Messages in this thread | | | Date | Fri, 3 Apr 2020 17:21:58 +0200 | From | Peter Zijlstra <> | Subject | Re: [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect |
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On Fri, Apr 03, 2020 at 04:35:00PM +0200, Jessica Yu wrote: > +++ Rasmus Villemoes [03/04/20 01:42 +0200]: > > On 02/04/2020 14.32, Thomas Gleixner wrote: > > > From: Peter Zijlstra <peterz@infradead.org> > > > > > > It turns out that with Split-Lock-Detect enabled (default) any VMX > > > hypervisor needs at least a little modification in order to not blindly > > > inject the #AC into the guest without the guest being ready for it. > > > > > > Since there is no telling which module implements a hypervisor, scan the > > > module text and look for the VMLAUNCH instruction. If found, the module is > > > assumed to be a hypervisor of some sort and SLD is disabled. > > > > How long does that scan take/add to module load time? Would it make > > sense to exempt in-tree modules? > > > > Rasmus > > I second Rasmus's question. It seems rather unfortunate that we have > to do this text scan for every module load on x86, when it doesn't > apply to the majority of them, and only to a handful of out-of-tree > hypervisor modules (assuming kvm is taken care of already). > > I wonder if it would make sense then to limit the text scans to just > out-of-tree modules (i.e., missing the intree modinfo flag)?
It would; didn't know there was one.
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