libhsakmt: Implement dmabuf export for RDMA

Implement hsaKmtExportDMABufHandle, which can be used for a new
upstreamable RDMA solution. It exports a DMABuf handle for an arbitrary
virtual address along with the offset of the address within the
allocation. It also checks that the size of the intended export does
not exceed the allocation.

This uses the new AMDKFD_IOC_EXPORT_DMABUF, which requires KFD ioctl
API version 1.12.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Change-Id: Ie5fdb1f73ab3c7fa36c315ce326b1fb89eacc8b6

src/memory.c

@@ -318,6 +318,20 @@ HSAKMT_STATUS HSAKMTAPI hsaKmtRegisterGraphicsHandleToNodes(HSAuint64 GraphicsRe
 	return ret;
 }
 
+HSAKMT_STATUS HSAKMTAPI hsaKmtExportDMABufHandle(void *MemoryAddress,
+						 HSAuint64 MemorySizeInBytes,
+						 int *DMABufFd,
+						 HSAuint64 *Offset)
+{
+	CHECK_KFD_OPEN();
+	CHECK_KFD_MINOR_VERSION(12);
+
+	pr_debug("[%s] address %p\n", __func__, MemoryAddress);
+
+	return fmm_export_dma_buf_fd(MemoryAddress, MemorySizeInBytes,
+				     DMABufFd, Offset);
+}
+
 HSAKMT_STATUS HSAKMTAPI hsaKmtShareMemory(void *MemoryAddress,
 					  HSAuint64 SizeInBytes,
 					  HsaSharedMemoryHandle *SharedMemoryHandle)