Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull hmm updates from Jason Gunthorpe:
 "This series adds a selftest for hmm_range_fault() and several of the
  DEVICE_PRIVATE migration related actions, and another simplification
  for hmm_range_fault()'s API.

   - Simplify hmm_range_fault() with a simpler return code, no
     HMM_PFN_SPECIAL, and no customizable output PFN format

   - Add a selftest for hmm_range_fault() and DEVICE_PRIVATE related
     functionality"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  MAINTAINERS: add HMM selftests
  mm/hmm/test: add selftests for HMM
  mm/hmm/test: add selftest driver for HMM
  mm/hmm: remove the customizable pfn format from hmm_range_fault
  mm/hmm: remove HMM_PFN_SPECIAL
  drm/amdgpu: remove dead code after hmm_range_fault()
  mm/hmm: make hmm_range_fault return 0 or -1

Documentation/vm/hmm.rst

@@ -161,7 +161,7 @@ device must complete the update before the driver callback returns.
 When the device driver wants to populate a range of virtual addresses, it can
 use::
 
-  long hmm_range_fault(struct hmm_range *range);
+  int hmm_range_fault(struct hmm_range *range);
 
 It will trigger a page fault on missing or read-only entries if write access is
 requested (see below). Page faults use the generic mm page fault code path just
@@ -184,10 +184,7 @@ The usage pattern is::
       range.notifier = &interval_sub;
       range.start = ...;
       range.end = ...;
-      range.pfns = ...;
-      range.flags = ...;
-      range.values = ...;
-      range.pfn_shift = ...;
+      range.hmm_pfns = ...;
 
       if (!mmget_not_zero(interval_sub->notifier.mm))
           return -EFAULT;
@@ -229,15 +226,10 @@ The hmm_range struct has 2 fields, default_flags and pfn_flags_mask, that specif
 fault or snapshot policy for the whole range instead of having to set them
 for each entry in the pfns array.
 
-For instance, if the device flags for range.flags are::
+For instance if the device driver wants pages for a range with at least read
+permission, it sets::
 
-    range.flags[HMM_PFN_VALID] = (1 << 63);
-    range.flags[HMM_PFN_WRITE] = (1 << 62);
-
-and the device driver wants pages for a range with at least read permission,
-it sets::
-
-    range->default_flags = (1 << 63);
+    range->default_flags = HMM_PFN_REQ_FAULT;
     range->pfn_flags_mask = 0;
 
 and calls hmm_range_fault() as described above. This will fill fault all pages
@@ -246,18 +238,18 @@ in the range with at least read permission.
 Now let's say the driver wants to do the same except for one page in the range for
 which it wants to have write permission. Now driver set::
 
-    range->default_flags = (1 << 63);
-    range->pfn_flags_mask = (1 << 62);
-    range->pfns[index_of_write] = (1 << 62);
+    range->default_flags = HMM_PFN_REQ_FAULT;
+    range->pfn_flags_mask = HMM_PFN_REQ_WRITE;
+    range->pfns[index_of_write] = HMM_PFN_REQ_WRITE;
 
 With this, HMM will fault in all pages with at least read (i.e., valid) and for the
 address == range->start + (index_of_write << PAGE_SHIFT) it will fault with
 write permission i.e., if the CPU pte does not have write permission set then HMM
 will call handle_mm_fault().
 
-Note that HMM will populate the pfns array with write permission for any page
-that is mapped with CPU write permission no matter what values are set
-in default_flags or pfn_flags_mask.
+After hmm_range_fault completes the flag bits are set to the current state of
+the page tables, ie HMM_PFN_VALID | HMM_PFN_WRITE will be set if the page is
+writable.
 
