| Subject | Re: [PATCH 3.13 044/187] x86_64/entry/xen: Do not invoke espfix64 on Xen | From | Ben Hutchings <> | Date | Wed, 17 Sep 2014 12:25:51 +0100 |
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On Mon, 2014-09-15 at 15:07 -0700, Kamal Mostafa wrote: > 3.13.11.7 -stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Andy Lutomirski <luto@amacapital.net> > > commit 7209a75d2009dbf7745e2fd354abf25c3deb3ca3 upstream. > > This moves the espfix64 logic into native_iret. To make this work, > it gets rid of the native patch for INTERRUPT_RETURN: > INTERRUPT_RETURN on native kernels is now 'jmp native_iret'. > > This changes the 16-bit SS behavior on Xen from OOPSing to leaking > some bits of the Xen hypervisor's RSP (I think). > > [ hpa: this is a nonzero cost on native, but probably not enough to > measure. Xen needs to fix this in their own code, probably doing > something equivalent to espfix64. ] > > Signed-off-by: Andy Lutomirski <luto@amacapital.net> > Link: http://lkml.kernel.org/r/7b8f1d8ef6597cb16ae004a43c56980a7de3cf94.1406129132.git.luto@amacapital.net > Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> > Signed-off-by: Kamal Mostafa <kamal@canonical.com> [...]
There's another fix related to espfix on Xen, commit 8762e5092828 ("x86/espfix/xen: Fix allocation of pages for paravirt page tables"). But I'm not sure whether it's actually needed after this.
Ben.
-- Ben Hutchings Beware of programmers who carry screwdrivers. - Leonard Brandwein [unhandled content-type:application/pgp-signature] |