drm/nouveau/mmu: add a privileged method to directly manage PTEs

This provides a somewhat more direct method of manipulating the GPU page
tables, which will be required to support SVM.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvif/if000c.h

@@ -15,6 +15,8 @@ struct nvif_vmm_v0 {
 #define NVIF_VMM_V0_PUT                                                    0x02
 #define NVIF_VMM_V0_MAP                                                    0x03
 #define NVIF_VMM_V0_UNMAP                                                  0x04
+#define NVIF_VMM_V0_PFNMAP                                                 0x05
+#define NVIF_VMM_V0_PFNCLR                                                 0x06
 
 struct nvif_vmm_page_v0 {
 	__u8  version;
@@ -62,4 +64,28 @@ struct nvif_vmm_unmap_v0 {
 	__u8  pad01[7];
 	__u64 addr;
 };
+
+struct nvif_vmm_pfnmap_v0 {
+	__u8  version;
+	__u8  page;
+	__u8  pad02[6];
+	__u64 addr;
+	__u64 size;
+#define NVIF_VMM_PFNMAP_V0_ADDR                           0xfffffffffffff000ULL
+#define NVIF_VMM_PFNMAP_V0_ADDR_SHIFT                                        12
+#define NVIF_VMM_PFNMAP_V0_APER                           0x00000000000000f0ULL
+#define NVIF_VMM_PFNMAP_V0_HOST                           0x0000000000000000ULL
+#define NVIF_VMM_PFNMAP_V0_VRAM                           0x0000000000000010ULL
+#define NVIF_VMM_PFNMAP_V0_W                              0x0000000000000002ULL
+#define NVIF_VMM_PFNMAP_V0_V                              0x0000000000000001ULL
+#define NVIF_VMM_PFNMAP_V0_NONE                           0x0000000000000000ULL
+	__u64 phys[];
+};
+
+struct nvif_vmm_pfnclr_v0 {
+	__u8  version;
+	__u8  pad01[7];
+	__u64 addr;
+	__u64 size;
+};
 #endif

drivers/gpu/drm/nouveau/include/nvkm/subdev/mmu.h

@@ -64,6 +64,7 @@ struct nvkm_vmm_map {
 	struct nvkm_mm_node *mem;
 	struct scatterlist *sgl;
 	dma_addr_t *dma;
+	u64 *pfn;
 	u64 off;
 
 	const struct nvkm_vmm_page *page;

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/uvmm.c

@@ -42,6 +42,69 @@ nvkm_uvmm_search(struct nvkm_client *client, u64 handle)
 	return nvkm_uvmm(object)->vmm;
 }
 
+static int
+nvkm_uvmm_mthd_pfnclr(struct nvkm_uvmm *uvmm, void *argv, u32 argc)
+{
+	struct nvkm_client *client = uvmm->object.client;
+	union {
+		struct nvif_vmm_pfnclr_v0 v0;
+	} *args = argv;
+	struct nvkm_vmm *vmm = uvmm->vmm;
+	int ret = -ENOSYS;
+	u64 addr, size;
+
+	if (!(ret = nvif_unpack(ret, &argv, &argc, args->v0, 0, 0, false))) {
+		addr = args->v0.addr;
+		size = args->v0.size;
+	} else
+		return ret;
+
+	if (!client->super)
+		return -ENOENT;
+
+	if (size) {
+		mutex_lock(&vmm->mutex);
+		ret = nvkm_vmm_pfn_unmap(vmm, addr, size);
+		mutex_unlock(&vmm->mutex);
+	}
+
+	return ret;
+}
+
+static int
+nvkm_uvmm_mthd_pfnmap(struct nvkm_uvmm *uvmm, void *argv, u32 argc)
+{
+	struct nvkm_client *client = uvmm->object.client;
+	union {
+		struct nvif_vmm_pfnmap_v0 v0;
+	} *args = argv;
+	struct nvkm_vmm *vmm = uvmm->vmm;
+	int ret = -ENOSYS;
+	u64 addr, size, *phys;
+	u8  page;
+
+	if (!(ret = nvif_unpack(ret, &argv, &argc, args->v0, 0, 0, true))) {
+		page = args->v0.page;
+		addr = args->v0.addr;
+		size = args->v0.size;
+		phys = args->v0.phys;
+		if (argc != (size >> page) * sizeof(args->v0.phys[0]))
+			return -EINVAL;
+	} else
+		return ret;
+
+	if (!client->super)
+		return -ENOENT;
+
+	if (size) {
+		mutex_lock(&vmm->mutex);
+		ret = nvkm_vmm_pfn_map(vmm, page, addr, size, phys);
+		mutex_unlock(&vmm->mutex);
+	}
+
+	return ret;
+}
+
 static int
 nvkm_uvmm_mthd_unmap(struct nvkm_uvmm *uvmm, void *argv, u32 argc)
 {
@@ -78,7 +141,7 @@ nvkm_uvmm_mthd_unmap(struct nvkm_uvmm *uvmm, void *argv, u32 argc)
 		goto done;
 	}
 
