drm/amdkfd: Use partial migrations in GPU page faults

This patch implements partial migration in gpu page fault according to migration
granularity(default 2MB) and not split svm range in cpu page fault handling.
A svm range may include pages from both system ram and vram of one gpu now.
These chagnes are expected to improve migration performance and reduce mmu
callback and TLB flush workloads.

Signed-off-by: Xiaogang Chen <xiaogang.chen@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 86 insertions, 64 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 6c25dab051d5..81d25a679427 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -442,10 +442,10 @@ svm_migrate_vma_to_vram(struct kfd_node *node, struct svm_range *prange,
 		goto out_free;
 	}
 	if (cpages != npages)
-		pr_debug("partial migration, 0x%lx/0x%llx pages migrated\n",
+		pr_debug("partial migration, 0x%lx/0x%llx pages collected\n",
 			 cpages, npages);
 	else
-		pr_debug("0x%lx pages migrated\n", cpages);
+		pr_debug("0x%lx pages collected\n", cpages);
 
 	r = svm_migrate_copy_to_vram(node, prange, &migrate, &mfence, scratch, ttm_res_offset);
 	migrate_vma_pages(&migrate);
@@ -479,6 +479,8 @@ out:
  * svm_migrate_ram_to_vram - migrate svm range from system to device
  * @prange: range structure
  * @best_loc: the device to migrate to
+ * @start_mgr: start page to migrate
+ * @last_mgr: last page to migrate
  * @mm: the process mm structure
  * @trigger: reason of migration
  *
@@ -489,6 +491,7 @@ out:
  */
 static int
 svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
+			unsigned long start_mgr, unsigned long last_mgr,
 			struct mm_struct *mm, uint32_t trigger)
 {
 	unsigned long addr, start, end;
@@ -498,23 +501,30 @@ svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
 	unsigned long cpages = 0;
 	long r = 0;
 
-	if (prange->actual_loc == best_loc) {
-		pr_debug("svms 0x%p [0x%lx 0x%lx] already on best_loc 0x%x\n",
-			 prange->svms, prange->start, prange->last, best_loc);
+	if (!best_loc) {
+		pr_debug("svms 0x%p [0x%lx 0x%lx] migrate to sys ram\n",
+			prange->svms, start_mgr, last_mgr);
 		return 0;
 	}
 
+	if (start_mgr < prange->start || last_mgr > prange->last) {
+		pr_debug("range [0x%lx 0x%lx] out prange [0x%lx 0x%lx]\n",
+				 start_mgr, last_mgr, prange->start, prange->last);
+		return -EFAULT;
+	}
+
 	node = svm_range_get_node_by_id(prange, best_loc);
 	if (!node) {
 		pr_debug("failed to get kfd node by id 0x%x\n", best_loc);
 		return -ENODEV;
 	}
 
-	pr_debug("svms 0x%p [0x%lx 0x%lx] to gpu 0x%x\n", prange->svms,
-		 prange->start, prange->last, best_loc);
+	pr_debug("svms 0x%p [0x%lx 0x%lx] in [0x%lx 0x%lx] to gpu 0x%x\n",
+		prange->svms, start_mgr, last_mgr, prange->start, prange->last,
+		best_loc);
 
-	start = prange->start << PAGE_SHIFT;
-	end = (prange->last + 1) << PAGE_SHIFT;
+	start = start_mgr << PAGE_SHIFT;
+	end = (last_mgr + 1) << PAGE_SHIFT;
 
 	r = svm_range_vram_node_new(node, prange, true);
 	if (r) {
@@ -544,8 +554,11 @@ svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
 
 	if (cpages) {
 		prange->actual_loc = best_loc;
-		svm_range_dma_unmap(prange);
-	} else {
+		prange->vram_pages = prange->vram_pages + cpages;
+	} else if (!prange->actual_loc) {
+		/* if no page migrated and all pages from prange are at
+		 * sys ram drop svm_bo got from svm_range_vram_node_new
+		 */
 		svm_range_vram_node_free(prange);
 	}
 
