[PATCH v2 5/7] iommu: Turn fault_data to iommufd private pointer

[Nicolin Chen]

A "fault_data" was added exclusively for the iommufd_fault_iopf_handler()
used by IOPF/PRI use cases, along with the attach_handle. Now, the iommufd
version of the sw_msi function will reuse the attach_handle and fault_data
for a non-fault case.

Rename "fault_data" to "iommufd_hwpt" so as not to confine it to a "fault"
case. Move it into a union to be the iommufd private pointer. A following
patch will move the iova_cookie to the union for dma-iommu too after the
iommufd_sw_msi implementation is added.

Since we have two unions now, add some simple comments for readability.

Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
---
 include/linux/iommu.h                | 6 ++++--
 drivers/iommu/iommufd/fault.c        | 2 +-
 drivers/iommu/iommufd/hw_pagetable.c | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 761c5e186de9..e93d2e918599 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -224,8 +224,10 @@ struct iommu_domain {
                      phys_addr_t msi_addr);
 #endif
 
-       void *fault_data;
-       union {
+       union { /* Pointer usable by owner of the domain */
+               struct iommufd_hw_pagetable *iommufd_hwpt; /* iommufd */
+       };
+       union { /* Fault handler */
                struct {
                        iommu_fault_handler_t handler;
                        void *handler_token;
diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index 931a3fbe6e32..c48d72c9668c 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -329,7 +329,7 @@ int iommufd_fault_iopf_handler(struct iopf_group *group)
        struct iommufd_hw_pagetable *hwpt;
        struct iommufd_fault *fault;
 
-       hwpt = group->attach_handle->domain->fault_data;
+       hwpt = group->attach_handle->domain->iommufd_hwpt;
        fault = hwpt->fault;
 
        spin_lock(&fault->lock);
diff --git a/drivers/iommu/iommufd/hw_pagetable.c 
b/drivers/iommu/iommufd/hw_pagetable.c
index 598be26a14e2..2641d50f46cf 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -406,10 +406,10 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
                }
                hwpt->fault = fault;
                hwpt->domain->iopf_handler = iommufd_fault_iopf_handler;
-               hwpt->domain->fault_data = hwpt;
                refcount_inc(&fault->obj.users);
                iommufd_put_object(ucmd->ictx, &fault->obj);
        }
+       hwpt->domain->iommufd_hwpt = hwpt;
 
        cmd->out_hwpt_id = hwpt->obj.id;
        rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
-- 
2.43.0