svn commit: r282259 - head/sys/amd64/vmm/io
Neel Natu
neel at FreeBSD.org
Wed Apr 29 23:44:29 UTC 2015
Author: neel
Date: Wed Apr 29 23:44:28 2015
New Revision: 282259
URL: https://svnweb.freebsd.org/changeset/base/282259
Log:
Re-implement RTC current time calculation to eliminate the possibility of
losing time.
The problem with the earlier implementation was that the uptime value
used by 'vrtc_curtime()' could be different than the uptime value when
'vrtc_time_update()' actually updated 'base_uptime'.
Fix this by calculating and updating the (rtctime, uptime) tuple together.
MFC after: 2 weeks
Modified:
head/sys/amd64/vmm/io/vrtc.c
Modified: head/sys/amd64/vmm/io/vrtc.c
==============================================================================
--- head/sys/amd64/vmm/io/vrtc.c Wed Apr 29 22:59:44 2015 (r282258)
+++ head/sys/amd64/vmm/io/vrtc.c Wed Apr 29 23:44:28 2015 (r282259)
@@ -142,20 +142,23 @@ update_enabled(struct vrtc *vrtc)
}
static time_t
-vrtc_curtime(struct vrtc *vrtc)
+vrtc_curtime(struct vrtc *vrtc, sbintime_t *basetime)
{
sbintime_t now, delta;
- time_t t;
+ time_t t, secs;
KASSERT(VRTC_LOCKED(vrtc), ("%s: vrtc not locked", __func__));
t = vrtc->base_rtctime;
+ *basetime = vrtc->base_uptime;
if (update_enabled(vrtc)) {
now = sbinuptime();
delta = now - vrtc->base_uptime;
KASSERT(delta >= 0, ("vrtc_curtime: uptime went backwards: "
"%#lx to %#lx", vrtc->base_uptime, now));
- t += delta / SBT_1S;
+ secs = delta / SBT_1S;
+ t += secs;
+ *basetime += secs * SBT_1S;
}
return (t);
}
@@ -390,9 +393,10 @@ fail:
}
static int
-vrtc_time_update(struct vrtc *vrtc, time_t newtime)
+vrtc_time_update(struct vrtc *vrtc, time_t newtime, sbintime_t newbase)
{
struct rtcdev *rtc;
+ sbintime_t oldbase;
time_t oldtime;
uint8_t alarm_sec, alarm_min, alarm_hour;
@@ -404,16 +408,21 @@ vrtc_time_update(struct vrtc *vrtc, time
alarm_hour = rtc->alarm_hour;
oldtime = vrtc->base_rtctime;
- VM_CTR2(vrtc->vm, "Updating RTC time from %#lx to %#lx",
+ VM_CTR2(vrtc->vm, "Updating RTC secs from %#lx to %#lx",
oldtime, newtime);
+ oldbase = vrtc->base_uptime;
+ VM_CTR2(vrtc->vm, "Updating RTC base uptime from %#lx to %#lx",
+ oldbase, newbase);
+ vrtc->base_uptime = newbase;
+
if (newtime == oldtime)
return (0);
/*
* If 'newtime' indicates that RTC updates are disabled then just
* record that and return. There is no need to do alarm interrupt
- * processing or update 'base_uptime' in this case.
+ * processing in this case.