-	nvkm_vmm_unmap_locked(vmm, vma);
+	nvkm_vmm_unmap_locked(vmm, vma, false);
 	ret = 0;
 done:
 	mutex_unlock(&vmm->mutex);
@@ -124,6 +187,11 @@ nvkm_uvmm_mthd_map(struct nvkm_uvmm *uvmm, void *argv, u32 argc)
 		goto fail;
 	}
 
+	if (ret = -EINVAL, vma->mapped && !vma->memory) {
+		VMM_DEBUG(vmm, "pfnmap %016llx", addr);
+		goto fail;
+	}
+
 	if (ret = -EINVAL, vma->addr != addr || vma->size != size) {
 		if (addr + size > vma->addr + vma->size || vma->memory ||
 		    (vma->refd == NVKM_VMA_PAGE_NONE && !vma->mapref)) {
@@ -271,6 +339,8 @@ nvkm_uvmm_mthd(struct nvkm_object *object, u32 mthd, void *argv, u32 argc)
 	case NVIF_VMM_V0_PUT   : return nvkm_uvmm_mthd_put   (uvmm, argv, argc);
 	case NVIF_VMM_V0_MAP   : return nvkm_uvmm_mthd_map   (uvmm, argv, argc);
 	case NVIF_VMM_V0_UNMAP : return nvkm_uvmm_mthd_unmap (uvmm, argv, argc);
+	case NVIF_VMM_V0_PFNMAP: return nvkm_uvmm_mthd_pfnmap(uvmm, argv, argc);
+	case NVIF_VMM_V0_PFNCLR: return nvkm_uvmm_mthd_pfnclr(uvmm, argv, argc);
 	default:
 		break;
 	}

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c

@@ -255,11 +255,23 @@ nvkm_vmm_unref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
 }
 
 static bool
-nvkm_vmm_unref_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
+nvkm_vmm_unref_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 ptes)
 {
 	const struct nvkm_vmm_desc *desc = it->desc;
 	const int type = desc->type == SPT;
 	struct nvkm_vmm_pt *pgt = it->pt[0];
+	bool dma;
+
+	if (pfn) {
+		/* Need to clear PTE valid bits before we dma_unmap_page(). */
+		dma = desc->func->pfn_clear(it->vmm, pgt->pt[type], ptei, ptes);
+		if (dma) {
+			/* GPU may have cached the PT, flush before unmap. */
+			nvkm_vmm_flush_mark(it);
+			nvkm_vmm_flush(it);
+			desc->func->pfn_unmap(it->vmm, pgt->pt[type], ptei, ptes);
+		}
+	}
 
