diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 09d8119024db..6850bd04bcb9 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -400,6 +400,7 @@ kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 	mig.end = end;
 	mig.src = &src_pfn;
 	mig.dst = &dst_pfn;
+	mig.flags = MIGRATE_VMA_SELECT_SYSTEM;
 
 	/*
 	 * We come here with mmap_lock write lock held just for
@@ -577,7 +578,8 @@ kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start,
 	mig.end = end;
 	mig.src = &src_pfn;
 	mig.dst = &dst_pfn;
-	mig.src_owner = &kvmppc_uvmem_pgmap;
+	mig.pgmap_owner = &kvmppc_uvmem_pgmap;
+	mig.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 
 	mutex_lock(&kvm->arch.uvmem_lock);
 	/* The requested page is already paged-out, nothing to do */
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index cc9993837508..951bd51f4834 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -140,6 +140,7 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct nouveau_drm *drm,
 {
 	struct device *dev = drm->dev->dev;
 	struct page *dpage, *spage;
+	struct nouveau_svmm *svmm;
 
 	spage = migrate_pfn_to_page(args->src[0]);
 	if (!spage || !(args->src[0] & MIGRATE_PFN_MIGRATE))
@@ -154,14 +155,19 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct nouveau_drm *drm,
 	if (dma_mapping_error(dev, *dma_addr))
 		goto error_free_page;
 
+	svmm = spage->zone_device_data;
+	mutex_lock(&svmm->mutex);
+	nouveau_svmm_invalidate(svmm, args->start, args->end);
 	if (drm->dmem->migrate.copy_func(drm, 1, NOUVEAU_APER_HOST, *dma_addr,
 			NOUVEAU_APER_VRAM, nouveau_dmem_page_addr(spage)))
 		goto error_dma_unmap;
+	mutex_unlock(&svmm->mutex);
 
 	args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
 	return 0;
 
 error_dma_unmap:
+	mutex_unlock(&svmm->mutex);
 	dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
 error_free_page:
 	__free_page(dpage);
@@ -182,7 +188,8 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
 		.end		= vmf->address + PAGE_SIZE,
 		.src		= &src,
 		.dst		= &dst,
-		.src_owner	= drm->dev,
+		.pgmap_owner	= drm->dev,
+		.flags		= MIGRATE_VMA_SELECT_DEVICE_PRIVATE,
 	};
 
 	/*
@@ -530,7 +537,8 @@ nouveau_dmem_init(struct nouveau_drm *drm)
 }
 
 static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
-		unsigned long src, dma_addr_t *dma_addr, u64 *pfn)
+		struct nouveau_svmm *svmm, unsigned long src,
+		dma_addr_t *dma_addr, u64 *pfn)
 {
 	struct device *dev = drm->dev->dev;
 	struct page *dpage, *spage;
@@ -560,6 +568,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
 			goto out_free_page;
 	}
 
+	dpage->zone_device_data = svmm;
 	*pfn = NVIF_VMM_PFNMAP_V0_V | NVIF_VMM_PFNMAP_V0_VRAM |
 		((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT);
 	if (src & MIGRATE_PFN_WRITE)
@@ -583,8 +592,8 @@ static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
 	unsigned long addr = args->start, nr_dma = 0, i;
 
 	for (i = 0; addr < args->end; i++) {
-		args->dst[i] = nouveau_dmem_migrate_copy_one(drm, args->src[i],
-				dma_addrs + nr_dma, pfns + i);
+		args->dst[i] = nouveau_dmem_migrate_copy_one(drm, svmm,
+				args->src[i], dma_addrs + nr_dma, pfns + i);
 		if (!dma_mapping_error(drm->dev->dev, dma_addrs[nr_dma]))
 			nr_dma++;
 		addr += PAGE_SIZE;
@@ -615,6 +624,8 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
 	struct migrate_vma args = {
 		.vma		= vma,
 		.start		= start,
+		.pgmap_owner	= drm->dev,
+		.flags		= MIGRATE_VMA_SELECT_SYSTEM,
 	};
 	unsigned long i;
 	u64 *pfns;
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 6586d9d39874..03c515eaf10f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -93,17 +93,6 @@ nouveau_ivmm_find(struct nouveau_svm *svm, u64 inst)
 	return NULL;
 }
 
-struct nouveau_svmm {
-	struct mmu_notifier notifier;
-	struct nouveau_vmm *vmm;
-	struct {
-		unsigned long start;
-		unsigned long limit;
-	} unmanaged;
-
-	struct mutex mutex;
-};
-
 #define SVMM_DBG(s,f,a...)                                                     \
 	NV_DEBUG((s)->vmm->cli->drm, "svm-%p: "f"\n", (s), ##a)
 #define SVMM_ERR(s,f,a...)                                                     \
@@ -246,7 +235,7 @@ nouveau_svmm_join(struct nouveau_svmm *svmm, u64 inst)
 }
 
 /* Invalidate SVMM address-range on GPU. */
-static void
+void
 nouveau_svmm_invalidate(struct nouveau_svmm *svmm, u64 start, u64 limit)
 {
 	if (limit > start) {
@@ -279,6 +268,14 @@ nouveau_svmm_invalidate_range_start(struct mmu_notifier *mn,
 	if (unlikely(!svmm->vmm))
 		goto out;
 
