[PATCH 1/2] habanalabs: define uAPI to export FD for DMA-BUF

[PATCH 1/2] habanalabs: define uAPI to export FD for DMA-BUF

[Oded Gabbay]

From: Oded Gabbay <ogabbay@habana.ai>

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@habana.ai>
Reviewed-by: Tomer Tayar <ttayar@habana.ai>
---
 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 a47a731e4527..aa3d8e0ba060 100644
--- a/include/uapi/misc/habanalabs.h
+++ b/include/uapi/misc/habanalabs.h
@@ -808,6 +808,10 @@ 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
@@ -878,11 +882,26 @@ 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;
@@ -919,6 +938,13 @@ 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;
 	};
 };
 
-- 
2.25.1

[PATCH 2/2] habanalabs: add support for dma-buf exporter

[Oded Gabbay]

From: Tomer Tayar <ttayar@habana.ai>

Implement the calls to the dma-buf kernel api to create a dma-buf
object backed by FD.

We block the option to mmap the DMA-BUF object because we don't support
DIRECT_IO and implicit P2P. We only implement support for explicit P2P
through importing the FD of the DMA-BUF.

In the export phase, we provide a static SG list to the DMA-BUF object
because in  Habanalabs's ASICs, the device memory is pinned and
immutable. Therefore, there is no need for dynamic mappings and pinning
callbacks.

Note that in GAUDI we don't have an MMU towards the device memory and
the user works on physical addresses. Therefore, the user doesn't pass
through the kernel driver to allocate memory there. As a result, only
for GAUDI we receive from the user a device memory physical address
(instead of a handle) and a size.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
---
 drivers/misc/habanalabs/Kconfig             |   1 +
 drivers/misc/habanalabs/common/context.c    |   4 +
 drivers/misc/habanalabs/common/habanalabs.h |  32 ++
 drivers/misc/habanalabs/common/memory.c     | 427 +++++++++++++++++++-
 drivers/misc/habanalabs/gaudi/gaudi.c       |   1 +
 drivers/misc/habanalabs/goya/goya.c         |   1 +
 6 files changed, 463 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/habanalabs/Kconfig b/drivers/misc/habanalabs/Kconfig
index 293d79811372..c82d2e7b2035 100644
--- a/drivers/misc/habanalabs/Kconfig
+++ b/drivers/misc/habanalabs/Kconfig
@@ -8,6 +8,7 @@ config HABANA_AI
 	depends on PCI && HAS_IOMEM
 	select GENERIC_ALLOCATOR
 	select HWMON
+	select DMA_SHARED_BUFFER
 	help
 	  Enables PCIe card driver for Habana's AI Processors (AIP) that are
 	  designed to accelerate Deep Learning inference and training workloads.
diff --git a/drivers/misc/habanalabs/common/context.c b/drivers/misc/habanalabs/common/context.c
index 19b6b045219e..5efedb24c06a 100644
--- a/drivers/misc/habanalabs/common/context.c
+++ b/drivers/misc/habanalabs/common/context.c
@@ -37,6 +37,8 @@ static void hl_ctx_fini(struct hl_ctx *ctx)
 
 	kfree(ctx->cs_pending);
 
+	mutex_destroy(&ctx->dmabuf_list_lock);
+
 	if (ctx->asid != HL_KERNEL_ASID_ID) {
 		dev_dbg(hdev->dev, "closing user context %d\n", ctx->asid);
 
@@ -146,6 +148,8 @@ int hl_ctx_init(struct hl_device *hdev, struct hl_ctx *ctx, bool is_kernel_ctx)
 	ctx->cs_sequence = 1;
 	INIT_LIST_HEAD(&ctx->pending_cb_list);
 	spin_lock_init(&ctx->pending_cb_lock);
+	INIT_LIST_HEAD(&ctx->dmabuf_list);
+	mutex_init(&ctx->dmabuf_list_lock);
 	spin_lock_init(&ctx->cs_lock);
 	atomic_set(&ctx->thread_ctx_switch_token, 1);
 	atomic_set(&ctx->thread_pending_cb_token, 1);
diff --git a/drivers/misc/habanalabs/common/habanalabs.h b/drivers/misc/habanalabs/common/habanalabs.h
index 6c9a81c2cfe7..e545574b1d38 100644
--- a/drivers/misc/habanalabs/common/habanalabs.h
+++ b/drivers/misc/habanalabs/common/habanalabs.h
@@ -20,6 +20,7 @@
 #include <linux/scatterlist.h>
 #include <linux/hashtable.h>
 #include <linux/debugfs.h>
+#include <linux/dma-buf.h>
 #include <linux/bitfield.h>
 #include <linux/genalloc.h>
 #include <linux/sched/signal.h>
@@ -1290,6 +1291,29 @@ struct hl_pending_cb {
 	u32			hw_queue_id;
 };
 
