This patch allows to set an eventfd for a patform device's interrupt,
and also to trigger the interrupt eventfd from userspace for testing.

Signed-off-by: Antonios Motakis <a.mota...@virtualopensystems.com>
---
 drivers/vfio/platform/vfio_platform.c         |  36 +++++++-
 drivers/vfio/platform/vfio_platform_irq.c     | 123 +++++++++++++++++++++++++-
 drivers/vfio/platform/vfio_platform_private.h |   7 ++
 3 files changed, 162 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform.c 
b/drivers/vfio/platform/vfio_platform.c
index 2e16595..8aa5d10 100644
--- a/drivers/vfio/platform/vfio_platform.c
+++ b/drivers/vfio/platform/vfio_platform.c
@@ -174,10 +174,40 @@ static long vfio_platform_ioctl(void *device_data,
 
                return copy_to_user((void __user *)arg, &info, minsz);
 
-       } else if (cmd == VFIO_DEVICE_SET_IRQS)
-               return -EINVAL;
+       } else if (cmd == VFIO_DEVICE_SET_IRQS) {
+               struct vfio_irq_set hdr;
+               int ret = 0;
+
+               minsz = offsetofend(struct vfio_irq_set, count);
+
+               if (copy_from_user(&hdr, (void __user *)arg, minsz))
+                       return -EFAULT;
+
+               if (hdr.argsz < minsz)
+                       return -EINVAL;
+
+               if (hdr.index >= vdev->num_irqs)
+                       return -EINVAL;
+
+               if (hdr.start != 0 || hdr.count > 1)
+                       return -EINVAL;
+
+               if (hdr.count == 0 &&
+                       (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE) ||
+                        !(hdr.flags & VFIO_IRQ_SET_ACTION_TRIGGER)))
+                       return -EINVAL;
+
+               if (hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
+                                 VFIO_IRQ_SET_ACTION_TYPE_MASK))
+                       return -EINVAL;
+
+               ret = vfio_platform_set_irqs_ioctl(vdev, hdr.flags, hdr.index,
+                                                  hdr.start, hdr.count,
+                                                  (void *)arg+minsz);
+
+               return ret;
 
-       else if (cmd == VFIO_DEVICE_RESET)
+       } else if (cmd == VFIO_DEVICE_RESET)
                return -EINVAL;
 
        return -ENOTTY;
diff --git a/drivers/vfio/platform/vfio_platform_irq.c 
b/drivers/vfio/platform/vfio_platform_irq.c
index 075c401..433edc1 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -31,6 +31,9 @@
 
 #include "vfio_platform_private.h"
 
+static int vfio_set_trigger(struct vfio_platform_device *vdev,
+                           int index, int fd);
+
 int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 {
        int cnt = 0, i;
@@ -47,9 +50,11 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 
        for (i = 0; i < cnt; i++) {
                struct vfio_platform_irq irq;
+               int hwirq = platform_get_irq(vdev->pdev, i);
 
-               irq.flags = 0;
+               irq.flags = VFIO_IRQ_INFO_EVENTFD;
                irq.count = 1;
+               irq.hwirq = hwirq;
 
                vdev->irq[i] = irq;
        }
@@ -59,5 +64,121 @@ int vfio_platform_irq_init(struct vfio_platform_device 
*vdev)
 
 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);
+
        kfree(vdev->irq);
 }
+
+static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
+{
+       struct eventfd_ctx *trigger = dev_id;
+
+       eventfd_signal(trigger, 1);
+
+       return IRQ_HANDLED;
+}
+
+static int vfio_set_trigger(struct vfio_platform_device *vdev,
+                           int index, int fd)
+{
+       struct vfio_platform_irq *irq = &vdev->irq[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->pdev->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, vfio_irq_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)
+{
+       struct vfio_platform_irq *irq = &vdev->irq[index];
+       uint8_t arr;
+       int32_t fd;
+
+       switch (flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
+       case VFIO_IRQ_SET_DATA_NONE:
+               if (count == 0)
+                       return vfio_set_trigger(vdev, index, -1);
+
+               vfio_irq_handler(irq->hwirq, irq);
+               return 0;
+
+       case VFIO_IRQ_SET_DATA_BOOL:
+               if (copy_from_user(&arr, data, sizeof(uint8_t)))
+                       return -EFAULT;
+
+               if (arr == 0x1) {
+                       vfio_irq_handler(irq->hwirq, irq);
+                       return 0;
+               }
+
+               return -EINVAL;
+
+       case VFIO_IRQ_SET_DATA_EVENTFD:
+               if (copy_from_user(&fd, data, sizeof(int32_t)))
+                       return -EFAULT;
+
+               return vfio_set_trigger(vdev, index, fd);
+       }
+
+       return -EFAULT;
+}
+
+int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
+                                uint32_t flags, unsigned index, unsigned start,
+                                unsigned count, void *data)
+{
+       int (*func)(struct vfio_platform_device *vdev, unsigned index,
+                   unsigned start, unsigned count, uint32_t flags,
+                   void *data) = NULL;
+
+       switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
+       case VFIO_IRQ_SET_ACTION_MASK:
+       case VFIO_IRQ_SET_ACTION_UNMASK:
+               /* XXX not implemented */
+               break;
+       case VFIO_IRQ_SET_ACTION_TRIGGER:
+               func = vfio_platform_set_irq_trigger;
+               break;
+       }
+
+       if (!func)
+               return -ENOTTY;
+
+       return func(vdev, index, start, count, flags, data);
+}
diff --git a/drivers/vfio/platform/vfio_platform_private.h 
b/drivers/vfio/platform/vfio_platform_private.h
index 9776cff..e21c15a 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -25,8 +25,11 @@
        ((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
 
 struct vfio_platform_irq {
+       struct eventfd_ctx      *trigger;
        u32                     flags;
        u32                     count;
+       int                     hwirq;
+       char                    *name;
 };
 
 struct vfio_platform_region {
@@ -47,4 +50,8 @@ extern int vfio_platform_irq_init(struct vfio_platform_device 
*vdev);
 
 extern void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev);
 
+extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
+                       uint32_t flags, unsigned index, unsigned start,
+                       unsigned count, void *data);
+
 #endif /* VFIO_PLATFORM_PRIVATE_H */
-- 
1.8.3.2

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