linux-kernel - Re: [PATCH v2 40/49] KVM: x86: Initialize guest cpu

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Message-ID: <Zqe2n4e4HtdgUWgm@google.com>
Date: Mon, 29 Jul 2024 08:34:55 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Maxim Levitsky <mlevitsk@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Hou Wenlong <houwenlong.hwl@...group.com>, 
	Kechen Lu <kechenl@...dia.com>, Oliver Upton <oliver.upton@...ux.dev>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yang Weijiang <weijiang.yang@...el.com>, 
	Robert Hoo <robert.hoo.linux@...il.com>
Subject: Re: [PATCH v2 40/49] KVM: x86: Initialize guest cpu_caps based on KVM support

On Wed, Jul 24, 2024, Maxim Levitsky wrote:
> On Mon, 2024-07-08 at 17:10 -0700, Sean Christopherson wrote:
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index 0e64a6332052..dbc3f6ce9203 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -448,7 +448,7 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
> >                 if (!entry)
> >                         continue;
> >  
> > -               cpuid_func_emulated(&emulated, cpuid.function);
> > +               cpuid_func_emulated(&emulated, cpuid.function, false);
> >  
> >                 /*
> >                  * A vCPU has a feature if it's supported by KVM and is enabled
> > @@ -1034,7 +1034,8 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
> >         return entry;
> >  }
> >  
> > -static int cpuid_func_emulated(struct kvm_cpuid_entry2 *entry, u32 func)
> > +static int cpuid_func_emulated(struct kvm_cpuid_entry2 *entry, u32 func,
> > +                              bool only_advertised)
> 
> I'll say, lets call this boolean, 'include_partially_emulated', 
> (basically features that kvm emulates but only partially,
> and thus doesn't advertise, aka mwait)
> 
> and then it doesn't look that bad, assuming that comes with a comment.

Works for me.  I was trying to figure out a way to say "emulated_on_ud", but I
can't get the polarity right, at least not without ridiculous verbosity.  E.g.
include_not_emulated_on_ud is awful.