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

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
Extension
.c
Size
6170 bytes
Lines
195
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/dma-fence.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/stacktrace.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include "amdgpu_amdkfd.h"
#include "kfd_svm.h"

static const struct dma_fence_ops amdkfd_fence_ops;
static atomic_t fence_seq = ATOMIC_INIT(0);

/* Eviction Fence
 * Fence helper functions to deal with KFD memory eviction.
 * Big Idea - Since KFD submissions are done by user queues, a BO cannot be
 *  evicted unless all the user queues for that process are evicted.
 *
 * All the BOs in a process share an eviction fence. When process X wants
 * to map VRAM memory but TTM can't find enough space, TTM will attempt to
 * evict BOs from its LRU list. TTM checks if the BO is valuable to evict
 * by calling ttm_device_funcs->eviction_valuable().
 *
 * ttm_device_funcs->eviction_valuable() - will return false if the BO belongs
 *  to process X. Otherwise, it will return true to indicate BO can be
 *  evicted by TTM.
 *
 * If ttm_device_funcs->eviction_valuable returns true, then TTM will continue
 * the evcition process for that BO by calling ttm_bo_evict --> amdgpu_bo_move
 * --> amdgpu_copy_buffer(). This sets up job in GPU scheduler.
 *
 * GPU Scheduler (amd_sched_main) - sets up a cb (fence_add_callback) to
 *  nofity when the BO is free to move. fence_add_callback --> enable_signaling
 *  --> amdgpu_amdkfd_fence.enable_signaling
 *
 * amdgpu_amdkfd_fence.enable_signaling - Start a work item that will quiesce
 * user queues and signal fence. The work item will also start another delayed
 * work item to restore BOs
 */

struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context,
				struct mm_struct *mm,
				struct svm_range_bo *svm_bo,
				u16 context_id)
{
	struct amdgpu_amdkfd_fence *fence;

	fence = kzalloc_obj(*fence);
	if (fence == NULL)
		return NULL;

	/* This reference gets released in amdkfd_fence_release */
	mmgrab(mm);
	fence->mm = mm;
	get_task_comm(fence->timeline_name, current);
	spin_lock_init(&fence->lock);
	fence->svm_bo = svm_bo;
	fence->context_id = context_id;
	dma_fence_init(&fence->base, &amdkfd_fence_ops, &fence->lock,
		   context, atomic_inc_return(&fence_seq));

	return fence;
}

struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f)
{
	struct amdgpu_amdkfd_fence *fence;

	if (!f)
		return NULL;

	fence = container_of(f, struct amdgpu_amdkfd_fence, base);
	if (f->ops == &amdkfd_fence_ops)
		return fence;

	return NULL;
}

static const char *amdkfd_fence_get_driver_name(struct dma_fence *f)
{
	return "amdgpu_amdkfd_fence";
}

static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f)
{
	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);

	return fence ? fence->timeline_name : NULL;
}

Annotation

Implementation Notes