Am 27.01.2018 um 02:09 schrieb Felix Kuehling:
> This fence is used by KFD to keep memory resident while user mode
> queues are enabled. Trying to evict memory will trigger the
> enable_signaling callback, which starts a KFD eviction, which
> involves preempting user mode queues before signaling the fence.
> There is one such fence per process.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/Makefile | 1 +
> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 15 ++
> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 196 +++++++++++++++++++++++
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h | 5 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 18 ++-
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 18 +++
> drivers/gpu/drm/amd/include/kgd_kfd_interface.h | 6 +
> 7 files changed, 256 insertions(+), 3 deletions(-)
> create mode 100644 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/Makefile b/drivers/gpu/drm/amd/amdgpu/Makefile
> index d6e5b72..43dc3f9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/Makefile
> +++ b/drivers/gpu/drm/amd/amdgpu/Makefile
> @@ -130,6 +130,7 @@ amdgpu-y += \
> # add amdkfd interfaces
> amdgpu-y += \
> amdgpu_amdkfd.o \
> + amdgpu_amdkfd_fence.o \
> amdgpu_amdkfd_gfx_v8.o
>
> # add cgs
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> index 2a519f9..8d92f5c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> @@ -29,6 +29,8 @@
> #include <linux/mmu_context.h>
> #include <kgd_kfd_interface.h>
>
> +extern const struct kgd2kfd_calls *kgd2kfd;
> +
> struct amdgpu_device;
>
> struct kgd_mem {
> @@ -37,6 +39,19 @@ struct kgd_mem {
> void *cpu_ptr;
> };
>
> +/* KFD Memory Eviction */
> +struct amdgpu_amdkfd_fence {
> + struct dma_fence base;
> + void *mm;
> + spinlock_t lock;
> + char timeline_name[TASK_COMM_LEN];
> +};
> +
> +struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context,
> + void *mm);
> +bool amd_kfd_fence_check_mm(struct dma_fence *f, void *mm);
> +struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f);
> +
> int amdgpu_amdkfd_init(void);
> void amdgpu_amdkfd_fini(void);
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> new file mode 100644
> index 0000000..252e44e
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> @@ -0,0 +1,196 @@
> +/*
> + * Copyright 2016-2018 Advanced Micro Devices, Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#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 "amdgpu_amdkfd.h"
> +
> +const struct dma_fence_ops amd_kfd_fence_ops;
> +static atomic_t fence_seq = ATOMIC_INIT(0);
> +
> +static int amd_kfd_fence_signal(struct dma_fence *f);
> +
> +/* 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_bo_driver->eviction_valuable().
> + *
> + * ttm_bo_driver->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_bo_driver->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,
> + void *mm)
> +{
> + struct amdgpu_amdkfd_fence *fence = NULL;
> +
> + fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> + if (fence == NULL)
> + return NULL;
> +
> + /* mm_struct mm is used as void pointer to identify the parent
> + * KFD process. Don't dereference it. Fence and any threads using
> + * mm is guranteed to be released before process termination.
> + */
> + fence->mm = mm;
That won't work. Fences can live much longer than any process who
created them.
I've already found a fence in a BO still living hours after the process
was killed and the pid long recycled.
I suggest to make fence->mm a real mm_struct pointer with reference
counting and then set it to NULL and drop the reference in
enable_signaling.
> + get_task_comm(fence->timeline_name, current);
> + spin_lock_init(&fence->lock);
> +
> + dma_fence_init(&fence->base, &amd_kfd_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 (fence && f->ops == &amd_kfd_fence_ops)
> + return fence;
> +
> + return NULL;
> +}
> +
> +static const char *amd_kfd_fence_get_driver_name(struct dma_fence *f)
> +{
> + return "amdgpu_amdkfd_fence";
> +}
> +
> +static const char *amd_kfd_fence_get_timeline_name(struct dma_fence *f)
> +{
> + struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
> +
> + return fence->timeline_name;
> +}
> +
> +/**
> + * amd_kfd_fence_enable_signaling - This gets called when TTM wants to evict
> + * a KFD BO and schedules a job to move the BO.