+/**
+ * struct hl_dmabuf_wrapper - a dma-buf wrapper object.
+ * @dmabuf: pointer to dma-buf object.
+ * @ctx: pointer to the dma-buf owner's context.
+ * @node: @node in a dma-buf wrapper objects list of a context.
+ * @phys_pg_pack: pointer to physical page pack if the dma-buf was exported for
+ *                memory allocation handle.
+ * @sgt: scatter-gather table that holds the exported pages.
+ * @total_size: total size of all exported pages.
+ * @handle: allocation handle or physical address of the exported memory.
+ * @fd: file descriptor which is associated with the dma_buf.
+ */
+struct hl_dmabuf_wrapper {
+	struct dma_buf			*dmabuf;
+	struct hl_ctx			*ctx;
+	struct hl_vm_phys_pg_pack	*phys_pg_pack;
+	struct list_head		node;
+	struct sg_table			sgt;
+	u64				total_size;
+	u64				handle;
+	int				fd;
+};
+
 /**
  * struct hl_ctx - user/kernel context.
  * @mem_hash: holds mapping from virtual address to virtual memory area
@@ -1305,10 +1329,12 @@ struct hl_pending_cb {
  * @mmu_lock: protects the MMU page tables. Any change to the PGT, modifying the
  *            MMU hash or walking the PGT requires talking this lock.
  * @hw_block_list_lock: protects the HW block memory list.
+ * @dmabuf_list_lock: protects the dma-buf wrapper objects list.
  * @debugfs_list: node in debugfs list of contexts.
  * pending_cb_list: list of pending command buffers waiting to be sent upon
  *                  next user command submission context.
  * @hw_block_mem_list: list of HW block virtual mapped addresses.
+ * @dmabuf_list: list of dma-buf wrapper objects.
  * @cs_counters: context command submission counters.
  * @cb_va_pool: device VA pool for command buffers which are mapped to the
  *              device's MMU.
@@ -1346,9 +1372,11 @@ struct hl_ctx {
 	struct mutex			mem_hash_lock;
 	struct mutex			mmu_lock;
 	struct mutex			hw_block_list_lock;
+	struct mutex			dmabuf_list_lock;
 	struct list_head		debugfs_list;
 	struct list_head		pending_cb_list;
 	struct list_head		hw_block_mem_list;
+	struct list_head		dmabuf_list;
 	struct hl_cs_counters_atomic	cs_counters;
 	struct gen_pool			*cb_va_pool;
 	u64				cs_sequence;
@@ -1598,6 +1626,7 @@ struct hl_vm_hw_block_list_node {
  * @npages: num physical pages in the pack.
  * @total_size: total size of all the pages in this list.
  * @mapping_cnt: number of shared mappings.
+ * @exporting_cnt: number of dma-buf exporting.
  * @asid: the context related to this list.
  * @page_size: size of each page in the pack.
  * @flags: HL_MEM_* flags related to this list.
@@ -1612,6 +1641,7 @@ struct hl_vm_phys_pg_pack {
 	u64			npages;
 	u64			total_size;
 	atomic_t		mapping_cnt;
+	atomic_t		exporting_cnt;
 	u32			asid;
 	u32			page_size;
 	u32			flags;
@@ -2137,6 +2167,7 @@ struct hl_mmu_funcs {
  *                          the error will be ignored by the driver during
  *                          device initialization. Mainly used to debug and
  *                          workaround firmware bugs
+ * @dram_pci_bar_start: start bus address of PCIe bar towards DRAM.
  * @last_successful_open_jif: timestamp (jiffies) of the last successful
  *                            device open.
  * @last_open_session_duration_jif: duration (jiffies) of the last device open
@@ -2264,6 +2295,7 @@ struct hl_device {
 	u64				max_power;
 	u64				clock_gating_mask;
 	u64				boot_error_status_mask;
+	u64				dram_pci_bar_start;
 	u64				last_successful_open_jif;
 	u64				last_open_session_duration_jif;
 	u64				open_counter;
diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
index 1cff1887e2e8..25e86030d738 100644
--- a/drivers/misc/habanalabs/common/memory.c
+++ b/drivers/misc/habanalabs/common/memory.c
@@ -15,7 +15,14 @@
 #define HL_MMU_DEBUG	0
 
