Commit a9498ee5 authored by Oded Gabbay's avatar Oded Gabbay
Browse files

habanalabs: define uAPI to export FD for DMA-BUF 



User process might want to share the device memory with another
driver/device, and to allow it to access it over PCIe (P2P).

To enable this, we utilize the dma-buf mechanism and add a dma-buf
exporter support, so the other driver can import the device memory and
access it.

The device memory is allocated using our existing allocation uAPI,
where the user will get a handle that represents the allocation.

The user will then need to call the new
uAPI (HL_MEM_OP_EXPORT_DMABUF_FD) and give the handle as a parameter.

The driver will return a FD that represents the DMA-BUF object that
was created to match that allocation.

Signed-off-by: default avatarOded Gabbay <ogabbay@kernel.org>
Reviewed-by: default avatarTomer Tayar <ttayar@habana.ai>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 81f8582e

include/uapi/misc/habanalabs.h

+27 −1
Original line number Diff line number Diff line
@@ -960,6 +960,10 @@ union hl_wait_cs_args { 
#define HL_MEM_OP_UNMAP			3

/* Opcode to map a hw block */

#define HL_MEM_OP_MAP_BLOCK		4

/* Opcode to create DMA-BUF object for an existing device memory allocation

 * and to export an FD of that DMA-BUF back to the caller

 */

#define HL_MEM_OP_EXPORT_DMABUF_FD	5



/* Memory flags */

#define HL_MEM_CONTIGUOUS	0x1
@@ -1031,11 +1035,26 @@ struct hl_mem_in { 
			/* Virtual address returned from HL_MEM_OP_MAP */

			__u64 device_virt_addr;

		} unmap;



		/* HL_MEM_OP_EXPORT_DMABUF_FD */

		struct {

			/* Handle returned from HL_MEM_OP_ALLOC. In Gaudi,

			 * where we don't have MMU for the device memory, the

			 * driver expects a physical address (instead of

			 * a handle) in the device memory space.

			 */

			__u64 handle;

			/* Size of memory allocation. Relevant only for GAUDI */

			__u64 mem_size;

		} export_dmabuf_fd;

	};



	/* HL_MEM_OP_* */

	__u32 op;

	/* HL_MEM_* flags */

	/* HL_MEM_* flags.

	 * For the HL_MEM_OP_EXPORT_DMABUF_FD opcode, this field holds the

	 * DMA-BUF file/FD flags.

	 */

	__u32 flags;

	/* Context ID - Currently not in use */

	__u32 ctx_id;
@@ -1072,6 +1091,13 @@ struct hl_mem_out { 


			__u32 pad;

		};



		/* Returned in HL_MEM_OP_EXPORT_DMABUF_FD. Represents the

		 * DMA-BUF object that was created to describe a memory

		 * allocation on the device's memory space. The FD should be

		 * passed to the importer driver

		 */

		__s32 fd;

	};

};