From: David Gibson <david@gibson.dropbear.id.au>
To: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
Cc: aik@ozlabs.ru, qemu-ppc@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH V5] spapr: Fix stale HTAB during live migration
Date: Tue, 26 Aug 2014 13:01:19 +1000 [thread overview]
Message-ID: <20140826030119.GM9923@voom.redhat.com> (raw)
In-Reply-To: <1408667050-10789-1-git-send-email-sam.mj@au1.ibm.com>
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On Fri, Aug 22, 2014 at 10:24:10AM +1000, Samuel Mendoza-Jonas wrote:
> If a guest reboots during a running migration, changes to the
> hash page table are not necessarily updated on the destination.
> Opening a new file descriptor to the HTAB forces the migration
> handler to resend the entire table.
Of course, arguably this is a kernel bug - the htab fd should probably
start re-reporting things if the htab reset ioctl() is called. But I
guess we need a workaround for existing kernels anyway.
However, don't we still have the bug for TCG mode? spapr_reset_htab()
just memset()s the whole hashtable in that case, which will actually
clear all the dirty bits, whereas we need to set them.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2014-08-26 3:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-22 0:24 [Qemu-devel] [PATCH V5] spapr: Fix stale HTAB during live migration Samuel Mendoza-Jonas
2014-08-26 3:01 ` David Gibson [this message]
2014-08-26 3:40 ` Sam Mendoza-Jonas
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