 /* use small pages for supporting non-pow2 (32M/40M/48M) DRAM phys page sizes */
-#define DRAM_POOL_PAGE_SIZE SZ_8M
+#define DRAM_POOL_PAGE_SIZE		SZ_8M
+
+/* dma-buf alignment requirements when exporting memory with address/size */
+#define DMA_BUF_MEM_ADDR_ALIGNMENT	SZ_32M
+#define DMA_BUF_MEM_SIZE_ALIGNMENT	SZ_32M
+
+/* dma-buf chunk size cannot exceed the scatterlist "unsigned int" length */
+#define DMA_BUF_CHUNK_MAX_SIZE		SZ_512M
 
 /*
  * The va ranges in context object contain a list with the available chunks of
@@ -347,6 +354,13 @@ static int free_device_memory(struct hl_ctx *ctx, struct hl_mem_in *args)
 			return -EINVAL;
 		}
 
+		if (atomic_read(&phys_pg_pack->exporting_cnt) > 0) {
+			dev_err(hdev->dev,
+				"handle %u is exported, cannot free\n",	handle);
+			spin_unlock(&vm->idr_lock);
+			return -EINVAL;
+		}
+
 		/*
 		 * must remove from idr before the freeing of the physical
 		 * pages as the refcount of the pool is also the trigger of the
@@ -1416,13 +1430,394 @@ int hl_hw_block_mmap(struct hl_fpriv *hpriv, struct vm_area_struct *vma)
 	return 0;
 }
 
