drm/xe: Use hmm_range_fault to populate user pages

This is an effort to unify hmmptr (aka system allocator)
and userptr code. hmm_range_fault is used to populate
a virtual address range for both hmmptr and userptr,
instead of hmmptr using hmm_range_fault and userptr
using get_user_pages_fast.

This also aligns with AMD gpu driver's behavior. In
long term, we plan to put some common helpers in this
area to drm layer so it can be re-used by different
vendors.

-v1
use the function with parameter to confirm whether lock is
acquired by the caller or needs to be acquired in hmm_range_fault.
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Oak Zeng <oak.zeng@intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412095237.1048599-3-himal.prasad.ghimiray@intel.com

drivers/gpu/drm/xe/xe_vm.c

@@ -39,6 +39,7 @@
 #include "xe_sync.h"
 #include "xe_trace.h"
 #include "xe_wa.h"
+#include "xe_hmm.h"
 
 static struct drm_gem_object *xe_vm_obj(struct xe_vm *vm)
 {
@@ -66,113 +67,14 @@ int xe_vma_userptr_check_repin(struct xe_userptr_vma *uvma)
 
 int xe_vma_userptr_pin_pages(struct xe_userptr_vma *uvma)
 {
-	struct xe_userptr *userptr = &uvma->userptr;
 	struct xe_vma *vma = &uvma->vma;
 	struct xe_vm *vm = xe_vma_vm(vma);
 	struct xe_device *xe = vm->xe;
-	const unsigned long num_pages = xe_vma_size(vma) >> PAGE_SHIFT;
-	struct page **pages;
-	bool in_kthread = !current->mm;
-	unsigned long notifier_seq;
-	int pinned, ret, i;
-	bool read_only = xe_vma_read_only(vma);
 
 	lockdep_assert_held(&vm->lock);
 	xe_assert(xe, xe_vma_is_userptr(vma));
-retry:
-	if (vma->gpuva.flags & XE_VMA_DESTROYED)
-		return 0;
-
-	notifier_seq = mmu_interval_read_begin(&userptr->notifier);
-	if (notifier_seq == userptr->notifier_seq)
-		return 0;
-
-	pages = kvmalloc_array(num_pages, sizeof(*pages), GFP_KERNEL);
-	if (!pages)
-		return -ENOMEM;
-
-	if (userptr->sg) {
-		dma_unmap_sgtable(xe->drm.dev,
-				  userptr->sg,
-				  read_only ? DMA_TO_DEVICE :
-				  DMA_BIDIRECTIONAL, 0);
-		sg_free_table(userptr->sg);
-		userptr->sg = NULL;
-	}
-
-	pinned = ret = 0;
-	if (in_kthread) {
-		if (!mmget_not_zero(userptr->notifier.mm)) {
-			ret = -EFAULT;
-			goto mm_closed;
-		}
-		kthread_use_mm(userptr->notifier.mm);
-	}
-
-	while (pinned < num_pages) {
-		ret = get_user_pages_fast(xe_vma_userptr(vma) +
-					  pinned * PAGE_SIZE,
-					  num_pages - pinned,
-					  read_only ? 0 : FOLL_WRITE,
-					  &pages[pinned]);
-		if (ret < 0)
-			break;
-
-		pinned += ret;
-		ret = 0;
-	}
-
-	if (in_kthread) {
-		kthread_unuse_mm(userptr->notifier.mm);
-		mmput(userptr->notifier.mm);
-	}
-mm_closed:
-	if (ret)
-		goto out;
-
-	ret = sg_alloc_table_from_pages_segment(&userptr->sgt, pages,
-						pinned, 0,
-						(u64)pinned << PAGE_SHIFT,
-						xe_sg_segment_size(xe->drm.dev),
-						GFP_KERNEL);
-	if (ret) {
-		userptr->sg = NULL;
-		goto out;
-	}
-	userptr->sg = &userptr->sgt;
-
-	ret = dma_map_sgtable(xe->drm.dev, userptr->sg,
-			      read_only ? DMA_TO_DEVICE :
-			      DMA_BIDIRECTIONAL,
-			      DMA_ATTR_SKIP_CPU_SYNC |
-			      DMA_ATTR_NO_KERNEL_MAPPING);
-	if (ret) {
-		sg_free_table(userptr->sg);
-		userptr->sg = NULL;
-		goto out;
-	}
-
-	for (i = 0; i < pinned; ++i) {
-		if (!read_only) {
-			lock_page(pages[i]);
-			set_page_dirty(pages[i]);
-			unlock_page(pages[i]);
-		}
 
-		mark_page_accessed(pages[i]);
-	}
-
-out:
-	release_pages(pages, pinned);
-	kvfree(pages);
-
-	if (!(ret < 0)) {
-		userptr->notifier_seq = notifier_seq;
-		if (xe_vma_userptr_check_repin(uvma) == -EAGAIN)
-			goto retry;
-	}
-
-	return ret < 0 ? ret : 0;
+	return xe_hmm_userptr_populate_range(uvma, false);
 }
 
 static bool preempt_fences_waiting(struct xe_vm *vm)
@@ -956,8 +858,6 @@ static struct xe_vma *xe_vma_create(struct xe_vm *vm,
 static void xe_vma_destroy_late(struct xe_vma *vma)
 {
 	struct xe_vm *vm = xe_vma_vm(vma);
-	struct xe_device *xe = vm->xe;
-	bool read_only = xe_vma_read_only(vma);
 
 	if (vma->ufence) {
 		xe_sync_ufence_put(vma->ufence);
@@ -965,16 +865,11 @@ static void xe_vma_destroy_late(struct xe_vma *vma)
 	}
 
 	if (xe_vma_is_userptr(vma)) {
-		struct xe_userptr *userptr = &to_userptr_vma(vma)->userptr;
+		struct xe_userptr_vma *uvma = to_userptr_vma(vma);
+		struct xe_userptr *userptr = &uvma->userptr;
 
-		if (userptr->sg) {
-			dma_unmap_sgtable(xe->drm.dev,
-					  userptr->sg,
-					  read_only ? DMA_TO_DEVICE :
-					  DMA_BIDIRECTIONAL, 0);
-			sg_free_table(userptr->sg);
-			userptr->sg = NULL;
-		}
+		if (userptr->sg)
+			xe_hmm_userptr_free_sg(uvma);
 
 		/*
 		 * Since userptr pages are not pinned, we can't remove