From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <jbeulich@suse.com>, Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH] tools/libxenguest: Fix migration's debug option
Date: Mon, 5 Jul 2021 11:06:43 +0100 [thread overview]
Message-ID: <f4301654-49c1-8b9a-a6c4-2b40d06641ae@citrix.com> (raw)
In-Reply-To: <5e4986ad-d3ec-18af-b1ea-ccbce57a70ff@suse.com>
On 05/07/2021 10:31, Jan Beulich wrote:
> On 05.07.2021 11:25, Olaf Hering wrote:
>> Am Mon, 5 Jul 2021 11:19:59 +0200
>> schrieb Jan Beulich <jbeulich@suse.com>:
>>
>>> "The interface" being which one? The tool stack can map the guest's
>>> grant table, so it is in the position to find out about all grants
>>> without further hypervisor help.
>> The interface means the code behind verify_frames.
>>
>> If there are indeed ways to query which pages belong to grants, how would the toolstack need to do that?
> Map the grant table of the guest and walk it, recording any MFN for
> which at least one valid r/w grant exists.
That doesn't help - Its still racy with in-flight IO. Also with updates
from Xen such as the wallclocks.
The only way to fix the IO problem is to disconnect the blk/net rings
before doing the final sweep for frames, but that clobbers any ability
to restart the VM on the source side if things go wrong at the destination.
I don't have an answer at all for the vcpu info frames.
~Andrew
next prev parent reply other threads:[~2021-07-05 10:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-02 19:03 [PATCH] tools/libxenguest: Fix migration's debug option Andrew Cooper
2021-07-05 7:53 ` Olaf Hering
2021-07-05 7:57 ` Jan Beulich
2021-07-05 8:02 ` Olaf Hering
2021-07-05 8:23 ` Jan Beulich
2021-07-05 8:32 ` Olaf Hering
2021-07-05 9:19 ` Jan Beulich
2021-07-05 9:25 ` Olaf Hering
2021-07-05 9:31 ` Jan Beulich
2021-07-05 10:06 ` Andrew Cooper [this message]
2021-07-05 10:36 ` Jan Beulich
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