@@ -663,9 +676,8 @@ out_oom:
  * Context: Process context, caller hold mmap read lock, prange->migrate_mutex
  *
  * Return:
- *   0 - success with all pages migrated
  *   negative values - indicate error
- *   positive values - partial migration, number of pages not migrated
+ *   positive values or zero - number of pages got migrated
  */
 static long
 svm_migrate_vma_to_ram(struct kfd_node *node, struct svm_range *prange,
@@ -676,6 +688,7 @@ svm_migrate_vma_to_ram(struct kfd_node *node, struct svm_range *prange,
 	uint64_t npages = (end - start) >> PAGE_SHIFT;
 	unsigned long upages = npages;
 	unsigned long cpages = 0;
+	unsigned long mpages = 0;
 	struct amdgpu_device *adev = node->adev;
 	struct kfd_process_device *pdd;
 	struct dma_fence *mfence = NULL;
@@ -725,10 +738,10 @@ svm_migrate_vma_to_ram(struct kfd_node *node, struct svm_range *prange,
 		goto out_free;
 	}
 	if (cpages != npages)
-		pr_debug("partial migration, 0x%lx/0x%llx pages migrated\n",
+		pr_debug("partial migration, 0x%lx/0x%llx pages collected\n",
 			 cpages, npages);
 	else
-		pr_debug("0x%lx pages migrated\n", cpages);
+		pr_debug("0x%lx pages collected\n", cpages);
 
 	r = svm_migrate_copy_to_ram(adev, prange, &migrate, &mfence,
 				    scratch, npages);
@@ -751,17 +764,21 @@ out_free:
 	kvfree(buf);
 out:
 	if (!r && cpages) {
+		mpages = cpages - upages;
 		pdd = svm_range_get_pdd_by_node(prange, node);
 		if (pdd)
-			WRITE_ONCE(pdd->page_out, pdd->page_out + cpages);
+			WRITE_ONCE(pdd->page_out, pdd->page_out + mpages);
 	}
-	return r ? r : upages;
+
+	return r ? r : mpages;
 }
 
 /**
  * svm_migrate_vram_to_ram - migrate svm range from device to system
  * @prange: range structure
  * @mm: process mm, use current->mm if NULL
+ * @start_mgr: start page need be migrated to sys ram
+ * @last_mgr: last page need be migrated to sys ram
  * @trigger: reason of migration
  * @fault_page: is from vmf->page, svm_migrate_to_ram(), this is CPU page fault callback
  *
@@ -771,6 +788,7 @@ out:
  * 0 - OK, otherwise error code
  */
 int svm_migrate_vram_to_ram(struct svm_range *prange, struct mm_struct *mm,
+			    unsigned long start_mgr, unsigned long last_mgr,
 			    uint32_t trigger, struct page *fault_page)
 {
 	struct kfd_node *node;
@@ -778,26 +796,33 @@ int svm_migrate_vram_to_ram(struct svm_range *prange, struct mm_struct *mm,
 	unsigned long addr;
 	unsigned long start;
 	unsigned long end;
-	unsigned long upages = 0;
+	unsigned long mpages = 0;
 	long r = 0;
 
+	/* this pragne has no any vram page to migrate to sys ram */
 	if (!prange->actual_loc) {
 		pr_debug("[0x%lx 0x%lx] already migrated to ram\n",
 			 prange->start, prange->last);
 		return 0;
 	}
 