+	/*
+	 * Ignore invalidation callbacks for device private pages since
+	 * the invalidation is handled as part of the migration process.
+	 */
+	if (update->event == MMU_NOTIFY_MIGRATE &&
+	    update->migrate_pgmap_owner == svmm->vmm->cli->drm->dev)
+		goto out;
+
 	if (limit > svmm->unmanaged.start && start < svmm->unmanaged.limit) {
 		if (start < svmm->unmanaged.start) {
 			nouveau_svmm_invalidate(svmm, start,
@@ -514,53 +511,68 @@ static const struct mmu_interval_notifier_ops nouveau_svm_mni_ops = {
 };
 
 static void nouveau_hmm_convert_pfn(struct nouveau_drm *drm,
-				    struct hmm_range *range, u64 *ioctl_addr)
+				    struct hmm_range *range,
+				    struct nouveau_pfnmap_args *args)
 {
-	unsigned long i, npages;
+	struct page *page;
 
 	/*
-	 * The ioctl_addr prepared here is passed through nvif_object_ioctl()
+	 * The address prepared here is passed through nvif_object_ioctl()
 	 * to an eventual DMA map in something like gp100_vmm_pgt_pfn()
 	 *
 	 * This is all just encoding the internal hmm representation into a
 	 * different nouveau internal representation.
 	 */
-	npages = (range->end - range->start) >> PAGE_SHIFT;
-	for (i = 0; i < npages; ++i) {
-		struct page *page;
-
-		if (!(range->hmm_pfns[i] & HMM_PFN_VALID)) {
-			ioctl_addr[i] = 0;
-			continue;
-		}
-
-		page = hmm_pfn_to_page(range->hmm_pfns[i]);
-		if (is_device_private_page(page))
-			ioctl_addr[i] = nouveau_dmem_page_addr(page) |
-					NVIF_VMM_PFNMAP_V0_V |
-					NVIF_VMM_PFNMAP_V0_VRAM;
-		else
-			ioctl_addr[i] = page_to_phys(page) |
-					NVIF_VMM_PFNMAP_V0_V |
-					NVIF_VMM_PFNMAP_V0_HOST;
-		if (range->hmm_pfns[i] & HMM_PFN_WRITE)
-			ioctl_addr[i] |= NVIF_VMM_PFNMAP_V0_W;
+	if (!(range->hmm_pfns[0] & HMM_PFN_VALID)) {
+		args->p.phys[0] = 0;
+		return;
 	}
+
+	page = hmm_pfn_to_page(range->hmm_pfns[0]);
+	/*
+	 * Only map compound pages to the GPU if the CPU is also mapping the
+	 * page as a compound page. Otherwise, the PTE protections might not be
+	 * consistent (e.g., CPU only maps part of a compound page).
+	 * Note that the underlying page might still be larger than the
+	 * CPU mapping (e.g., a PUD sized compound page partially mapped with
+	 * a PMD sized page table entry).
+	 */
+	if (hmm_pfn_to_map_order(range->hmm_pfns[0])) {
+		unsigned long addr = args->p.addr;
+
+		args->p.page = hmm_pfn_to_map_order(range->hmm_pfns[0]) +
+				PAGE_SHIFT;
+		args->p.size = 1UL << args->p.page;
+		args->p.addr &= ~(args->p.size - 1);
+		page -= (addr - args->p.addr) >> PAGE_SHIFT;
+	}
+	if (is_device_private_page(page))
+		args->p.phys[0] = nouveau_dmem_page_addr(page) |
+				NVIF_VMM_PFNMAP_V0_V |
+				NVIF_VMM_PFNMAP_V0_VRAM;
+	else
+		args->p.phys[0] = page_to_phys(page) |
+				NVIF_VMM_PFNMAP_V0_V |
+				NVIF_VMM_PFNMAP_V0_HOST;
+	if (range->hmm_pfns[0] & HMM_PFN_WRITE)
+		args->p.phys[0] |= NVIF_VMM_PFNMAP_V0_W;
 }
 
 static int nouveau_range_fault(struct nouveau_svmm *svmm,
-			       struct nouveau_drm *drm, void *data, u32 size,
-			       unsigned long hmm_pfns[], u64 *ioctl_addr,
+			       struct nouveau_drm *drm,
+			       struct nouveau_pfnmap_args *args, u32 size,
+			       unsigned long hmm_flags,
 			       struct svm_notifier *notifier)
 {
 	unsigned long timeout =
 		jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 	/* Have HMM fault pages within the fault window to the GPU. */
+	unsigned long hmm_pfns[1];
 	struct hmm_range range = {
 		.notifier = &notifier->notifier,
 		.start = notifier->notifier.interval_tree.start,
 		.end = notifier->notifier.interval_tree.last + 1,
-		.pfn_flags_mask = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_WRITE,
+		.default_flags = hmm_flags,
 		.hmm_pfns = hmm_pfns,
 		.dev_private_owner = drm->dev,
 	};
@@ -576,11 +588,6 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 		ret = hmm_range_fault(&range);
 		mmap_read_unlock(mm);
 		if (ret) {
-			/*
-			 * FIXME: the input PFN_REQ flags are destroyed on
-			 * -EBUSY, we need to regenerate them, also for the
-			 * other continue below
-			 */
 			if (ret == -EBUSY)
 				continue;
 			return ret;
@@ -595,10 +602,10 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 		break;
 	}
 
