[PATCH 06/25] drm/amdgpu: Add KFD eviction fence

Oded Gabbay oded.gabbay at gmail.com
Sun Feb 11 12:42:07 UTC 2018


On Wed, Feb 7, 2018 at 3:32 AM, Felix Kuehling <Felix.Kuehling at amd.com> wrote:
> 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.
>
> v2:
> * Grab a reference to mm_struct
> * Dereference fence after NULL check
> * Simplify fence release, no need to signal without anyone waiting
> * Added signed-off-by Harish, who is the original author of this code
>
> Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan at amd.com>
> 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 | 179 +++++++++++++++++++++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h         |   5 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c         |  21 ++-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c          |  18 +++
>  drivers/gpu/drm/amd/include/kgd_kfd_interface.h  |   6 +
>  7 files changed, 241 insertions(+), 4 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..492c7af 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;
> +       struct mm_struct *mm;
> +       spinlock_t lock;
> +       char timeline_name[TASK_COMM_LEN];
> +};
> +
> +struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context,
> +                                                      struct mm_struct *mm);
> +bool amd_kfd_fence_check_mm(struct dma_fence *f, struct mm_struct *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..cf2f1e9
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> @@ -0,0 +1,179 @@
> +/*
> + * 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 <linux/sched/mm.h>
> +#include "amdgpu_amdkfd.h"
> +
> +const struct dma_fence_ops amd_kfd_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_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,
> +                                                      struct mm_struct *mm)
> +{
> +       struct amdgpu_amdkfd_fence *fence = NULL;
> +
> +       fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> +       if (fence == NULL)
> +               return NULL;
> +
> +       /* This reference gets released in amd_kfd_fence_release */
> +       mmgrab(mm);
> +       fence->mm = mm;
> +       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(fence->mm, f))
> +               return true;
> +
> +       return false;
> +}
> +
> +/**
> + * amd_kfd_fence_release - callback that fence can be freed
> + *
> + * @fence: fence
> + *
> + * This function is called when the reference count becomes zero.
> + * Drops the mm_struct reference and 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 */
> +
> +       mmdrop(fence->mm);
> +       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, struct mm_struct *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..b8d3b87 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;
> @@ -85,11 +86,20 @@ 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 drm_sched_fence *s_fence;
> +       struct amdgpu_amdkfd_fence *kfd_fence;
> +
> +       if (!f)
> +               return AMDGPU_FENCE_OWNER_UNDEFINED;
>
> +       s_fence = to_drm_sched_fence(f);
>         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 +214,18 @@ 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 94eab548..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,
> --
> 2.7.4
>

Hi Felix,
Do you object to me changing amd_kfd_ to amdkfd_ in the various
structures and functions ?
So far, we don't have anything with prefix of amd_kfd_ so I would like
to keep on consistency.

Other then that, this patch is:
Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>


Oded


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