DMA faults can be detected by IOMMU at device level. Adding a pointer
to struct device allows IOMMU subsystem to report relevant faults
back to the device driver for further handling.
For direct assigned device (or user space drivers), guest OS holds
responsibility to handle and respond per device IOMMU fault.
Therefore we need fault reporting mechanism to propagate faults beyond
IOMMU subsystem.

There are two other IOMMU data pointers under struct device today, here
we introduce iommu_param as a parent pointer such that all device IOMMU
data can be consolidated here. The idea was suggested here by Greg KH
and Joerg. The name iommu_param is chosen here since iommu_data has been used.

Suggested-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com>
Link: https://lkml.org/lkml/2017/10/6/81
---
 include/linux/device.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index 0059b99..7c79e4e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -41,6 +41,7 @@ struct iommu_ops;
 struct iommu_group;
 struct iommu_fwspec;
 struct dev_pin_info;
+struct iommu_param;
 
 struct bus_attribute {
        struct attribute        attr;
@@ -897,6 +898,7 @@ struct dev_links_info {
  *             device (i.e. the bus driver that discovered the device).
  * @iommu_group: IOMMU group the device belongs to.
  * @iommu_fwspec: IOMMU-specific properties supplied by firmware.
+ * @iommu_param: Per device generic IOMMU runtime data
  *
  * @offline_disabled: If set, the device is permanently online.
  * @offline:   Set after successful invocation of bus type's .offline().
@@ -986,6 +988,7 @@ struct device {
        void    (*release)(struct device *dev);
        struct iommu_group      *iommu_group;
        struct iommu_fwspec     *iommu_fwspec;
+       struct iommu_param      *iommu_param;
 
        bool                    offline_disabled:1;
        bool                    offline:1;
-- 
2.7.4

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