Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 23 Jun 2021 20:47:59 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH 25/54] KVM: x86/mmu: Add helpers to query mmu_role bits
Message-ID: <YNOd/0RxSnqmDBvd@google.com>
References: <20210622175739.3610207-1-seanjc@google.com>
 <20210622175739.3610207-26-seanjc@google.com>
 <1babfd1c-bee1-12e5-a9d9-9507891efdfd@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1babfd1c-bee1-12e5-a9d9-9507891efdfd@redhat.com>
Precedence: bulk

On Wed, Jun 23, 2021, Paolo Bonzini wrote:
> On 22/06/21 19:57, Sean Christopherson wrote:
> > +static inline bool is_##reg##_##name(struct kvm_mmu *mmu)	\
> 
> What do you think about calling these is_mmu_##name?  The point of having
> these helpers is that the register doesn't count, and they return the
> effective value (e.g. false in most EPT cases).

I strongly prefer to keep <reg> in the name, both to match the mmu_role bits and
to make it a bit more clear that it's reflective (modified) register state, as
opposed to PTEs or even something else entirely.  E.g. I always struggled to
remember the purpose of mmu->nx flag.

I wouldn't be opposed to is_mmu_##reg##_##name() though.  I omitted the "mmu"
part because it was loosely implied by the "struct kvm_mmu" param, and to keep
line lengths short.  But being explicit is usually a good thing, and looking at
the code I don't see any lines that would wrap if "mmu" were added.

> > +{								\
> > +	return !!(mmu->mmu_role. base_or_ext . reg##_##name);	\
> > +}
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr0, pg);
> > +BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, pse);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, pae);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, smep);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, smap);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, pke);
> > +BUILD_MMU_ROLE_ACCESSOR(ext,  cr4, la57);
> > +BUILD_MMU_ROLE_ACCESSOR(base, efer, nx);
> > +
> >   struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu)
>