Re: [PATCH v2 0/9] i386/cpu: Support APX for KVM

[Zhao Liu <zhao1.liu@intel.com>]

On Thu, Dec 11, 2025 at 09:08:33AM +0100, Paolo Bonzini wrote:
> Date: Thu, 11 Dec 2025 09:08:33 +0100
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: Re: [PATCH v2 0/9] i386/cpu: Support APX for KVM
> 
> On 12/11/25 08:09, Zhao Liu wrote:
> > Hi,
> > 
> > This series adds APX (Advanced Performance Extensions) support in QEMU
> > to enable APX in Guest based on KVM (RFC v1 [1]).
> > 
> > This series is based on CET v5:
> > 
> > https://lore.kernel.org/qemu-devel/20251211060801.3600039-1-zhao1.liu@intel.com/
> > 
> > And you can also find the code here:
> > 
> > https://gitlab.com/zhao.liu/qemu/-/commits/i386-all-for-dmr-v2.1-12-10-2025
> > 
> > Compared with v1 [2], v2 adds:
> >   * HMP support ("print" & "info registers").
> >   * gdbstub support.
> > 
> > Thanks for your review!
> 
> Great, thanks!  Just one question, should the CPUID feature be "apx" or
> "apxf" (and therefore CPUID_7_1_EDX_APXF)?  I can fix that myself of course.

Good point! I didn't realize this.

1) Per APX spec:

(APX adds) CPUID Enumeration for APX_F (APX Foundation).

2) And gcc also use apx_f:

https://codebrowser.dev/gcc/gcc/config/i386/cpuid.h.html#_M/bit_APX_F

3) ...and we already have "avx512f".

So you're right, I should use "apxf" and CPUID_7_1_EDX_APXF.

Since APX CPUID appears in several patches, I can respin a new version
quickly.

Thanks,
Zhao