lock));
 
-    before = mktime(tm->tm_year, tm->tm_mon, tm->tm_mday,
+    before = mktime(tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
                    tm->tm_hour, tm->tm_min, tm->tm_sec);
     
     tm->tm_sec = from_bcd(s, s->hw.cmos_data[RTC_SECONDS]);
@@ -179,7 +179,7 @@ static void rtc_set_time(RTCState *s)
     tm->tm_mon = from_bcd(s, s->hw.cmos_data[RTC_MONTH]) - 1;
     tm->tm_year = from_bcd(s, s->hw.cmos_data[RTC_YEAR]) + 100;
 
-    after = mktime(tm->tm_year, tm->tm_mon, tm->tm_mday,
+    after = mktime(tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
                    tm->tm_hour, tm->tm_min, tm->tm_sec);
 
     /* We use the guest's setting of the RTC to define the local-time