> + * If fence is already signaled return true.
> + * If fence is not signaled schedule a evict KFD process work item.
> + */
> +static bool amd_kfd_fence_enable_signaling(struct dma_fence *f)
> +{
> + struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
> +
> + if (!fence)
> + return false;
> +
> + if (dma_fence_is_signaled(f))
> + return true;
> +
> + if (!kgd2kfd->schedule_evict_and_restore_process(
> + (struct mm_struct *)fence->mm, f))
> + return true;
> +
> + return false;
> +}
> +
> +static int amd_kfd_fence_signal(struct dma_fence *f)
> +{
> + unsigned long flags;
> + int ret;
> +
> + spin_lock_irqsave(f->lock, flags);
> + /* Set enabled bit so cb will called */
> + set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &f->flags);
Mhm, why is that necessary?
> + ret = dma_fence_signal_locked(f);
> + spin_unlock_irqrestore(f->lock, flags);
> +
> + return ret;
> +}
> +
> +/**
> + * amd_kfd_fence_release - callback that fence can be freed
> + *
> + * @fence: fence
> + *
> + * This function is called when the reference count becomes zero.
> + * It just RCU schedules freeing up the fence.
> + */
> +static void amd_kfd_fence_release(struct dma_fence *f)
> +{
> + struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
> + /* Unconditionally signal the fence. The process is getting
> + * terminated.
> + */
> + if (WARN_ON(!fence))
> + return; /* Not an amdgpu_amdkfd_fence */
> +
> + amd_kfd_fence_signal(f);
> + kfree_rcu(f, rcu);
> +}
> +
> +/**
> + * amd_kfd_fence_check_mm - Check if @mm is same as that of the fence @f
> + * if same return TRUE else return FALSE.
> + *
> + * @f: [IN] fence
> + * @mm: [IN] mm that needs to be verified
> + */
> +bool amd_kfd_fence_check_mm(struct dma_fence *f, void *mm)
> +{
> + struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
> +
> + if (!fence)
> + return false;
> + else if (fence->mm == mm)
> + return true;
> +
> + return false;
> +}
> +
> +const struct dma_fence_ops amd_kfd_fence_ops = {
> + .get_driver_name = amd_kfd_fence_get_driver_name,
> + .get_timeline_name = amd_kfd_fence_get_timeline_name,
> + .enable_signaling = amd_kfd_fence_enable_signaling,
> + .signaled = NULL,
> + .wait = dma_fence_default_wait,
> + .release = amd_kfd_fence_release,
> +};
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> index 65d5a4e..ca00dd2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> @@ -36,8 +36,9 @@
> #define AMDGPU_MAX_UVD_ENC_RINGS 2
>
> /* some special values for the owner field */
> -#define AMDGPU_FENCE_OWNER_UNDEFINED ((void*)0ul)
> -#define AMDGPU_FENCE_OWNER_VM ((void*)1ul)
> +#define AMDGPU_FENCE_OWNER_UNDEFINED ((void *)0ul)
> +#define AMDGPU_FENCE_OWNER_VM ((void *)1ul)
> +#define AMDGPU_FENCE_OWNER_KFD ((void *)2ul)
>
> #define AMDGPU_FENCE_FLAG_64BIT (1 << 0)
> #define AMDGPU_FENCE_FLAG_INT (1 << 1)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
> index df65c66..0cb31d9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
> @@ -31,6 +31,7 @@
> #include <drm/drmP.h>
> #include "amdgpu.h"
> #include "amdgpu_trace.h"
> +#include "amdgpu_amdkfd.h"
>
> struct amdgpu_sync_entry {
> struct hlist_node node;
> @@ -86,10 +87,18 @@ static bool amdgpu_sync_same_dev(struct amdgpu_device *adev,
> static void *amdgpu_sync_get_owner(struct dma_fence *f)
> {
> struct drm_sched_fence *s_fence = to_drm_sched_fence(f);
> + struct amdgpu_amdkfd_fence *kfd_fence;
> +
> + if (!f)
> + return AMDGPU_FENCE_OWNER_UNDEFINED;
When you add the extra NULL check here then please move the
to_drm_sched_fence() after it as well.
