[v6,1/5] KVM: s390: clean up redundant 'kvm_run' parameters
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Message ID 20200623131418.31473-2-tianjia.zhang@linux.alibaba.com
State Not Applicable
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  • clean up redundant 'kvm_run' parameters
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Commit Message

Tianjia Zhang June 23, 2020, 1:14 p.m. UTC
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(-)

Comments

Christian Borntraeger June 23, 2020, 3:31 p.m. UTC | #1
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);
>  
>
Tianjia Zhang June 24, 2020, 2:39 a.m. UTC | #2
On 2020/6/23 23:31, Christian Borntraeger wrote:
> 
> 
> 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.

Yes, this is a full architecture optimization. Some of the architecture 
optimization has been merged into the mainline. I think it is necessary 
to unify this optimization. This is also the meaning of Paolo.
You can refer to the email of the previous version:
https://lkml.org/lkml/2020/4/27/16

Thanks,
Tianjia
Paolo Bonzini July 10, 2020, 7:48 a.m. UTC | #3
On 23/06/20 17:31, Christian Borntraeger wrote:
> 
> 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. 

Yes, it adds lines of code but they're just

+	struct kvm_run *kvm_run = vcpu->run;

You could avoid the LoC increase by repeating vcpu->run over and over,
but I think the code overall is clearer.

Paolo

Patch
diff mbox series

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);