+static int hl_dmabuf_attach(struct dma_buf *dmabuf,
+#ifdef _HAS_DMA_BUF_OP_ATTACH_WITH_DEV
+				struct device *dev,
+#endif
+				struct dma_buf_attachment *attachment)
+{
+	struct hl_dmabuf_wrapper *hl_dmabuf = dmabuf->priv;
+	struct hl_device *hdev = hl_dmabuf->ctx->hdev;
+
+	dev_dbg(hdev->dev, "attaching dma-buf, handle 0x%llx, fd %d\n",
+		hl_dmabuf->handle, hl_dmabuf->fd);
+
+	attachment->priv = hl_dmabuf;
+
+	return 0;
+}
+
+static void hl_dmabuf_detach(struct dma_buf *dmabuf,
+				struct dma_buf_attachment *attachment)
+{
+	struct hl_dmabuf_wrapper *hl_dmabuf = dmabuf->priv;
+	struct hl_device *hdev = hl_dmabuf->ctx->hdev;
+
+	dev_dbg(hdev->dev, "detaching dma-buf, handle 0x%llx, fd %d\n",
+		hl_dmabuf->handle, hl_dmabuf->fd);
+}
+
+static struct sg_table *hl_map_dmabuf(struct dma_buf_attachment *attachment,
+					enum dma_data_direction dir)
+{
+	struct hl_dmabuf_wrapper *hl_dmabuf = attachment->priv;
+	struct hl_device *hdev = hl_dmabuf->ctx->hdev;
+
+	dev_dbg(hdev->dev, "mapping dma-buf, handle 0x%llx, fd %d\n",
+		hl_dmabuf->handle, hl_dmabuf->fd);
+
+	return &hl_dmabuf->sgt;
+}
+
+static void hl_unmap_dmabuf(struct dma_buf_attachment *attachment,
+				  struct sg_table *table,
+				  enum dma_data_direction dir)
+{
+	struct hl_dmabuf_wrapper *hl_dmabuf = attachment->priv;
+	struct hl_device *hdev = hl_dmabuf->ctx->hdev;
+
+	dev_dbg(hdev->dev, "unmapping dma-buf, handle 0x%llx, fd %d\n",
+		hl_dmabuf->handle, hl_dmabuf->fd);
+}
+
+static void hl_release_dmabuf(struct dma_buf *dmabuf)
+{
+	struct hl_dmabuf_wrapper *hl_dmabuf = dmabuf->priv;
+	struct hl_ctx *ctx = hl_dmabuf->ctx;
+	struct hl_device *hdev = ctx->hdev;
+
+	dev_dbg(hdev->dev, "releasing dma-buf, handle 0x%llx, fd %d\n",
+		hl_dmabuf->handle, hl_dmabuf->fd);
+
+	if (hl_dmabuf->phys_pg_pack)
+		atomic_dec(&hl_dmabuf->phys_pg_pack->exporting_cnt);
+
+	mutex_lock(&ctx->dmabuf_list_lock);
+	list_del(&hl_dmabuf->node);
+	mutex_unlock(&ctx->dmabuf_list_lock);
+
+	hl_ctx_put(hl_dmabuf->ctx);
+
+	sg_free_table(&hl_dmabuf->sgt);
+	kfree(hl_dmabuf);
+}
+
+static const struct dma_buf_ops habanalabs_dmabuf_ops = {
+	.attach = hl_dmabuf_attach,
+	.detach = hl_dmabuf_detach,
+	.map_dma_buf = hl_map_dmabuf,
+	.unmap_dma_buf = hl_unmap_dmabuf,
+	.release = hl_release_dmabuf,
+};
+
+static int alloc_sgt_from_device_pages(struct hl_ctx *ctx, struct sg_table *sgt,
+					u64 *pages, u64 npages, u64 page_size)
+{
+	struct hl_device *hdev = ctx->hdev;
+	struct asic_fixed_properties *prop = &hdev->asic_prop;
+	u64 chunk_size, bar_address;
+	struct scatterlist *sg;
+	int rc, i, j, nents, cur_page;
+
+	/* Get number of non-contiguous chunks */
+	for (i = 1, nents = 1, chunk_size = page_size ; i < npages ; i++) {
+		if (pages[i - 1] + page_size != pages[i] ||
+				chunk_size + page_size >
+					DMA_BUF_CHUNK_MAX_SIZE) {
+			nents++;
+			chunk_size = page_size;
+			continue;
+		}
+
+		chunk_size += page_size;
+	}
+
+	rc = sg_alloc_table(sgt, nents, GFP_KERNEL | __GFP_ZERO);
+	if (rc)
+		return rc;
+
+	/* Merge pages and put them into the scatterlist */
+	cur_page = 0;
+	for_each_sg(sgt->sgl, sg, nents, i) {
+		chunk_size = page_size;
+		for (j = cur_page + 1 ; j < npages ; j++) {
+			if (pages[j - 1] + page_size != pages[j] ||
+					chunk_size + page_size >
+						DMA_BUF_CHUNK_MAX_SIZE)
+				break;
+			chunk_size += page_size;
+		}
+
+		bar_address = hdev->dram_pci_bar_start +
+				(pages[cur_page] - prop->dram_base_address);
+		if (bar_address + chunk_size >
+				hdev->dram_pci_bar_start +
+						prop->dram_pci_bar_size) {
+			dev_err(hdev->dev,
+				"DRAM memory range is outside of PCI BAR boundaries, address 0x%llx, size 0x%llx\n",
+				pages[cur_page], chunk_size);
