drm/amdkfd: Export DMABufs from KFD using GEM handles

Create GEM handles for exporting DMABufs using GEM-Prime APIs. The GEM
handles are created in a drm_client_dev context to avoid exposing them
in user mode contexts through a DMABuf import.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c

@@ -142,6 +142,7 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 {
 	int i;
 	int last_valid_bit;
+	int ret;
 
 	amdgpu_amdkfd_gpuvm_init_mem_limits();
 
@@ -160,6 +161,12 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 			.enable_mes = adev->enable_mes,
 		};
 
+		ret = drm_client_init(&adev->ddev, &adev->kfd.client, "kfd", NULL);
+		if (ret) {
+			dev_err(adev->dev, "Failed to init DRM client: %d\n", ret);
+			return;
+		}
+
 		/* this is going to have a few of the MSBs set that we need to
 		 * clear
 		 */
@@ -198,6 +205,10 @@ void amdgpu_amdkfd_device_init(struct amdgpu_device *adev)
 
 		adev->kfd.init_complete = kgd2kfd_device_init(adev->kfd.dev,
 							&gpu_resources);
+		if (adev->kfd.init_complete)
+			drm_client_register(&adev->kfd.client);
+		else
+			drm_client_release(&adev->kfd.client);
 
 		amdgpu_amdkfd_total_mem_size += adev->gmc.real_vram_size;
 

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h

@@ -33,6 +33,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/memremap.h>
 #include <kgd_kfd_interface.h>
+#include <drm/drm_client.h>
 #include "amdgpu_sync.h"
 #include "amdgpu_vm.h"
 #include "amdgpu_xcp.h"
@@ -83,6 +84,7 @@ struct kgd_mem {
 
 	struct amdgpu_sync sync;
 
+	uint32_t gem_handle;
 	bool aql_queue;
 	bool is_imported;
 };
@@ -105,6 +107,9 @@ struct amdgpu_kfd_dev {
 
 	/* HMM page migration MEMORY_DEVICE_PRIVATE mapping */
 	struct dev_pagemap pgmap;
+
+	/* Client for KFD BO GEM handle allocations */
+	struct drm_client_dev client;
 };
 
 enum kgd_engine_type {

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

@@ -25,6 +25,7 @@
 #include <linux/pagemap.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/task.h>
+#include <linux/fdtable.h>
 #include <drm/ttm/ttm_tt.h>
 
 #include <drm/drm_exec.h>
@@ -806,13 +807,22 @@ kfd_mem_dmaunmap_attachment(struct kgd_mem *mem,
 static int kfd_mem_export_dmabuf(struct kgd_mem *mem)
 {
 	if (!mem->dmabuf) {
-		struct dma_buf *ret = amdgpu_gem_prime_export(
-			&mem->bo->tbo.base,
+		struct amdgpu_device *bo_adev;
+		struct dma_buf *dmabuf;
+		int r, fd;
+
+		bo_adev = amdgpu_ttm_adev(mem->bo->tbo.bdev);
+		r = drm_gem_prime_handle_to_fd(&bo_adev->ddev, bo_adev->kfd.client.file,
+					       mem->gem_handle,
 			mem->alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_WRITABLE ?
-				DRM_RDWR : 0);
-		if (IS_ERR(ret))
-			return PTR_ERR(ret);
-		mem->dmabuf = ret;
+					       DRM_RDWR : 0, &fd);
+		if (r)
+			return r;
+		dmabuf = dma_buf_get(fd);
+		close_fd(fd);
+		if (WARN_ON_ONCE(IS_ERR(dmabuf)))
+			return PTR_ERR(dmabuf);
+		mem->dmabuf = dmabuf;
 	}
 
 	return 0;
@@ -1778,6 +1788,9 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 		pr_debug("Failed to allow vma node access. ret %d\n", ret);
 		goto err_node_allow;
 	}
+	ret = drm_gem_handle_create(adev->kfd.client.file, gobj, &(*mem)->gem_handle);
+	if (ret)
+		goto err_gem_handle_create;
 	bo = gem_to_amdgpu_bo(gobj);
 	if (bo_type == ttm_bo_type_sg) {
 		bo->tbo.sg = sg;
@@ -1829,6 +1842,8 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 err_pin_bo:
 err_validate_bo:
 	remove_kgd_mem_from_kfd_bo_list(*mem, avm->process_info);
+	drm_gem_handle_delete(adev->kfd.client.file, (*mem)->gem_handle);
+err_gem_handle_create:
 	drm_vma_node_revoke(&gobj->vma_node, drm_priv);
 err_node_allow:
 	/* Don't unreserve system mem limit twice */
@@ -1941,8 +1956,12 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 
 	/* Free the BO*/
 	drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
-	if (mem->dmabuf)
+	if (!mem->is_imported)
+		drm_gem_handle_delete(adev->kfd.client.file, mem->gem_handle);
+	if (mem->dmabuf) {
 		dma_buf_put(mem->dmabuf);
+		mem->dmabuf = NULL;
+	}
 	mutex_destroy(&mem->lock);
 
 	/* If this releases the last reference, it will end up calling

drivers/gpu/drm/amd/amdkfd/kfd_chardev.c

@@ -1855,8 +1855,8 @@ static uint32_t get_process_num_bos(struct kfd_process *p)
 	return num_of_bos;
 }
 
-static int criu_get_prime_handle(struct kgd_mem *mem, int flags,
-				      u32 *shared_fd)
+static int criu_get_prime_handle(struct kgd_mem *mem,
+				 int flags, u32 *shared_fd)
 {
 	struct dma_buf *dmabuf;
 	int ret;