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

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Date:   Wed, 22 Apr 2020 15:45:43 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Tianjia Zhang <tianjia.zhang@...ux.alibaba.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 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/ ?

> 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?

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