+			rc = -EINVAL;
+			goto err_sg_free_table;
+		}
+
+		sg_set_page(sg, NULL, chunk_size, 0);
+		sg_dma_address(sg) = bar_address;
+		sg_dma_len(sg) = chunk_size;
+
+		cur_page = j;
+	}
+
+	return 0;
+
+err_sg_free_table:
+	sg_free_table(sgt);
+	return rc;
+}
+
+static int _export_dmabuf_common(struct hl_ctx *ctx,
+			struct hl_dmabuf_wrapper *hl_dmabuf, u64 *pages,
+			u64 npages, u64 page_size, int flags, int *dmabuf_fd)
+{
+	struct hl_device *hdev = ctx->hdev;
+	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+	int rc;
+
+	rc = alloc_sgt_from_device_pages(ctx, &hl_dmabuf->sgt, pages, npages,
+						page_size);
+	if (rc) {
+		dev_err(hdev->dev,
+			"failed to create a scatterlist table for exported device memory\n");
+		return rc;
+	}
+
+	exp_info.ops = &habanalabs_dmabuf_ops;
+	exp_info.size = hl_dmabuf->total_size;
+	exp_info.flags = flags;
+	exp_info.priv = hl_dmabuf;
+	hl_dmabuf->dmabuf = dma_buf_export(&exp_info);
+	if (IS_ERR(hl_dmabuf->dmabuf)) {
+		dev_err(hdev->dev, "failed to export dma-buf\n");
+		rc = PTR_ERR(hl_dmabuf->dmabuf);
+		goto err_sg_free_table;
+	}
+
+	hl_dmabuf->fd = dma_buf_fd(hl_dmabuf->dmabuf, flags);
+	if (hl_dmabuf->fd < 0) {
+		dev_err(hdev->dev,
+			"failed to get a file descriptor for a dma-buf\n");
+		rc = hl_dmabuf->fd;
+		goto err_dma_buf_put;
+	}
+
+	hl_dmabuf->ctx = ctx;
+	hl_ctx_get(hdev, hl_dmabuf->ctx);
+
+	mutex_lock(&ctx->dmabuf_list_lock);
+	list_add(&hl_dmabuf->node, &ctx->dmabuf_list);
+	mutex_unlock(&ctx->dmabuf_list_lock);
+
+	*dmabuf_fd = hl_dmabuf->fd;
+
+	return 0;
+
+err_dma_buf_put:
+	dma_buf_put(hl_dmabuf->dmabuf);
+err_sg_free_table:
+	sg_free_table(&hl_dmabuf->sgt);
+	return rc;
+}
+
+static int export_dmabuf_common(struct hl_ctx *ctx,
+			struct hl_dmabuf_wrapper *hl_dmabuf, u64 *pages,
+			u64 npages, u64 page_size, int flags, int *dmabuf_fd)
+{
+	u64 *split_pages, npages_orig;
+	u32 split_factor;
+	int rc, i, j;
+
+	if (page_size <= DMA_BUF_CHUNK_MAX_SIZE)
+		return _export_dmabuf_common(ctx, hl_dmabuf, pages, npages,
+						page_size, flags, dmabuf_fd);
+
+	/* page_size is a multiple of DMA_BUF_MEM_SIZE_ALIGNMENT */
+	split_factor = (u32) div_u64(page_size, DMA_BUF_MEM_SIZE_ALIGNMENT);
+	npages_orig = npages;
+	npages *= split_factor;
+	page_size = DMA_BUF_MEM_SIZE_ALIGNMENT;
+
+	split_pages = kcalloc(npages, sizeof(*split_pages), GFP_KERNEL);
+	if (!split_pages)
+		return -ENOMEM;
+
+	for (i = 0 ; i < npages_orig ; i++)
+		for (j = 0 ; j < split_factor ; j++)
+			split_pages[i * split_factor + j] =
+					pages[i] + j * page_size;
+
+	rc = _export_dmabuf_common(ctx, hl_dmabuf, split_pages, npages,
+					page_size, flags, dmabuf_fd);
+
+	kfree(split_pages);
+
+	return rc;
+}
+
+/**
+ * export_dmabuf_from_addr() - export a dma-buf object for the given memory
+ *                             address and size.
+ * @ctx: pointer to the context structure.
+ * @device_addr:  device memory physical address.
+ * @size: size of device memory.
+ * @flags: DMA-BUF file/FD flags.
+ * @dmabuf_fd: pointer to result FD that represents the dma-buf object.
+ *
+ * Create and export a dma-buf object for an existing memory allocation inside
+ * the device memory, and return a FD which is associated with the dma-buf
+ * object.
+ *
+ * Return: 0 on success, non-zero for failure.
+ */
+static int export_dmabuf_from_addr(struct hl_ctx *ctx, u64 device_addr,
+					u64 size, int flags, int *dmabuf_fd)
+{
+	struct hl_device *hdev = ctx->hdev;
+	struct asic_fixed_properties *prop = &hdev->asic_prop;
+	struct hl_dmabuf_wrapper *hl_dmabuf;
+	int rc;
+
+	dev_dbg(hdev->dev, "exporting dma-buf for addr 0x%llx, size 0x%llx\n",
+			device_addr, size);
+
