diff --git a/drivers/infiniband/core/uverbs_ioctl.c b/drivers/infiniband/core/uverbs_ioctl.c
index 990f0724acc6b..d9799706c58e9 100644
--- a/drivers/infiniband/core/uverbs_ioctl.c
+++ b/drivers/infiniband/core/uverbs_ioctl.c
@@ -337,6 +337,14 @@ static int uverbs_process_attr(struct bundle_priv *pbundle,
 
 		break;
 
+	case UVERBS_ATTR_TYPE_RAW_FD:
+		if (uattr->attr_data.reserved || uattr->len != 0 ||
+		    uattr->data_s64 < INT_MIN || uattr->data_s64 > INT_MAX)
+			return -EINVAL;
+		/* _uverbs_get_const_signed() is the accessor */
+		e->ptr_attr.data = uattr->data_s64;
+		break;
+
 	case UVERBS_ATTR_TYPE_IDRS_ARRAY:
 		return uverbs_process_idrs_array(pbundle, attr_uapi,
 						 &e->objs_arr_attr, uattr,
diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c
index 28cf0aa61ada6..27efe40b8b527 100644
--- a/drivers/infiniband/hw/mlx5/devx.c
+++ b/drivers/infiniband/hw/mlx5/devx.c
@@ -2175,32 +2175,39 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_SUBSCRIBE_EVENT)(
 
 static int devx_umem_get(struct mlx5_ib_dev *dev, struct ib_ucontext *ucontext,
 			 struct uverbs_attr_bundle *attrs,
-			 struct devx_umem *obj)
+			 struct devx_umem *obj, u32 access_flags)
 {
 	u64 addr;
 	size_t size;
-	u32 access;
 	int err;
 
 	if (uverbs_copy_from(&addr, attrs, MLX5_IB_ATTR_DEVX_UMEM_REG_ADDR) ||
 	    uverbs_copy_from(&size, attrs, MLX5_IB_ATTR_DEVX_UMEM_REG_LEN))
 		return -EFAULT;
 
-	err = uverbs_get_flags32(&access, attrs,
-				 MLX5_IB_ATTR_DEVX_UMEM_REG_ACCESS,
-				 IB_ACCESS_LOCAL_WRITE |
-				 IB_ACCESS_REMOTE_WRITE |
-				 IB_ACCESS_REMOTE_READ);
+	err = ib_check_mr_access(&dev->ib_dev, access_flags);
 	if (err)
 		return err;
 
-	err = ib_check_mr_access(&dev->ib_dev, access);
-	if (err)
-		return err;
+	if (uverbs_attr_is_valid(attrs, MLX5_IB_ATTR_DEVX_UMEM_REG_DMABUF_FD)) {
+		struct ib_umem_dmabuf *umem_dmabuf;
+		int dmabuf_fd;
+
+		err = uverbs_get_raw_fd(&dmabuf_fd, attrs,
+					MLX5_IB_ATTR_DEVX_UMEM_REG_DMABUF_FD);
+		if (err)
+			return -EFAULT;
 
-	obj->umem = ib_umem_get_peer(&dev->ib_dev, addr, size, access, 0);
-	if (IS_ERR(obj->umem))
-		return PTR_ERR(obj->umem);
+		umem_dmabuf = ib_umem_dmabuf_get_pinned(
+			&dev->ib_dev, addr, size, dmabuf_fd, access_flags);
+		if (IS_ERR(umem_dmabuf))
+			return PTR_ERR(umem_dmabuf);
+		obj->umem = &umem_dmabuf->umem;
+	} else {
+		obj->umem = ib_umem_get(&dev->ib_dev, addr, size, access_flags);
+		if (IS_ERR(obj->umem))
+			return PTR_ERR(obj->umem);
+	}
 	return 0;
 }
 
@@ -2239,7 +2246,8 @@ static unsigned int devx_umem_find_best_pgsize(struct ib_umem *umem,
 static int devx_umem_reg_cmd_alloc(struct mlx5_ib_dev *dev,
 				   struct uverbs_attr_bundle *attrs,
 				   struct devx_umem *obj,
-				   struct devx_umem_reg_cmd *cmd)
+				   struct devx_umem_reg_cmd *cmd,
+				   int access)
 {
 	unsigned long pgsz_bitmap;
 	unsigned int page_size;
@@ -2290,6 +2298,9 @@ static int devx_umem_reg_cmd_alloc(struct mlx5_ib_dev *dev,
 	if (obj->umem->is_peer)
 		MLX5_SET(umem, umem, ats, MLX5_CAP_GEN(dev->mdev, ats));
 
+	if (mlx5_umem_needs_ats(dev, obj->umem, access))
+		MLX5_SET(umem, umem, ats, 1);
+
 	mlx5_ib_populate_pas(obj->umem, page_size, mtt,
 			     (obj->umem->writable ? MLX5_IB_MTT_WRITE : 0) |
 				     MLX5_IB_MTT_READ);
@@ -2307,20 +2318,30 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_UMEM_REG)(
 	struct mlx5_ib_ucontext *c = rdma_udata_to_drv_context(
 		&attrs->driver_udata, struct mlx5_ib_ucontext, ibucontext);
 	struct mlx5_ib_dev *dev = to_mdev(c->ibucontext.device);
+	int access_flags;
 	int err;
 
 	if (!c->devx_uid)
 		return -EINVAL;
 
+	err = uverbs_get_flags32(&access_flags, attrs,
+				 MLX5_IB_ATTR_DEVX_UMEM_REG_ACCESS,
+				 IB_ACCESS_LOCAL_WRITE |
+				 IB_ACCESS_REMOTE_WRITE |
+				 IB_ACCESS_REMOTE_READ |
+				 IB_ACCESS_RELAXED_ORDERING);
+	if (err)
+		return err;
+
 	obj = kzalloc(sizeof(struct devx_umem), GFP_KERNEL);
 	if (!obj)
 		return -ENOMEM;
 
-	err = devx_umem_get(dev, &c->ibucontext, attrs, obj);
+	err = devx_umem_get(dev, &c->ibucontext, attrs, obj, access_flags);
 	if (err)
 		goto err_obj_free;
 
-	err = devx_umem_reg_cmd_alloc(dev, attrs, obj, &cmd);
+	err = devx_umem_reg_cmd_alloc(dev, attrs, obj, &cmd, access_flags);
 	if (err)
 		goto err_umem_release;
 