-	nouveau_hmm_convert_pfn(drm, &range, ioctl_addr);
+	nouveau_hmm_convert_pfn(drm, &range, args);
 
 	svmm->vmm->vmm.object.client->super = true;
-	ret = nvif_object_ioctl(&svmm->vmm->vmm.object, data, size, NULL);
+	ret = nvif_object_ioctl(&svmm->vmm->vmm.object, args, size, NULL);
 	svmm->vmm->vmm.object.client->super = false;
 	mutex_unlock(&svmm->mutex);
 
@@ -615,17 +622,12 @@ nouveau_svm_fault(struct nvif_notify *notify)
 	struct nvif_object *device = &svm->drm->client.device.object;
 	struct nouveau_svmm *svmm;
 	struct {
-		struct {
-			struct nvif_ioctl_v0 i;
-			struct nvif_ioctl_mthd_v0 m;
-			struct nvif_vmm_pfnmap_v0 p;
-		} i;
-		u64 phys[16];
+		struct nouveau_pfnmap_args i;
+		u64 phys[1];
 	} args;
-	unsigned long hmm_pfns[ARRAY_SIZE(args.phys)];
-	struct vm_area_struct *vma;
+	unsigned long hmm_flags;
 	u64 inst, start, limit;
-	int fi, fn, pi, fill;
+	int fi, fn;
 	int replay = 0, ret;
 
 	/* Parse available fault buffer entries into a cache, and update
@@ -692,10 +694,34 @@ nouveau_svm_fault(struct nvif_notify *notify)
 		 * window into a single update.
 		 */
 		start = buffer->fault[fi]->addr;
-		limit = start + (ARRAY_SIZE(args.phys) << PAGE_SHIFT);
+		limit = start + PAGE_SIZE;
 		if (start < svmm->unmanaged.limit)
 			limit = min_t(u64, limit, svmm->unmanaged.start);
-		SVMM_DBG(svmm, "wndw %016llx-%016llx", start, limit);
+
+		/*
+		 * Prepare the GPU-side update of all pages within the
+		 * fault window, determining required pages and access
+		 * permissions based on pending faults.
+		 */
+		args.i.p.addr = start;
+		args.i.p.page = PAGE_SHIFT;
+		args.i.p.size = PAGE_SIZE;
+		/*
+		 * Determine required permissions based on GPU fault
+		 * access flags.
+		 * XXX: atomic?
+		 */
+		switch (buffer->fault[fi]->access) {
+		case 0: /* READ. */
+			hmm_flags = HMM_PFN_REQ_FAULT;
+			break;
+		case 3: /* PREFETCH. */
+			hmm_flags = 0;
+			break;
+		default:
+			hmm_flags = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_WRITE;
+			break;
+		}
 
 		mm = svmm->notifier.mm;
 		if (!mmget_not_zero(mm)) {
@@ -703,117 +729,48 @@ nouveau_svm_fault(struct nvif_notify *notify)
 			continue;
 		}
 
-		/* Intersect fault window with the CPU VMA, cancelling
-		 * the fault if the address is invalid.
-		 */
-		mmap_read_lock(mm);
-		vma = find_vma_intersection(mm, start, limit);
-		if (!vma) {
-			SVMM_ERR(svmm, "wndw %016llx-%016llx", start, limit);
-			mmap_read_unlock(mm);
-			mmput(mm);
-			nouveau_svm_fault_cancel_fault(svm, buffer->fault[fi]);
-			continue;
+		notifier.svmm = svmm;
+		ret = mmu_interval_notifier_insert(&notifier.notifier, mm,
+						   args.i.p.addr, args.i.p.size,
+						   &nouveau_svm_mni_ops);
+		if (!ret) {
+			ret = nouveau_range_fault(svmm, svm->drm, &args.i,
+				sizeof(args), hmm_flags, &notifier);
+			mmu_interval_notifier_remove(&notifier.notifier);
 		}
-		start = max_t(u64, start, vma->vm_start);
-		limit = min_t(u64, limit, vma->vm_end);
-		mmap_read_unlock(mm);
-		SVMM_DBG(svmm, "wndw %016llx-%016llx", start, limit);
-
-		if (buffer->fault[fi]->addr != start) {
-			SVMM_ERR(svmm, "addr %016llx", buffer->fault[fi]->addr);
-			mmput(mm);
-			nouveau_svm_fault_cancel_fault(svm, buffer->fault[fi]);
-			continue;
-		}
-
-		/* Prepare the GPU-side update of all pages within the
-		 * fault window, determining required pages and access
-		 * permissions based on pending faults.
-		 */
-		args.i.p.page = PAGE_SHIFT;
-		args.i.p.addr = start;
-		for (fn = fi, pi = 0;;) {
-			/* Determine required permissions based on GPU fault
-			 * access flags.
-			 *XXX: atomic?
-			 */
-			switch (buffer->fault[fn]->access) {
-			case 0: /* READ. */
-				hmm_pfns[pi++] = HMM_PFN_REQ_FAULT;
-				break;
-			case 3: /* PREFETCH. */
-				hmm_pfns[pi++] = 0;
-				break;
-			default:
-				hmm_pfns[pi++] = HMM_PFN_REQ_FAULT |
-						 HMM_PFN_REQ_WRITE;
-				break;
-			}
-			args.i.p.size = pi << PAGE_SHIFT;
+		mmput(mm);
 
+		limit = args.i.p.addr + args.i.p.size;
+		for (fn = fi; ++fn < buffer->fault_nr; ) {
 			/* It's okay to skip over duplicate addresses from the
 			 * same SVMM as faults are ordered by access type such
 			 * that only the first one needs to be handled.
 			 *
 			 * ie. WRITE faults appear first, thus any handling of
 			 * pending READ faults will already be satisfied.
+			 * But if a large page is mapped, make sure subsequent
+			 * fault addresses have sufficient access permission.
 			 */
-			while (++fn < buffer->fault_nr &&
-			       buffer->fault[fn]->svmm == svmm &&
-			       buffer->fault[fn    ]->addr ==
-			       buffer->fault[fn - 1]->addr);
-
-			/* If the next fault is outside the window, or all GPU
-			 * faults have been dealt with, we're done here.
-			 */
-			if (fn >= buffer->fault_nr ||
-			    buffer->fault[fn]->svmm != svmm ||
-			    buffer->fault[fn]->addr >= limit)
+			if (buffer->fault[fn]->svmm != svmm ||
+			    buffer->fault[fn]->addr >= limit ||
+			    (buffer->fault[fi]->access == 0 /* READ. */ &&
+			     !(args.phys[0] & NVIF_VMM_PFNMAP_V0_V)) ||
+			    (buffer->fault[fi]->access != 0 /* READ. */ &&
+			     buffer->fault[fi]->access != 3 /* PREFETCH. */ &&
+			     !(args.phys[0] & NVIF_VMM_PFNMAP_V0_W)))
 				break;
-
-			/* Fill in the gap between this fault and the next. */
-			fill = (buffer->fault[fn    ]->addr -
-				buffer->fault[fn - 1]->addr) >> PAGE_SHIFT;
-			while (--fill)
-				hmm_pfns[pi++] = 0;
 		}
 
-		SVMM_DBG(svmm, "wndw %016llx-%016llx covering %d fault(s)",
-			 args.i.p.addr,
-			 args.i.p.addr + args.i.p.size, fn - fi);
+		/* If handling failed completely, cancel all faults. */
+		if (ret) {
+			while (fi < fn) {
+				struct nouveau_svm_fault *fault =
+					buffer->fault[fi++];
 
-		notifier.svmm = svmm;
-		ret = mmu_interval_notifier_insert(&notifier.notifier,
-						   svmm->notifier.mm,
-						   args.i.p.addr, args.i.p.size,
-						   &nouveau_svm_mni_ops);
-		if (!ret) {
-			ret = nouveau_range_fault(
-				svmm, svm->drm, &args,
-				sizeof(args.i) + pi * sizeof(args.phys[0]),
-				hmm_pfns, args.phys, &notifier);
-			mmu_interval_notifier_remove(&notifier.notifier);
-		}
-		mmput(mm);
-
-		/* Cancel any faults in the window whose pages didn't manage
-		 * to keep their valid bit, or stay writeable when required.
-		 *
-		 * If handling failed completely, cancel all faults.
-		 */
-		while (fi < fn) {
-			struct nouveau_svm_fault *fault = buffer->fault[fi++];
-			pi = (fault->addr - args.i.p.addr) >> PAGE_SHIFT;
-			if (ret ||
-			     !(args.phys[pi] & NVIF_VMM_PFNMAP_V0_V) ||
-			    (!(args.phys[pi] & NVIF_VMM_PFNMAP_V0_W) &&
-			     fault->access != 0 && fault->access != 3)) {
 				nouveau_svm_fault_cancel_fault(svm, fault);
-				continue;
 			}
+		} else
 			replay++;
-		}
 	}
 
 	/* Issue fault replay to the GPU. */
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.h b/drivers/gpu/drm/nouveau/nouveau_svm.h
index f0fcd1b72e8b..e7d63d7f0c2d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.h
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.h
@@ -1,11 +1,21 @@
 #ifndef __NOUVEAU_SVM_H__
 #define __NOUVEAU_SVM_H__
 #include <nvif/os.h>
+#include <linux/mmu_notifier.h>
 struct drm_device;
 struct drm_file;
 struct nouveau_drm;
 
-struct nouveau_svmm;
+struct nouveau_svmm {
+	struct mmu_notifier notifier;
+	struct nouveau_vmm *vmm;
+	struct {
+		unsigned long start;
+		unsigned long limit;
+	} unmanaged;
+
+	struct mutex mutex;
+};
 
 #if IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM)
 void nouveau_svm_init(struct nouveau_drm *);
@@ -19,6 +29,7 @@ int nouveau_svmm_join(struct nouveau_svmm *, u64 inst);
 void nouveau_svmm_part(struct nouveau_svmm *, u64 inst);
 int nouveau_svmm_bind(struct drm_device *, void *, struct drm_file *);
 
