Re: [Xen-devel] Problems using xl migrate

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Sat, Nov 22, 2014 at 07:24:21PM +0000, M A Young wrote:
> While investigating a bug reported on Red Hat Bugzilla
> https://bugzilla.redhat.com/show_bug.cgi?id=1166461
> I discovered the following
> 
> xl migrate --debug domid localhost does indeed fail for Xen 4.4 pv (the bug
> report is for Xen 4.3 hvm ) when xl migrate domid localhost works. There are
> actually two issues here
> 
> * the segfault in libxl-save-helper --restore-domain (as reported in the bug
> above) occurs if the guest memory is 1024M (on my 4G box) and is presumably
> because the allocated memory eventually runs out
> 
> * the segfault doesn't occur if the guest memory is 128M, but the migration
> still fails. The first attached file contains the log from a run with xl -v
> migrate --debug domid localhost (with mfn and duplicated lines stripped out
> to make the size manageable).
> 
> I then tried xen 4.5-rc1 to see if the bug was fixed and found that xl
> migrate doesn't work for me at all - see the second attached file for the
> output of xl -v migrate domid localhost .
> 
>       Mchael Young

[...]
> xc: detail: delta 15801ms, dom0 95%, target 0%, sent 543Mb/s, dirtied 0Mb/s 
> 314 pages
> xc: detail: Mapping order 0,  268; first pfn 3fcf4
> xc: detail: delta 23ms, dom0 100%, target 0%, sent 447Mb/s, dirtied 0Mb/s 0 
> pages
> xc: detail: Start last iteration
> xc: Reloading memory pages: 262213/262144  100%xc: detail: SUSPEND shinfo 
> 00082fbc
> xc: detail: delta 17ms, dom0 58%, target 58%, sent 0Mb/s, dirtied 1033Mb/s 
> 536 pages
> xc: detail: delta 8ms, dom0 100%, target 0%, sent 2195Mb/s, dirtied 2195Mb/s 
> 536 pages
> xc: detail: Total pages sent= 262749 (1.00x)
> xc: detail: (of which 0 were fixups)
> xc: detail: All memory is saved
> xc: error: Error querying maximum number of MSRs for VCPU0 (1 = Operation not 
> permitted): Internal error

Per your description this is the output of "xl -v migrate domid
localhost", so no "--debug" is involved. (Just to make sure...)

This error message means a domctl fails, which should be addressed
first?

FWIW I tried "xl -v migrate domid localhost" for a PV guest it worked
for me. :-(

Is there anything I need to do to trigger this failure?

Wei.

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