linux-kernel - Re: [PATCH v2 02/13] x86/kvm/emulate: Introduce COP1

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Message-ID: <20250430190521.GP4439@noisy.programming.kicks-ass.net>
Date: Wed, 30 Apr 2025 21:05:21 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: x86@...nel.org, kys@...rosoft.com, haiyangz@...rosoft.com,
	wei.liu@...nel.org, decui@...rosoft.com, tglx@...utronix.de,
	mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
	hpa@...or.com, seanjc@...gle.com, pbonzini@...hat.com,
	ardb@...nel.org, kees@...nel.org, Arnd Bergmann <arnd@...db.de>,
	gregkh@...uxfoundation.org, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	linux-efi@...r.kernel.org, samitolvanen@...gle.com,
	ojeda@...nel.org
Subject: Re: [PATCH v2 02/13] x86/kvm/emulate: Introduce COP1

On Wed, Apr 30, 2025 at 09:19:38AM -0700, Josh Poimboeuf wrote:
> On Wed, Apr 30, 2025 at 01:07:36PM +0200, Peter Zijlstra wrote:
> > +++ b/arch/x86/kvm/emulate.c
> > @@ -267,11 +267,56 @@ static void invalidate_registers(struct
> >  		     X86_EFLAGS_PF|X86_EFLAGS_CF)
> >  
> >  #ifdef CONFIG_X86_64
> > -#define ON64(x) x
> > +#define ON64(x...) x
> >  #else
> >  #define ON64(x)
> 
> Doesn't the 32-bit version need to be 
> 
>   #define ON64(x...)
> 
> since it now accepts multiple "args"?

Right, so far the robot hasn't complained, but yeah, consistency would
demand this :-)

> > -FASTOP1(not);
> > -FASTOP1(neg);
> > -FASTOP1(inc);
> > -FASTOP1(dec);
> > +COP1(not);
> > +COP1(neg);
> > +COP1(inc);
> > +COP1(dec);
> 
> I assume COP stands for "C op", but that will never be obvious.

Aww :-)

Right before sending I wondered if EM_ASM_*() would be a better
namespace.