Messages in this thread | | | Date | Mon, 7 Feb 2022 14:04:04 -0800 | From | Kees Cook <> | Subject | Re: [PATCH v2 1/6] x86/cpu: Allow feature bit names from /proc/cpuinfo in clearcpuid= |
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On Thu, Jan 27, 2022 at 12:56:21PM +0100, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > Having to give the X86_FEATURE array indices in order to disable a > feature bit for testing is not really user-friendly. So accept the > feature bit names too. > > Some feature bits don't have names so there the array indices are still > accepted, of course. > > Clearing CPUID flags is not something which should be done in production > so taint the kernel too. > > An exemplary cmdline would then be something like: > > clearcpuid=de,440,smca,succory,bmi1,3dnow > > ("succory" is wrong on purpose). And it says: > > [ 0.000000] Clearing CPUID bits: de 13:24 smca bmi1 3dnow > > Signed-off-by: Borislav Petkov <bp@suse.de>
I like the taint flag addition!
Even though it reports what it does actually clear, do you think it might be more "friendly" to yell about unknown stuff too? i.e.:
[ 0.000000] Clearing CPUID bits: unknown bit 'succory' [ 0.000000] Clearing CPUID bits: de 13:24 smca bmi1 3dnow
Either way:
Reviewed-by: Kees Cook <keescook@chromium.org>
-- Kees Cook
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