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xen-ia64-devel
RE: [Xen-ia64-devel] Mapping invalid address
And lookup_domain_mpa() may return zero if there is
no existing ("legal") mapping and it is unable to
"create" a mapping.
Yes, this should be fixed, but its not clear *how* it
should be fixed. If a native OS tries to access a
non-existent machine address, I think an MCA happens,
so Xen should probably do the same, killing the guest.
However, I have seen this problem occur sometimes and I am
not sure of the cause, so left it as a printk. Perhaps,
at a minimum, the printk in lookup_domain_mpa should
shout ***FIXME!*** louder.
Note also that an itc.d instruction is defined to
only return an illop fault if psr.ic is on so the
failure return in vcpu_itc_d is also wrong (especially
if translate_domain_pte() *does* get changed to return
a zero on failure.
Dan
> -----Original Message-----
> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf
> Of Tristan Gingold
> Sent: Friday, March 17, 2006 7:35 AM
> To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-ia64-devel] Mapping invalid address
>
> Hi,
>
> when domU tries to map an bad mpa, it maps page 0 instead.
>
> This is how vcpu_itc_d works:
> pteval = translate_domain_pte(pte,ifa,itir);
> if (!pteval) return IA64_ILLOP_FAULT;
>
> Because translate_domain_pte end is:
> pteval2 = lookup_domain_mpa(d,mpaddr);
> pteval2 &= _PAGE_PPN_MASK; // ignore non-addr bits
> pteval2 |= _PAGE_PL_2; // force PL0->2 (PL3 is unaffected)
> pteval2 = (pteval & ~_PAGE_PPN_MASK) | pteval2;
> return pteval2;
> }
>
> Therefore, translate_domain_pte never returns 0.
>
> it is expected, or should we fix this behavior ?
>
> Tristan.
>
>
>
> _______________________________________________
> Xen-ia64-devel mailing list
> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
>
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