*/
if (newtime == VRTC_BROKEN_TIME) {
vrtc->base_rtctime = VRTC_BROKEN_TIME;
@@ -459,8 +468,6 @@ vrtc_time_update(struct vrtc *vrtc, time
if (uintr_enabled(vrtc))
vrtc_set_reg_c(vrtc, rtc->reg_c | RTCIR_UPDATE);
- vrtc->base_uptime = sbinuptime();
-
return (0);
}
@@ -531,7 +538,7 @@ static void
vrtc_callout_handler(void *arg)
{
struct vrtc *vrtc = arg;
- sbintime_t freqsbt;
+ sbintime_t freqsbt, basetime;
time_t rtctime;
int error;
@@ -553,8 +560,8 @@ vrtc_callout_handler(void *arg)
vrtc_set_reg_c(vrtc, vrtc->rtcdev.reg_c | RTCIR_PERIOD);
if (aintr_enabled(vrtc) || uintr_enabled(vrtc)) {
- rtctime = vrtc_curtime(vrtc);
- error = vrtc_time_update(vrtc, rtctime);
+ rtctime = vrtc_curtime(vrtc, &basetime);
+ error = vrtc_time_update(vrtc, rtctime, basetime);
KASSERT(error == 0, ("%s: vrtc_time_update error %d",
__func__, error));
}
@@ -619,7 +626,7 @@ static int
vrtc_set_reg_b(struct vrtc *vrtc, uint8_t newval)
{
struct rtcdev *rtc;
- sbintime_t oldfreq, newfreq;
+ sbintime_t oldfreq, newfreq, basetime;
time_t curtime, rtctime;
int error;
uint8_t oldval, changed;
@@ -640,12 +647,13 @@ vrtc_set_reg_b(struct vrtc *vrtc, uint8_
if (changed & RTCSB_HALT) {
if ((newval & RTCSB_HALT) == 0) {
rtctime = rtc_to_secs(vrtc);
+ basetime = sbinuptime();
if (rtctime == VRTC_BROKEN_TIME) {
if (rtc_flag_broken_time)
return (-1);
}
} else {
- curtime = vrtc_curtime(vrtc);
+ curtime = vrtc_curtime(vrtc, &basetime);
KASSERT(curtime == vrtc->base_rtctime, ("%s: mismatch "
"between vrtc basetime (%#lx) and curtime (%#lx)",
__func__, vrtc->base_rtctime, curtime));
@@ -664,7 +672,7 @@ vrtc_set_reg_b(struct vrtc *vrtc, uint8_
rtctime = VRTC_BROKEN_TIME;
rtc->reg_b &= ~RTCSB_UINTR;
}
- error = vrtc_time_update(vrtc, rtctime);
+ error = vrtc_time_update(vrtc, rtctime, basetime);
KASSERT(error == 0, ("vrtc_time_update error %d", error));
}
@@ -744,7 +752,7 @@ vrtc_set_time(struct vm *vm, time_t secs
vrtc = vm_rtc(vm);
VRTC_LOCK(vrtc);
- error = vrtc_time_update(vrtc, secs);
+ error = vrtc_time_update(vrtc, secs, sbinuptime());
VRTC_UNLOCK(vrtc);
if (error) {
@@ -761,11 +769,12 @@ time_t
vrtc_get_time(struct vm *vm)
{
struct vrtc *vrtc;
+ sbintime_t basetime;
time_t t;
vrtc = vm_rtc(vm);
VRTC_LOCK(vrtc);
- t = vrtc_curtime(vrtc);
+ t = vrtc_curtime(vrtc, &basetime);
VRTC_UNLOCK(vrtc);
return (t);
@@ -802,6 +811,7 @@ int
vrtc_nvram_read(struct vm *vm, int offset, uint8_t *retval)
{
struct vrtc *vrtc;
+ sbintime_t basetime;
time_t curtime;
uint8_t *ptr;
@@ -818,7 +828,7 @@ vrtc_nvram_read(struct vm *vm, int offse
* Update RTC date/time fields if necessary.
*/
if (offset < 10 || offset == RTC_CENTURY) {
- curtime = vrtc_curtime(vrtc);
+ curtime = vrtc_curtime(vrtc, &basetime);
secs_to_rtc(curtime, vrtc, 0);
}
@@ -858,6 +868,7 @@ vrtc_data_handler(struct vm *vm, int vcp
{
struct vrtc *vrtc;
struct rtcdev *rtc;
+ sbintime_t basetime;
time_t curtime;
int error, offset;
@@ -875,8 +886,8 @@ vrtc_data_handler(struct vm *vm, int vcp
}
error = 0;
- curtime = vrtc_curtime(vrtc);
- vrtc_time_update(vrtc, curtime);
+ curtime = vrtc_curtime(vrtc, &basetime);
+ vrtc_time_update(vrtc, curtime, basetime);
/*
* Update RTC date/time fields if necessary.
@@ -939,7 +950,7 @@ vrtc_data_handler(struct vm *vm, int vcp
*/
if (offset == RTC_CENTURY && !rtc_halted(vrtc)) {
curtime = rtc_to_secs(vrtc);
- error = vrtc_time_update(vrtc, curtime);
+ error = vrtc_time_update(vrtc, curtime, sbinuptime());
KASSERT(!error, ("vrtc_time_update error %d", error));
if (curtime == VRTC_BROKEN_TIME && rtc_flag_broken_time)
error = -1;
@@ -993,7 +1004,7 @@ vrtc_init(struct vm *vm)
VRTC_LOCK(vrtc);
vrtc->base_rtctime = VRTC_BROKEN_TIME;
- vrtc_time_update(vrtc, curtime);
+ vrtc_time_update(vrtc, curtime, sbinuptime());
secs_to_rtc(curtime, vrtc, 0);
VRTC_UNLOCK(vrtc);
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