APPLIED[B:azure-4.15/F:azure]: [b:azure-4.15,f:azure][PATCH 0/2] Keep Chrony time in sync

[Ian May]

Applied to:
  bionic/linux-azure-4.15
  focal/linux-azure

Thanks,
Ian

On 2020-12-15 17:12:21 , Kelsey Skunberg wrote:
> BugLink: https://bugs.launchpad.net/bugs/1896784
> 
> SRU Justification:
> 
> [Impact]
> 
> Microsoft would like to request a change to the time keeping method in
> the Azure images.
> 
> We would like to request that an Azure image uses the Azure host for
> time sync by default.  This will require the use of the Chrony package.
> 
> The Chrony package would need to be installed by default in all images
> and be configured to use /dev/ptp0 for timekeeping.
> 
> There is a request for two patches to be backported so Chrony time can
> stay in sync before being set as the default.
> 
> Patches are already in the 5.8 kernel. Only needed for azure 5.4 and
> 4.15
> 
> 
> [Fix]
> 
> backport these two patches:
> b46b4a8a57c3 ("hv_utils: drain the timesync packets on onchannelcallback")
> 90b125f4cd26 ("hv_utils: return error if host timesysnc update is stale")
> 
> [Test Case]
> 
> Desired test cases:
>  - verify Chrony time can stay in sync
>  - verify caller is notified if host timesync update is stale
>  - verify all timesync packets are drained on onchannelcallback to avoid
>    stale packets
> 
> Microsoft holds test cases for the above. They verified a 4.15 and 5.4
> test kernels with the above patches backported to work as expected.
> 
> [Regression Potential]
> 
> Caller may get an error now if host timesync messages were not processed
> by the guest. This wasn't getting reported to the caller before and may
> appear to be a regression if it occurs. 
> 
> Regression potential may also lay in still incorrectly managing timesync
> packets on onchannelcallback.
> 
> Vineeth Pillai (2):
>   hv_utils: return error if host timesysnc update is stale
>   hv_utils: drain the timesync packets on onchannelcallback
> 
>  drivers/hv/hv_util.c | 64 ++++++++++++++++++++++++++++++++++----------
>  1 file changed, 50 insertions(+), 14 deletions(-)
> 
> -- 
> 2.25.1
> 
> 
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