[PATCH v7 5/8] KVM: arm/arm64: Support a vgic interrupt line level sample function

[Auger Eric]

Hi Christoffer,

On 07/12/17 11:54, Christoffer Dall wrote:
> The GIC sometimes need to sample the physical line of a mapped
> interrupt.  As we know this to be notoriously slow, provide a callback
> function for devices (such as the timer) which can do this much faster
> than talking to the distributor, for example by comparing a few
> in-memory values.  Fall back to the good old method of poking the
> physical GIC if no callback is provided.
> 
> Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> ---
>  include/kvm/arm_vgic.h    | 13 ++++++++++++-
>  virt/kvm/arm/arch_timer.c |  3 ++-
>  virt/kvm/arm/vgic/vgic.c  | 12 +++++++++---
>  3 files changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 8c896540a72c..cdbd142ca7f2 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -130,6 +130,17 @@ struct vgic_irq {
>  	u8 priority;
>  	enum vgic_irq_config config;	/* Level or edge */
>  
> +	/*
> +	 * Callback function pointer to in-kernel devices that can tell us the
> +	 * state of the input level of mapped level-triggered IRQ faster than
> +	 * peaking into the physical GIC.
> +	 *
> +	 * Always called in non-preemptible section and the functions can use
> +	 * kvm_arm_get_running_vcpu() to get the vcpu pointer for private
> +	 * IRQs.
> +	 */
> +	bool (*get_input_level)(int vintid);
> +
>  	void *owner;			/* Opaque pointer to reserve an interrupt
>  					   for in-kernel devices. */
>  };
> @@ -331,7 +342,7 @@ void kvm_vgic_init_cpu_hardware(void);
>  int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  			bool level, void *owner);
>  int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
> -			  u32 vintid);
> +			  u32 vintid, bool (*get_input_level)(int vindid));
>  int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid);
>  bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int vintid);
>  
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index dd5aca05c500..e78ba5e20f74 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -840,7 +840,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
>  		return -EINVAL;
>  	}
>  
> -	ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq);
> +	ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq,
> +				    NULL);
>  	if (ret)
>  		return ret;
>  
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 607cbbc27a1c..eadabb249d2a 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
Nit: the comment "Get the input level of a mapped IRQ directly from the
physical GIC" is not strictly correct anymore
> @@ -151,6 +151,9 @@ bool vgic_get_phys_line_level(struct vgic_irq *irq)
>  
>  	BUG_ON(!irq->hw);
>  
> +	if (irq->get_input_level)
> +		return irq->get_input_level(irq->intid);
> +
>  	WARN_ON(irq_get_irqchip_state(irq->host_irq,
>  				      IRQCHIP_STATE_PENDING,
>  				      &line_level));
> @@ -436,7 +439,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  
>  /* @irq->irq_lock must be held */
>  static int kvm_vgic_map_irq(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
> -			    unsigned int host_irq)
> +			    unsigned int host_irq,
> +			    bool (*get_input_level)(int vindid))
>  {
>  	struct irq_desc *desc;
>  	struct irq_data *data;
> @@ -456,6 +460,7 @@ static int kvm_vgic_map_irq(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
>  	irq->hw = true;
>  	irq->host_irq = host_irq;
>  	irq->hwintid = data->hwirq;
> +	irq->get_input_level = get_input_level;
>  	return 0;
>  }
>  
> @@ -464,10 +469,11 @@ static inline void kvm_vgic_unmap_irq(struct vgic_irq *irq)
>  {
>  	irq->hw = false;
>  	irq->hwintid = 0;
> +	irq->get_input_level = NULL;
>  }
>  
>  int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
> -			  u32 vintid)
> +			  u32 vintid, bool (*get_input_level)(int vindid))
>  {
>  	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, vintid);
>  	unsigned long flags;
> @@ -476,7 +482,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
>  	BUG_ON(!irq);
>  
>  	spin_lock_irqsave(&irq->irq_lock, flags);
> -	ret = kvm_vgic_map_irq(vcpu, irq, host_irq);
> +	ret = kvm_vgic_map_irq(vcpu, irq, host_irq, get_input_level);
>  	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	vgic_put_irq(vcpu->kvm, irq);
>  
> 
Reviewed-by: Eric Auger <eric.auger at redhat.com>

Thanks

Eric