[PATCH 28/35] drm/amdkfd: add svm_bo eviction mechanism support
Felix Kuehling
Felix.Kuehling at amd.com
Thu Jan 7 03:01:20 UTC 2021
From: Alex Sierra <alex.sierra at amd.com>
svm_bo eviction mechanism is different from regular BOs.
Every SVM_BO created contains one eviction fence and one
worker item for eviction process.
SVM_BOs can be attached to one or more pranges.
For SVM_BO eviction mechanism, TTM will start to call
enable_signal callback for every SVM_BO until VRAM space
is available.
Here, all the ttm_evict calls are synchronous, this guarantees
that each eviction has completed and the fence has signaled before
it returns.
Signed-off-by: Alex Sierra <alex.sierra at amd.com>
Signed-off-by: Philip Yang <Philip.Yang at amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 197 ++++++++++++++++++++-------
drivers/gpu/drm/amd/amdkfd/kfd_svm.h | 13 +-
2 files changed, 160 insertions(+), 50 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 7346255f7c27..63b745a06740 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -34,6 +34,7 @@
#define AMDGPU_SVM_RANGE_RESTORE_DELAY_MS 1
+static void svm_range_evict_svm_bo_worker(struct work_struct *work);
/**
* svm_range_unlink - unlink svm_range from lists and interval tree
* @prange: svm range structure to be removed
@@ -260,7 +261,15 @@ static void svm_range_bo_release(struct kref *kref)
list_del_init(&prange->svm_bo_list);
}
spin_unlock(&svm_bo->list_lock);
-
+ if (!dma_fence_is_signaled(&svm_bo->eviction_fence->base)) {
+ /* We're not in the eviction worker.
+ * Signal the fence and synchronize with any
+ * pending eviction work.
+ */
+ dma_fence_signal(&svm_bo->eviction_fence->base);
+ cancel_work_sync(&svm_bo->eviction_work);
+ }
+ dma_fence_put(&svm_bo->eviction_fence->base);
amdgpu_bo_unref(&svm_bo->bo);
kfree(svm_bo);
}
@@ -273,6 +282,62 @@ static void svm_range_bo_unref(struct svm_range_bo *svm_bo)
kref_put(&svm_bo->kref, svm_range_bo_release);
}
+static bool svm_range_validate_svm_bo(struct svm_range *prange)
+{
+ spin_lock(&prange->svm_bo_lock);
+ if (!prange->svm_bo) {
+ spin_unlock(&prange->svm_bo_lock);
+ return false;
+ }
+ if (prange->mm_nodes) {
+ /* We still have a reference, all is well */
+ spin_unlock(&prange->svm_bo_lock);
+ return true;
+ }
+ if (svm_bo_ref_unless_zero(prange->svm_bo)) {
+ if (READ_ONCE(prange->svm_bo->evicting)) {
+ struct dma_fence *f;
+ struct svm_range_bo *svm_bo;
+ /* The BO is getting evicted,
+ * we need to get a new one
+ */
+ spin_unlock(&prange->svm_bo_lock);
+ svm_bo = prange->svm_bo;
+ f = dma_fence_get(&svm_bo->eviction_fence->base);
+ svm_range_bo_unref(prange->svm_bo);
+ /* wait for the fence to avoid long spin-loop
+ * at list_empty_careful
+ */
+ dma_fence_wait(f, false);
+ dma_fence_put(f);
+ } else {
+ /* The BO was still around and we got
+ * a new reference to it
+ */
+ spin_unlock(&prange->svm_bo_lock);
+ pr_debug("reuse old bo svms 0x%p [0x%lx 0x%lx]\n",
+ prange->svms, prange->it_node.start,
+ prange->it_node.last);
+
+ prange->mm_nodes = prange->svm_bo->bo->tbo.mem.mm_node;
+ return true;
+ }
+
+ } else {
+ spin_unlock(&prange->svm_bo_lock);
+ }
+
+ /* We need a new svm_bo. Spin-loop to wait for concurrent
+ * svm_range_bo_release to finish removing this range from
+ * its range list. After this, it is safe to reuse the
+ * svm_bo pointer and svm_bo_list head.
