Re: [Xen-devel] d273:v3: reserved bit in page table (ec=0019)

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 16/07/2009 17:21, "Christopher S. Aker" <caker@xxxxxxxxxxxx> wrote:

> Xen 3.3-testing @ changeset 18651, 64bit
> dom0 2.6.18.8 @ changeset 888, PAE
> 
> Files: http://theshore.net/~caker/xen/BUGS/1.22/
> 
> (XEN) d273:v3: reserved bit in page table (ec=0019)

Unexpected page fault due to a reserved bit set in a guest page directory
entry...

> (XEN) Pagetable walk from 00000000c0101347:
> (XEN)  L4[0x000] = 000000067c36a027 0000000000016495
> (XEN)  L3[0x003] = 000000067c06c027 0000000000016793
> (XEN)  L2[0x000] = 00001f5e9d00f403 ffffffffffffffff
                     ^^^^^^^^^^^^^^^^
Bogus PDE -- the bottom 12 bits are potentially okay (although I don't think
Linux uses the _PAGE_AVAIL bits) but the physical address is definitely
bogus. Begs the question where the bogus PDE came from of course, since that
would be the actual bug. The crash report here is the symptom when the PDE
actually next gets used.

 -- Keir



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