From: Vineeth Pillai <virem...@linux.microsoft.com> [ Upstream commit 90b125f4cd2697f949f5877df723a0b710693dd0 ]
If for any reason, host timesync messages were not processed by the guest, hv_ptp_gettime() returns a stale value and the caller (clock_gettime, PTP ioctl etc) has no means to know this now. Return an error so that the caller knows about this. Signed-off-by: Vineeth Pillai <virem...@linux.microsoft.com> Reviewed-by: Michael Kelley <mikel...@microsoft.com> Link: https://lore.kernel.org/r/20200821152523.99364-1-virem...@linux.microsoft.com Signed-off-by: Wei Liu <wei....@kernel.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- drivers/hv/hv_util.c | 46 +++++++++++++++++++++++++++++++++----------- 1 file changed, 35 insertions(+), 11 deletions(-) diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c index 92ee0fe4c919e..1f86e8d9b018d 100644 --- a/drivers/hv/hv_util.c +++ b/drivers/hv/hv_util.c @@ -282,26 +282,52 @@ static struct { spinlock_t lock; } host_ts; -static struct timespec64 hv_get_adj_host_time(void) +static inline u64 reftime_to_ns(u64 reftime) { - struct timespec64 ts; - u64 newtime, reftime; + return (reftime - WLTIMEDELTA) * 100; +} + +/* + * Hard coded threshold for host timesync delay: 600 seconds + */ +static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC; + +static int hv_get_adj_host_time(struct timespec64 *ts) +{ + u64 newtime, reftime, timediff_adj; unsigned long flags; + int ret = 0; spin_lock_irqsave(&host_ts.lock, flags); reftime = hv_read_reference_counter(); - newtime = host_ts.host_time + (reftime - host_ts.ref_time); - ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100); + + /* + * We need to let the caller know that last update from host + * is older than the max allowable threshold. clock_gettime() + * and PTP ioctl do not have a documented error that we could + * return for this specific case. Use ESTALE to report this. + */ + timediff_adj = reftime - host_ts.ref_time; + if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) { + pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n", + (timediff_adj * 100)); + ret = -ESTALE; + } + + newtime = host_ts.host_time + timediff_adj; + *ts = ns_to_timespec64(reftime_to_ns(newtime)); spin_unlock_irqrestore(&host_ts.lock, flags); - return ts; + return ret; } static void hv_set_host_time(struct work_struct *work) { - struct timespec64 ts = hv_get_adj_host_time(); - do_settimeofday64(&ts); + struct timespec64 ts; + + if (!hv_get_adj_host_time(&ts)) + do_settimeofday64(&ts); } /* @@ -622,9 +648,7 @@ static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta) static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts) { - *ts = hv_get_adj_host_time(); - - return 0; + return hv_get_adj_host_time(ts); } static struct ptp_clock_info ptp_hyperv_info = { -- 2.25.1
