[RFC 06/17] VFIO: add vfio_external_{mask|is_active|set_automasked}

[eric.auger@linaro.org (Eric Auger)]

Introduces 3 new external functions aimed at doing actions
on VFIO devices:
- mask VFIO IRQ
- get the active status of VFIO IRQ (active at interrupt
  controller level or masked by the level-sensitive automasking).
- change the automasked property and switch the IRQ handler
  (between automasked/ non automasked)

Their implementation is based on bus specific callbacks.

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@linaro.org>

---

v5 -> v6:
- implementation now uses external ops
- prototype changed (index, start, count) and returns int

V4: creation
---
 drivers/vfio/vfio.c  | 39 +++++++++++++++++++++++++++++++++++++++
 include/linux/vfio.h | 16 ++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 2fb29df..af6901e 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1527,6 +1527,45 @@ long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)
 }
 EXPORT_SYMBOL_GPL(vfio_external_check_extension);
 
+int vfio_external_mask(struct vfio_device *vdev, unsigned index,
+			unsigned start, unsigned count)
+{
+	if (vdev->ops->external_ops &&
+		vdev->ops->external_ops->mask)
+		return vdev->ops->external_ops->mask(vdev->device_data,
+						     index, start, count);
+	else
+		return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(vfio_external_mask);
+
+int vfio_external_is_active(struct vfio_device *vdev, unsigned index,
+			     unsigned start, unsigned count)
+{
+	if (vdev->ops->external_ops &&
+		vdev->ops->external_ops->is_active)
+		return vdev->ops->external_ops->is_active(vdev->device_data,
+							  index, start, count);
+	else
+		return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(vfio_external_is_active);
+
+int vfio_external_set_automasked(struct vfio_device *vdev,
+				  unsigned index, unsigned start,
+				  unsigned count, bool automasked)
+{
+	if (vdev->ops->external_ops &&
+		vdev->ops->external_ops->set_automasked)
+		return vdev->ops->external_ops->set_automasked(
+							vdev->device_data,
+							index, start,
+							count, automasked);
+	else
+		return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(vfio_external_set_automasked);
+
 /**
  * Module/class support
  */
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index d79e8a9..31d3c95 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -107,6 +107,22 @@ extern int vfio_external_user_iommu_id(struct vfio_group *group);
 extern long vfio_external_check_extension(struct vfio_group *group,
 					  unsigned long arg);
 
+extern int vfio_external_mask(struct vfio_device *vdev, unsigned index,
+			       unsigned start, unsigned count);
+/*
+ * 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 int vfio_external_is_active(struct vfio_device *vdev,
+				    unsigned index, unsigned start,
+				    unsigned count);
+
+extern int vfio_external_set_automasked(struct vfio_device *vdev,
+					 unsigned index, unsigned start,
+					 unsigned count, bool automasked);
+
 struct pci_dev;
 #ifdef CONFIG_EEH
 extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
-- 
1.9.1