[Xen-devel] Should shadow_fault_fast_fail abort?

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Hi Tim:

I noticed your recent patch turned off PFEC_reserved_bit in case
another CPU had already modified a magic PTE.  It seems that it
still leaves PFEC_page_present enabled.  This could confuse the
guest if the PTE modification is such that the PTE is now present
and valid.  In fact the guest may treat it as a protection fault.

You could turn the present bit off, but that is not strictly correct
if say an MMIO va was reused for normal memory.

The safest solution is probably to just return EXCRET_fault_fixed
and let the CPU figure it out.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel