iommufd: Associate fault object with iommufd_hw_pgtable

When allocating a user iommufd_hw_pagetable, the user space is allowed to
associate a fault object with the hw_pagetable by specifying the fault
object ID in the page table allocation data and setting the
IOMMU_HWPT_FAULT_ID_VALID flag bit.

On a successful return of hwpt allocation, the user can retrieve and
respond to page faults by reading and writing the file interface of the
fault object.

Once a fault object has been associated with a hwpt, the hwpt is
iopf-capable, indicated by hwpt->fault is non NULL. Attaching,
detaching, or replacing an iopf-capable hwpt to an RID or PASID will
differ from those that are not iopf-capable.

Link: https://lore.kernel.org/r/20240702063444.105814-9-baolu.lu@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index 4934ae5726383fd6b3ff19bf878d91d15dd5bd51..54d6cd20a6730d4ea82d9aa89b290ffc2f7b003e 100644 (file)
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -414,3 +414,20 @@ out_abort:
 
        return rc;
 }
+
+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;
+       fault = hwpt->fault;
+
+       mutex_lock(&fault->mutex);
+       list_add_tail(&group->node, &fault->deliver);
+       mutex_unlock(&fault->mutex);
+
+       wake_up_interruptible(&fault->wait_queue);
+
+       return 0;
+}

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 33d142f8057d70a77f44e842afdd84b1bee0a970..e63f80f087d1b400337b82240522cf3cbc1499f8 100644 (file)
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -8,6 +8,15 @@
 #include "../iommu-priv.h"
 #include "iommufd_private.h"
 
+static void __iommufd_hwpt_destroy(struct iommufd_hw_pagetable *hwpt)
+{
+       if (hwpt->domain)
+               iommu_domain_free(hwpt->domain);
+
+       if (hwpt->fault)
+               refcount_dec(&hwpt->fault->obj.users);
+}
+
 void iommufd_hwpt_paging_destroy(struct iommufd_object *obj)
 {
        struct iommufd_hwpt_paging *hwpt_paging =
@@ -22,9 +31,7 @@ void iommufd_hwpt_paging_destroy(struct iommufd_object *obj)
                                         hwpt_paging->common.domain);
        }
 
-       if (hwpt_paging->common.domain)
-               iommu_domain_free(hwpt_paging->common.domain);
-
+       __iommufd_hwpt_destroy(&hwpt_paging->common);
        refcount_dec(&hwpt_paging->ioas->obj.users);
 }
 
@@ -49,9 +56,7 @@ void iommufd_hwpt_nested_destroy(struct iommufd_object *obj)
        struct iommufd_hwpt_nested *hwpt_nested =
                container_of(obj, struct iommufd_hwpt_nested, common.obj);
 
-       if (hwpt_nested->common.domain)
-               iommu_domain_free(hwpt_nested->common.domain);
-
+       __iommufd_hwpt_destroy(&hwpt_nested->common);
        refcount_dec(&hwpt_nested->parent->common.obj.users);
 }
 
@@ -213,7 +218,8 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
        struct iommufd_hw_pagetable *hwpt;
        int rc;
 
-       if (flags || !user_data->len || !ops->domain_alloc_user)
+       if ((flags & ~IOMMU_HWPT_FAULT_ID_VALID) ||
+           !user_data->len || !ops->domain_alloc_user)
                return ERR_PTR(-EOPNOTSUPP);
        if (parent->auto_domain || !parent->nest_parent)
                return ERR_PTR(-EINVAL);
@@ -227,7 +233,8 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
        refcount_inc(&parent->common.obj.users);
        hwpt_nested->parent = parent;
 
-       hwpt->domain = ops->domain_alloc_user(idev->dev, flags,
+       hwpt->domain = ops->domain_alloc_user(idev->dev,
+                                             flags & ~IOMMU_HWPT_FAULT_ID_VALID,
                                              parent->common.domain, user_data);
        if (IS_ERR(hwpt->domain)) {
                rc = PTR_ERR(hwpt->domain);
@@ -308,6 +315,21 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
                goto out_put_pt;
        }
 
+       if (cmd->flags & IOMMU_HWPT_FAULT_ID_VALID) {
+               struct iommufd_fault *fault;
+
+               fault = iommufd_get_fault(ucmd, cmd->fault_id);
+               if (IS_ERR(fault)) {
+                       rc = PTR_ERR(fault);
+                       goto out_hwpt;
+               }
+               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);
+       }
+
        cmd->out_hwpt_id = hwpt->obj.id;
        rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
        if (rc)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index aa4c26c87cb9f6019af84f29aec43b0f180735d7..92efe30a8f0d00fa92197261b26c69c09fd4fd9a 100644 (file)
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -458,8 +458,17 @@ struct iommufd_attach_handle {
 /* Convert an iommu attach handle to iommufd handle. */
 #define to_iommufd_handle(hdl) container_of(hdl, struct iommufd_attach_handle, handle)
 
+static inline struct iommufd_fault *
+iommufd_get_fault(struct iommufd_ucmd *ucmd, u32 id)
+{
+       return container_of(iommufd_get_object(ucmd->ictx, id,
+                                              IOMMUFD_OBJ_FAULT),
+                           struct iommufd_fault, obj);
+}
+
 int iommufd_fault_alloc(struct iommufd_ucmd *ucmd);
 void iommufd_fault_destroy(struct iommufd_object *obj);
+int iommufd_fault_iopf_handler(struct iopf_group *group);
 
 int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
                                    struct iommufd_device *idev);

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 70b8a38fcd46409c6d28129bb2b9e0728f4c12c6..ede2b464a7619ad24d0cb06a9fe6f0c63f64285b 100644 (file)
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -357,10 +357,13 @@ struct iommu_vfio_ioas {
  *                                the parent HWPT in a nesting configuration.
  * @IOMMU_HWPT_ALLOC_DIRTY_TRACKING: Dirty tracking support for device IOMMU is
  *                                   enforced on device attachment
+ * @IOMMU_HWPT_FAULT_ID_VALID: The fault_id field of hwpt allocation data is
+ *                             valid.
  */
 enum iommufd_hwpt_alloc_flags {
        IOMMU_HWPT_ALLOC_NEST_PARENT = 1 << 0,
        IOMMU_HWPT_ALLOC_DIRTY_TRACKING = 1 << 1,
+       IOMMU_HWPT_FAULT_ID_VALID = 1 << 2,
 };
 
 /**
@@ -412,6 +415,9 @@ enum iommu_hwpt_data_type {
  * @data_type: One of enum iommu_hwpt_data_type
  * @data_len: Length of the type specific data
  * @data_uptr: User pointer to the type specific data
+ * @fault_id: The ID of IOMMUFD_FAULT object. Valid only if flags field of
+ *            IOMMU_HWPT_FAULT_ID_VALID is set.
+ * @__reserved2: Padding to 64-bit alignment. Must be 0.
  *
  * Explicitly allocate a hardware page table object. This is the same object
  * type that is returned by iommufd_device_attach() and represents the
@@ -442,6 +448,8 @@ struct iommu_hwpt_alloc {
        __u32 data_type;
        __u32 data_len;
        __aligned_u64 data_uptr;
+       __u32 fault_id;
+       __u32 __reserved2;
 };
 #define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)