[PATCH 06/25] drm/amdgpu: Add KFD eviction fence
Felix Kuehling
felix.kuehling at amd.com
Sun Jan 28 23:42:02 UTC 2018
On 2018-01-27 04:16 AM, Christian König wrote:
> Am 27.01.2018 um 02:09 schrieb Felix Kuehling:
[snip]
>> +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.
I agree. But enable_signaling may be too early to drop the reference.
amd_kfd_fence_check_mm could still be called later from
amdgpu_ttm_bo_eviction_valuable, as long as the fence hasn't signaled yet.
The safe place is problably in amd_kfd_fence_release.
>
>> + 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?
This only gets called from fence_release below. I think this is to avoid
needlessly scheduling an eviction/restore cycle when an eviction fence
gets destroyed that hasn't been triggered before, probably during
process termination.
Harish, do you remember any other reason for this?
>
>> + 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.
Yeah, makes sense.
Regards,
Felix
>
> 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,
>
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