IB/core: Introduce ib_reg_user_mr

Add ib_reg_user_mr() for kernel ULPs to register user MRs.

The common use case that uses this function is a userspace application
that allocates memory for HCA access but the responsibility to register
the memory at the HCA is on an kernel ULP. This ULP that acts as an agent
for the userspace application.

This function is intended to be used without a user context so vendor
drivers need to be aware of calling reg_user_mr() device operation with
udata equal to NULL.

Among all drivers, i40iw is the only driver which relies on presence
of udata, so check udata existence for that driver.

Signed-off-by: Moni Shoua <[email protected]>
Reviewed-by: Guy Levi <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>

drivers/infiniband/core/verbs.c

@@ -1990,6 +1990,36 @@ EXPORT_SYMBOL(ib_resize_cq);
 
 /* Memory regions */
 
+struct ib_mr *ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
+			     u64 virt_addr, int access_flags)
+{
+	struct ib_mr *mr;
+
+	if (access_flags & IB_ACCESS_ON_DEMAND) {
+		if (!(pd->device->attrs.device_cap_flags &
+		      IB_DEVICE_ON_DEMAND_PAGING)) {
+			pr_debug("ODP support not available\n");
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	mr = pd->device->ops.reg_user_mr(pd, start, length, virt_addr,
+					 access_flags, NULL);
+
+	if (IS_ERR(mr))
+		return mr;
+
+	mr->device = pd->device;
+	mr->pd = pd;
+	mr->dm = NULL;
+	atomic_inc(&pd->usecnt);
+	mr->res.type = RDMA_RESTRACK_MR;
+	rdma_restrack_kadd(&mr->res);
+
+	return mr;
+}
+EXPORT_SYMBOL(ib_reg_user_mr);
+
 int ib_dereg_mr_user(struct ib_mr *mr, struct ib_udata *udata)
 {
 	struct ib_pd *pd = mr->pd;

drivers/infiniband/hw/efa/efa_verbs.c

@@ -1358,7 +1358,7 @@ struct ib_mr *efa_reg_mr(struct ib_pd *ibpd, u64 start, u64 length,
 	int inline_size;
 	int err;
 
-	if (udata->inlen &&
+	if (udata && udata->inlen &&
 	    !ib_is_udata_cleared(udata, 0, sizeof(udata->inlen))) {
 		ibdev_dbg(&dev->ibdev,
 			  "Incompatible ABI params, udata not cleared\n");

drivers/infiniband/hw/i40iw/i40iw_verbs.c

@@ -1756,6 +1756,9 @@ static struct ib_mr *i40iw_reg_user_mr(struct ib_pd *pd,
 	int ret;
 	int pg_shift;
 
+	if (!udata)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	if (iwdev->closing)
 		return ERR_PTR(-ENODEV);
 

include/rdma/ib_verbs.h

@@ -4153,6 +4153,12 @@ static inline void ib_dma_free_coherent(struct ib_device *dev,
 	dma_free_coherent(dev->dma_device, size, cpu_addr, dma_handle);
 }
 
+/* ib_reg_user_mr - register a memory region for virtual addresses from kernel
+ * space. This function should be called when 'current' is the owning MM.
+ */
+struct ib_mr *ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
+			     u64 virt_addr, int mr_access_flags);
+
 /**
  * ib_dereg_mr_user - Deregisters a memory region and removes it from the
  *   HCA translation table.