 
 Represent and manage device memory from core kernel point of view

MAINTAINERS

@@ -7768,7 +7768,9 @@ L:	linux-mm@kvack.org
 S:	Maintained
 F:	Documentation/vm/hmm.rst
 F:	include/linux/hmm*
+F:	lib/test_hmm*
 F:	mm/hmm*
+F:	tools/testing/selftests/vm/*hmm*
 
 HOST AP DRIVER
 M:	Jouni Malinen <j@w1.fi>

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -766,18 +766,6 @@ struct amdgpu_ttm_tt {
 };
 
 #ifdef CONFIG_DRM_AMDGPU_USERPTR
-/* flags used by HMM internal, not related to CPU/GPU PTE flags */
-static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {
-	(1 << 0), /* HMM_PFN_VALID */
-	(1 << 1), /* HMM_PFN_WRITE */
-};
-
-static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {
-	0xfffffffffffffffeUL, /* HMM_PFN_ERROR */
-	0, /* HMM_PFN_NONE */
-	0xfffffffffffffffcUL /* HMM_PFN_SPECIAL */
-};
-
 /**
  * amdgpu_ttm_tt_get_user_pages - get device accessible pages that back user
  * memory and start HMM tracking CPU page table update
@@ -816,18 +804,15 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 		goto out;
 	}
 	range->notifier = &bo->notifier;
-	range->flags = hmm_range_flags;
-	range->values = hmm_range_values;
-	range->pfn_shift = PAGE_SHIFT;
 	range->start = bo->notifier.interval_tree.start;
 	range->end = bo->notifier.interval_tree.last + 1;
-	range->default_flags = hmm_range_flags[HMM_PFN_VALID];
+	range->default_flags = HMM_PFN_REQ_FAULT;
 	if (!amdgpu_ttm_tt_is_readonly(ttm))
-		range->default_flags |= range->flags[HMM_PFN_WRITE];
+		range->default_flags |= HMM_PFN_REQ_WRITE;
 
-	range->pfns = kvmalloc_array(ttm->num_pages, sizeof(*range->pfns),
-				     GFP_KERNEL);
-	if (unlikely(!range->pfns)) {
+	range->hmm_pfns = kvmalloc_array(ttm->num_pages,
+					 sizeof(*range->hmm_pfns), GFP_KERNEL);
+	if (unlikely(!range->hmm_pfns)) {
 		r = -ENOMEM;
 		goto out_free_ranges;
 	}
@@ -852,27 +837,23 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 	down_read(&mm->mmap_sem);
 	r = hmm_range_fault(range);
 	up_read(&mm->mmap_sem);
-	if (unlikely(r <= 0)) {
+	if (unlikely(r)) {
 		/*
 		 * FIXME: This timeout should encompass the retry from
 		 * mmu_interval_read_retry() as well.
 		 */
-		if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
+		if (r == -EBUSY && !time_after(jiffies, timeout))
 			goto retry;
 		goto out_free_pfns;
 	}
 
-	for (i = 0; i < ttm->num_pages; i++) {
-		/* FIXME: The pages cannot be touched outside the notifier_lock */
-		pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
-		if (unlikely(!pages[i])) {
-			pr_err("Page fault failed for pfn[%lu] = 0x%llx\n",
-			       i, range->pfns[i]);
-			r = -ENOMEM;
-
-			goto out_free_pfns;
-		}
-	}
+	/*
+	 * Due to default_flags, all pages are HMM_PFN_VALID or
+	 * hmm_range_fault() fails. FIXME: The pages cannot be touched outside
+	 * the notifier_lock, and mmu_interval_read_retry() must be done first.
+	 */
+	for (i = 0; i < ttm->num_pages; i++)
+		pages[i] = hmm_pfn_to_page(range->hmm_pfns[i]);
 
 	gtt->range = range;
 	mmput(mm);
@@ -882,7 +863,7 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 out_unlock:
 	up_read(&mm->mmap_sem);
 out_free_pfns:
-	kvfree(range->pfns);
+	kvfree(range->hmm_pfns);
 out_free_ranges:
 	kfree(range);
 out:
@@ -907,7 +888,7 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm)
 	DRM_DEBUG_DRIVER("user_pages_done 0x%llx pages 0x%lx\n",
 		gtt->userptr, ttm->num_pages);
 