@@ -2852,6 +2873,8 @@ DECLARE_UVERBS_NAMED_METHOD(
 	UVERBS_ATTR_PTR_IN(MLX5_IB_ATTR_DEVX_UMEM_REG_LEN,
 			   UVERBS_ATTR_TYPE(u64),
 			   UA_MANDATORY),
+	UVERBS_ATTR_RAW_FD(MLX5_IB_ATTR_DEVX_UMEM_REG_DMABUF_FD,
+			   UA_OPTIONAL),
 	UVERBS_ATTR_FLAGS_IN(MLX5_IB_ATTR_DEVX_UMEM_REG_ACCESS,
 			     enum ib_access_flags),
 	UVERBS_ATTR_CONST_IN(MLX5_IB_ATTR_DEVX_UMEM_REG_PGSZ_BITMAP,
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index bf20a388eabe1..6886cf90fab7d 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -1615,4 +1615,40 @@ static inline bool rt_supported(int ts_cap)
 	return ts_cap == MLX5_TIMESTAMP_FORMAT_CAP_REAL_TIME ||
 	       ts_cap == MLX5_TIMESTAMP_FORMAT_CAP_FREE_RUNNING_AND_REAL_TIME;
 }
+
+/*
+ * PCI Peer to Peer is a trainwreck. If no switch is present then things
+ * sometimes work, depending on the pci_distance_p2p logic for excluding broken
+ * root complexes. However if a switch is present in the path, then things get
+ * really ugly depending on how the switch is setup. This table assumes that the
+ * root complex is strict and is validating that all req/reps are matches
+ * perfectly - so any scenario where it sees only half the transaction is a
+ * failure.
+ *
+ * CR/RR/DT  ATS RO P2P
+ * 00X       X   X  OK
+ * 010       X   X  fails (request is routed to root but root never sees comp)
+ * 011       0   X  fails (request is routed to root but root never sees comp)
+ * 011       1   X  OK
+ * 10X       X   1  OK
+ * 101       X   0  fails (completion is routed to root but root didn't see req)
+ * 110       X   0  SLOW
+ * 111       0   0  SLOW
+ * 111       1   0  fails (completion is routed to root but root didn't see req)
+ * 111       1   1  OK
+ *
+ * Unfortunately we cannot reliably know if a switch is present or what the
+ * CR/RR/DT ACS settings are, as in a VM that is all hidden. Assume that
+ * CR/RR/DT is 111 if the ATS cap is enabled and follow the last three rows.
+ *
+ * For now assume if the umem is a dma_buf then it is P2P.
+ */
+static inline bool mlx5_umem_needs_ats(struct mlx5_ib_dev *dev,
+				       struct ib_umem *umem, int access_flags)
+{
+	if (!MLX5_CAP_GEN(dev->mdev, ats) || !umem->is_dmabuf)
+		return false;
+	return access_flags & IB_ACCESS_RELAXED_ORDERING;
+}
+
 #endif /* MLX5_IB_H */
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index b938093ffa3fb..406076e353d79 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -960,7 +960,8 @@ static struct mlx5_ib_mr *alloc_cacheable_mr(struct ib_pd *pd,
 	 * cache then synchronously create an uncached one.
 	 */
 	if (!ent || ent->limit == 0 ||
-	    !mlx5_ib_can_reconfig_with_umr(dev, 0, access_flags)) {
+	    !mlx5_ib_can_reconfig_with_umr(dev, 0, access_flags) ||
+	    mlx5_umem_needs_ats(dev, umem, access_flags)) {
 		mutex_lock(&dev->slow_path_mutex);
 		mr = reg_create(pd, umem, iova, access_flags, page_size, false);
 		mutex_unlock(&dev->slow_path_mutex);
@@ -1334,6 +1335,9 @@ static struct mlx5_ib_mr *reg_create(struct ib_pd *pd, struct ib_umem *umem,
 	MLX5_SET(mkc, mkc, translations_octword_size,
 		 get_octo_len(iova, umem->length, mr->page_shift));
 	MLX5_SET(mkc, mkc, log_page_size, mr->page_shift);
+	if (mlx5_umem_needs_ats(dev, umem, access_flags))
+		MLX5_SET(mkc, mkc, ma_translation_mode, 1);
+
 	if (umem->is_peer)
 		MLX5_SET(mkc, mkc, ma_translation_mode,
 			 MLX5_CAP_GEN(dev->mdev, ats));
diff --git a/include/rdma/uverbs_ioctl.h b/include/rdma/uverbs_ioctl.h
index 23bb404aba12c..9d45a5b203169 100644
--- a/include/rdma/uverbs_ioctl.h
+++ b/include/rdma/uverbs_ioctl.h
@@ -24,6 +24,7 @@ enum uverbs_attr_type {
 	UVERBS_ATTR_TYPE_PTR_OUT,
 	UVERBS_ATTR_TYPE_IDR,
 	UVERBS_ATTR_TYPE_FD,
+	UVERBS_ATTR_TYPE_RAW_FD,
 	UVERBS_ATTR_TYPE_ENUM_IN,
 	UVERBS_ATTR_TYPE_IDRS_ARRAY,
 };
@@ -521,6 +522,11 @@ struct uapi_definition {
 			  .u.obj.access = _access,                             \
 			  __VA_ARGS__ } })
 
+#define UVERBS_ATTR_RAW_FD(_attr_id, ...)                                      \
+	(&(const struct uverbs_attr_def){                                      \
+		.id = (_attr_id),                                              \
+		.attr = { .type = UVERBS_ATTR_TYPE_RAW_FD, __VA_ARGS__ } })
+
 #define UVERBS_ATTR_PTR_IN(_attr_id, _type, ...)                               \
 	(&(const struct uverbs_attr_def){                                      \
 		.id = _attr_id,                                                \
@@ -999,4 +1005,11 @@ _uverbs_get_const_unsigned(u64 *to,
 		 uverbs_get_const_default_unsigned(_to, _attrs_bundle, _idx,   \
 						    _default))
 
+static inline int
+uverbs_get_raw_fd(int *to, const struct uverbs_attr_bundle *attrs_bundle,
+		  size_t idx)
+{
+	return uverbs_get_const_signed(to, attrs_bundle, idx);
+}
+
 #endif
diff --git a/include/uapi/rdma/mlx5_user_ioctl_cmds.h b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
index e539c84d63f1a..0af52cc0d4621 100644
--- a/include/uapi/rdma/mlx5_user_ioctl_cmds.h
+++ b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
@@ -174,6 +174,7 @@ enum mlx5_ib_devx_umem_reg_attrs {
 	MLX5_IB_ATTR_DEVX_UMEM_REG_ACCESS,
 	MLX5_IB_ATTR_DEVX_UMEM_REG_OUT_ID,
 	MLX5_IB_ATTR_DEVX_UMEM_REG_PGSZ_BITMAP,
+	MLX5_IB_ATTR_DEVX_UMEM_REG_DMABUF_FD,
 };
 
 enum mlx5_ib_devx_umem_dereg_attrs {