linux-kernel - Re: [PATCH] KVM: APIC: add helper func to remove duplicate code in kvm_pv_send

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Date:   Mon, 11 Nov 2019 15:10:19 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linmiaohe <linmiaohe@...wei.com>, rkrcmar@...hat.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, hpa@...or.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] KVM: APIC: add helper func to remove duplicate code in
 kvm_pv_send_ipi

On 09/11/19 10:46, linmiaohe wrote:
> From: Miaohe Lin <linmiaohe@...wei.com>
> 
> There are some duplicate code in kvm_pv_send_ipi when deal with ipi
> bitmap. Add helper func to remove it, and eliminate odd out label,
> get rid of unnecessary kvm_lapic_irq field init and so on.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  arch/x86/kvm/lapic.c | 65 ++++++++++++++++++++------------------------
>  1 file changed, 29 insertions(+), 36 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index b29d00b661ff..2f8f10103f5f 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -557,60 +557,53 @@ int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
>  			irq->level, irq->trig_mode, dest_map);
>  }
>  
> +static int __pv_send_ipi(unsigned long *ipi_bitmap, struct kvm_apic_map *map,
> +			 struct kvm_lapic_irq *irq, u32 min)
> +{
> +	int i, count = 0;
> +	struct kvm_vcpu *vcpu;
> +
> +	if (min > map->max_apic_id)
> +		return 0;
> +
> +	for_each_set_bit(i, ipi_bitmap,
> +		min((u32)BITS_PER_LONG, (map->max_apic_id - min + 1))) {
> +		if (map->phys_map[min + i]) {
> +			vcpu = map->phys_map[min + i]->vcpu;
> +			count += kvm_apic_set_irq(vcpu, irq, NULL);
> +		}
> +	}
> +
> +	return count;
> +}
> +
>  int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
>  		    unsigned long ipi_bitmap_high, u32 min,
>  		    unsigned long icr, int op_64_bit)
>  {
> -	int i;
>  	struct kvm_apic_map *map;
> -	struct kvm_vcpu *vcpu;
>  	struct kvm_lapic_irq irq = {0};
>  	int cluster_size = op_64_bit ? 64 : 32;
> -	int count = 0;
> +	int count;
> +
> +	if (icr & (APIC_DEST_MASK | APIC_SHORT_MASK))
> +		return -KVM_EINVAL;
>  
>  	irq.vector = icr & APIC_VECTOR_MASK;
>  	irq.delivery_mode = icr & APIC_MODE_MASK;
>  	irq.level = (icr & APIC_INT_ASSERT) != 0;
>  	irq.trig_mode = icr & APIC_INT_LEVELTRIG;
>  
> -	if (icr & APIC_DEST_MASK)
> -		return -KVM_EINVAL;
> -	if (icr & APIC_SHORT_MASK)
> -		return -KVM_EINVAL;
> -
>  	rcu_read_lock();
>  	map = rcu_dereference(kvm->arch.apic_map);
>  
> -	if (unlikely(!map)) {
> -		count = -EOPNOTSUPP;
> -		goto out;
> +	count = -EOPNOTSUPP;
> +	if (likely(map)) {
> +		count = __pv_send_ipi(&ipi_bitmap_low, map, &irq, min);
> +		min += cluster_size;
> +		count += __pv_send_ipi(&ipi_bitmap_high, map, &irq, min);
>  	}
>  
> -	if (min > map->max_apic_id)
> -		goto out;
> -	/* Bits above cluster_size are masked in the caller.  */
> -	for_each_set_bit(i, &ipi_bitmap_low,
> -		min((u32)BITS_PER_LONG, (map->max_apic_id - min + 1))) {
> -		if (map->phys_map[min + i]) {
> -			vcpu = map->phys_map[min + i]->vcpu;
> -			count += kvm_apic_set_irq(vcpu, &irq, NULL);
> -		}
> -	}
> -
> -	min += cluster_size;
> -
> -	if (min > map->max_apic_id)
> -		goto out;
> -
> -	for_each_set_bit(i, &ipi_bitmap_high,
> -		min((u32)BITS_PER_LONG, (map->max_apic_id - min + 1))) {
> -		if (map->phys_map[min + i]) {
> -			vcpu = map->phys_map[min + i]->vcpu;
> -			count += kvm_apic_set_irq(vcpu, &irq, NULL);
> -		}
> -	}
> -
> -out:
>  	rcu_read_unlock();
>  	return count;
>  }
> 

Queued, thanks.

Paolo