mm/hmm/mirror: device page fault handler

This handles page fault on behalf of device driver, unlike handle_mm_fault() it does not trigger migration back to system memory for device memory. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Jérôme Glisse <[email protected]> Signed-off-by: Evgeny Baskakov <[email protected]> Signed-off-by: John Hubbard <[email protected]> Signed-off-by: Mark Hairgrove <[email protected]> Signed-off-by: Sherry Cheung <[email protected]> Signed-off-by: Subhash Gutti <[email protected]> Cc: Aneesh Kumar <[email protected]> Cc: Balbir Singh <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Dan Williams <[email protected]> Cc: David Nellans <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Ross Zwisler <[email protected]> Cc: Vladimir Davydov <[email protected]> Cc: Bob Liu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
morbidrsa · Sep 9, 2017 · 74eee18 · 74eee18
1 parent da4c3c7
commit 74eee18
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diff --git a/include/linux/hmm.h b/include/linux/hmm.h
@@ -292,6 +292,33 @@ int hmm_vma_get_pfns(struct vm_area_struct *vma,
 		     unsigned long end,
 		     hmm_pfn_t *pfns);
 bool hmm_vma_range_done(struct vm_area_struct *vma, struct hmm_range *range);
+
+
+/*
+ * Fault memory on behalf of device driver. Unlike handle_mm_fault(), this will
+ * not migrate any device memory back to system memory. The hmm_pfn_t array will
+ * be updated with the fault result and current snapshot of the CPU page table
+ * for the range.
+ *
+ * The mmap_sem must be taken in read mode before entering and it might be
+ * dropped by the function if the block argument is false. In that case, the
+ * function returns -EAGAIN.
+ *
+ * Return value does not reflect if the fault was successful for every single
+ * address or not. Therefore, the caller must to inspect the hmm_pfn_t array to
+ * determine fault status for each address.
+ *
+ * Trying to fault inside an invalid vma will result in -EINVAL.
+ *
+ * See the function description in mm/hmm.c for further documentation.
+ */
+int hmm_vma_fault(struct vm_area_struct *vma,
+		  struct hmm_range *range,
+		  unsigned long start,
+		  unsigned long end,
+		  hmm_pfn_t *pfns,
+		  bool write,
+		  bool block);
 #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */