linux-kernel - Re: [PATCH v2 1/7] KVM: s390: clean up redundant 'kvm

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Message-ID: <e115bcf6-edf3-7465-f592-4e93e5ad984c@linux.alibaba.com>
Date:   Thu, 23 Apr 2020 10:54:35 +0800
From:   Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     pbonzini@...hat.com, tsbogend@...ha.franken.de, paulus@...abs.org,
        mpe@...erman.id.au, benh@...nel.crashing.org,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        heiko.carstens@...ibm.com, gor@...ux.ibm.com,
        sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, maz@...nel.org, james.morse@....com,
        julien.thierry.kdev@...il.com, suzuki.poulose@....com,
        christoffer.dall@....com, peterx@...hat.com, thuth@...hat.com,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
        kvm-ppc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/7] KVM: s390: clean up redundant 'kvm_run' parameters



On 2020/4/22 21:45, Cornelia Huck wrote:
> On Wed, 22 Apr 2020 20:58:04 +0800
> Tianjia Zhang <tianjia.zhang@...ux.alibaba.com> 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/ ?
> 

Yes, it should be replaced like this.

>> 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 <tianjia.zhang@...ux.alibaba.com>
>> ---
>>   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?
> 

Why not replace `vcpu->run->` to `kvm_run->` ? If not, there will be 
both styles of code, which is confusing. I will be confused and think 
that this is something different.

Thanks,
Tianjia

>>   			restore_gs_cb(current->thread.gs_cb);
>>   		}
>>   		preempt_enable();