Re: "X86_PV_VCPU_MSRS record truncated" during domain restore

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 21/07/2016 09:39, Massimo Colombi wrote:
> This is the output of verify-stream-v2:
>
> [user@dom0 scripts]$ sudo xl save fedora-23-dvm /fedora-23-dvm-savefile
> Saving to /fedora-23-dvm-savefile new xl format (info 0x3/0x0/1991)
> xc: info: Saving domain 4, type x86 PV
> xc: Frames: 912384/912384  100%
> xc: End of stream: 0/0    0%
>
> [user@dom0 scripts]$ ./verify-stream-v2 -f xl -i /fedora-23-dvm-savefile
> Stream Error:
> Traceback (most recent call last):
>   File "./verify-stream-v2", line 82, in read_stream
>     VerifyLibxl(info, stream_read).verify()
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxl.py",
> line 82, in verify
>     while self.verify_record() != REC_TYPE_end:
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxl.py",
> line 136, in verify_record
>     record_verifiers[rtype](self, content[:length])
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxl.py",
> line 155, in verify_record_libxc_context
>     VerifyLibxc(self.info, self.read).verify()
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxc.py",
> line 132, in verify
>     while self.verify_record() != REC_TYPE_end:
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxc.py",
> line 227, in verify_record
>     record_verifiers[rtype](self, content[:length])
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxc.py",
> line 429, in <lambda>
>     VerifyLibxc.verify_record_x86_pv_vcpu_generic(s, x, "msrs"),
>   File "/usr/lib64/python2.7/site-packages/xen/migration/libxc.py",
> line 323, in verify_record_x86_pv_vcpu_generic
>     " bytes long" % (name, minsz))
> RecordError: X86_PV_VCPU_msrs record length must be at least 8 bytes long
>
>
> On 07/21/2016 02:10 AM, Andrew Cooper wrote:
>> Is it possible to do an `xl save` equivalent on the domain, and run
>> tools/python/scripts/verify-stream-v2 against the resulting file?  That
>> should identify whether it is a malformed X86_PV_VCPU_MSRS record but
>> otherwise intact stream, or whether the stream becomes corrupted
>> elsewhere?
>
> Thanks for your explanation of the bug.

I should also improve the reported error message.

Do you mind rerunning with an extra -v to dump a list of the records
found in the stream?

~Andrew

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