+ */
+ while (!list_empty_careful(&prange->svm_bo_list))
+ ;
+
+ return false;
+}
+
static struct svm_range_bo *svm_range_bo_new(void)
{
struct svm_range_bo *svm_bo;
@@ -292,71 +357,54 @@ int
svm_range_vram_node_new(struct amdgpu_device *adev, struct svm_range *prange,
bool clear)
{
- struct amdkfd_process_info *process_info;
struct amdgpu_bo_param bp;
struct svm_range_bo *svm_bo;
struct amdgpu_bo *bo;
struct kfd_process *p;
+ struct mm_struct *mm;
int r;
- pr_debug("[0x%lx 0x%lx]\n", prange->it_node.start,
- prange->it_node.last);
- spin_lock(&prange->svm_bo_lock);
- if (prange->svm_bo) {
- if (prange->mm_nodes) {
- /* We still have a reference, all is well */
- spin_unlock(&prange->svm_bo_lock);
- return 0;
- }
- if (svm_bo_ref_unless_zero(prange->svm_bo)) {
- /* The BO was still around and we got
- * a new reference to it
- */
- spin_unlock(&prange->svm_bo_lock);
- pr_debug("reuse old bo [0x%lx 0x%lx]\n",
- prange->it_node.start, prange->it_node.last);
-
- prange->mm_nodes = prange->svm_bo->bo->tbo.mem.mm_node;
- return 0;
- }
-
- spin_unlock(&prange->svm_bo_lock);
-
- /* We need a new svm_bo. Spin-loop to wait for concurrent
- * svm_range_bo_release to finish removing this range from
- * its range list. After this, it is safe to reuse the
- * svm_bo pointer and svm_bo_list head.
- */
- while (!list_empty_careful(&prange->svm_bo_list))
- ;
+ p = container_of(prange->svms, struct kfd_process, svms);
+ pr_debug("pasid: %x svms 0x%p [0x%lx 0x%lx]\n", p->pasid, prange->svms,
+ prange->it_node.start, prange->it_node.last);
- } else {
- spin_unlock(&prange->svm_bo_lock);
- }
+ if (svm_range_validate_svm_bo(prange))
+ return 0;
svm_bo = svm_range_bo_new();
if (!svm_bo) {
pr_debug("failed to alloc svm bo\n");
return -ENOMEM;
}
-
+ mm = get_task_mm(p->lead_thread);
+ if (!mm) {
+ pr_debug("failed to get mm\n");
+ kfree(svm_bo);
+ return -ESRCH;
+ }
+ svm_bo->svms = prange->svms;
+ svm_bo->eviction_fence =
+ amdgpu_amdkfd_fence_create(dma_fence_context_alloc(1),
+ mm,
+ svm_bo);
+ mmput(mm);
+ INIT_WORK(&svm_bo->eviction_work, svm_range_evict_svm_bo_worker);
+ svm_bo->evicting = 0;
memset(&bp, 0, sizeof(bp));
bp.size = prange->npages * PAGE_SIZE;
bp.byte_align = PAGE_SIZE;
bp.domain = AMDGPU_GEM_DOMAIN_VRAM;
bp.flags = AMDGPU_GEM_CREATE_NO_CPU_ACCESS;
bp.flags |= clear ? AMDGPU_GEM_CREATE_VRAM_CLEARED : 0;
+ bp.flags |= AMDGPU_AMDKFD_CREATE_SVM_BO;
bp.type = ttm_bo_type_device;
bp.resv = NULL;
r = amdgpu_bo_create(adev, &bp, &bo);
if (r) {
pr_debug("failed %d to create bo\n", r);
- kfree(svm_bo);
- return r;
+ goto create_bo_failed;
}
-
- p = container_of(prange->svms, struct kfd_process, svms);
r = amdgpu_bo_reserve(bo, true);
if (r) {
pr_debug("failed %d to reserve bo\n", r);
@@ -369,8 +417,7 @@ svm_range_vram_node_new(struct amdgpu_device *adev, struct svm_range *prange,
amdgpu_bo_unreserve(bo);
goto reserve_bo_failed;
}
- process_info = p->kgd_process_info;
- amdgpu_bo_fence(bo, &process_info->eviction_fence->base, true);
+ amdgpu_bo_fence(bo, &svm_bo->eviction_fence->base, true);
amdgpu_bo_unreserve(bo);
@@ -380,14 +427,16 @@ svm_range_vram_node_new(struct amdgpu_device *adev, struct svm_range *prange,
prange->offset = 0;
spin_lock(&svm_bo->list_lock);
- list_add(&prange->svm_bo_list, &svm_bo->range_list);
+ list_add_rcu(&prange->svm_bo_list, &svm_bo->range_list);
spin_unlock(&svm_bo->list_lock);
return 0;
reserve_bo_failed:
- kfree(svm_bo);
amdgpu_bo_unref(&bo);
+create_bo_failed:
+ dma_fence_put(&svm_bo->eviction_fence->base);
+ kfree(svm_bo);
prange->mm_nodes = NULL;
return r;
