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From:   Yu Zhao <yuzhao@google.com>
Date:   Fri, 14 Jul 2023 22:30:37 -0600
Message-ID: <CAOUHufady0XkgFWSL6-Mb+HFEyaQ33DJCinsjidRw2DTR9F8yQ@mail.gmail.com>
Subject: Re: [RFC PATCH v3 09/11] KVM: Add new members to struct kvm_gfn_range
 to operate on
To:     Sean Christopherson <seanjc@google.com>
Cc:     isaku.yamahata@intel.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>, chen.bo@intel.com,
        linux-coco@lists.linux.dev,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Vishal Annapurve <vannapurve@google.com>,
        Michael Roth <michael.roth@amd.com>,
        Yuan Yao <yuan.yao@linux.intel.com>
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On Thu, Jul 13, 2023 at 4:10=E2=80=AFPM Sean Christopherson <seanjc@google.=
com> wrote:
>
> +Yu
>
> On Wed, Jun 28, 2023, isaku.yamahata@intel.com wrote:
> >  void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm,
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 1a47cedae8a1..5ca0c8ee4292 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -260,7 +260,13 @@ struct kvm_gfn_range {
> >       struct kvm_memory_slot *slot;
> >       gfn_t start;
> >       gfn_t end;
> > -     pte_t pte;
> > +     union {
> > +             unsigned long attributes;
> > +             pte_t pte;
> > +             unsigned long callback_arg; /* needs a better name */
> > +     };
>
> Making the union needs to be done in a separate patch.  And coming back t=
o this
> with fresh eyes, I think it makes sense to give the union a name.  I thin=
k an
> anonymous union is actually worse in the long run, and there aren't _that=
_ many
> instances to update.  E.g. that way a single build-time assertion can cap=
ture
> all uses, and it makes it more obvious that the usage is poking into a un=
ion.
>
> I'll post a patch separately so that it can be picked up for the MGLRU se=
ries
> (and maybe even merged ahead of both).

Thanks a lot, Sean. And sorry for having not addressed your comments
on v2 -- I'm wrapping up a few other projects and will be focusing on
addressing all pending comments in a couple of weeks.