 	/* Drop PTE references. */
 	pgt->refs[type] -= ptes;
@@ -349,7 +361,7 @@ nvkm_vmm_ref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
 }
 
 static bool
-nvkm_vmm_ref_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
+nvkm_vmm_ref_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 ptes)
 {
 	const struct nvkm_vmm_desc *desc = it->desc;
 	const int type = desc->type == SPT;
@@ -379,7 +391,7 @@ nvkm_vmm_sparse_ptes(const struct nvkm_vmm_desc *desc,
 }
 
 static bool
-nvkm_vmm_sparse_unref_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
+nvkm_vmm_sparse_unref_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 ptes)
 {
 	struct nvkm_vmm_pt *pt = it->pt[0];
 	if (it->desc->type == PGD)
@@ -387,14 +399,14 @@ nvkm_vmm_sparse_unref_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
 	else
 	if (it->desc->type == LPT)
 		memset(&pt->pte[ptei], 0x00, sizeof(pt->pte[0]) * ptes);
-	return nvkm_vmm_unref_ptes(it, ptei, ptes);
+	return nvkm_vmm_unref_ptes(it, pfn, ptei, ptes);
 }
 
 static bool
-nvkm_vmm_sparse_ref_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
+nvkm_vmm_sparse_ref_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 ptes)
 {
 	nvkm_vmm_sparse_ptes(it->desc, it->pt[0], ptei, ptes);
-	return nvkm_vmm_ref_ptes(it, ptei, ptes);
+	return nvkm_vmm_ref_ptes(it, pfn, ptei, ptes);
 }
 
 static bool
@@ -487,8 +499,8 @@ nvkm_vmm_ref_swpt(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgd, u32 pdei)
 
 static inline u64
 nvkm_vmm_iter(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
-	      u64 addr, u64 size, const char *name, bool ref,
-	      bool (*REF_PTES)(struct nvkm_vmm_iter *, u32, u32),
+	      u64 addr, u64 size, const char *name, bool ref, bool pfn,
+	      bool (*REF_PTES)(struct nvkm_vmm_iter *, bool pfn, u32, u32),
 	      nvkm_vmm_pte_func MAP_PTES, struct nvkm_vmm_map *map,
 	      nvkm_vmm_pxe_func CLR_PTES)
 {
@@ -548,7 +560,7 @@ nvkm_vmm_iter(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 		}
 
 		/* Handle PTE updates. */
-		if (!REF_PTES || REF_PTES(&it, ptei, ptes)) {
+		if (!REF_PTES || REF_PTES(&it, pfn, ptei, ptes)) {
 			struct nvkm_mmu_pt *pt = pgt->pt[type];
 			if (MAP_PTES || CLR_PTES) {
 				if (MAP_PTES)
@@ -590,7 +602,7 @@ static void
 nvkm_vmm_ptes_sparse_put(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 			 u64 addr, u64 size)
 {
-	nvkm_vmm_iter(vmm, page, addr, size, "sparse unref", false,
+	nvkm_vmm_iter(vmm, page, addr, size, "sparse unref", false, false,
 		      nvkm_vmm_sparse_unref_ptes, NULL, NULL,
 		      page->desc->func->invalid ?
 		      page->desc->func->invalid : page->desc->func->unmap);
@@ -602,8 +614,8 @@ nvkm_vmm_ptes_sparse_get(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 {
 	if ((page->type & NVKM_VMM_PAGE_SPARSE)) {
 		u64 fail = nvkm_vmm_iter(vmm, page, addr, size, "sparse ref",
-					 true, nvkm_vmm_sparse_ref_ptes, NULL,
-					 NULL, page->desc->func->sparse);
+					 true, false, nvkm_vmm_sparse_ref_ptes,
+					 NULL, NULL, page->desc->func->sparse);
 		if (fail != ~0ULL) {
 			if ((size = fail - addr))
 				nvkm_vmm_ptes_sparse_put(vmm, page, addr, size);
@@ -666,11 +678,11 @@ nvkm_vmm_ptes_sparse(struct nvkm_vmm *vmm, u64 addr, u64 size, bool ref)
 
