Re: [PATCH v6 1/5] KVM: s390: clean up redundant 'kvm_run' parameters

From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
	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, cohuck@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, chenhuacai@gmail.com
Cc: 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
Subject: Re: [PATCH v6 1/5] KVM: s390: clean up redundant 'kvm_run' parameters
Date: Tue, 23 Jun 2020 17:31:34 +0200	[thread overview]
Message-ID: <c49f8814-c7ea-6884-91c5-3dcd40c6509f@de.ibm.com> (raw)
In-Reply-To: <20200623131418.31473-2-tianjia.zhang@linux.alibaba.com>


On 23.06.20 15:14, Tianjia Zhang wrote:
> In the current kvm version, 'kvm_run' has been included in the 'kvm_vcpu'
> structure. For historical reasons, many kvm-related function 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@linux.alibaba.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)

Tinajia,

I have trouble seeing value in this particular patch. We add LOCs
without providing any noticable benefit. All other patches in this series at
least reduce the amount of code. So I would defer this to Paolo if he prefers
to have this way across all architectures. 
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d47c19718615..f5f96dc33712 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -4175,8 +4175,9 @@ 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;
>  
> @@ -4242,8 +4243,10 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  	/* SIE will load etoken directly from SDNX and therefore kvm_run */
>  }
>  
> -static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> +static void sync_regs(struct kvm_vcpu *vcpu)
>  {
> +	struct kvm_run *kvm_run = vcpu->run;
> +
>  	if (kvm_run->kvm_dirty_regs & KVM_SYNC_PREFIX)
>  		kvm_s390_set_prefix(vcpu, kvm_run->s.regs.prefix);
>  	if (kvm_run->kvm_dirty_regs & KVM_SYNC_CRS) {
> @@ -4272,7 +4275,7 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  
>  	/* Sync fmt2 only data */
>  	if (likely(!kvm_s390_pv_cpu_is_protected(vcpu))) {
> -		sync_regs_fmt2(vcpu, kvm_run);
> +		sync_regs_fmt2(vcpu);
>  	} else {
>  		/*
>  		 * In several places we have to modify our internal view to
> @@ -4291,8 +4294,10 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  	kvm_run->kvm_dirty_regs = 0;
>  }
>  
> -static void store_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> +static void store_regs_fmt2(struct kvm_vcpu *vcpu)
>  {
> +	struct kvm_run *kvm_run = vcpu->run;
> +
>  	kvm_run->s.regs.todpr = vcpu->arch.sie_block->todpr;
>  	kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
>  	kvm_run->s.regs.gbea = vcpu->arch.sie_block->gbea;
> @@ -4312,8 +4317,10 @@ static void store_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  	/* SIE will save etoken directly into SDNX and therefore kvm_run */
>  }
>  
> -static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> +static void store_regs(struct kvm_vcpu *vcpu)
>  {
> +	struct kvm_run *kvm_run = vcpu->run;
> +
>  	kvm_run->psw_mask = vcpu->arch.sie_block->gpsw.mask;
>  	kvm_run->psw_addr = vcpu->arch.sie_block->gpsw.addr;
>  	kvm_run->s.regs.prefix = kvm_s390_get_prefix(vcpu);
> @@ -4332,7 +4339,7 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  	current->thread.fpu.fpc = vcpu->arch.host_fpregs.fpc;
>  	current->thread.fpu.regs = vcpu->arch.host_fpregs.regs;
>  	if (likely(!kvm_s390_pv_cpu_is_protected(vcpu)))
> -		store_regs_fmt2(vcpu, kvm_run);
> +		store_regs_fmt2(vcpu);
>  }
>  
>  int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> @@ -4370,7 +4377,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>  		goto out;
>  	}
>  
> -	sync_regs(vcpu, kvm_run);
> +	sync_regs(vcpu);
>  	enable_cpu_timer_accounting(vcpu);
>  
>  	might_fault();
> @@ -4392,7 +4399,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>  	}
>  
>  	disable_cpu_timer_accounting(vcpu);
> -	store_regs(vcpu, kvm_run);
> +	store_regs(vcpu);
>  
>  	kvm_sigset_deactivate(vcpu);
>  
>