[PATCH 12/36] HMM: add dirty range helper (to toggle dirty bit inside mirror page table).

[j.glisse@gmail.com]

From: JA(C)rA'me 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.

Signed-off-by: JA(C)rA'me Glisse <jglisse@redhat.com>
---
 include/linux/hmm.h |  3 +++
 mm/hmm.c            | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index ec05df8..186f497 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -253,6 +253,9 @@ 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 4cab3f2..21fda9f 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -940,6 +940,53 @@ 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.
+ * Usefull 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);
+	for (addr = start; addr != end;) {
+		unsigned long cend, next;
+		dma_addr_t *hmm_pte;
+
+		hmm_pte = hmm_pt_iter_update(&iter, &mirror->pt, addr);
+		if (!hmm_pte) {
+			addr = hmm_pt_iter_next(&iter, &mirror->pt,
+						addr, end);
+			continue;
+		}
+		cend = hmm_pt_level_next(&mirror->pt, addr, end,
+					 mirror->pt.llevel - 1);
+		do {
+			next = hmm_pt_level_next(&mirror->pt, addr, cend,
+						 mirror->pt.llevel);
+			if (!hmm_pte_test_valid_pfn(hmm_pte) ||
+			    !hmm_pte_test_write(hmm_pte))
+				continue;
+			hmm_pte_set_dirty(hmm_pte);
+		} while (addr = next, hmm_pte++, addr != cend);
+	}
+	hmm_pt_iter_fini(&iter, &mirror->pt);
+}
+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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