+	if (start_mgr < prange->start || last_mgr > prange->last) {
+		pr_debug("range [0x%lx 0x%lx] out prange [0x%lx 0x%lx]\n",
+				 start_mgr, last_mgr, prange->start, prange->last);
+		return -EFAULT;
+	}
+
 	node = svm_range_get_node_by_id(prange, prange->actual_loc);
 	if (!node) {
 		pr_debug("failed to get kfd node by id 0x%x\n", prange->actual_loc);
 		return -ENODEV;
 	}
 	pr_debug("svms 0x%p prange 0x%p [0x%lx 0x%lx] from gpu 0x%x to ram\n",
-		 prange->svms, prange, prange->start, prange->last,
+		 prange->svms, prange, start_mgr, last_mgr,
 		 prange->actual_loc);
 
-	start = prange->start << PAGE_SHIFT;
-	end = (prange->last + 1) << PAGE_SHIFT;
+	start = start_mgr << PAGE_SHIFT;
+	end = (last_mgr + 1) << PAGE_SHIFT;
 
 	for (addr = start; addr < end;) {
 		unsigned long next;
@@ -816,14 +841,21 @@ int svm_migrate_vram_to_ram(struct svm_range *prange, struct mm_struct *mm,
 			pr_debug("failed %ld to migrate prange %p\n", r, prange);
 			break;
 		} else {
-			upages += r;
+			mpages += r;
 		}
 		addr = next;
 	}
 
-	if (r >= 0 && !upages) {
-		svm_range_vram_node_free(prange);
-		prange->actual_loc = 0;
+	if (r >= 0) {
+		prange->vram_pages -= mpages;
+
+		/* prange does not have vram page set its actual_loc to system
+		 * and drop its svm_bo ref
+		 */
+		if (prange->vram_pages == 0 && prange->ttm_res) {
+			prange->actual_loc = 0;
+			svm_range_vram_node_free(prange);
+		}
 	}
 
 	return r < 0 ? r : 0;
@@ -833,17 +865,23 @@ int svm_migrate_vram_to_ram(struct svm_range *prange, struct mm_struct *mm,
  * svm_migrate_vram_to_vram - migrate svm range from device to device
  * @prange: range structure
  * @best_loc: the device to migrate to
+ * @start: start page need be migrated to sys ram
+ * @last: last page need be migrated to sys ram
  * @mm: process mm, use current->mm if NULL
  * @trigger: reason of migration
  *
  * Context: Process context, caller hold mmap read lock, svms lock, prange lock
  *
+ * migrate all vram pages in prange to sys ram, then migrate
+ * [start, last] pages from sys ram to gpu node best_loc.
+ *
  * Return:
  * 0 - OK, otherwise error code
  */
 static int
 svm_migrate_vram_to_vram(struct svm_range *prange, uint32_t best_loc,
-			 struct mm_struct *mm, uint32_t trigger)
+			unsigned long start, unsigned long last,
+			struct mm_struct *mm, uint32_t trigger)
 {
 	int r, retries = 3;
 
@@ -855,7 +893,8 @@ svm_migrate_vram_to_vram(struct svm_range *prange, uint32_t best_loc,
 	pr_debug("from gpu 0x%x to gpu 0x%x\n", prange->actual_loc, best_loc);
 
 	do {
-		r = svm_migrate_vram_to_ram(prange, mm, trigger, NULL);
+		r = svm_migrate_vram_to_ram(prange, mm, prange->start, prange->last,
+								trigger, NULL);
 		if (r)
 			return r;
 	} while (prange->actual_loc && --retries);
@@ -863,17 +902,21 @@ svm_migrate_vram_to_vram(struct svm_range *prange, uint32_t best_loc,
 	if (prange->actual_loc)
 		return -EDEADLK;
 
-	return svm_migrate_ram_to_vram(prange, best_loc, mm, trigger);
+	return svm_migrate_ram_to_vram(prange, best_loc, start, last, mm, trigger);
 }
 
 int
 svm_migrate_to_vram(struct svm_range *prange, uint32_t best_loc,
-		    struct mm_struct *mm, uint32_t trigger)
+			unsigned long start, unsigned long last,
+			struct mm_struct *mm, uint32_t trigger)
 {
-	if  (!prange->actual_loc)
-		return svm_migrate_ram_to_vram(prange, best_loc, mm, trigger);
+	if  (!prange->actual_loc || prange->actual_loc == best_loc)
+		return svm_migrate_ram_to_vram(prange, best_loc, start, last,
+						mm, trigger);
+
 	else
-		return svm_migrate_vram_to_vram(prange, best_loc, mm, trigger);
+		return svm_migrate_vram_to_vram(prange, best_loc, start, last,
+						mm, trigger);
 