 static void
 nvkm_vmm_ptes_unmap_put(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
-			u64 addr, u64 size, bool sparse)
+			u64 addr, u64 size, bool sparse, bool pfn)
 {
 	const struct nvkm_vmm_desc_func *func = page->desc->func;
 	nvkm_vmm_iter(vmm, page, addr, size, "unmap + unref",
-		      false, nvkm_vmm_unref_ptes, NULL, NULL,
+		      false, pfn, nvkm_vmm_unref_ptes, NULL, NULL,
 		      sparse ? func->sparse : func->invalid ? func->invalid :
 							      func->unmap);
 }
@@ -681,10 +693,10 @@ nvkm_vmm_ptes_get_map(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 		      nvkm_vmm_pte_func func)
 {
 	u64 fail = nvkm_vmm_iter(vmm, page, addr, size, "ref + map", true,
-				 nvkm_vmm_ref_ptes, func, map, NULL);
+				 false, nvkm_vmm_ref_ptes, func, map, NULL);
 	if (fail != ~0ULL) {
 		if ((size = fail - addr))
-			nvkm_vmm_ptes_unmap_put(vmm, page, addr, size, false);
+			nvkm_vmm_ptes_unmap_put(vmm, page, addr, size, false, false);
 		return -ENOMEM;
 	}
 	return 0;
@@ -692,10 +704,11 @@ nvkm_vmm_ptes_get_map(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 
 static void
 nvkm_vmm_ptes_unmap(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
-		    u64 addr, u64 size, bool sparse)
+		    u64 addr, u64 size, bool sparse, bool pfn)
 {
 	const struct nvkm_vmm_desc_func *func = page->desc->func;
-	nvkm_vmm_iter(vmm, page, addr, size, "unmap", false, NULL, NULL, NULL,
+	nvkm_vmm_iter(vmm, page, addr, size, "unmap", false, pfn,
+		      NULL, NULL, NULL,
 		      sparse ? func->sparse : func->invalid ? func->invalid :
 							      func->unmap);
 }
@@ -705,7 +718,7 @@ nvkm_vmm_ptes_map(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 		  u64 addr, u64 size, struct nvkm_vmm_map *map,
 		  nvkm_vmm_pte_func func)
 {
-	nvkm_vmm_iter(vmm, page, addr, size, "map", false,
+	nvkm_vmm_iter(vmm, page, addr, size, "map", false, false,
 		      NULL, func, map, NULL);
 }
 
@@ -713,7 +726,7 @@ static void
 nvkm_vmm_ptes_put(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 		  u64 addr, u64 size)
 {
-	nvkm_vmm_iter(vmm, page, addr, size, "unref", false,
+	nvkm_vmm_iter(vmm, page, addr, size, "unref", false, false,
 		      nvkm_vmm_unref_ptes, NULL, NULL, NULL);
 }
 
@@ -721,7 +734,7 @@ static int
 nvkm_vmm_ptes_get(struct nvkm_vmm *vmm, const struct nvkm_vmm_page *page,
 		  u64 addr, u64 size)
 {
-	u64 fail = nvkm_vmm_iter(vmm, page, addr, size, "ref", true,
+	u64 fail = nvkm_vmm_iter(vmm, page, addr, size, "ref", true, false,
 				 nvkm_vmm_ref_ptes, NULL, NULL, NULL);
 	if (fail != ~0ULL) {
 		if (fail != addr)
@@ -935,12 +948,41 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
 	return vma;
 }
 
