Re: [Xen-devel] 32bit PAE PV guest on 64bit hypervisor

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

Jeremy Fitzhardinge wrote:
> Mukesh Rathor wrote:
> > Hi,
> >
> > Been chasing down this message from guest boot:
> >
> > (XEN) mm.c:1841:d1 Error pfn 7f36a: rd=ffff8300cea28080,
> > od=0000000000000000, caf=00000000, taf=0000000000000000
> > (XEN) mm.c:730:d1 Error getting mfn 7f36a (pfn 5555555555555555) from L1
> > entry 000000007f36a025 for dom1
> > (XEN) mm.c:3700:d1 ptwr_emulate: fixing up invalid PAE PTE
> > 000000007f36a025
> >
> > Firstly, on a >64GB system, looks like a 32bit guest can get mfn above 
> > 64G.
> > The above msg comes when the PV guest tries to do WP check. To that end,
> > it does set_pte for mapping a (some swapper) temp page in test_wp_bit():
> >
> >       __set_fixmap(FIX_WP_TEST, __pa_symbol(&swapper_pg_dir), 
> > PAGE_READONLY);
> >       boot_cpu_data.wp_works_ok = do_test_wp_bit();
> >       clear_fixmap(FIX_WP_TEST);
> >
> > ...
> > /* use writable pagetables */
> > static inline void set_pte(pte_t *ptep, pte_t pte)
> > {
> >         ptep->pte_high = pte.pte_high;
> >     smp_wmb();
> >     ptep->pte_low = pte.pte_low;
> > }
> What kernel version is this?
>
>    J
While I was debugging 2.6.18-92, I see code is same on 2.6.18-128.
The xen version, just in case, 3.3.1.

Thanks,
Mukesh



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