Messages in this thread | | | Date | Wed, 5 Oct 2022 14:04:09 +0200 | Subject | Re: Finish removing MPX from arch/x86? | From | Paolo Bonzini <> |
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On 10/4/22 19:34, Dave Hansen wrote: > We zapped the userspace MPX ABIs and most of its supporting code in here: > > 45fc24e89b7c ("x86/mpx: remove MPX from arch/x86") > > But, the XSAVE enabling and KVM code were left in place. This let folks > at least keep running guests with MPX. > > It's been a couple of years and I don't think I've had a single person > opine about the loss of MPX. Intel also followed through and there's no > MPX to be found on newer CPUs like my "Tiger Lake" 11th Gen Intel(R) > Core(TM) i7-1165G7. > > Is it time to zap MPX from arch/x86/kvm/?
I agree that the likelihood of anybody complaining about MPX is low but Jim is right that the timeline for removing it is unfortunately quite long.
Removing MPX from XFEATURE_MASK_USER_SUPPORTED is possible, though we need to add a new XFEATURE_MASK_GUEST_SUPPORTED that includes MPX. I'll take a look.
Also, it's worth noting that MPX lives in the sigcontext ABI because it uses the non-compacted format. Because of that it is not possible to remove the structs from include/asm/fpu/types.h, for example.
Paolo
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