On 04/12/17 10:15, Jan Beulich wrote: >>>> On 03.07.17 at 16:56, wrote: >>>>> On 31.05.17 at 13:54, wrote: >>>>>> On 31.05.17 at 13:08, <[email protected]> wrote: >>>> On 31/05/17 08:15, Jan Beulich wrote: >>>>> The flag is really only meant for those, both HVM and 32-bit PV tell >>>>> kernel from user mode based on CPL/RPL. Remove the all-question-marks >>>>> comment and let's be on the safe side here and also suppress clearing >>>>> for 32-bit PV (this isn't a fast path after all). >>>>> >>>>> Signed-off-by: Jan Beulich <[email protected]> >>>> Wouldn't it just be safer to disallow starting a 64bit PV guest in user >>>> mode? >>>> >>>> No real kernel would do such a thing, and keeping the corner case around >>>> is bad from an attack-surface point of view. >>> If it really was "starting a guest", I would probably agree. But we're >>> talking about starting a vCPU, and I could see uses for this (not the >>> least in XTF). After all the operation allows for enough state to be >>> set up such that further initialization inside the guest may not be >>> necessary. >> Any opinion here, or change of opinion on the original patch? > I'd really like to get this off my list.
My opinion is unchanged. This isn't a useful piece of functionality, and it definitely doesn't warrant the attack surface it brings. ~Andrew _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
