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: Oded Gabbay <ogab...@kernel.org>
Reviewed-by: Tomer Tayar <tta...@habana.ai>
Reviewed-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Acked-by: Daniel Vetter <daniel.vet...@ffwll.ch>
---
Changes in v7:
- Change the type of the fd variable returned from IOCTL to be __s32
include/uapi/misc/habanalabs.h | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/include/uapi/misc/habanalabs.h b/include/uapi/misc/habanalabs.h
index ccfcb4d188fc..f980fbfb1a0e 100644
--- a/include/uapi/misc/habanalabs.h
+++ b/include/uapi/misc/habanalabs.h
@@ -959,6 +959,10 @@ 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
@@ -1030,11 +1034,26 @@ 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;
@@ -1071,6 +1090,13 @@ 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;
};
};
--
2.17.1