+	if (!IS_ALIGNED(device_addr, DMA_BUF_MEM_ADDR_ALIGNMENT)) {
+		dev_err(hdev->dev,
+			"address of exported device memory should be aligned to 0x%x, address 0x%llx\n",
+			DMA_BUF_MEM_ADDR_ALIGNMENT, device_addr);
+		return -EINVAL;
+	}
+
+	if (!size) {
+		dev_err(hdev->dev,
+			"size of exported device memory should be greater than 0\n");
+		return -EINVAL;
+	}
+
+	if (!IS_ALIGNED(size, DMA_BUF_MEM_SIZE_ALIGNMENT)) {
+		dev_err(hdev->dev,
+			"size of exported device memory should be aligned to 0x%x, size 0x%llx\n",
+			DMA_BUF_MEM_SIZE_ALIGNMENT, device_addr);
+		return -EINVAL;
+	}
+
+	if (device_addr < prop->dram_user_base_address ||
+			device_addr + size > prop->dram_end_address) {
+		dev_err(hdev->dev,
+			"DRAM memory range is outside of DRAM boundaries, address 0x%llx, size 0x%llx\n",
+			device_addr, size);
+		return -EINVAL;
+	}
+
+	hl_dmabuf = kzalloc(sizeof(*hl_dmabuf), GFP_KERNEL);
+	if (!hl_dmabuf)
+		return -ENOMEM;
+
+	hl_dmabuf->handle = device_addr;
+	hl_dmabuf->total_size = size;
+
+	rc = export_dmabuf_common(ctx, hl_dmabuf, &device_addr, 1, size, flags,
+					dmabuf_fd);
+	if (rc)
+		goto err_free_dmabuf_wrapper;
+
+	return 0;
+
+err_free_dmabuf_wrapper:
+	kfree(hl_dmabuf);
+	return rc;
+}
+
+/**
+ * export_dmabuf_from_handle() - export a dma-buf object for the given memory
+ *                               handle.
+ * @ctx: pointer to the context structure.
+ * @handle: device memory allocation handle.
+ * @flags: DMA-BUF file/FD flags.
+ * @dmabuf_fd: pointer to result FD that represents the dma-buf object.
+ *
+ * Create and export a dma-buf object for an existing memory allocation inside
+ * the device memory, and return a FD which is associated with the dma-buf
+ * object.
+ *
+ * Return: 0 on success, non-zero for failure.
+ */
+static int export_dmabuf_from_handle(struct hl_ctx *ctx, u64 handle, int flags,
+					int *dmabuf_fd)
+{
+	struct hl_device *hdev = ctx->hdev;
+	struct hl_vm_phys_pg_pack *phys_pg_pack;
+	struct hl_dmabuf_wrapper *hl_dmabuf;
+	struct hl_vm *vm = &hdev->vm;
+	enum vm_type_t *vm_type;
+	u32 idr_handle;
+	int rc;
+
+	dev_dbg(hdev->dev, "exporting dma-buf for handle 0x%llx\n", handle);
+
+	idr_handle = lower_32_bits(handle);
+
+	spin_lock(&vm->idr_lock);
+
+	phys_pg_pack = idr_find(&vm->phys_pg_pack_handles, idr_handle);
+	if (!phys_pg_pack) {
+		spin_unlock(&vm->idr_lock);
+		dev_err(hdev->dev, "no match for handle 0x%x\n", idr_handle);
+		return -EINVAL;
+	}
+
+	/* increment now to avoid freeing device memory while exporting */
+	atomic_inc(&phys_pg_pack->exporting_cnt);
+
+	spin_unlock(&vm->idr_lock);
+
+	vm_type = (enum vm_type_t *) phys_pg_pack;
+	if (*vm_type != VM_TYPE_PHYS_PACK) {
+		dev_err(hdev->dev, "handle 0x%llx is not for DRAM memory\n",
+				handle);
+		rc = -EINVAL;
+		goto err_dec_exporting_cnt;
+	}
+
+	hl_dmabuf = kzalloc(sizeof(*hl_dmabuf), GFP_KERNEL);
+	if (!hl_dmabuf) {
+		rc = -ENOMEM;
+		goto err_dec_exporting_cnt;
+	}
+
+	hl_dmabuf->phys_pg_pack = phys_pg_pack;
+	hl_dmabuf->handle = handle;
+	hl_dmabuf->total_size = phys_pg_pack->total_size;
+
+	rc = export_dmabuf_common(ctx, hl_dmabuf, phys_pg_pack->pages,
+				phys_pg_pack->npages, phys_pg_pack->page_size,
+				flags, dmabuf_fd);
+	if (rc)
+		goto err_free_dmabuf_wrapper;
+
+	return 0;
+
+err_free_dmabuf_wrapper:
+	kfree(hl_dmabuf);
+err_dec_exporting_cnt:
+	atomic_dec(&phys_pg_pack->exporting_cnt);
+	return rc;
+}
+
 static int mem_ioctl_no_mmu(struct hl_fpriv *hpriv, union hl_mem_args *args)
 {
 	struct hl_device *hdev = hpriv->hdev;
 	struct hl_ctx *ctx = hpriv->ctx;
 	u64 block_handle, device_addr = 0;
 	u32 handle = 0, block_size;
-	int rc;
+	int rc, dmabuf_fd = -EBADF;
 
