Re: [PATCH 18/22] KVM: SVM: add GMET bit definitions

[Paolo Bonzini]

Il sab 21 mar 2026, 16:42 Borislav Petkov <bp@xxxxxxxxx> ha scritto:
>
> On Sat, Mar 21, 2026 at 02:51:47PM +0100, Paolo Bonzini wrote:
> > I prefer to be consistent with all the other ones in word 15.
>
> Sorry, no, /proc/cpuinfo is an ABI.

I am not sure what you mean by ABI in this context, maybe "there are
rules for whether to add stuff to cpuinfo.rst"? If so, GMET matches
what cpuinfo.rst says:

* the kernel knows about the feature enough to have an X86_FEATURE bit
* the kernel supports it and is currently making it available to userspace
* the hardware supports it.

The bullet that applies here is the second from the above list: 1)
this series makes the feature available for userspace and guests to
use it, 2) that requires explicit support, it's not just a bunch of
new instructions.

I agree that not all word 15 features should be added to
/proc/cpuinfo, if that's what you meant by referencing cpuinfo.rst.
For example these days something like AVIC would not be added to
/proc/cpuinfo because it's transparent to userspace and guests.

Paolo