On 10/31/2014 08:36 PM, Alex Williamson wrote:
> On Mon, 2014-10-27 at 19:07 +0100, Antonios Motakis wrote:
>> Level sensitive interrupts are exposed as maskable and automasked
>> interrupts and are masked and disabled automatically when they fire.
>>
>> Signed-off-by: Antonios Motakis <a.mota...@virtualopensystems.com>
>> ---
>>  drivers/vfio/platform/vfio_platform_irq.c     | 102 
>> +++++++++++++++++++++++++-
>>  drivers/vfio/platform/vfio_platform_private.h |   2 +
>>  2 files changed, 100 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_irq.c 
>> b/drivers/vfio/platform/vfio_platform_irq.c
>> index 2ac8ed7..563abf6 100644
>> --- a/drivers/vfio/platform/vfio_platform_irq.c
>> +++ b/drivers/vfio/platform/vfio_platform_irq.c
>> @@ -31,18 +31,108 @@
>>  
>>  #include "vfio_platform_private.h"
>>  
>> +static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
>> +{
>> +    unsigned long flags;
>> +
>> +    spin_lock_irqsave(&irq_ctx->lock, flags);
>> +
>> +    if (!irq_ctx->masked) {
>> +            disable_irq(irq_ctx->hwirq);
>> +            irq_ctx->masked = true;
>> +    }
>> +
>> +    spin_unlock_irqrestore(&irq_ctx->lock, flags);
>> +}
>> +
>>  static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
>>                                  unsigned index, unsigned start,
>>                                  unsigned count, uint32_t flags, void *data)
>>  {
>> -    return -EINVAL;
>> +    if (start != 0 || count != 1)
>> +            return -EINVAL;
>> +
>> +    if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
>> +            return -EINVAL;
>> +
>> +    if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
>> +            return -EINVAL; /* not implemented yet */
>> +
>> +    if (flags & VFIO_IRQ_SET_DATA_NONE) {
>> +            vfio_platform_mask(&vdev->irqs[index]);
>> +
>> +    } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
>> +            uint8_t mask = *(uint8_t *)data;
>> +
>> +            if (mask)
>> +                    vfio_platform_mask(&vdev->irqs[index]);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
>> +{
>> +    unsigned long flags;
>> +
>> +    spin_lock_irqsave(&irq_ctx->lock, flags);
>> +
>> +    if (irq_ctx->masked) {
>> +            enable_irq(irq_ctx->hwirq);
>> +            irq_ctx->masked = false;
>> +    }
>> +
>> +    spin_unlock_irqrestore(&irq_ctx->lock, flags);
>>  }
>>  
>>  static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
>>                                  unsigned index, unsigned start,
>>                                  unsigned count, uint32_t flags, void *data)
>>  {
>> -    return -EINVAL;
>> +    if (start != 0 || count != 1)
>> +            return -EINVAL;
>> +
>> +    if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
>> +            return -EINVAL;
>> +
>> +    if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
>> +            return -EINVAL; /* not implemented yet */
>> +
>> +    if (flags & VFIO_IRQ_SET_DATA_NONE) {
>> +            vfio_platform_unmask(&vdev->irqs[index]);
>> +
>> +    } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
>> +            uint8_t unmask = *(uint8_t *)data;
>> +
>> +            if (unmask)
>> +                    vfio_platform_unmask(&vdev->irqs[index]);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static irqreturn_t vfio_maskable_irq_handler(int irq, void *dev_id)
>> +{
>> +    struct vfio_platform_irq *irq_ctx = dev_id;
>> +    unsigned long flags;
>> +    int ret = IRQ_NONE;
>> +
>> +    spin_lock_irqsave(&irq_ctx->lock, flags);
>> +
>> +    if (!irq_ctx->masked) {
>> +            ret = IRQ_HANDLED;
>> +
>> +            /* automask maskable interrupts */
>> +            disable_irq_nosync(irq_ctx->hwirq);
>> +            irq_ctx->masked = true;
>> +    }
>> +
>> +    spin_unlock_irqrestore(&irq_ctx->lock, flags);
>> +
>> +    if (ret == IRQ_HANDLED)
>> +            eventfd_signal(irq_ctx->trigger, 1);
>> +
>> +    return ret;
> 
> This is not just a maskable irq handler, but specifically a level (aka
> automasked) handler.  So this should only be used for AUTOMASKED irqs.
> 
>>  }

Antonios, Alex,

When turning forwarded IRQ modality on/off, I guess I now should the
swap the handlers (free_irq, request_irq) adding some extra complexity
in the driver compared to the previous implementation. Do you confirm
this is the prefered way?

Thanks

Eric

>>  
>>  static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
>> @@ -103,7 +193,7 @@ static int vfio_platform_set_irq_trigger(struct 
>> vfio_platform_device *vdev,
>>      irq_handler_t handler;
>>  
>>      if (vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE)
>> -            return -EINVAL; /* not implemented */
>> +            handler = vfio_maskable_irq_handler;
> 
> As noted in the previous patch, this should be a test for AUTOMASKED,
> not just MASKABLE.
> 
>>      else
>>              handler = vfio_irq_handler;
>>  
>> @@ -175,13 +265,17 @@ int vfio_platform_irq_init(struct vfio_platform_device 
>> *vdev)
>>              if (hwirq < 0)
>>                      goto err;
>>  
>> +            spin_lock_init(&vdev->irqs[i].lock);
>> +
>>              vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
>>  
>>              if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
>> -                    vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE;
>> +                    vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE
>> +                                            | VFIO_IRQ_INFO_AUTOMASKED;
>>  
>>              vdev->irqs[i].count = 1;
>>              vdev->irqs[i].hwirq = hwirq;
>> +            vdev->irqs[i].masked = false;
>>      }
>>  
>>      vdev->num_irqs = cnt;
>> diff --git a/drivers/vfio/platform/vfio_platform_private.h 
>> b/drivers/vfio/platform/vfio_platform_private.h
>> index a3f2411..d25c4cd 100644
>> --- a/drivers/vfio/platform/vfio_platform_private.h
>> +++ b/drivers/vfio/platform/vfio_platform_private.h
>> @@ -30,6 +30,8 @@ struct vfio_platform_irq {
>>      int                     hwirq;
>>      char                    *name;
>>      struct eventfd_ctx      *trigger;
>> +    bool                    masked;
>> +    spinlock_t              lock;
>>  };
>>  
>>  struct vfio_platform_region {
> 
> 
> 

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