Christian.
>
> if (s_fence)
> return s_fence->owner;
>
> + kfd_fence = to_amdgpu_amdkfd_fence(f);
> + if (kfd_fence)
> + return AMDGPU_FENCE_OWNER_KFD;
> +
> return AMDGPU_FENCE_OWNER_UNDEFINED;
> }
>
> @@ -204,11 +213,18 @@ int amdgpu_sync_resv(struct amdgpu_device *adev,
> for (i = 0; i < flist->shared_count; ++i) {
> f = rcu_dereference_protected(flist->shared[i],
> reservation_object_held(resv));
> + /* We only want to trigger KFD eviction fences on
> + * evict or move jobs. Skip KFD fences otherwise.
> + */
> + fence_owner = amdgpu_sync_get_owner(f);
> + if (fence_owner == AMDGPU_FENCE_OWNER_KFD &&
> + owner != AMDGPU_FENCE_OWNER_UNDEFINED)
> + continue;
> +
> if (amdgpu_sync_same_dev(adev, f)) {
> /* VM updates are only interesting
> * for other VM updates and moves.
> */
> - fence_owner = amdgpu_sync_get_owner(f);
> if ((owner != AMDGPU_FENCE_OWNER_UNDEFINED) &&
> (fence_owner != AMDGPU_FENCE_OWNER_UNDEFINED) &&
> ((owner == AMDGPU_FENCE_OWNER_VM) !=
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index e4bb435..c3f33d3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -46,6 +46,7 @@
> #include "amdgpu.h"
> #include "amdgpu_object.h"
> #include "amdgpu_trace.h"
> +#include "amdgpu_amdkfd.h"
> #include "bif/bif_4_1_d.h"
>
> #define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT)
> @@ -1170,6 +1171,23 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
> {
> unsigned long num_pages = bo->mem.num_pages;
> struct drm_mm_node *node = bo->mem.mm_node;
> + struct reservation_object_list *flist;
> + struct dma_fence *f;
> + int i;
> +
> + /* If bo is a KFD BO, check if the bo belongs to the current process.
> + * If true, then return false as any KFD process needs all its BOs to
> + * be resident to run successfully
> + */
> + flist = reservation_object_get_list(bo->resv);
> + if (flist) {
> + for (i = 0; i < flist->shared_count; ++i) {
> + f = rcu_dereference_protected(flist->shared[i],
> + reservation_object_held(bo->resv));
> + if (amd_kfd_fence_check_mm(f, current->mm))
> + return false;
> + }
> + }
>
> switch (bo->mem.mem_type) {
> case TTM_PL_TT:
> diff --git a/drivers/gpu/drm/amd/include/kgd_kfd_interface.h b/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
> index 94eab54..9e35249 100644
> --- a/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
> +++ b/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
> @@ -30,6 +30,7 @@
>
> #include <linux/types.h>
> #include <linux/bitmap.h>
> +#include <linux/dma-fence.h>
>
> struct pci_dev;
>
> @@ -286,6 +287,9 @@ struct kfd2kgd_calls {
> *
> * @resume: Notifies amdkfd about a resume action done to a kgd device
> *
> + * @schedule_evict_and_restore_process: Schedules work queue that will prepare
> + * for safe eviction of KFD BOs that belong to the specified process.
> + *
> * This structure contains function callback pointers so the kgd driver
> * will notify to the amdkfd about certain status changes.
> *
> @@ -300,6 +304,8 @@ struct kgd2kfd_calls {
> void (*interrupt)(struct kfd_dev *kfd, const void *ih_ring_entry);
> void (*suspend)(struct kfd_dev *kfd);
> int (*resume)(struct kfd_dev *kfd);
> + int (*schedule_evict_and_restore_process)(struct mm_struct *mm,
> + struct dma_fence *fence);
> };
>
> int kgd2kfd_init(unsigned interface_version,
