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.pisare...@gmail.com> --- vl.c | 58 +++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 23 deletions(-) diff --git a/vl.c b/vl.c index 10c4275..78a8a68 100644 --- a/vl.c +++ b/vl.c @@ -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; @@ -785,32 +787,42 @@ void qemu_system_vmstop_request(RunState state) } /***********************************************************/ -/* real time host monotonic timer */ - -static time_t qemu_timedate(void) -{ - return qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000; -} - -/***********************************************************/ /* RTC reference time/date access */ +static time_t qemu_ref_timedate(void) +{ + 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; +} + 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 +831,7 @@ 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; @@ -829,9 +842,6 @@ int qemu_timedate_diff(struct tm *tm) seconds = mktime(&tmp); break; } - case RTC_BASE_DATETIME: - seconds = mktimegm(tm) + rtc_host_datetime_offset; - break; default: /* gcc complains: ‘seconds’ may be used uninitialized */ g_assert_not_reached(); @@ -839,10 +849,10 @@ int qemu_timedate_diff(struct tm *tm) break; } - 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; @@ -868,8 +878,8 @@ 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) @@ -888,7 +898,7 @@ 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"); @@ -3039,6 +3049,8 @@ int main(int argc, char **argv, char **envp) exit(1); } 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; QLIST_INIT (&vm_change_state_head); os_setup_early_signal_handling(); -- 2.7.4