+void nouveau_svmm_invalidate(struct nouveau_svmm *svmm, u64 start, u64 limit);
 u64 *nouveau_pfns_alloc(unsigned long npages);
 void nouveau_pfns_free(u64 *pfns);
 void nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index 199f94e15c5f..19a6804e3989 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1204,7 +1204,6 @@ nvkm_vmm_pfn_unmap(struct nvkm_vmm *vmm, u64 addr, u64 size)
 /*TODO:
  * - Avoid PT readback (for dma_unmap etc), this might end up being dealt
  *   with inside HMM, which would be a lot nicer for us to deal with.
- * - Multiple page sizes (particularly for huge page support).
  * - Support for systems without a 4KiB page size.
  */
 int
@@ -1220,8 +1219,8 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
 	/* Only support mapping where the page size of the incoming page
 	 * array matches a page size available for direct mapping.
 	 */
-	while (page->shift && page->shift != shift &&
-	       page->desc->func->pfn == NULL)
+	while (page->shift && (page->shift != shift ||
+	       page->desc->func->pfn == NULL))
 		page++;
 
 	if (!page->shift || !IS_ALIGNED(addr, 1ULL << shift) ||
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
index d86287565542..7eabe9fe0d2b 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c
@@ -79,8 +79,12 @@ gp100_vmm_pgt_pfn(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 	dma_addr_t addr;
 
 	nvkm_kmap(pt->memory);
-	while (ptes--) {
+	for (; ptes; ptes--, map->pfn++) {
 		u64 data = 0;
+
+		if (!(*map->pfn & NVKM_VMM_PFN_V))
+			continue;
+
 		if (!(*map->pfn & NVKM_VMM_PFN_W))
 			data |= BIT_ULL(6); /* RO. */
 
@@ -100,7 +104,6 @@ gp100_vmm_pgt_pfn(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 		}
 
 		VMM_WO064(pt, vmm, ptei++ * 8, data);
-		map->pfn++;
 	}
 	nvkm_done(pt->memory);
 }
@@ -258,12 +261,96 @@ gp100_vmm_pd0_unmap(struct nvkm_vmm *vmm,
 	VMM_FO128(pt, vmm, pdei * 0x10, 0ULL, 0ULL, pdes);
 }
 
+static void
+gp100_vmm_pd0_pfn_unmap(struct nvkm_vmm *vmm,
+			struct nvkm_mmu_pt *pt, u32 ptei, u32 ptes)
+{
+	struct device *dev = vmm->mmu->subdev.device->dev;
+	dma_addr_t addr;
+
+	nvkm_kmap(pt->memory);
+	while (ptes--) {
+		u32 datalo = nvkm_ro32(pt->memory, pt->base + ptei * 16 + 0);
+		u32 datahi = nvkm_ro32(pt->memory, pt->base + ptei * 16 + 4);
+		u64 data   = (u64)datahi << 32 | datalo;
+
+		if ((data & (3ULL << 1)) != 0) {
+			addr = (data >> 8) << 12;
+			dma_unmap_page(dev, addr, 1UL << 21, DMA_BIDIRECTIONAL);
+		}
+		ptei++;
+	}
+	nvkm_done(pt->memory);
+}
+
+static bool
+gp100_vmm_pd0_pfn_clear(struct nvkm_vmm *vmm,
+			struct nvkm_mmu_pt *pt, u32 ptei, u32 ptes)
+{
+	bool dma = false;
+
+	nvkm_kmap(pt->memory);
+	while (ptes--) {
+		u32 datalo = nvkm_ro32(pt->memory, pt->base + ptei * 16 + 0);
+		u32 datahi = nvkm_ro32(pt->memory, pt->base + ptei * 16 + 4);
+		u64 data   = (u64)datahi << 32 | datalo;
+
+		if ((data & BIT_ULL(0)) && (data & (3ULL << 1)) != 0) {
+			VMM_WO064(pt, vmm, ptei * 16, data & ~BIT_ULL(0));
+			dma = true;
+		}
+		ptei++;
+	}
+	nvkm_done(pt->memory);
+	return dma;
+}
+
+static void
+gp100_vmm_pd0_pfn(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
+		  u32 ptei, u32 ptes, struct nvkm_vmm_map *map)
+{
+	struct device *dev = vmm->mmu->subdev.device->dev;
+	dma_addr_t addr;
+
+	nvkm_kmap(pt->memory);
+	for (; ptes; ptes--, map->pfn++) {
+		u64 data = 0;
+
+		if (!(*map->pfn & NVKM_VMM_PFN_V))
+			continue;
+
+		if (!(*map->pfn & NVKM_VMM_PFN_W))
+			data |= BIT_ULL(6); /* RO. */
+
+		if (!(*map->pfn & NVKM_VMM_PFN_VRAM)) {
+			addr = *map->pfn >> NVKM_VMM_PFN_ADDR_SHIFT;
+			addr = dma_map_page(dev, pfn_to_page(addr), 0,
+					    1UL << 21, DMA_BIDIRECTIONAL);
+			if (!WARN_ON(dma_mapping_error(dev, addr))) {
+				data |= addr >> 4;
+				data |= 2ULL << 1; /* SYSTEM_COHERENT_MEMORY. */
+				data |= BIT_ULL(3); /* VOL. */
+				data |= BIT_ULL(0); /* VALID. */
+			}
+		} else {
+			data |= (*map->pfn & NVKM_VMM_PFN_ADDR) >> 4;
+			data |= BIT_ULL(0); /* VALID. */
+		}
+
+		VMM_WO064(pt, vmm, ptei++ * 16, data);
+	}
+	nvkm_done(pt->memory);
+}
+
 static const struct nvkm_vmm_desc_func
 gp100_vmm_desc_pd0 = {
 	.unmap = gp100_vmm_pd0_unmap,
 	.sparse = gp100_vmm_pd0_sparse,
 	.pde = gp100_vmm_pd0_pde,
 	.mem = gp100_vmm_pd0_mem,
+	.pfn = gp100_vmm_pd0_pfn,
+	.pfn_clear = gp100_vmm_pd0_pfn_clear,
+	.pfn_unmap = gp100_vmm_pd0_pfn_unmap,
 };
 
