Re: [Xen-devel] [PATCH 0 of 5] update xenctx to dump pagetables

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hi, 

At 17:26 +0200 on 20 Jun (1308590816), Olaf Hering wrote:
> The code to walk the pagetables is/was based on
> xc_translate_foreign_address(), but I still think I have some major bugs in
> there (the last patch). I cant figure out why some l3/l2/l1 entries can not 
> be mapped.
> Any help with getting that output fixed for at least a a 64bit PV guest is 
> much
> appreciated.

I didn't spot anything broken in the walker (though it will need a bunch
of cleaning up) and the output looks very plausible.  I take it this is
a PV guest?  Is it a well-behaved one or a broken post-migrate one?

One thing that might be causing trouble is if the domain's not paused
while you do the walk, then you might see inconsistent tables, though
I'd expect them to be garbage rather than looking like this.  Your patch
3/5 does seem to make the pausing conditional where before it always
happened. 

Tim.

> part of xenctx output:
> ...
>   0 l4e  ff 00000000a1240067:  x   0     a1240000 0 0 1 A c t u W P
>   0 l3e 1ff 00000000bc133067:  x   0     bc133000 0 0 s 1 A c t U W P
>   0 l2e  64 00000000a1471067:  x   0     a1471000 0 0 s 1 A c t U W P
>   0 l1e  46 80000000bd56f167:  X   0     bd56f000 0 G p s D A c t U W P     
> 7fffcc846000
>   0 l1e  47 80000000bd57c167:  X   0     bd57c000 0 G p s D A c t U W P     
> 7fffcc847000
>   0 l1e  48 80000000bd5af165:  X   0     bd5af000 0 G p s D A c t U w P     
> 7fffcc848000
>   0 l1e  db 00000000a1972125:  x   0     a1972000 0 G p s d A c t U w P     
> 7fffcc8db000
>   0 l4e 100 000000013fff8067:  x   0    13fff8000 0 0 1 A c t u W P
> xc_map_foreign_range l3: Invalid argument
>   0 l4e 101 000000013fff0063:  x   0    13fff0000 0 0 1 A c t u W P
> xc_map_foreign_range l3: Invalid argument
>   0 l4e 102 00000000bc5b0063:  x   0     bc5b0000 0 0 1 A c t u W P
>   0 l3e  fe 00000000a7ed2067:  x   0     a7ed2000 0 0 s 1 A c t U W P
>   0 l2e 163 00000000a154a067:  x   0     a154a000 0 0 s 1 A c t U W P
>   0 l1e 1eb 00000000bc1a7067:  x   0     bc1a7000 0 g p s D A c t U W P     
> 813fac7eb000
>   0 l1e 1ec 00000000a154f067:  x   0     a154f000 0 g p s D A c t U W P     
> 813fac7ec000
> ...
> 
> in dmesg:
> ...
> (XEN) mm.c:880:d0 Error getting mfn 13fff8 (pfn 5555555555555555) from L1 
> entry 800000013fff8625 for l1e_owner=0, pg_owner=19
> (XEN) mm.c:880:d0 Error getting mfn 13fff0 (pfn 5555555555555555) from L1 
> entry 800000013fff0625 for l1e_owner=0, pg_owner=19


-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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