vfio/platform: trigger an interrupt via eventfd

This patch allows to set an eventfd for a platform device's interrupt,
and also to trigger the interrupt eventfd from userspace for testing.
Level sensitive interrupts are marked as maskable and are handled in
a later patch. Edge triggered interrupts are not advertised as maskable
and are implemented here using a simple and efficient IRQ handler.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
[Baptiste Reynal: fix masked interrupt initialization]
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index df5c919..611ec80 100644 (file)
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -39,12 +39,92 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
        return -EINVAL;
 }
 
+static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
+{
+       struct vfio_platform_irq *irq_ctx = dev_id;
+
+       eventfd_signal(irq_ctx->trigger, 1);
+
+       return IRQ_HANDLED;
+}
+
+static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
+                           int fd, irq_handler_t handler)
+{
+       struct vfio_platform_irq *irq = &vdev->irqs[index];
+       struct eventfd_ctx *trigger;
+       int ret;
+
+       if (irq->trigger) {
+               free_irq(irq->hwirq, irq);
+               kfree(irq->name);
+               eventfd_ctx_put(irq->trigger);
+               irq->trigger = NULL;
+       }
+
+       if (fd < 0) /* Disable only */
+               return 0;
+
+       irq->name = kasprintf(GFP_KERNEL, "vfio-irq[%d](%s)",
+                                               irq->hwirq, vdev->name);
+       if (!irq->name)
+               return -ENOMEM;
+
+       trigger = eventfd_ctx_fdget(fd);
+       if (IS_ERR(trigger)) {
+               kfree(irq->name);
+               return PTR_ERR(trigger);
+       }
+
+       irq->trigger = trigger;
+
+       ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
+       if (ret) {
+               kfree(irq->name);
+               eventfd_ctx_put(trigger);
+               irq->trigger = NULL;
+               return ret;
+       }
+
+       return 0;
+}
+
 static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
                                         unsigned index, unsigned start,
                                         unsigned count, uint32_t flags,
                                         void *data)
 {
-       return -EINVAL;
+       struct vfio_platform_irq *irq = &vdev->irqs[index];
+       irq_handler_t handler;
+
+       if (vdev->irqs[index].flags & VFIO_IRQ_INFO_AUTOMASKED)
+               return -EINVAL; /* not implemented */
+       else
+               handler = vfio_irq_handler;
+
+       if (!count && (flags & VFIO_IRQ_SET_DATA_NONE))
+               return vfio_set_trigger(vdev, index, -1, handler);
+
+       if (start != 0 || count != 1)
+               return -EINVAL;
+
+       if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
+               int32_t fd = *(int32_t *)data;
+
+               return vfio_set_trigger(vdev, index, fd, handler);
+       }
+
+       if (flags & VFIO_IRQ_SET_DATA_NONE) {
+               handler(irq->hwirq, irq);
+
+       } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+               uint8_t trigger = *(uint8_t *)data;
+
+               if (trigger)
+                       handler(irq->hwirq, irq);
+       }
+
+       return 0;
 }
 
 int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
@@ -90,7 +170,12 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
                if (hwirq < 0)
                        goto err;
 
-               vdev->irqs[i].flags = 0;
+               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
+                                               | VFIO_IRQ_INFO_AUTOMASKED;
+
                vdev->irqs[i].count = 1;
                vdev->irqs[i].hwirq = hwirq;
        }
@@ -105,6 +190,11 @@ err:
 
 void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
 {
+       int i;
+
+       for (i = 0; i < vdev->num_irqs; i++)
+               vfio_set_trigger(vdev, i, -1, NULL);
+
        vdev->num_irqs = 0;
        kfree(vdev->irqs);
 }

diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index b119a6c..aa01cc3 100644 (file)
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -31,6 +31,8 @@ struct vfio_platform_irq {
        u32                     flags;
        u32                     count;
        int                     hwirq;
+       char                    *name;
+       struct eventfd_ctx      *trigger;
 };
 
 struct vfio_platform_region {