@@ -621,7 +670,7 @@ svm_range_split_nodes(struct svm_range *new, struct svm_range *old,
new->mm_nodes = old->mm_nodes;
spin_lock(&new->svm_bo->list_lock);
- list_add(&new->svm_bo_list, &new->svm_bo->range_list);
+ list_add_rcu(&new->svm_bo_list, &new->svm_bo->range_list);
spin_unlock(&new->svm_bo->list_lock);
return 0;
@@ -1353,7 +1402,7 @@ struct svm_range *svm_range_clone(struct svm_range *old)
new->offset = old->offset;
new->svm_bo = svm_range_bo_ref(old->svm_bo);
spin_lock(&new->svm_bo->list_lock);
- list_add(&new->svm_bo_list, &new->svm_bo->range_list);
+ list_add_rcu(&new->svm_bo_list, &new->svm_bo->range_list);
spin_unlock(&new->svm_bo->list_lock);
}
new->flags = old->flags;
@@ -1964,6 +2013,62 @@ svm_range_trigger_migration(struct mm_struct *mm, struct svm_range *prange,
return r;
}
+int svm_range_schedule_evict_svm_bo(struct amdgpu_amdkfd_fence *fence)
+{
+ if (!fence)
+ return -EINVAL;
+
+ if (dma_fence_is_signaled(&fence->base))
+ return 0;
+
+ if (fence->svm_bo) {
+ WRITE_ONCE(fence->svm_bo->evicting, 1);
+ schedule_work(&fence->svm_bo->eviction_work);
+ }
+
+ return 0;
+}
+
+static void svm_range_evict_svm_bo_worker(struct work_struct *work)
+{
+ struct svm_range_bo *svm_bo;
+ struct svm_range *prange;
+ struct kfd_process *p;
+ struct mm_struct *mm;
+ int srcu_idx;
+
+ svm_bo = container_of(work, struct svm_range_bo, eviction_work);
+ if (!svm_bo_ref_unless_zero(svm_bo))
+ return; /* svm_bo was freed while eviction was pending */
+
+ /* svm_range_bo_release destroys this worker thread. So during
+ * the lifetime of this thread, kfd_process and mm will be valid.
+ */
+ p = container_of(svm_bo->svms, struct kfd_process, svms);
+ mm = p->mm;
+ if (!mm)
+ return;
+
+ mmap_read_lock(mm);
+ srcu_idx = srcu_read_lock(&svm_bo->svms->srcu);
+ list_for_each_entry_rcu(prange, &svm_bo->range_list, svm_bo_list) {
+ pr_debug("svms 0x%p [0x%lx 0x%lx]\n", prange->svms,
+ prange->it_node.start, prange->it_node.last);
+ mutex_lock(&prange->mutex);
+ svm_migrate_vram_to_ram(prange, svm_bo->eviction_fence->mm);
+ mutex_unlock(&prange->mutex);
+ }
+ srcu_read_unlock(&svm_bo->svms->srcu, srcu_idx);
+ mmap_read_unlock(mm);
+
+ dma_fence_signal(&svm_bo->eviction_fence->base);
+ /* This is the last reference to svm_bo, after svm_range_vram_node_free
+ * has been called in svm_migrate_vram_to_ram
+ */
+ WARN_ONCE(kref_read(&svm_bo->kref) != 1, "This was not the last reference\n");
+ svm_range_bo_unref(svm_bo);
+}
+
static int
svm_range_set_attr(struct kfd_process *p, uint64_t start, uint64_t size,
uint32_t nattr, struct kfd_ioctl_svm_attribute *attrs)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
index e546f36ef709..143573621956 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
@@ -33,10 +33,14 @@
#include "kfd_priv.h"
struct svm_range_bo {
- struct amdgpu_bo *bo;
- struct kref kref;
- struct list_head range_list; /* all svm ranges shared this bo */
- spinlock_t list_lock;
+ struct amdgpu_bo *bo;
+ struct kref kref;
+ struct list_head range_list; /* all svm ranges shared this bo */
+ spinlock_t list_lock;
+ struct amdgpu_amdkfd_fence *eviction_fence;
+ struct work_struct eviction_work;
+ struct svm_range_list *svms;
+ uint32_t evicting;
};
/**
* struct svm_range - shared virtual memory range
@@ -123,5 +127,6 @@ int svm_range_split_by_granularity(struct kfd_process *p, unsigned long addr,
struct list_head *list);
int svm_range_restore_pages(struct amdgpu_device *adev,
unsigned int pasid, uint64_t addr);
+int svm_range_schedule_evict_svm_bo(struct amdgpu_amdkfd_fence *fence);
#endif /* KFD_SVM_H_ */
--
2.29.2
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