+static void
+nvkm_vma_dump(struct nvkm_vma *vma)
+{
+	printk(KERN_ERR "%016llx %016llx %c%c%c%c%c%c%c%c%c %p\n",
+	       vma->addr, (u64)vma->size,
+	       vma->used ? '-' : 'F',
+	       vma->mapref ? 'R' : '-',
+	       vma->sparse ? 'S' : '-',
+	       vma->page != NVKM_VMA_PAGE_NONE ? '0' + vma->page : '-',
+	       vma->refd != NVKM_VMA_PAGE_NONE ? '0' + vma->refd : '-',
+	       vma->part ? 'P' : '-',
+	       vma->user ? 'U' : '-',
+	       vma->busy ? 'B' : '-',
+	       vma->mapped ? 'M' : '-',
+	       vma->memory);
+}
+
+static void
+nvkm_vmm_dump(struct nvkm_vmm *vmm)
+{
+	struct nvkm_vma *vma;
+	list_for_each_entry(vma, &vmm->list, head) {
+		nvkm_vma_dump(vma);
+	}
+}
+
 static void
 nvkm_vmm_dtor(struct nvkm_vmm *vmm)
 {
 	struct nvkm_vma *vma;
 	struct rb_node *node;
 
+	if (0)
+		nvkm_vmm_dump(vmm);
+
 	while ((node = rb_first(&vmm->root))) {
 		struct nvkm_vma *vma = rb_entry(node, typeof(*vma), tree);
 		nvkm_vmm_put(vmm, &vma);
@@ -1105,33 +1147,216 @@ nvkm_vmm_new_(const struct nvkm_vmm_func *func, struct nvkm_mmu *mmu,
 	return nvkm_vmm_ctor(func, mmu, hdr, managed, addr, size, key, name, *pvmm);
 }
 
