From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 23 Apr 2020 12:39:01 +0200 From: Cornelia Huck Subject: Re: [PATCH v2 1/7] KVM: s390: clean up redundant 'kvm_run' parameters Message-ID: <20200423123901.72a4c6a4.cohuck@redhat.com> In-Reply-To: <5e1e126d-f1b0-196c-594b-4289d0afb9a8@linux.alibaba.com> References: <20200422125810.34847-1-tianjia.zhang@linux.alibaba.com> <20200422125810.34847-2-tianjia.zhang@linux.alibaba.com> <20200422154543.2efba3dd.cohuck@redhat.com> <20200422180403.03f60b0c.cohuck@redhat.com> <5e1e126d-f1b0-196c-594b-4289d0afb9a8@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: To: Tianjia Zhang Cc: Christian Borntraeger , pbonzini@redhat.com, tsbogend@alpha.franken.de, paulus@ozlabs.org, mpe@ellerman.id.au, benh@kernel.crashing.org, frankja@linux.ibm.com, david@redhat.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, sean.j.christopherson@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, maz@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, christoffer.dall@arm.com, peterx@redhat.com, thuth@redhat.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org On Thu, 23 Apr 2020 11:01:43 +0800 Tianjia Zhang wrote: > On 2020/4/23 0:04, Cornelia Huck wrote: > > On Wed, 22 Apr 2020 17:58:04 +0200 > > Christian Borntraeger wrote: > > > >> On 22.04.20 15:45, Cornelia Huck wrote: > >>> On Wed, 22 Apr 2020 20:58:04 +0800 > >>> Tianjia Zhang wrote: > >>> > >>>> In the current kvm version, 'kvm_run' has been included in the 'kvm_vcpu' > >>>> structure. Earlier than historical reasons, many kvm-related function > >>> > >>> s/Earlier than/For/ ? > >>> > >>>> parameters retain the 'kvm_run' and 'kvm_vcpu' parameters at the same time. > >>>> This patch does a unified cleanup of these remaining redundant parameters. > >>>> > >>>> Signed-off-by: Tianjia Zhang > >>>> --- > >>>> arch/s390/kvm/kvm-s390.c | 37 ++++++++++++++++++++++--------------- > >>>> 1 file changed, 22 insertions(+), 15 deletions(-) > >>>> > >>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > >>>> index e335a7e5ead7..d7bb2e7a07ff 100644 > >>>> --- a/arch/s390/kvm/kvm-s390.c > >>>> +++ b/arch/s390/kvm/kvm-s390.c > >>>> @@ -4176,8 +4176,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) > >>>> return rc; > >>>> } > >>>> > >>>> -static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) > >>>> +static void sync_regs_fmt2(struct kvm_vcpu *vcpu) > >>>> { > >>>> + struct kvm_run *kvm_run = vcpu->run; > >>>> struct runtime_instr_cb *riccb; > >>>> struct gs_cb *gscb; > >>>> > >>>> @@ -4235,7 +4236,7 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) > >>>> } > >>>> if (vcpu->arch.gs_enabled) { > >>>> current->thread.gs_cb = (struct gs_cb *) > >>>> - &vcpu->run->s.regs.gscb; > >>>> + &kvm_run->s.regs.gscb; > >>> > >>> Not sure if these changes (vcpu->run-> => kvm_run->) are really worth > >>> it. (It seems they amount to at least as much as the changes advertised > >>> in the patch description.) > >>> > >>> Other opinions? > >> > >> Agreed. It feels kind of random. Maybe just do the first line (move kvm_run from the > >> function parameter list into the variable declaration)? Not sure if this is better. > >> > > > > There's more in this patch that I cut... but I think just moving > > kvm_run from the parameter list would be much less disruptive. > > > > I think there are two kinds of code(`vcpu->run->` and `kvm_run->`), but > there will be more disruptive, not less. I just fail to see the benefit; sure, kvm_run-> is convenient, but the current code is just fine, and any rework should be balanced against the cost (e.g. cluttering git annotate).