-	WARN_ONCE(!gtt->range || !gtt->range->pfns,
+	WARN_ONCE(!gtt->range || !gtt->range->hmm_pfns,
 		"No user pages to check\n");
 
 	if (gtt->range) {
@@ -917,7 +898,7 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm)
 		 */
 		r = mmu_interval_read_retry(gtt->range->notifier,
 					 gtt->range->notifier_seq);
-		kvfree(gtt->range->pfns);
+		kvfree(gtt->range->hmm_pfns);
 		kfree(gtt->range);
 		gtt->range = NULL;
 	}
@@ -1008,8 +989,7 @@ static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
 
 		for (i = 0; i < ttm->num_pages; i++) {
 			if (ttm->pages[i] !=
-				hmm_device_entry_to_page(gtt->range,
-					      gtt->range->pfns[i]))
+			    hmm_pfn_to_page(gtt->range->hmm_pfns[i]))
 				break;
 		}
 

drivers/gpu/drm/nouveau/nouveau_dmem.c

@@ -85,7 +85,7 @@ static inline struct nouveau_dmem *page_to_dmem(struct page *page)
 	return container_of(page->pgmap, struct nouveau_dmem, pagemap);
 }
 
-static unsigned long nouveau_dmem_page_addr(struct page *page)
+unsigned long nouveau_dmem_page_addr(struct page *page)
 {
 	struct nouveau_dmem_chunk *chunk = page->zone_device_data;
 	unsigned long idx = page_to_pfn(page) - chunk->pfn_first;
@@ -671,28 +671,3 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
 out:
 	return ret;
 }
-
-void
-nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
-			 struct hmm_range *range)
-{
-	unsigned long i, npages;
-
-	npages = (range->end - range->start) >> PAGE_SHIFT;
-	for (i = 0; i < npages; ++i) {
-		struct page *page;
-		uint64_t addr;
-
-		page = hmm_device_entry_to_page(range, range->pfns[i]);
-		if (page == NULL)
-			continue;
-
-		if (!is_device_private_page(page))
-			continue;
-
-		addr = nouveau_dmem_page_addr(page);
-		range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
-		range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;
-		range->pfns[i] |= NVIF_VMM_PFNMAP_V0_VRAM;
-	}
-}

drivers/gpu/drm/nouveau/nouveau_dmem.h

@@ -37,9 +37,8 @@ int nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
 			     struct vm_area_struct *vma,
 			     unsigned long start,
 			     unsigned long end);
+unsigned long nouveau_dmem_page_addr(struct page *page);
 
-void nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
-			      struct hmm_range *range);
 #else /* IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM) */
 static inline void nouveau_dmem_init(struct nouveau_drm *drm) {}
 static inline void nouveau_dmem_fini(struct nouveau_drm *drm) {}

drivers/gpu/drm/nouveau/nouveau_svm.c

@@ -369,19 +369,6 @@ nouveau_svmm_init(struct drm_device *dev, void *data,
 	return ret;
 }
 
-static const u64
-nouveau_svm_pfn_flags[HMM_PFN_FLAG_MAX] = {
-	[HMM_PFN_VALID         ] = NVIF_VMM_PFNMAP_V0_V,
-	[HMM_PFN_WRITE         ] = NVIF_VMM_PFNMAP_V0_W,
-};
-
-static const u64
-nouveau_svm_pfn_values[HMM_PFN_VALUE_MAX] = {
-	[HMM_PFN_ERROR  ] = ~NVIF_VMM_PFNMAP_V0_V,
-	[HMM_PFN_NONE   ] =  NVIF_VMM_PFNMAP_V0_NONE,
-	[HMM_PFN_SPECIAL] = ~NVIF_VMM_PFNMAP_V0_V,
-};
-
 /* Issue fault replay for GPU to retry accesses that faulted previously. */
 static void
 nouveau_svm_fault_replay(struct nouveau_svm *svm)
@@ -519,9 +506,45 @@ static const struct mmu_interval_notifier_ops nouveau_svm_mni_ops = {
 	.invalidate = nouveau_svm_range_invalidate,
 };
 