 static void
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index f4a09ed223ac..866a0fa104c4 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -37,16 +37,17 @@
  *                     will fail. Must be combined with HMM_PFN_REQ_FAULT.
  */
 enum hmm_pfn_flags {
-	/* Output flags */
+	/* Output fields and flags */
 	HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1),
 	HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2),
 	HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
+	HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
 
 	/* Input flags */
 	HMM_PFN_REQ_FAULT = HMM_PFN_VALID,
 	HMM_PFN_REQ_WRITE = HMM_PFN_WRITE,
 
-	HMM_PFN_FLAGS = HMM_PFN_VALID | HMM_PFN_WRITE | HMM_PFN_ERROR,
+	HMM_PFN_FLAGS = 0xFFUL << HMM_PFN_ORDER_SHIFT,
 };
 
 /*
@@ -61,6 +62,25 @@ static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
 	return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
 }
 
+/*
+ * hmm_pfn_to_map_order() - return the CPU mapping size order
+ *
+ * This is optionally useful to optimize processing of the pfn result
+ * array. It indicates that the page starts at the order aligned VA and is
+ * 1<<order bytes long.  Every pfn within an high order page will have the
+ * same pfn flags, both access protections and the map_order.  The caller must
+ * be careful with edge cases as the start and end VA of the given page may
+ * extend past the range used with hmm_range_fault().
+ *
+ * This must be called under the caller 'user_lock' after a successful
+ * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
+ * already.
+ */
+static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn)
+{
+	return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F;
+}
+
 /*
  * struct hmm_range - track invalidation lock on virtual address range
  *
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 3e546cbf03dd..540998d9810b 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -180,6 +180,11 @@ static inline unsigned long migrate_pfn(unsigned long pfn)
 	return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID;
 }
 
+enum migrate_vma_direction {
+	MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
+	MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
+};
+
 struct migrate_vma {
 	struct vm_area_struct	*vma;
 	/*
@@ -199,11 +204,14 @@ struct migrate_vma {
 
 	/*
 	 * Set to the owner value also stored in page->pgmap->owner for
-	 * migrating out of device private memory.  If set only device
-	 * private pages with this owner are migrated.  If not set
-	 * device private pages are not migrated at all.
+	 * migrating out of device private memory. The flags also need to
+	 * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE.
+	 * The caller should always set this field when using mmu notifier
+	 * callbacks to avoid device MMU invalidations for device private
+	 * pages that are not being migrated.
 	 */
-	void			*src_owner;
+	void			*pgmap_owner;
+	unsigned long		flags;
 };
 
 int migrate_vma_setup(struct migrate_vma *args);
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index fc68f3570e19..c6f0708195cd 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -38,6 +38,10 @@ struct mmu_interval_notifier;
  *
  * @MMU_NOTIFY_RELEASE: used during mmu_interval_notifier invalidate to signal
  * that the mm refcount is zero and the range is no longer accessible.
+ *
+ * @MMU_NOTIFY_MIGRATE: used during migrate_vma_collect() invalidate to signal
+ * a device driver to possibly ignore the invalidation if the
+ * migrate_pgmap_owner field matches the driver's device private pgmap owner.
  */
 enum mmu_notifier_event {
 	MMU_NOTIFY_UNMAP = 0,
@@ -46,6 +50,7 @@ enum mmu_notifier_event {
 	MMU_NOTIFY_PROTECTION_PAGE,
 	MMU_NOTIFY_SOFT_DIRTY,
 	MMU_NOTIFY_RELEASE,
+	MMU_NOTIFY_MIGRATE,
 };
 
 #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0)
@@ -264,6 +269,7 @@ struct mmu_notifier_range {
 	unsigned long end;
 	unsigned flags;
 	enum mmu_notifier_event event;
+	void *migrate_pgmap_owner;
 };
 
 static inline int mm_has_notifiers(struct mm_struct *mm)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index a2a82262b97b..e7dc3de355b7 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -214,6 +214,14 @@ static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
 {
 	struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
 
+	/*
+	 * Ignore invalidation callbacks for device private pages since
+	 * the invalidation is handled as part of the migration process.
+	 */
+	if (range->event == MMU_NOTIFY_MIGRATE &&
+	    range->migrate_pgmap_owner == dmirror->mdevice)
+		return true;
+
 	if (mmu_notifier_range_blockable(range))
 		mutex_lock(&dmirror->mutex);
 	else if (!mutex_trylock(&dmirror->mutex))
@@ -585,15 +593,6 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 		 */
 		spage = migrate_pfn_to_page(*src);
 
