linux-kernel - Re: [RFC v5 06/13] VFIO: platform: add vfio_external_{mask|is_active|set

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Date:	Tue, 31 Mar 2015 11:20:05 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Eric Auger <eric.auger@...aro.org>
Cc:	eric.auger@...com, christoffer.dall@...aro.org,
	marc.zyngier@....com, linux-arm-kernel@...ts.infradead.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	patches@...aro.org, pbonzini@...hat.com,
	kim.phillips@...escale.com, b.reynal@...tualopensystems.com,
	feng.wu@...el.com
Subject: Re: [RFC v5 06/13] VFIO: platform: add
 vfio_external_{mask|is_active|set_automasked}

On Thu, 2015-03-19 at 15:55 +0100, Eric Auger wrote:
> Introduces 3 new external functions aimed at doining some actions
> on VFIO platform devices:
> - mask a VFIO IRQ
> - get the active status of a VFIO IRQ (active at interrupt
>   controller level or masked by the level-sensitive automasking).
> - change the automasked property and the VFIO handler
> 
> Note there is no way to discriminate between user-space
> masking and automasked handler masking. As a consequence, is_active
> will return true in case the IRQ was masked by the user-space.
> 
> Signed-off-by: Eric Auger <eric.auger@...aro.org>
> 
> ---
> 
> V4: creation
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 43 +++++++++++++++++++++++++++++++
>  include/linux/vfio.h                      | 14 ++++++++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 8eb65c1..49994cb 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -231,6 +231,49 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
>  	return 0;
>  }
>  
> +void vfio_external_mask(struct vfio_platform_device *vdev, int index)
> +{
> +	vfio_platform_mask(&vdev->irqs[index]);
> +}
> +EXPORT_SYMBOL_GPL(vfio_external_mask);
> +
> +bool vfio_external_is_active(struct vfio_platform_device *vdev, int index)
> +{
> +	unsigned long flags;
> +	struct vfio_platform_irq *irq = &vdev->irqs[index];
> +	bool active, masked, outstanding;
> +	int ret;
> +
> +	spin_lock_irqsave(&irq->lock, flags);
> +
> +	ret = irq_get_irqchip_state(irq->hwirq, IRQCHIP_STATE_ACTIVE, &active);
> +	BUG_ON(ret);
> +	masked = irq->masked;
> +	outstanding = active || masked;
> +
> +	spin_unlock_irqrestore(&irq->lock, flags);
> +	return outstanding;
> +}
> +EXPORT_SYMBOL_GPL(vfio_external_is_active);
> +
> +void vfio_external_set_automasked(struct vfio_platform_device *vdev,
> +				  int index, bool automasked)
> +{
> +	unsigned long flags;
> +	struct vfio_platform_irq *irq = &vdev->irqs[index];
> +
> +	spin_lock_irqsave(&irq->lock, flags);
> +	if (automasked) {
> +		irq->flags |= VFIO_IRQ_INFO_AUTOMASKED;
> +		irq->handler = vfio_automasked_irq_handler;
> +	} else {
> +		irq->flags &= ~VFIO_IRQ_INFO_AUTOMASKED;
> +		irq->handler = vfio_irq_handler;
> +	}
> +	spin_unlock_irqrestore(&irq->lock, flags);
> +}
> +EXPORT_SYMBOL_GPL(vfio_external_set_automasked);
> +


This is where the abstraction breaks down.  These are
vfio_external_foo() interfaces, yet they assume a specific type of
device, a vfio platform device.  Either the name should reflect that or
they should be hosted in vfio-core with a callout to the device specific
implementations.  Can we make kvm-vfio deal only in struct vfio_device
and struct device?

>  static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
>  					 unsigned index, unsigned start,
>  					 unsigned count, uint32_t flags,
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index b18c38f..7aa6330 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -105,6 +105,20 @@ extern struct vfio_device *vfio_device_get_external_user(struct file *filep);
>  extern void vfio_device_put_external_user(struct vfio_device *vdev);
>  extern struct device *vfio_external_base_device(struct vfio_device *vdev);
>  
> +struct vfio_platform_device;
> +extern void vfio_external_mask(struct vfio_platform_device *vdev, int index);
> +/*
> + * returns whether the VFIO IRQ is active:
> + * true if not yet deactivated at interrupt controller level or if
> + * automasked (level sensitive IRQ). Unfortunately there is no way to
> + * discriminate between handler auto-masking and user-space masking
> + */
> +extern bool vfio_external_is_active(struct vfio_platform_device *vdev,
> +				    int index);
> +
> +extern void vfio_external_set_automasked(struct vfio_platform_device *vdev,
> +					 int index, bool automasked);
> +
>  struct pci_dev;
>  #ifdef CONFIG_EEH
>  extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);



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