Re: [PATCH v1] KVM: s390: use switch vs jump table in interrupt.c

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

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On 06.02.2018 15:17, David Hildenbrand wrote:
> Just like for the interception handlers, let's also use a switch-case
> in our interrupt delivery code.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

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


> ---
>  arch/s390/kvm/interrupt.c | 84 ++++++++++++++++++++++++++++-------------------
>  1 file changed, 50 insertions(+), 34 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index aabf46f5f883..3ea9cfa31b16 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -187,12 +187,6 @@ static int cpu_timer_irq_pending(struct kvm_vcpu *vcpu)
>  	return kvm_s390_get_cpu_timer(vcpu) >> 63;
>  }
> 
> -static inline int is_ioirq(unsigned long irq_type)
> -{
> -	return ((irq_type >= IRQ_PEND_IO_ISC_7) &&
> -		(irq_type <= IRQ_PEND_IO_ISC_0));
> -}
> -
>  static uint64_t isc_to_isc_bits(int isc)
>  {
>  	return (0x80 >> isc) << 24;
> @@ -1011,24 +1005,6 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
>  	return rc;
>  }
> 
> -typedef int (*deliver_irq_t)(struct kvm_vcpu *vcpu);
> -
> -static const deliver_irq_t deliver_irq_funcs[] = {
> -	[IRQ_PEND_MCHK_EX]        = __deliver_machine_check,
> -	[IRQ_PEND_MCHK_REP]       = __deliver_machine_check,
> -	[IRQ_PEND_PROG]           = __deliver_prog,
> -	[IRQ_PEND_EXT_EMERGENCY]  = __deliver_emergency_signal,
> -	[IRQ_PEND_EXT_EXTERNAL]   = __deliver_external_call,
> -	[IRQ_PEND_EXT_CLOCK_COMP] = __deliver_ckc,
> -	[IRQ_PEND_EXT_CPU_TIMER]  = __deliver_cpu_timer,
> -	[IRQ_PEND_RESTART]        = __deliver_restart,
> -	[IRQ_PEND_SET_PREFIX]     = __deliver_set_prefix,
> -	[IRQ_PEND_PFAULT_INIT]    = __deliver_pfault_init,
> -	[IRQ_PEND_EXT_SERVICE]    = __deliver_service,
> -	[IRQ_PEND_PFAULT_DONE]    = __deliver_pfault_done,
> -	[IRQ_PEND_VIRTIO]         = __deliver_virtio,
> -};
> -
>  /* Check whether an external call is pending (deliverable or not) */
>  int kvm_s390_ext_call_pending(struct kvm_vcpu *vcpu)
>  {
> @@ -1192,7 +1168,6 @@ void kvm_s390_clear_local_irqs(struct kvm_vcpu *vcpu)
>  int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
> -	deliver_irq_t func;
>  	int rc = 0;
>  	unsigned long irq_type;
>  	unsigned long irqs;
> @@ -1212,16 +1187,57 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
>  	while ((irqs = deliverable_irqs(vcpu)) && !rc) {
>  		/* bits are in the reverse order of interrupt priority */
>  		irq_type = find_last_bit(&irqs, IRQ_PEND_COUNT);
> -		if (is_ioirq(irq_type)) {
> +		switch (irq_type) {
> +		case IRQ_PEND_IO_ISC_0:
> +		case IRQ_PEND_IO_ISC_1:
> +		case IRQ_PEND_IO_ISC_2:
> +		case IRQ_PEND_IO_ISC_3:
> +		case IRQ_PEND_IO_ISC_4:
> +		case IRQ_PEND_IO_ISC_5:
> +		case IRQ_PEND_IO_ISC_6:
> +		case IRQ_PEND_IO_ISC_7:
>  			rc = __deliver_io(vcpu, irq_type);
> -		} else {
> -			func = deliver_irq_funcs[irq_type];
> -			if (!func) {
> -				WARN_ON_ONCE(func == NULL);
> -				clear_bit(irq_type, &li->pending_irqs);
> -				continue;
> -			}
> -			rc = func(vcpu);
> +			break;
> +		case IRQ_PEND_MCHK_EX:
> +		case IRQ_PEND_MCHK_REP:
> +			rc = __deliver_machine_check(vcpu);
> +			break;
> +		case IRQ_PEND_PROG:
> +			rc = __deliver_prog(vcpu);
> +			break;
> +		case IRQ_PEND_EXT_EMERGENCY:
> +			rc = __deliver_emergency_signal(vcpu);
> +			break;
> +		case IRQ_PEND_EXT_EXTERNAL:
> +			rc = __deliver_external_call(vcpu);
> +			break;
> +		case IRQ_PEND_EXT_CLOCK_COMP:
> +			rc = __deliver_ckc(vcpu);
> +			break;
> +		case IRQ_PEND_EXT_CPU_TIMER:
> +			rc = __deliver_cpu_timer(vcpu);
> +			break;
> +		case IRQ_PEND_RESTART:
> +			rc = __deliver_restart(vcpu);
> +			break;
> +		case IRQ_PEND_SET_PREFIX:
> +			rc = __deliver_set_prefix(vcpu);
> +			break;
> +		case IRQ_PEND_PFAULT_INIT:
> +			rc = __deliver_pfault_init(vcpu);
> +			break;
> +		case IRQ_PEND_EXT_SERVICE:
> +			rc = __deliver_service(vcpu);
> +			break;
> +		case IRQ_PEND_PFAULT_DONE:
> +			rc = __deliver_pfault_done(vcpu);
> +			break;
> +		case IRQ_PEND_VIRTIO:
> +			rc = __deliver_virtio(vcpu);
> +			break;
> +		default:
> +			WARN_ONCE(1, "Unknown pending irq type %ld", irq_type);
> +			clear_bit(irq_type, &li->pending_irqs);
>  		}
>  	}
> 



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