+static void nouveau_hmm_convert_pfn(struct nouveau_drm *drm,
+				    struct hmm_range *range, u64 *ioctl_addr)
+{
+	unsigned long i, npages;
+
+	/*
+	 * The ioctl_addr 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;
+	}
+}
+
 static int nouveau_range_fault(struct nouveau_svmm *svmm,
 			       struct nouveau_drm *drm, void *data, u32 size,
-			       u64 *pfns, struct svm_notifier *notifier)
+			       unsigned long hmm_pfns[], u64 *ioctl_addr,
+			       struct svm_notifier *notifier)
 {
 	unsigned long timeout =
 		jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
@@ -530,26 +553,27 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 		.notifier = &notifier->notifier,
 		.start = notifier->notifier.interval_tree.start,
 		.end = notifier->notifier.interval_tree.last + 1,
-		.pfns = pfns,
-		.flags = nouveau_svm_pfn_flags,
-		.values = nouveau_svm_pfn_values,
-		.pfn_shift = NVIF_VMM_PFNMAP_V0_ADDR_SHIFT,
+		.pfn_flags_mask = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_WRITE,
+		.hmm_pfns = hmm_pfns,
 	};
 	struct mm_struct *mm = notifier->notifier.mm;
-	long ret;
+	int ret;
 
 	while (true) {
 		if (time_after(jiffies, timeout))
 			return -EBUSY;
 
 		range.notifier_seq = mmu_interval_read_begin(range.notifier);
-		range.default_flags = 0;
-		range.pfn_flags_mask = -1UL;
 		down_read(&mm->mmap_sem);
 		ret = hmm_range_fault(&range);
 		up_read(&mm->mmap_sem);
-		if (ret <= 0) {
-			if (ret == 0 || ret == -EBUSY)
+		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;
 		}
@@ -563,7 +587,7 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 		break;
 	}
 
-	nouveau_dmem_convert_pfn(drm, &range);
+	nouveau_hmm_convert_pfn(drm, &range, ioctl_addr);
 
 	svmm->vmm->vmm.object.client->super = true;
 	ret = nvif_object_ioctl(&svmm->vmm->vmm.object, data, size, NULL);
@@ -590,6 +614,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
 		} i;
 		u64 phys[16];
 	} args;
+	unsigned long hmm_pfns[ARRAY_SIZE(args.phys)];
 	struct vm_area_struct *vma;
 	u64 inst, start, limit;
 	int fi, fn, pi, fill;
@@ -705,12 +730,17 @@ nouveau_svm_fault(struct nvif_notify *notify)
 			 * access flags.
 			 *XXX: atomic?
 			 */
-			if (buffer->fault[fn]->access != 0 /* READ. */ &&
-			    buffer->fault[fn]->access != 3 /* PREFETCH. */) {
-				args.phys[pi++] = NVIF_VMM_PFNMAP_V0_V |
-						  NVIF_VMM_PFNMAP_V0_W;
-			} else {
-				args.phys[pi++] = NVIF_VMM_PFNMAP_V0_V;
+			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;
 
@@ -738,7 +768,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
 			fill = (buffer->fault[fn    ]->addr -
 				buffer->fault[fn - 1]->addr) >> PAGE_SHIFT;
 			while (--fill)
-				args.phys[pi++] = NVIF_VMM_PFNMAP_V0_NONE;
+				hmm_pfns[pi++] = 0;
 		}
 
 		SVMM_DBG(svmm, "wndw %016llx-%016llx covering %d fault(s)",
@@ -754,7 +784,7 @@ nouveau_svm_fault(struct nvif_notify *notify)
 			ret = nouveau_range_fault(
 				svmm, svm->drm, &args,
 				sizeof(args.i) + pi * sizeof(args.phys[0]),
-				args.phys, &notifier);
+				hmm_pfns, args.phys, &notifier);
 			mmu_interval_notifier_remove(&notifier.notifier);
 		}
 		mmput(mm);

