Re: [Qemu-devel] [PATCH V5] spapr: Fix stale HTAB during live migration

[David Gibson]

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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