Re: [PATCH v2 2/2] KVM: s390: use switch vs jump table in intercept.c

[Janosch Frank <frankja@linux.vnet.ibm.com>]

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On 06.02.2018 13:47, Christian Borntraeger wrote:
> Instead of having huge jump tables for function selection,
> let's use normal switch/case statements for the instruction
> handlers in intercept.c We can now also get rid of
> intercept_handler_t.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>

Looks good to me and results in less scrolling to find the handlers.

Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>


> ---
>  arch/s390/kvm/intercept.c | 51 +++++++++++++++++++++++++++--------------------
>  arch/s390/kvm/kvm-s390.h  |  2 --
>  2 files changed, 29 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
> index 9c7d70715862..07c6e81163bf 100644
> --- a/arch/s390/kvm/intercept.c
> +++ b/arch/s390/kvm/intercept.c
> @@ -22,22 +22,6 @@
>  #include "trace.h"
>  #include "trace-s390.h"
> 
> -
> -static const intercept_handler_t instruction_handlers[256] = {
> -	[0x01] = kvm_s390_handle_01,
> -	[0x82] = kvm_s390_handle_lpsw,
> -	[0x83] = kvm_s390_handle_diag,
> -	[0xaa] = kvm_s390_handle_aa,
> -	[0xae] = kvm_s390_handle_sigp,
> -	[0xb2] = kvm_s390_handle_b2,
> -	[0xb6] = kvm_s390_handle_stctl,
> -	[0xb7] = kvm_s390_handle_lctl,
> -	[0xb9] = kvm_s390_handle_b9,
> -	[0xe3] = kvm_s390_handle_e3,
> -	[0xe5] = kvm_s390_handle_e5,
> -	[0xeb] = kvm_s390_handle_eb,
> -};
> -
>  u8 kvm_s390_get_ilen(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
> @@ -129,16 +113,39 @@ static int handle_validity(struct kvm_vcpu *vcpu)
> 
>  static int handle_instruction(struct kvm_vcpu *vcpu)
>  {
> -	intercept_handler_t handler;
> -
>  	vcpu->stat.exit_instruction++;
>  	trace_kvm_s390_intercept_instruction(vcpu,
>  					     vcpu->arch.sie_block->ipa,
>  					     vcpu->arch.sie_block->ipb);
> -	handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
> -	if (handler)
> -		return handler(vcpu);
> -	return -EOPNOTSUPP;
> +
> +	switch (vcpu->arch.sie_block->ipa >> 8) {
> +	case 0x01:
> +		return kvm_s390_handle_01(vcpu);
> +	case 0x82:
> +		return kvm_s390_handle_lpsw(vcpu);
> +	case 0x83:
> +		return kvm_s390_handle_diag(vcpu);
> +	case 0xaa:
> +		return kvm_s390_handle_aa(vcpu);
> +	case 0xae:
> +		return kvm_s390_handle_sigp(vcpu);
> +	case 0xb2:
> +		return kvm_s390_handle_b2(vcpu);
> +	case 0xb6:
> +		return kvm_s390_handle_stctl(vcpu);
> +	case 0xb7:
> +		return kvm_s390_handle_lctl(vcpu);
> +	case 0xb9:
> +		return kvm_s390_handle_b9(vcpu);
> +	case 0xe3:
> +		return kvm_s390_handle_e3(vcpu);
> +	case 0xe5:
> +		return kvm_s390_handle_e5(vcpu);
> +	case 0xeb:
> +		return kvm_s390_handle_eb(vcpu);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
>  }
> 
>  static int inject_prog_on_prog_intercept(struct kvm_vcpu *vcpu)
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index bd31b37b0e6f..3c0a975c2477 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -19,8 +19,6 @@
>  #include <asm/processor.h>
>  #include <asm/sclp.h>
> 
> -typedef int (*intercept_handler_t)(struct kvm_vcpu *vcpu);
> -
>  /* Transactional Memory Execution related macros */
>  #define IS_TE_ENABLED(vcpu)	((vcpu->arch.sie_block->ecb & ECB_TE))
>  #define TDB_FORMAT1		1
> 



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