 	switch (args->in.op) {
 	case HL_MEM_OP_ALLOC:
@@ -1471,6 +1866,16 @@ static int mem_ioctl_no_mmu(struct hl_fpriv *hpriv, union hl_mem_args *args)
 		args->out.block_size = block_size;
 		break;
 
+	case HL_MEM_OP_EXPORT_DMABUF_FD:
+		rc = export_dmabuf_from_addr(ctx,
+				args->in.export_dmabuf_fd.handle,
+				args->in.export_dmabuf_fd.mem_size,
+				args->in.flags,
+				&dmabuf_fd);
+		memset(args, 0, sizeof(*args));
+		args->out.fd = dmabuf_fd;
+		break;
+
 	default:
 		dev_err(hdev->dev, "Unknown opcode for memory IOCTL\n");
 		rc = -ENOTTY;
@@ -1489,7 +1894,7 @@ int hl_mem_ioctl(struct hl_fpriv *hpriv, void *data)
 	struct hl_ctx *ctx = hpriv->ctx;
 	u64 block_handle, device_addr = 0;
 	u32 handle = 0, block_size;
-	int rc;
+	int rc, dmabuf_fd = -EBADF;
 
 	if (!hl_device_operational(hdev, &status)) {
 		dev_warn_ratelimited(hdev->dev,
@@ -1580,6 +1985,22 @@ int hl_mem_ioctl(struct hl_fpriv *hpriv, void *data)
 		args->out.block_size = block_size;
 		break;
 
+	case HL_MEM_OP_EXPORT_DMABUF_FD:
+		if (hdev->asic_prop.dram_supports_virtual_memory)
+			rc = export_dmabuf_from_handle(ctx,
+					args->in.export_dmabuf_fd.handle,
+					args->in.flags,
+					&dmabuf_fd);
+		else
+			rc = export_dmabuf_from_addr(ctx,
+					args->in.export_dmabuf_fd.handle,
+					args->in.export_dmabuf_fd.mem_size,
+					args->in.flags,
+					&dmabuf_fd);
+		memset(args, 0, sizeof(*args));
+		args->out.fd = dmabuf_fd;
+		break;
+
 	default:
 		dev_err(hdev->dev, "Unknown opcode for memory IOCTL\n");
 		rc = -ENOTTY;
diff --git a/drivers/misc/habanalabs/gaudi/gaudi.c b/drivers/misc/habanalabs/gaudi/gaudi.c
index a673e404f777..3a66e56d7cd5 100644
--- a/drivers/misc/habanalabs/gaudi/gaudi.c
+++ b/drivers/misc/habanalabs/gaudi/gaudi.c
@@ -685,6 +685,7 @@ static int gaudi_early_init(struct hl_device *hdev)
 	}
 
 	prop->dram_pci_bar_size = pci_resource_len(pdev, HBM_BAR_ID);
+	hdev->dram_pci_bar_start = pci_resource_start(pdev, HBM_BAR_ID);
 
 	/* If FW security is enabled at this point it means no access to ELBI */
 	if (hdev->asic_prop.fw_security_enabled) {
diff --git a/drivers/misc/habanalabs/goya/goya.c b/drivers/misc/habanalabs/goya/goya.c
index 5a837c0b4d76..ad2c6f788030 100644
--- a/drivers/misc/habanalabs/goya/goya.c
+++ b/drivers/misc/habanalabs/goya/goya.c
@@ -617,6 +617,7 @@ static int goya_early_init(struct hl_device *hdev)
 	}
 
 	prop->dram_pci_bar_size = pci_resource_len(pdev, DDR_BAR_ID);
+	hdev->dram_pci_bar_start = pci_resource_start(pdev, DDR_BAR_ID);
 
 	/* If FW security is enabled at this point it means no access to ELBI */
 	if (hdev->asic_prop.fw_security_enabled) {
-- 
2.25.1