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hv_utils: return error if host timesysnc update is stale

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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 <viremana@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20200821152523.99364-1-viremana@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Vineeth Pillai 2020-08-21 15:25:23 +00:00 committed by Wei Liu
parent b9d8cf2eb3
commit 90b125f4cd
1 changed files with 35 additions and 11 deletions
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46
drivers/hv/hv_util.c
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@ -282,26 +282,52 @@ static struct {
spinlock_t lock; spinlock_t lock;
} host_ts; } host_ts;
static struct timespec64 hv_get_adj_host_time(void) static inline u64 reftime_to_ns(u64 reftime)
{ {
struct timespec64 ts; return (reftime - WLTIMEDELTA) * 100;
u64 newtime, reftime; }
/*
* 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; unsigned long flags;
int ret = 0;
spin_lock_irqsave(&host_ts.lock, flags); spin_lock_irqsave(&host_ts.lock, flags);
reftime = hv_read_reference_counter(); 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); spin_unlock_irqrestore(&host_ts.lock, flags);
return ts; return ret;
} }
static void hv_set_host_time(struct work_struct *work) 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) static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
{ {
*ts = hv_get_adj_host_time(); return hv_get_adj_host_time(ts);
return 0;
} }
static struct ptp_clock_info ptp_hyperv_info = { static struct ptp_clock_info ptp_hyperv_info = {