-		/*
-		 * Don't migrate device private pages from our own driver or
-		 * others. For our own we would do a device private memory copy
-		 * not a migration and for others, we would need to fault the
-		 * other device's page into system memory first.
-		 */
-		if (spage && is_zone_device_page(spage))
-			continue;
-
 		dpage = dmirror_devmem_alloc_page(mdevice);
 		if (!dpage)
 			continue;
@@ -702,7 +701,8 @@ static int dmirror_migrate(struct dmirror *dmirror,
 		args.dst = dst_pfns;
 		args.start = addr;
 		args.end = next;
-		args.src_owner = NULL;
+		args.pgmap_owner = dmirror->mdevice;
+		args.flags = MIGRATE_VMA_SELECT_SYSTEM;
 		ret = migrate_vma_setup(&args);
 		if (ret)
 			goto out;
@@ -766,6 +766,10 @@ static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
 		*perm |= HMM_DMIRROR_PROT_WRITE;
 	else
 		*perm |= HMM_DMIRROR_PROT_READ;
+	if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
+		*perm |= HMM_DMIRROR_PROT_PMD;
+	else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
+		*perm |= HMM_DMIRROR_PROT_PUD;
 }
 
 static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
@@ -987,7 +991,7 @@ static void dmirror_devmem_free(struct page *page)
 }
 
 static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
-						struct dmirror_device *mdevice)
+						      struct dmirror *dmirror)
 {
 	const unsigned long *src = args->src;
 	unsigned long *dst = args->dst;
@@ -1009,6 +1013,7 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
 			continue;
 
 		lock_page(dpage);
+		xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
 		copy_highpage(dpage, spage);
 		*dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
 		if (*src & MIGRATE_PFN_WRITE)
@@ -1017,15 +1022,6 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
 	return 0;
 }
 
-static void dmirror_devmem_fault_finalize_and_map(struct migrate_vma *args,
-						  struct dmirror *dmirror)
-{
-	/* Invalidate the device's page table mapping. */
-	mutex_lock(&dmirror->mutex);
-	dmirror_do_update(dmirror, args->start, args->end);
-	mutex_unlock(&dmirror->mutex);
-}
-
 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 {
 	struct migrate_vma args;
@@ -1049,16 +1045,21 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 	args.end = args.start + PAGE_SIZE;
 	args.src = &src_pfns;
 	args.dst = &dst_pfns;
-	args.src_owner = dmirror->mdevice;
+	args.pgmap_owner = dmirror->mdevice;
+	args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 
 	if (migrate_vma_setup(&args))
 		return VM_FAULT_SIGBUS;
 
-	ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror->mdevice);
+	ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
 	if (ret)
 		return ret;
 	migrate_vma_pages(&args);
-	dmirror_devmem_fault_finalize_and_map(&args, dmirror);
+	/*
+	 * No device finalize step is needed since
+	 * dmirror_devmem_fault_alloc_and_copy() will have already
+	 * invalidated the device page table.
+	 */
 	migrate_vma_finalize(&args);
 	return 0;
 }
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 67b3b2e6ff5d..670b4ef2a5b6 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -40,6 +40,8 @@ struct hmm_dmirror_cmd {
  * HMM_DMIRROR_PROT_NONE: unpopulated PTE or PTE with no access
  * HMM_DMIRROR_PROT_READ: read-only PTE
  * HMM_DMIRROR_PROT_WRITE: read/write PTE
+ * HMM_DMIRROR_PROT_PMD: PMD sized page is fully mapped by same permissions
+ * HMM_DMIRROR_PROT_PUD: PUD sized page is fully mapped by same permissions
  * HMM_DMIRROR_PROT_ZERO: special read-only zero page
  * HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL: Migrated device private page on the
  *					device the ioctl() is made
@@ -51,6 +53,8 @@ enum {
 	HMM_DMIRROR_PROT_NONE			= 0x00,
 	HMM_DMIRROR_PROT_READ			= 0x01,
 	HMM_DMIRROR_PROT_WRITE			= 0x02,
+	HMM_DMIRROR_PROT_PMD			= 0x04,
+	HMM_DMIRROR_PROT_PUD			= 0x08,
 	HMM_DMIRROR_PROT_ZERO			= 0x10,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL	= 0x20,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
diff --git a/mm/hmm.c b/mm/hmm.c
index e9a545751108..0809baee49d0 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -165,12 +165,19 @@ static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
 	return hmm_pfns_fill(addr, end, range, 0);
 }
 
