RDMA/core: Introduce a DMAH object and its alloc/free APIs

Introduce a new DMA handle (DMAH) object along with its corresponding
allocation and deallocation APIs.

This DMAH object encapsulates attributes intended for use in DMA
transactions.

While its initial purpose is to support TPH functionality, it is
designed to be extensible for future features such as DMA PCI multipath,
PCI UIO configurations, PCI traffic class selection, and more.

Further details:
----------------
We ensure that a caller requesting a DMA handle for a specific CPU ID is
permitted to be scheduled on it. This prevent a potential security issue
where a non privilege user may trigger DMA operations toward a CPU that
it's not allowed to run on.

We manage reference counting for the DMAH object and its consumers
(e.g., memory regions) as will be detailed in subsequent patches in the
series.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/2cad097e849597e49d6b61e6865dba878257f371.1752752567.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>

3 files changed, 47 insertions, 0 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 3fb1c963eeb0..9ad253687935 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -42,6 +42,7 @@
 #include <rdma/signature.h>
 #include <uapi/rdma/rdma_user_ioctl.h>
 #include <uapi/rdma/ib_user_ioctl_verbs.h>
+#include <linux/pci-tph.h>
 
 #define IB_FW_VERSION_NAME_MAX	ETHTOOL_FWVERS_LEN
 
@@ -1846,6 +1847,27 @@ struct ib_dm {
 	atomic_t	   usecnt;
 };
 
+/* bit values to mark existence of ib_dmah fields */
+enum {
+	IB_DMAH_CPU_ID_EXISTS,
+	IB_DMAH_MEM_TYPE_EXISTS,
+	IB_DMAH_PH_EXISTS,
+};
+
+struct ib_dmah {
+	struct ib_device *device;
+	struct ib_uobject *uobject;
+	/*
+	 * Implementation details of the RDMA core, don't use in drivers:
+	 */
+	struct rdma_restrack_entry res;
+	u32 cpu_id;
+	enum tph_mem_type mem_type;
+	atomic_t usecnt;
+	u8 ph;
+	u8 valid_fields; /* use IB_DMAH_XXX_EXISTS */
+};
+
 struct ib_mr {
 	struct ib_device  *device;
 	struct ib_pd	  *pd;
@@ -2573,6 +2595,9 @@ struct ib_device_ops {
 				  struct ib_dm_alloc_attr *attr,
 				  struct uverbs_attr_bundle *attrs);
 	int (*dealloc_dm)(struct ib_dm *dm, struct uverbs_attr_bundle *attrs);
+	int (*alloc_dmah)(struct ib_dmah *ibdmah,
+			  struct uverbs_attr_bundle *attrs);
+	int (*dealloc_dmah)(struct ib_dmah *dmah, struct uverbs_attr_bundle *attrs);
 	struct ib_mr *(*reg_dm_mr)(struct ib_pd *pd, struct ib_dm *dm,
 				   struct ib_dm_mr_attr *attr,
 				   struct uverbs_attr_bundle *attrs);
@@ -2730,6 +2755,7 @@ struct ib_device_ops {
 	DECLARE_RDMA_OBJ_SIZE(ib_ah);
 	DECLARE_RDMA_OBJ_SIZE(ib_counters);
 	DECLARE_RDMA_OBJ_SIZE(ib_cq);
+	DECLARE_RDMA_OBJ_SIZE(ib_dmah);
 	DECLARE_RDMA_OBJ_SIZE(ib_mw);
 	DECLARE_RDMA_OBJ_SIZE(ib_pd);
 	DECLARE_RDMA_OBJ_SIZE(ib_qp);
diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h
index 0d69ded73bf2..8a9bcf77dace 100644
--- a/include/rdma/restrack.h
+++ b/include/rdma/restrack.h
@@ -57,6 +57,10 @@ enum rdma_restrack_type {
 	 */
 	RDMA_RESTRACK_SRQ,
 	/**
+	 * @RDMA_RESTRACK_DMAH: DMA handle
+	 */
+	RDMA_RESTRACK_DMAH,
+	/**
 	 * @RDMA_RESTRACK_MAX: Last entry, used for array dclarations
 	 */
 	RDMA_RESTRACK_MAX
diff --git a/include/uapi/rdma/ib_user_ioctl_cmds.h b/include/uapi/rdma/ib_user_ioctl_cmds.h
index ece923ab48a0..3bb72a259c29 100644
--- a/include/uapi/rdma/ib_user_ioctl_cmds.h
+++ b/include/uapi/rdma/ib_user_ioctl_cmds.h
@@ -55,6 +55,7 @@ enum uverbs_default_objects {
 	UVERBS_OBJECT_DM,
 	UVERBS_OBJECT_COUNTERS,
 	UVERBS_OBJECT_ASYNC_EVENT,
+	UVERBS_OBJECT_DMAH,
 };
 
 enum {
@@ -240,6 +241,22 @@ enum uverbs_methods_dm {
 	UVERBS_METHOD_DM_FREE,
 };
 
+enum uverbs_attrs_alloc_dmah_cmd_attr_ids {
+	UVERBS_ATTR_ALLOC_DMAH_HANDLE,
+	UVERBS_ATTR_ALLOC_DMAH_CPU_ID,
+	UVERBS_ATTR_ALLOC_DMAH_TPH_MEM_TYPE,
+	UVERBS_ATTR_ALLOC_DMAH_PH,
+};
+
+enum uverbs_attrs_free_dmah_cmd_attr_ids {
+	UVERBS_ATTR_FREE_DMA_HANDLE,
+};
+
+enum uverbs_methods_dmah {
+	UVERBS_METHOD_DMAH_ALLOC,
+	UVERBS_METHOD_DMAH_FREE,
+};
+
 enum uverbs_attrs_reg_dm_mr_cmd_attr_ids {
 	UVERBS_ATTR_REG_DM_MR_HANDLE,
 	UVERBS_ATTR_REG_DM_MR_OFFSET,