+static struct nvkm_vma *
+nvkm_vmm_pfn_split_merge(struct nvkm_vmm *vmm, struct nvkm_vma *vma,
+			 u64 addr, u64 size, u8 page, bool map)
+{
+	struct nvkm_vma *prev = NULL;
+	struct nvkm_vma *next = NULL;
+
+	if (vma->addr == addr && vma->part && (prev = node(vma, prev))) {
+		if (prev->memory || prev->mapped != map)
+			prev = NULL;
+	}
+
+	if (vma->addr + vma->size == addr + size && (next = node(vma, next))) {
+		if (!next->part ||
+		    next->memory || next->mapped != map)
+			next = NULL;
+	}
+
+	if (prev || next)
+		return nvkm_vmm_node_merge(vmm, prev, vma, next, size);
+	return nvkm_vmm_node_split(vmm, vma, addr, size);
+}
+
+int
+nvkm_vmm_pfn_unmap(struct nvkm_vmm *vmm, u64 addr, u64 size)
+{
+	struct nvkm_vma *vma = nvkm_vmm_node_search(vmm, addr);
+	struct nvkm_vma *next;
+	u64 limit = addr + size;
+	u64 start = addr;
+
+	if (!vma)
+		return -EINVAL;
+
+	do {
+		if (!vma->mapped || vma->memory)
+			continue;
+
+		size = min(limit - start, vma->size - (start - vma->addr));
+
+		nvkm_vmm_ptes_unmap_put(vmm, &vmm->func->page[vma->refd],
+					start, size, false, true);
+
+		next = nvkm_vmm_pfn_split_merge(vmm, vma, start, size, 0, false);
+		if (!WARN_ON(!next)) {
+			vma = next;
+			vma->refd = NVKM_VMA_PAGE_NONE;
+			vma->mapped = false;
+		}
+	} while ((vma = node(vma, next)) && (start = vma->addr) < limit);
+
+	return 0;
+}
+
+/*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
+nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
+{
+	const struct nvkm_vmm_page *page = vmm->func->page;
+	struct nvkm_vma *vma, *tmp;
+	u64 limit = addr + size;
+	u64 start = addr;
+	int pm = size >> shift;
+	int pi = 0;
+
+	/* 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)
+		page++;
+
+	if (!page->shift || !IS_ALIGNED(addr, 1ULL << shift) ||
+			    !IS_ALIGNED(size, 1ULL << shift) ||
+	    addr + size < addr || addr + size > vmm->limit) {
+		VMM_DEBUG(vmm, "paged map %d %d %016llx %016llx\n",
+			  shift, page->shift, addr, size);
+		return -EINVAL;
+	}
+
+	if (!(vma = nvkm_vmm_node_search(vmm, addr)))
+		return -ENOENT;
+
+	do {
+		bool map = !!(pfn[pi] & NVKM_VMM_PFN_V);
+		bool mapped = vma->mapped;
+		u64 size = limit - start;
+		u64 addr = start;
+		int pn, ret = 0;
+
+		/* Narrow the operation window to cover a single action (page
+		 * should be mapped or not) within a single VMA.
+		 */
+		for (pn = 0; pi + pn < pm; pn++) {
+			if (map != !!(pfn[pi + pn] & NVKM_VMM_PFN_V))
+				break;
+		}
+		size = min_t(u64, size, pn << page->shift);
+		size = min_t(u64, size, vma->size + vma->addr - addr);
+
+		/* Reject any operation to unmanaged regions, and areas that
+		 * have nvkm_memory objects mapped in them already.
+		 */
+		if (!vma->mapref || vma->memory) {
+			ret = -EINVAL;
+			goto next;
+		}
+
+		/* In order to both properly refcount GPU page tables, and
+		 * prevent "normal" mappings and these direct mappings from
+		 * interfering with each other, we need to track contiguous
+		 * ranges that have been mapped with this interface.
+		 *
+		 * Here we attempt to either split an existing VMA so we're
+		 * able to flag the region as either unmapped/mapped, or to
+		 * merge with adjacent VMAs that are already compatible.
+		 *
+		 * If the region is already compatible, nothing is required.
+		 */
+		if (map != mapped) {
+			tmp = nvkm_vmm_pfn_split_merge(vmm, vma, addr, size,
+						       page -
+						       vmm->func->page, map);
+			if (WARN_ON(!tmp)) {
+				ret = -ENOMEM;
+				goto next;
+			}
+
+			if ((tmp->mapped = map))
+				tmp->refd = page - vmm->func->page;
+			else
+				tmp->refd = NVKM_VMA_PAGE_NONE;
+			vma = tmp;
+		}
+
+		/* Update HW page tables. */
+		if (map) {
+			struct nvkm_vmm_map args;
+			args.page = page;
+			args.pfn = &pfn[pi];
+
+			if (!mapped) {
+				ret = nvkm_vmm_ptes_get_map(vmm, page, addr,
+							    size, &args, page->
+							    desc->func->pfn);
+			} else {
+				nvkm_vmm_ptes_map(vmm, page, addr, size, &args,
+						  page->desc->func->pfn);
+			}
+		} else {
+			if (mapped) {
+				nvkm_vmm_ptes_unmap_put(vmm, page, addr, size,
+							false, true);
+			}
+		}
+
+next:
+		/* Iterate to next operation. */
+		if (vma->addr + vma->size == addr + size)
+			vma = node(vma, next);
+		start += size;
+
+		if (ret) {
+			/* Failure is signalled by clearing the valid bit on
+			 * any PFN that couldn't be modified as requested.
+			 */
+			while (size) {
+				pfn[pi++] = NVKM_VMM_PFN_NONE;
+				size -= 1 << page->shift;
+			}
+		} else {
+			pi += size >> page->shift;
+		}
+	} while (vma && start < limit);
+
+	return 0;
+}
+
 void
 nvkm_vmm_unmap_region(struct nvkm_vmm *vmm, struct nvkm_vma *vma)
 {
-	struct nvkm_vma *next = node(vma, next);
 	struct nvkm_vma *prev = NULL;
+	struct nvkm_vma *next;
 
 	nvkm_memory_tags_put(vma->memory, vmm->mmu->subdev.device, &vma->tags);
 	nvkm_memory_unref(&vma->memory);
 	vma->mapped = false;
 
