Messages in this thread | | | Date | Fri, 3 Apr 2020 18:12:05 +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 09:01:56AM -0700, Sean Christopherson wrote: > On Fri, Apr 03, 2020 at 05:21:58PM +0200, Peter Zijlstra wrote: > > On Fri, Apr 03, 2020 at 04:35:00PM +0200, Jessica Yu wrote:
> > > 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. > > Rather than scanning modules at all, what about hooking native_write_cr4() > to kill SLD if CR4.VMXE is toggled on and the caller didn't increment a > "sld safe" counter?
And then you're hoping that the module uses that and not:
asm volatile ("mov %0, cr4" :: "r" (val));
I think I feel safer with the scanning to be fair. Also with the intree hint on, we can extend the scanning for out-of-tree modules for more dodgy crap we really don't want modules to do, like for example the above.
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