diff options
| author | Peter Martincic <pmartincic@microsoft.com> | 2023-11-27 13:35:24 -0800 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2024-03-01 08:19:06 +0000 |
| commit | adf47524b56a791734ae24da8412c6579e2fab4f (patch) | |
| tree | 868b3b9d4810131da98af73676216b1413513735 /drivers/hv | |
| parent | d206a76d7d2726f3b096037f2079ce0bd3ba329b (diff) | |
hv_utils: Allow implicit ICTIMESYNCFLAG_SYNC
Hyper-V hosts can omit the _SYNC flag to due a bug on resume from modern
suspend. In such a case, the guest may fail to update its time-of-day to
account for the period when it was suspended, and could proceed with a
significantly wrong time-of-day. In such a case when the guest is
significantly behind, fix it by treating a _SAMPLE the same as if _SYNC
was received so that the guest time-of-day is updated.
This is hidden behind param hv_utils.timesync_implicit.
Signed-off-by: Peter Martincic <pmartincic@microsoft.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20231127213524.52783-1-pmartincic@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20231127213524.52783-1-pmartincic@linux.microsoft.com>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/hv_util.c | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c index 42aec2c5606a..9c97c4065fe7 100644 --- a/drivers/hv/hv_util.c +++ b/drivers/hv/hv_util.c @@ -296,6 +296,11 @@ static struct { spinlock_t lock; } host_ts; +static bool timesync_implicit; + +module_param(timesync_implicit, bool, 0644); +MODULE_PARM_DESC(timesync_implicit, "If set treat SAMPLE as SYNC when clock is behind"); + static inline u64 reftime_to_ns(u64 reftime) { return (reftime - WLTIMEDELTA) * 100; @@ -345,6 +350,29 @@ static void hv_set_host_time(struct work_struct *work) } /* + * Due to a bug on Hyper-V hosts, the sync flag may not always be sent on resume. + * Force a sync if the guest is behind. + */ +static inline bool hv_implicit_sync(u64 host_time) +{ + struct timespec64 new_ts; + struct timespec64 threshold_ts; + + new_ts = ns_to_timespec64(reftime_to_ns(host_time)); + ktime_get_real_ts64(&threshold_ts); + + threshold_ts.tv_sec += 5; + + /* + * If guest behind the host by 5 or more seconds. + */ + if (timespec64_compare(&new_ts, &threshold_ts) >= 0) + return true; + + return false; +} + +/* * Synchronize time with host after reboot, restore, etc. * * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM. @@ -384,7 +412,8 @@ static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags) spin_unlock_irqrestore(&host_ts.lock, flags); /* Schedule work to do do_settimeofday64() */ - if (adj_flags & ICTIMESYNCFLAG_SYNC) + if ((adj_flags & ICTIMESYNCFLAG_SYNC) || + (timesync_implicit && hv_implicit_sync(host_ts.host_time))) schedule_work(&adj_time_work); } |