Messages in this thread | | | Date | Thu, 30 Jul 2015 13:18:20 -0400 | From | Boris Ostrovsky <> | Subject | Re: [Xen-devel] [PATCH v5 0/4] x86: modify_ldt improvement, test, and config option |
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On 07/30/2015 01:06 PM, Andrew Cooper wrote: > On 30/07/15 17:31, Boris Ostrovsky wrote: >> On 07/30/2015 12:12 PM, Andrew Cooper wrote: >>> On 30/07/15 17:05, Borislav Petkov wrote: >>>> On Thu, Jul 30, 2015 at 11:53:34AM -0400, Boris Ostrovsky wrote: >>>>> As far as Xen guests are concerned, >>>>> >>>>> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> >>>> Does that mean, this patch 1/4 fixes the 32bit issue you guys are still >>>> debugging on the v4 thread? Or does that need more fixing? >>>> >>> I was going to say... This v5 pre-dates figuring out what was wrong with >>> 32bit Xen. v5 1/4 is still susceptible. >>> >>> Boris: does your Tested-by cover v5 + proposed fix? >>> >> Only V5, no extra changes. > Including running the ldt_gdt test?
Yes, except that 32-on-64 doesn't work, but that's not Xen-specific.
Still, user-visible behavior changes.
> >> And perhaps dropping aliases in xen_alloc_ldt() may be sufficient >> since with that done we will only have one mapping so a subsequent >> fault will have "correct" cr2 provided by the hypervisor (from your >> earlier email it sounded that hypervisor may have been providing >> incorrect cr2 if alias exists) > They are sufficient to fix the first of the two bugs, but the free side > still has no protection against a missing l2, unless I am missing > something in the rest of the series?
Without aliases a subsequent fault *will* fill correct l2, won't it?
-boris
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