include/linux/hmm.h

@@ -19,51 +19,47 @@
 #include <linux/mmu_notifier.h>
 
 /*
- * hmm_pfn_flag_e - HMM flag enums
+ * On output:
+ * 0             - The page is faultable and a future call with 
+ *                 HMM_PFN_REQ_FAULT could succeed.
+ * HMM_PFN_VALID - the pfn field points to a valid PFN. This PFN is at
+ *                 least readable. If dev_private_owner is !NULL then this could
+ *                 point at a DEVICE_PRIVATE page.
+ * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
+ * HMM_PFN_ERROR - accessing the pfn is impossible and the device should
+ *                 fail. ie poisoned memory, special pages, no vma, etc
  *
- * Flags:
- * HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
- * HMM_PFN_WRITE: CPU page table has write permission set
- *
- * The driver provides a flags array for mapping page protections to device
- * PTE bits. If the driver valid bit for an entry is bit 3,
- * i.e., (entry & (1 << 3)), then the driver must provide
- * an array in hmm_range.flags with hmm_range.flags[HMM_PFN_VALID] == 1 << 3.
- * Same logic apply to all flags. This is the same idea as vm_page_prot in vma
- * except that this is per device driver rather than per architecture.
+ * On input:
+ * 0                 - Return the current state of the page, do not fault it.
+ * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault()
+ *                     will fail
+ * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault()
+ *                     will fail. Must be combined with HMM_PFN_REQ_FAULT.
  */
-enum hmm_pfn_flag_e {
-	HMM_PFN_VALID = 0,
-	HMM_PFN_WRITE,
-	HMM_PFN_FLAG_MAX
+enum hmm_pfn_flags {
+	/* Output 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),
+
+	/* 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_value_e - HMM pfn special value
- *
- * Flags:
- * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory
- * HMM_PFN_NONE: corresponding CPU page table entry is pte_none()
- * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the
- *      result of vmf_insert_pfn() or vm_insert_page(). Therefore, it should not
- *      be mirrored by a device, because the entry will never have HMM_PFN_VALID
- *      set and the pfn value is undefined.
+ * hmm_pfn_to_page() - return struct page pointed to by a device entry
  *
- * Driver provides values for none entry, error entry, and special entry.
- * Driver can alias (i.e., use same value) error and special, but
- * it should not alias none with error or special.
- *
- * HMM pfn value returned by hmm_vma_get_pfns() or hmm_vma_fault() will be:
- * hmm_range.values[HMM_PFN_ERROR] if CPU page table entry is poisonous,
- * hmm_range.values[HMM_PFN_NONE] if there is no CPU page table entry,
- * hmm_range.values[HMM_PFN_SPECIAL] if CPU page table entry is a special one
+ * 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.
  */
-enum hmm_pfn_value_e {
-	HMM_PFN_ERROR,
-	HMM_PFN_NONE,
-	HMM_PFN_SPECIAL,
-	HMM_PFN_VALUE_MAX
-};
+static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
+{
+	return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
+}
 
 /*
  * struct hmm_range - track invalidation lock on virtual address range
@@ -72,12 +68,9 @@ enum hmm_pfn_value_e {
  * @notifier_seq: result of mmu_interval_read_begin()
  * @start: range virtual start address (inclusive)
  * @end: range virtual end address (exclusive)
- * @pfns: array of pfns (big enough for the range)
- * @flags: pfn flags to match device driver page table
- * @values: pfn value for some special case (none, special, error, ...)
+ * @hmm_pfns: array of pfns (big enough for the range)
  * @default_flags: default flags for the range (write, read, ... see hmm doc)
  * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
- * @pfn_shift: pfn shift value (should be <= PAGE_SHIFT)
  * @dev_private_owner: owner of device private pages
  */
 struct hmm_range {
@@ -85,42 +78,16 @@ struct hmm_range {
 	unsigned long		notifier_seq;
 	unsigned long		start;
 	unsigned long		end;
-	uint64_t		*pfns;
-	const uint64_t		*flags;
-	const uint64_t		*values;
-	uint64_t		default_flags;
-	uint64_t		pfn_flags_mask;
-	uint8_t			pfn_shift;
+	unsigned long		*hmm_pfns;
+	unsigned long		default_flags;
+	unsigned long		pfn_flags_mask;
 	void			*dev_private_owner;
 };
 