 }
 
@@ -889,10 +932,9 @@ svm_migrate_to_vram(struct svm_range *prange, uint32_t best_loc,
  */
 static vm_fault_t svm_migrate_to_ram(struct vm_fault *vmf)
 {
+	unsigned long start, last, size;
 	unsigned long addr = vmf->address;
 	struct svm_range_bo *svm_bo;
-	enum svm_work_list_ops op;
-	struct svm_range *parent;
 	struct svm_range *prange;
 	struct kfd_process *p;
 	struct mm_struct *mm;
@@ -929,51 +971,31 @@ static vm_fault_t svm_migrate_to_ram(struct vm_fault *vmf)
 
 	mutex_lock(&p->svms.lock);
 
-	prange = svm_range_from_addr(&p->svms, addr, &parent);
+	prange = svm_range_from_addr(&p->svms, addr, NULL);
 	if (!prange) {
 		pr_debug("failed get range svms 0x%p addr 0x%lx\n", &p->svms, addr);
 		r = -EFAULT;
 		goto out_unlock_svms;
 	}
 
-	mutex_lock(&parent->migrate_mutex);
-	if (prange != parent)
-		mutex_lock_nested(&prange->migrate_mutex, 1);
+	mutex_lock(&prange->migrate_mutex);
 
 	if (!prange->actual_loc)
 		goto out_unlock_prange;
 
-	svm_range_lock(parent);
-	if (prange != parent)
-		mutex_lock_nested(&prange->lock, 1);
-	r = svm_range_split_by_granularity(p, mm, addr, parent, prange);
-	if (prange != parent)
-		mutex_unlock(&prange->lock);
-	svm_range_unlock(parent);
-	if (r) {
-		pr_debug("failed %d to split range by granularity\n", r);
-		goto out_unlock_prange;
-	}
+	/* Align migration range start and size to granularity size */
+	size = 1UL << prange->granularity;
+	start = max(ALIGN_DOWN(addr, size), prange->start);
+	last = min(ALIGN(addr + 1, size) - 1, prange->last);
 
-	r = svm_migrate_vram_to_ram(prange, vmf->vma->vm_mm,
-				    KFD_MIGRATE_TRIGGER_PAGEFAULT_CPU,
-				    vmf->page);
+	r = svm_migrate_vram_to_ram(prange, vmf->vma->vm_mm, start, last,
+						KFD_MIGRATE_TRIGGER_PAGEFAULT_CPU, vmf->page);
 	if (r)
 		pr_debug("failed %d migrate svms 0x%p range 0x%p [0x%lx 0x%lx]\n",
-			 r, prange->svms, prange, prange->start, prange->last);
-
-	/* xnack on, update mapping on GPUs with ACCESS_IN_PLACE */
-	if (p->xnack_enabled && parent == prange)
-		op = SVM_OP_UPDATE_RANGE_NOTIFIER_AND_MAP;
-	else
-		op = SVM_OP_UPDATE_RANGE_NOTIFIER;
-	svm_range_add_list_work(&p->svms, parent, mm, op);
-	schedule_deferred_list_work(&p->svms);
+			r, prange->svms, prange, start, last);
 
 out_unlock_prange:
-	if (prange != parent)
-		mutex_unlock(&prange->migrate_mutex);
-	mutex_unlock(&parent->migrate_mutex);
+	mutex_unlock(&prange->migrate_mutex);
 out_unlock_svms:
 	mutex_unlock(&p->svms.lock);
 out_unref_process: