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From: Oded Gabbay <ogabbay@kernel.org>
To: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, jgg@ziepe.ca
Cc: christian.koenig@amd.com, daniel.vetter@ffwll.ch,
	galpress@amazon.com, sleybo@amazon.com,
	dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org,
	linux-media@vger.kernel.org, dledford@redhat.com,
	airlied@gmail.com, alexander.deucher@amd.com, leonro@nvidia.com,
	hch@lst.de, amd-gfx@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org
Subject: [PATCH v6 1/2] habanalabs: define uAPI to export FD for DMA-BUF
Date: Sun, 12 Sep 2021 19:53:08 +0300	[thread overview]
Message-ID: <20210912165309.98695-2-ogabbay@kernel.org> (raw)
In-Reply-To: <20210912165309.98695-1-ogabbay@kernel.org>

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 <ogabbay@kernel.org>
Reviewed-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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 042e96f99d85..b1def68bf5d3 100644
--- a/include/uapi/misc/habanalabs.h
+++ b/include/uapi/misc/habanalabs.h
@@ -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
+		 */
+		__u64 fd;
 	};
 };
 
-- 
2.17.1


  reply	other threads:[~2021-09-12 16:53 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-12 16:53 [PATCH v6 0/2] Add p2p via dmabuf to habanalabs Oded Gabbay
2021-09-12 16:53 ` Oded Gabbay [this message]
2021-09-28 17:13   ` [PATCH v6 1/2] habanalabs: define uAPI to export FD for DMA-BUF Jason Gunthorpe
2021-09-28 19:12     ` Oded Gabbay
2021-09-12 16:53 ` [PATCH v6 2/2] habanalabs: add support for dma-buf exporter Oded Gabbay
2021-09-28 17:36   ` Jason Gunthorpe
2021-09-28 21:17     ` Oded Gabbay
2021-09-30 12:46       ` Oded Gabbay
2021-10-01 14:52         ` Jason Gunthorpe
2021-10-01 14:50       ` Jason Gunthorpe
2021-09-14 14:18 ` [PATCH v6 0/2] Add p2p via dmabuf to habanalabs Daniel Vetter
2021-09-14 14:58   ` Oded Gabbay
2021-09-14 16:12   ` Jason Gunthorpe
2021-09-15  7:45     ` Oded Gabbay
2021-09-16 12:31       ` Daniel Vetter
2021-09-16 12:44         ` Oded Gabbay
2021-09-16 13:16           ` Oded Gabbay
2021-09-17 12:25           ` Daniel Vetter
2021-09-16 13:10         ` Jason Gunthorpe
2021-09-17 12:30           ` Daniel Vetter
2021-09-18  8:38             ` Oded Gabbay
2021-09-23  9:22               ` Oded Gabbay
2021-09-28  7:04                 ` Oded Gabbay
2021-09-30  9:13                   ` Daniel Vetter

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