mm/hmm: check the device private page owner in hmm_range_fault()

hmm_range_fault() will succeed for any kind of device private memory, even if it doesn't belong to the calling entity. While nouveau has some crude checks for that, they are broken because they assume nouveau is the only user of device private memory. Fix this by passing in an expected pgmap owner in the hmm_range_fault structure. If a device_private page is found and doesn't match the owner then it is treated as an non-present and non-faultable page. This prevents a bug in amdgpu, where it doesn't know how to handle device_private pages, but hmm_range_fault would return them anyhow.

Christoph Hellwig committed 6 years ago

Commit 08ddddd1 parent 17ffdc43 files · +11 −13Browse files

Unified · Split

3 files

drivers/gpu/drm/nouveau/nouveau_dmem.c +0 −12
include/linux/hmm.h +2 −0
mm/hmm.c +9 −1

drivers/gpu/drm/nouveau/nouveau_dmem.c+0−12

 	return ret;
 }
-static inline bool
-nouveau_dmem_page(struct nouveau_drm *drm, struct page *page)
-{
-	return is_device_private_page(page) && drm->dmem == page_to_dmem(page);
-}
 void
 nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
 			 struct hmm_range *range)
 		if (!is_device_private_page(page))
 			continue;
-		if (!nouveau_dmem_page(drm, page)) {
-			WARN(1, "Some unknown device memory !\n");
-			range->pfns[i] = 0;
-			continue;
-		}
 		addr = nouveau_dmem_page_addr(page);
 		range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
 		range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;

include/linux/hmm.h+2−0

  * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
  * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
  * @valid: pfns array did not change since it has been fill by an HMM function
+ * @dev_private_owner: owner of device private pages
  */
 struct hmm_range {
 	struct mmu_interval_notifier *notifier;
 	uint64_t		default_flags;
 	uint64_t		pfn_flags_mask;
 	uint8_t			pfn_shift;
+	void			*dev_private_owner;
 };
 /*

mm/hmm.c+9−1

 		unsigned long end, uint64_t *pfns, pmd_t pmd);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+static inline bool hmm_is_device_private_entry(struct hmm_range *range,
+		swp_entry_t entry)
+{
+	return is_device_private_entry(entry) &&
+		device_private_entry_to_page(entry)->pgmap->owner ==
+		range->dev_private_owner;
+}
 static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
 {
 	if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
 		 * Never fault in device private pages pages, but just report
 		 * the PFN even if not present.
 		 */
-		if (is_device_private_entry(entry)) {
+		if (hmm_is_device_private_entry(range, entry)) {
 			*pfn = hmm_device_entry_from_pfn(range,
 					    swp_offset(entry));
 			*pfn |= range->flags[HMM_PFN_VALID];