From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Antoine Damhet <antoine.damhet@blade-group.com>, vkuznets@redhat.com
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Juan Quintela <quintela@redhat.com>,
qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [BUG] Migration hv_time rollback
Date: Wed, 16 Sep 2020 12:29:56 +0100 [thread overview]
Message-ID: <20200916112956.GE2833@work-vm> (raw)
In-Reply-To: <20200916090602.blkm7eym6g5bnvvk@tartarus>
cc'ing in Vitaly who knows about the hv stuff.
* Antoine Damhet (antoine.damhet@blade-group.com) wrote:
> Hi,
>
> We are experiencing timestamp rollbacks during live-migration of
> Windows 10 guests with the following qemu configuration (linux 5.4.46
> and qemu master):
> ```
> $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...]
> ```
How big a jump are you seeing, and how did you notice it in the guest?
Dave
> I have tracked the bug to the fact that `kvmclock` is not exposed and
> disabled from qemu PoV but is in fact used by `hv-time` (in KVM).
>
> I think we should enable the `kvmclock` (qemu device) if `hv-time` is
> present and add Hyper-V support for the `kvmclock_current_nsec`
> function.
>
> I'm asking for advice because I am unsure this is the _right_ approach
> and how to keep migration compatibility between qemu versions.
>
> Thank you all,
>
> --
> Antoine 'xdbob' Damhet
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2020-09-16 11:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 9:06 [BUG] Migration hv_time rollback Antoine Damhet
2020-09-16 11:29 ` Dr. David Alan Gilbert [this message]
2020-09-16 11:59 ` Vitaly Kuznetsov
2020-09-16 12:14 ` Antoine Damhet
2020-09-16 11:59 ` Antoine Damhet
2020-09-16 12:16 ` Vitaly Kuznetsov
2020-09-16 12:50 ` Vitaly Kuznetsov
2020-09-16 13:25 ` Antoine Damhet
2020-09-16 13:05 ` Paolo Bonzini
2020-09-16 13:17 ` Vitaly Kuznetsov
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