+static inline unsigned long hmm_pfn_flags_order(unsigned long order)
+{
+	return order << HMM_PFN_ORDER_SHIFT;
+}
+
 static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
 						 pmd_t pmd)
 {
 	if (pmd_protnone(pmd))
 		return 0;
-	return pmd_write(pmd) ? (HMM_PFN_VALID | HMM_PFN_WRITE) : HMM_PFN_VALID;
+	return (pmd_write(pmd) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
+				 HMM_PFN_VALID) |
+	       hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -389,7 +396,9 @@ static inline unsigned long pud_to_hmm_pfn_flags(struct hmm_range *range,
 {
 	if (!pud_present(pud))
 		return 0;
-	return pud_write(pud) ? (HMM_PFN_VALID | HMM_PFN_WRITE) : HMM_PFN_VALID;
+	return (pud_write(pud) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
+				 HMM_PFN_VALID) |
+	       hmm_pfn_flags_order(PUD_SHIFT - PAGE_SHIFT);
 }
 
 static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
@@ -474,7 +483,8 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
 
 	i = (start - range->start) >> PAGE_SHIFT;
 	pfn_req_flags = range->hmm_pfns[i];
-	cpu_flags = pte_to_hmm_pfn_flags(range, entry);
+	cpu_flags = pte_to_hmm_pfn_flags(range, entry) |
+		    hmm_pfn_flags_order(huge_page_order(hstate_vma(vma)));
 	required_fault =
 		hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
 	if (required_fault) {
diff --git a/mm/migrate.c b/mm/migrate.c
index 40cd7016ae6f..4fcc465736ff 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2276,7 +2276,9 @@ again:
 				goto next;
 
 			page = device_private_entry_to_page(entry);
-			if (page->pgmap->owner != migrate->src_owner)
+			if (!(migrate->flags &
+				MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
+			    page->pgmap->owner != migrate->pgmap_owner)
 				goto next;
 
 			mpfn = migrate_pfn(page_to_pfn(page)) |
@@ -2284,7 +2286,7 @@ again:
 			if (is_write_device_private_entry(entry))
 				mpfn |= MIGRATE_PFN_WRITE;
 		} else {
-			if (migrate->src_owner)
+			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
 				goto next;
 			pfn = pte_pfn(pte);
 			if (is_zero_pfn(pfn)) {
@@ -2379,8 +2381,14 @@ static void migrate_vma_collect(struct migrate_vma *migrate)
 {
 	struct mmu_notifier_range range;
 
-	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL,
+	/*
+	 * Note that the pgmap_owner is passed to the mmu notifier callback so
+	 * that the registered device driver can skip invalidating device
+	 * private page mappings that won't be migrated.
+	 */
+	mmu_notifier_range_init(&range, MMU_NOTIFY_MIGRATE, 0, migrate->vma,
 			migrate->vma->vm_mm, migrate->start, migrate->end);
+	range.migrate_pgmap_owner = migrate->pgmap_owner;
 	mmu_notifier_invalidate_range_start(&range);
 
 	walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end,
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 79db22604019..91d38a29956b 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -881,8 +881,9 @@ TEST_F(hmm, migrate)
 }
 
 /*
- * Migrate anonymous memory to device private memory and fault it back to system
- * memory.
+ * Migrate anonymous memory to device private memory and fault some of it back
+ * to system memory, then try migrating the resulting mix of system and device
+ * private memory to the device.
  */
 TEST_F(hmm, migrate_fault)
 {
@@ -924,8 +925,17 @@ TEST_F(hmm, migrate_fault)
 	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
 		ASSERT_EQ(ptr[i], i);
 
-	/* Fault pages back to system memory and check them. */
-	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+	/* Fault half the pages back to system memory and check them. */
+	for (i = 0, ptr = buffer->ptr; i < size / (2 * sizeof(*ptr)); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Migrate memory to the device again. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
 		ASSERT_EQ(ptr[i], i);
 
 	hmm_buffer_free(buffer);
@@ -1291,6 +1301,82 @@ TEST_F(hmm2, snapshot)
 	hmm_buffer_free(buffer);
 }
 
+/*
+ * Test the hmm_range_fault() HMM_PFN_PMD flag for large pages that
+ * should be mapped by a large page table entry.
+ */
+TEST_F(hmm, compound)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	int *ptr;
+	unsigned char *m;
+	int ret;
+	long pagesizes[4];
+	int n, idx;
+	unsigned long i;
+
+	/* Skip test if we can't allocate a hugetlbfs page. */
+
+	n = gethugepagesizes(pagesizes, 4);
+	if (n <= 0)
+		return;
+	for (idx = 0; --n > 0; ) {
+		if (pagesizes[n] < pagesizes[idx])
+			idx = n;
+	}
+	size = ALIGN(TWOMEG, pagesizes[idx]);
+	npages = size >> self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->ptr = get_hugepage_region(size, GHR_STRICT);
+	if (buffer->ptr == NULL) {
+		free(buffer);
+		return;
+	}
+
+	buffer->size = size;
+	buffer->mirror = malloc(npages);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Initialize the pages the device will snapshot in buffer->ptr. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	for (i = 0; i < npages; ++i)
+		ASSERT_EQ(m[i], HMM_DMIRROR_PROT_WRITE |
+				HMM_DMIRROR_PROT_PMD);
+
+	/* Make the region read-only. */
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	for (i = 0; i < npages; ++i)
+		ASSERT_EQ(m[i], HMM_DMIRROR_PROT_READ |
+				HMM_DMIRROR_PROT_PMD);
+
+	free_hugepage_region(buffer->ptr);
+	buffer->ptr = NULL;
+	hmm_buffer_free(buffer);
+}
+
 /*
  * Test two devices reading the same memory (double mapped).
  */