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Fixes RTC bug with base datetime shifts in clock=vm

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This makes all current "-rtc" option parameters combinations produce
fixed/unambiguous RTC timedate reference for hardware emulation
frontends.
It restores determinism of guest execution when used with clock=vm and
specified base <datetime> value.

Buglink: https://bugs.launchpad.net/qemu/+bug/1797033
Signed-off-by: Artem Pisarenko <artem.k.pisarenko@gmail.com>
Message-Id: <1d963c3e013dfedafa1f6edb9fb219b7e49e39da.1539846575.git.artem.k.pisarenko@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Artem Pisarenko 2018-10-18 13:12:54 +06:00 committed by Paolo Bonzini
parent 7e166ebd8c
commit eb6a520991
1 changed files with 39 additions and 23 deletions
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62
vl.c
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@ -152,8 +152,10 @@ static enum {
RTC_BASE_LOCALTIME,
RTC_BASE_DATETIME,
} rtc_base_type = RTC_BASE_UTC;
static int rtc_host_datetime_offset = -1; /* valid only for host rtc_clock and
rtc_base_type=RTC_BASE_DATETIME */
static time_t rtc_ref_start_datetime;
static int rtc_realtime_clock_offset; /* used only with QEMU_CLOCK_REALTIME */
static int rtc_host_datetime_offset = -1; /* valid & used only with
RTC_BASE_DATETIME */
QEMUClockType rtc_clock;
int vga_interface_type = VGA_NONE;
static DisplayOptions dpy;
@ -247,6 +249,7 @@ static struct {
static QemuOptsList qemu_rtc_opts = {
.name = "rtc",
.head = QTAILQ_HEAD_INITIALIZER(qemu_rtc_opts.head),
.merge_lists = true,
.desc = {
{
.name = "base",
@ -785,32 +788,42 @@ void qemu_system_vmstop_request(RunState state)
}
/***********************************************************/
/* real time host monotonic timer */
static time_t qemu_timedate(void)
/* RTC reference time/date access */
static time_t qemu_ref_timedate(void)
{
return qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
time_t value = qemu_clock_get_ms(rtc_clock) / 1000;
switch (rtc_clock) {
case QEMU_CLOCK_REALTIME:
value -= rtc_realtime_clock_offset;
/* no break */
case QEMU_CLOCK_VIRTUAL:
value += rtc_ref_start_datetime;
break;
case QEMU_CLOCK_HOST:
if (rtc_base_type == RTC_BASE_DATETIME) {
value -= rtc_host_datetime_offset;
}
break;
default:
assert(0);
}
return value;
}
/***********************************************************/
/* RTC reference time/date access */
void qemu_get_timedate(struct tm *tm, int offset)
{
time_t ti = qemu_timedate();
time_t ti = qemu_ref_timedate();
ti += offset;
switch (rtc_base_type) {
case RTC_BASE_DATETIME:
case RTC_BASE_UTC:
gmtime_r(&ti, tm);
break;
case RTC_BASE_LOCALTIME:
localtime_r(&ti, tm);
break;
case RTC_BASE_DATETIME:
ti -= rtc_host_datetime_offset;
gmtime_r(&ti, tm);
break;
}
}
@ -819,6 +832,7 @@ int qemu_timedate_diff(struct tm *tm)
time_t seconds;
switch (rtc_base_type) {
case RTC_BASE_DATETIME:
case RTC_BASE_UTC:
seconds = mktimegm(tm);
break;
@ -829,17 +843,14 @@ int qemu_timedate_diff(struct tm *tm)
seconds = mktime(&tmp);
break;
}
case RTC_BASE_DATETIME:
seconds = mktimegm(tm) + rtc_host_datetime_offset;
break;
default:
abort();
}
return seconds - qemu_timedate();
return seconds - qemu_ref_timedate();
}
static void configure_rtc_host_datetime_offset(const char *startdate)
static void configure_rtc_base_datetime(const char *startdate)
{
time_t rtc_start_datetime;
struct tm tm;
@ -865,14 +876,19 @@ static void configure_rtc_host_datetime_offset(const char *startdate)
"'2006-06-17T16:01:21' or '2006-06-17'\n");
exit(1);
}
rtc_host_datetime_offset = (qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000)
- rtc_start_datetime;
rtc_host_datetime_offset = rtc_ref_start_datetime - rtc_start_datetime;
rtc_ref_start_datetime = rtc_start_datetime;
}
static void configure_rtc(QemuOpts *opts)
{
const char *value;
/* Set defaults */
rtc_clock = QEMU_CLOCK_HOST;
rtc_ref_start_datetime = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
rtc_realtime_clock_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
value = qemu_opt_get(opts, "base");
if (value) {
if (!strcmp(value, "utc")) {
@ -885,7 +901,7 @@ static void configure_rtc(QemuOpts *opts)
replay_add_blocker(blocker);
} else {
rtc_base_type = RTC_BASE_DATETIME;
configure_rtc_host_datetime_offset(value);
configure_rtc_base_datetime(value);
}
}
value = qemu_opt_get(opts, "clock");
@ -3035,7 +3051,6 @@ int main(int argc, char **argv, char **envp)
error_reportf_err(err, "cannot initialize crypto: ");
exit(1);
}
rtc_clock = QEMU_CLOCK_HOST;
QLIST_INIT (&vm_change_state_head);
os_setup_early_signal_handling();
@ -3755,7 +3770,6 @@ int main(int argc, char **argv, char **envp)
if (!opts) {
exit(1);
}
configure_rtc(opts);
break;
case QEMU_OPTION_tb_size:
#ifndef CONFIG_TCG
@ -3973,6 +3987,8 @@ int main(int argc, char **argv, char **envp)
exit(EXIT_FAILURE);
}
configure_rtc(qemu_find_opts_singleton("rtc"));
machine_class = select_machine();
set_memory_options(&ram_slots, &maxram_size, machine_class);