[PATCH 12/15] HMM: add dirty range helper (toggle dirty bit inside mirror page table) v2.

["Jérôme Glisse" <jglisse@redhat.com>]

Device driver must properly toggle the dirty inside the mirror page table
so dirtyness is properly accounted when core mm code needs to know. Provide
a simple helper to toggle that bit for a range of address.

Changed since v1:
  - Adapt to HMM page table changes.

Signed-off-by: JA(C)rA'me Glisse <jglisse@redhat.com>
---
 include/linux/hmm.h |  3 +++
 mm/hmm.c            | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 10e1558..4bc132a 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -268,6 +268,9 @@ int hmm_mirror_fault(struct hmm_mirror *mirror, struct hmm_event *event);
 void hmm_mirror_range_discard(struct hmm_mirror *mirror,
 			      unsigned long start,
 			      unsigned long end);
+void hmm_mirror_range_dirty(struct hmm_mirror *mirror,
+			    unsigned long start,
+			    unsigned long end);
 
 
 #endif /* CONFIG_HMM */
diff --git a/mm/hmm.c b/mm/hmm.c
index 5b3aec0..fa59581 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -920,6 +920,44 @@ void hmm_mirror_range_discard(struct hmm_mirror *mirror,
 }
 EXPORT_SYMBOL(hmm_mirror_range_discard);
 
+/* hmm_mirror_range_dirty() - toggle dirty bit for a range of address.
+ *
+ * @mirror: The mirror struct.
+ * @start: Start address of the range to discard (inclusive).
+ * @end: End address of the range to discard (exclusive).
+ *
+ * Call when device driver want to toggle the dirty bit for a range of address.
+ * Useful when the device driver just want to toggle the bit for whole range
+ * without walking the mirror page table itself.
+ *
+ * Note this function does not directly dirty the page behind an address, but
+ * this will happen once address is invalidated or discard by device driver or
+ * core mm code.
+ */
+void hmm_mirror_range_dirty(struct hmm_mirror *mirror,
+			    unsigned long start,
+			    unsigned long end)
+{
+	struct hmm_pt_iter iter;
+	unsigned long addr;
+
+	hmm_pt_iter_init(&iter, &mirror->pt);
+	for (addr = start; addr != end;) {
+		unsigned long next = end;
+		dma_addr_t *hmm_pte;
+
+		hmm_pte = hmm_pt_iter_walk(&iter, &addr, &next);
+		for (; hmm_pte && addr != next; hmm_pte++, addr += PAGE_SIZE) {
+			if (!hmm_pte_test_valid_pfn(hmm_pte) ||
+			    !hmm_pte_test_write(hmm_pte))
+				continue;
+			hmm_pte_set_dirty(hmm_pte);
+		}
+	}
+	hmm_pt_iter_fini(&iter);
+}
+EXPORT_SYMBOL(hmm_mirror_range_dirty);
+
 /* hmm_mirror_register() - register mirror against current process for a device.
  *
  * @mirror: The mirror struct being registered.
-- 
1.9.3

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