-	if (!vma->part || ((prev = node(vma, prev)), prev->mapped))
+	if (vma->part && (prev = node(vma, prev)) && prev->mapped)
 		prev = NULL;
-	if (!next->part || next->mapped)
+	if ((next = node(vma, next)) && (!next->part || next->mapped))
 		next = NULL;
 	nvkm_vmm_node_merge(vmm, prev, vma, next, vma->size);
 }
 
 void
-nvkm_vmm_unmap_locked(struct nvkm_vmm *vmm, struct nvkm_vma *vma)
+nvkm_vmm_unmap_locked(struct nvkm_vmm *vmm, struct nvkm_vma *vma, bool pfn)
 {
 	const struct nvkm_vmm_page *page = &vmm->func->page[vma->refd];
 
 	if (vma->mapref) {
-		nvkm_vmm_ptes_unmap_put(vmm, page, vma->addr, vma->size, vma->sparse);
+		nvkm_vmm_ptes_unmap_put(vmm, page, vma->addr, vma->size, vma->sparse, pfn);
 		vma->refd = NVKM_VMA_PAGE_NONE;
 	} else {
-		nvkm_vmm_ptes_unmap(vmm, page, vma->addr, vma->size, vma->sparse);
+		nvkm_vmm_ptes_unmap(vmm, page, vma->addr, vma->size, vma->sparse, pfn);
 	}
 
 	nvkm_vmm_unmap_region(vmm, vma);
@@ -1142,7 +1367,7 @@ nvkm_vmm_unmap(struct nvkm_vmm *vmm, struct nvkm_vma *vma)
 {
 	if (vma->memory) {
 		mutex_lock(&vmm->mutex);
-		nvkm_vmm_unmap_locked(vmm, vma);
+		nvkm_vmm_unmap_locked(vmm, vma, false);
 		mutex_unlock(&vmm->mutex);
 	}
 }
@@ -1341,7 +1566,8 @@ nvkm_vmm_put_locked(struct nvkm_vmm *vmm, struct nvkm_vma *vma)
 				 * the page tree.
 				 */
 				nvkm_vmm_ptes_unmap_put(vmm, &page[refd], addr,
-							size, vma->sparse);
+							size, vma->sparse,
+							!mem);
 			} else
 			if (refd != NVKM_VMA_PAGE_NONE) {
 				/* Drop allocation-time PTE references. */
@@ -1577,7 +1803,7 @@ nvkm_vmm_join(struct nvkm_vmm *vmm, struct nvkm_memory *inst)
 }
 
 static bool
-nvkm_vmm_boot_ptes(struct nvkm_vmm_iter *it, u32 ptei, u32 ptes)
+nvkm_vmm_boot_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 ptes)
 {
 	const struct nvkm_vmm_desc *desc = it->desc;
 	const int type = desc->type == SPT;
@@ -1599,7 +1825,7 @@ nvkm_vmm_boot(struct nvkm_vmm *vmm)
 	if (ret)
 		return ret;
 
-	nvkm_vmm_iter(vmm, page, vmm->start, limit, "bootstrap", false,
+	nvkm_vmm_iter(vmm, page, vmm->start, limit, "bootstrap", false, false,
 		      nvkm_vmm_boot_ptes, NULL, NULL, NULL);
 	vmm->bootstrapped = true;
 	return 0;

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h

@@ -67,6 +67,10 @@ struct nvkm_vmm_desc_func {
 	nvkm_vmm_pte_func mem;
 	nvkm_vmm_pte_func dma;
 	nvkm_vmm_pte_func sgl;
+
+	nvkm_vmm_pte_func pfn;
+	bool (*pfn_clear)(struct nvkm_vmm *, struct nvkm_mmu_pt *, u32 ptei, u32 ptes);
+	nvkm_vmm_pxe_func pfn_unmap;
 };
 
 extern const struct nvkm_vmm_desc_func gf100_vmm_pgd;
@@ -166,8 +170,20 @@ int nvkm_vmm_get_locked(struct nvkm_vmm *, bool getref, bool mapref,
 			bool sparse, u8 page, u8 align, u64 size,
 			struct nvkm_vma **pvma);
 void nvkm_vmm_put_locked(struct nvkm_vmm *, struct nvkm_vma *);
-void nvkm_vmm_unmap_locked(struct nvkm_vmm *, struct nvkm_vma *);
-void nvkm_vmm_unmap_region(struct nvkm_vmm *vmm, struct nvkm_vma *vma);
+void nvkm_vmm_unmap_locked(struct nvkm_vmm *, struct nvkm_vma *, bool pfn);
+void nvkm_vmm_unmap_region(struct nvkm_vmm *, struct nvkm_vma *);
+
+#define NVKM_VMM_PFN_ADDR                                 0xfffffffffffff000ULL
+#define NVKM_VMM_PFN_ADDR_SHIFT                                              12
+#define NVKM_VMM_PFN_APER                                 0x00000000000000f0ULL
+#define NVKM_VMM_PFN_HOST                                 0x0000000000000000ULL
+#define NVKM_VMM_PFN_VRAM                                 0x0000000000000010ULL
+#define NVKM_VMM_PFN_W                                    0x0000000000000002ULL
+#define NVKM_VMM_PFN_V                                    0x0000000000000001ULL
+#define NVKM_VMM_PFN_NONE                                 0x0000000000000000ULL
+
+int nvkm_vmm_pfn_map(struct nvkm_vmm *, u8 page, u64 addr, u64 size, u64 *pfn);
+int nvkm_vmm_pfn_unmap(struct nvkm_vmm *, u64 addr, u64 size);
 
 struct nvkm_vma *nvkm_vma_tail(struct nvkm_vma *, u64 tail);
 

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmmgp100.c

@@ -27,6 +27,81 @@
 #include <nvif/ifc00d.h>
 #include <nvif/unpack.h>
 
+static void
+gp100_vmm_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 * 8 + 0);
+		u32 datahi = nvkm_ro32(pt->memory, pt->base + ptei * 8 + 4);
+		u64 data   = (u64)datahi << 32 | datalo;
+		if ((data & (3ULL << 1)) != 0) {
+			addr = (data >> 8) << 12;
+			dma_unmap_page(dev, addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+		}
+		ptei++;
+	}
+	nvkm_done(pt->memory);
+}
+
+static bool
+gp100_vmm_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 * 8 + 0);
+		u32 datahi = nvkm_ro32(pt->memory, pt->base + ptei * 8 + 4);
+		u64 data   = (u64)datahi << 32 | datalo;
+		if ((data & BIT_ULL(0)) && (data & (3ULL << 1)) != 0) {
+			VMM_WO064(pt, vmm, ptei * 8, data & ~BIT_ULL(0));
+			dma = true;
+		}
+		ptei++;
+	}
+	nvkm_done(pt->memory);
+	return dma;
+}
+
+static void
+gp100_vmm_pgt_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);
+	while (ptes--) {
+		u64 data = 0;
+		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,
+					    PAGE_SIZE, 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++ * 8, data);
+		map->pfn++;
+	}
+	nvkm_done(pt->memory);
+}
+
 static inline void
 gp100_vmm_pgt_pte(struct nvkm_vmm *vmm, struct nvkm_mmu_pt *pt,
 		  u32 ptei, u32 ptes, struct nvkm_vmm_map *map, u64 addr)
@@ -89,6 +164,9 @@ gp100_vmm_desc_spt = {
 	.mem = gp100_vmm_pgt_mem,
 	.dma = gp100_vmm_pgt_dma,
 	.sgl = gp100_vmm_pgt_sgl,
+	.pfn = gp100_vmm_pgt_pfn,
+	.pfn_clear = gp100_vmm_pfn_clear,
+	.pfn_unmap = gp100_vmm_pfn_unmap,
 };
 
 static void