-/*
- * hmm_device_entry_to_page() - return struct page pointed to by a device entry
- * @range: range use to decode device entry value
- * @entry: device entry value to get corresponding struct page from
- * Return: struct page pointer if entry is a valid, NULL otherwise
- *
- * If the device entry is valid (ie valid flag set) then return the struct page
- * matching the entry value. Otherwise return NULL.
- */
-static inline struct page *hmm_device_entry_to_page(const struct hmm_range *range,
-						    uint64_t entry)
-{
-	if (entry == range->values[HMM_PFN_NONE])
-		return NULL;
-	if (entry == range->values[HMM_PFN_ERROR])
-		return NULL;
-	if (entry == range->values[HMM_PFN_SPECIAL])
-		return NULL;
-	if (!(entry & range->flags[HMM_PFN_VALID]))
-		return NULL;
-	return pfn_to_page(entry >> range->pfn_shift);
-}
-
 /*
  * Please see Documentation/vm/hmm.rst for how to use the range API.
  */
-long hmm_range_fault(struct hmm_range *range);
+int hmm_range_fault(struct hmm_range *range);
 
 /*
  * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range

lib/Kconfig.debug

@@ -2218,6 +2218,19 @@ config TEST_MEMINIT
 
 	  If unsure, say N.
 
+config TEST_HMM
+	tristate "Test HMM (Heterogeneous Memory Management)"
+	depends on TRANSPARENT_HUGEPAGE
+	depends on DEVICE_PRIVATE
+	select HMM_MIRROR
+	select MMU_NOTIFIER
+	help
+	  This is a pseudo device driver solely for testing HMM.
+	  Say M here if you want to build the HMM test module.
+	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
+
+	  If unsure, say N.
+
 endif # RUNTIME_TESTING_MENU
 
 config MEMTEST

lib/Makefile

@@ -92,6 +92,7 @@ obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o
 obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
 obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
 obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
+obj-$(CONFIG_TEST_HMM) += test_hmm.o
 
 obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/
 

lib/test_hmm_uapi.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * This is a module to test the HMM (Heterogeneous Memory Management) API
+ * of the kernel. It allows a userspace program to expose its entire address
+ * space through the HMM test module device file.
+ */
+#ifndef _LIB_TEST_HMM_UAPI_H
+#define _LIB_TEST_HMM_UAPI_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/*
+ * Structure to pass to the HMM test driver to mimic a device accessing
+ * system memory and ZONE_DEVICE private memory through device page tables.
+ *
+ * @addr: (in) user address the device will read/write
+ * @ptr: (in) user address where device data is copied to/from
+ * @npages: (in) number of pages to read/write
+ * @cpages: (out) number of pages copied
+ * @faults: (out) number of device page faults seen
+ */
+struct hmm_dmirror_cmd {
+	__u64		addr;
+	__u64		ptr;
+	__u64		npages;
+	__u64		cpages;
+	__u64		faults;
+};
+
+/* Expose the address space of the calling process through hmm device file */
+#define HMM_DMIRROR_READ		_IOWR('H', 0x00, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_WRITE		_IOWR('H', 0x01, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_MIGRATE		_IOWR('H', 0x02, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
+
+/*
+ * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
+ * HMM_DMIRROR_PROT_ERROR: no valid mirror PTE for this page
+ * 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_ZERO: special read-only zero page
+ * HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL: Migrated device private page on the
+ *					device the ioctl() is made
+ * HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE: Migrated device private page on some
+ *					other device
+ */
+enum {
+	HMM_DMIRROR_PROT_ERROR			= 0xFF,
+	HMM_DMIRROR_PROT_NONE			= 0x00,
+	HMM_DMIRROR_PROT_READ			= 0x01,
+	HMM_DMIRROR_PROT_WRITE			= 0x02,
+	HMM_DMIRROR_PROT_ZERO			= 0x10,
+	HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL	= 0x20,
+	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
+};
+
+#endif /* _LIB_TEST_HMM_UAPI_H */

tools/testing/selftests/vm/.gitignore

@@ -17,3 +17,4 @@ gup_benchmark
 va_128TBswitch
 map_fixed_noreplace
 write_to_hugetlbfs
+hmm-tests

tools/testing/selftests/vm/Makefile

@@ -7,6 +7,7 @@ CFLAGS = -Wall -I ../../../../usr/include $(EXTRA_CFLAGS)
 LDLIBS = -lrt
 TEST_GEN_FILES = compaction_test
 TEST_GEN_FILES += gup_benchmark
+TEST_GEN_FILES += hmm-tests
 TEST_GEN_FILES += hugepage-mmap
 TEST_GEN_FILES += hugepage-shm
 TEST_GEN_FILES += map_hugetlb
@@ -33,6 +34,8 @@ TEST_FILES := test_vmalloc.sh
 KSFT_KHDR_INSTALL := 1
 include ../lib.mk
 
+$(OUTPUT)/hmm-tests: LDLIBS += -lhugetlbfs -lpthread
+
 $(OUTPUT)/userfaultfd: LDLIBS += -lpthread
 
 $(OUTPUT)/mlock-random-test: LDLIBS += -lcap

tools/testing/selftests/vm/config

 CONFIG_SYSVIPC=y
 CONFIG_USERFAULTFD=y
 CONFIG_TEST_VMALLOC=m
+CONFIG_DEVICE_PRIVATE=y
+CONFIG_TEST_HMM=m

tools/testing/selftests/vm/run_vmtests

@@ -307,4 +307,20 @@ else
 	echo "[FAIL]"
 	exitcode=1
 fi
+
+echo "running HMM smoke test"
+echo "------------------------------------"
+./test_hmm.sh smoke
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+	echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+	echo "[SKIP]"
+	exitcode=$ksft_skip
+else
+	echo "[FAIL]"
+	exitcode=1
+fi
+
 exit $exitcode

tools/testing/selftests/vm/test_hmm.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2018 Uladzislau Rezki (Sony) <urezki@gmail.com>
+#
+# This is a test script for the kernel test driver to analyse vmalloc
+# allocator. Therefore it is just a kernel module loader. You can specify
+# and pass different parameters in order to:
+#     a) analyse performance of vmalloc allocations;
+#     b) stressing and stability check of vmalloc subsystem.
+
+TEST_NAME="test_hmm"
+DRIVER="test_hmm"
+
+# 1 if fails
+exitcode=1
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+check_test_requirements()
+{
+	uid=$(id -u)
+	if [ $uid -ne 0 ]; then
+		echo "$0: Must be run as root"
+		exit $ksft_skip
+	fi
+
+	if ! which modprobe > /dev/null 2>&1; then
+		echo "$0: You need modprobe installed"
+		exit $ksft_skip
+	fi
+
+	if ! modinfo $DRIVER > /dev/null 2>&1; then
+		echo "$0: You must have the following enabled in your kernel:"
+		echo "CONFIG_TEST_HMM=m"
+		exit $ksft_skip
+	fi
+}
+
+load_driver()
+{
+	modprobe $DRIVER > /dev/null 2>&1
+	if [ $? == 0 ]; then
+		major=$(awk "\$2==\"HMM_DMIRROR\" {print \$1}" /proc/devices)
+		mknod /dev/hmm_dmirror0 c $major 0
+		mknod /dev/hmm_dmirror1 c $major 1
+	fi
+}
+
+unload_driver()
+{
+	modprobe -r $DRIVER > /dev/null 2>&1
+	rm -f /dev/hmm_dmirror?
+}
+
+run_smoke()
+{
+	echo "Running smoke test. Note, this test provides basic coverage."
+
+	load_driver
+	$(dirname "${BASH_SOURCE[0]}")/hmm-tests
+	unload_driver
+}
+
+usage()
+{
+	echo -n "Usage: $0"
+	echo
+	echo "Example usage:"
+	echo
+	echo "# Shows help message"
+	echo "./${TEST_NAME}.sh"
+	echo
+	echo "# Smoke testing"
+	echo "./${TEST_NAME}.sh smoke"
+	echo
+	exit 0
+}
+
+function run_test()
+{
+	if [ $# -eq 0 ]; then
+		usage
+	else
+		if [ "$1" = "smoke" ]; then
+			run_smoke
+		else
+			usage
+		fi
+	fi
+}
+
+check_test_requirements
+run_test $@
+
+exit 0