linux-kernel - [PATCH v12 12/29] HMM: add dirty range helper (toggle dirty bit inside mirror page table) v2.

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Date:	Tue,  8 Mar 2016 15:43:05 -0500
From:	Jérôme Glisse <jglisse@...hat.com>
To:	akpm@...ux-foundation.org, <linux-kernel@...r.kernel.org>,
	linux-mm@...ck.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>, <joro@...tes.org>,
	Mel Gorman <mgorman@...e.de>, "H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <jweiner@...hat.com>,
	Larry Woodman <lwoodman@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Dave Airlie <airlied@...hat.com>,
	Brendan Conoboy <blc@...hat.com>,
	Joe Donohue <jdonohue@...hat.com>,
	Christophe Harle <charle@...dia.com>,
	Duncan Poole <dpoole@...dia.com>,
	Sherry Cheung <SCheung@...dia.com>,
	Subhash Gutti <sgutti@...dia.com>,
	John Hubbard <jhubbard@...dia.com>,
	Mark Hairgrove <mhairgrove@...dia.com>,
	Lucien Dunning <ldunning@...dia.com>,
	Cameron Buschardt <cabuschardt@...dia.com>,
	Arvind Gopalakrishnan <arvindg@...dia.com>,
	Haggai Eran <haggaie@...lanox.com>,
	Shachar Raindel <raindel@...lanox.com>,
	Liran Liss <liranl@...lanox.com>,
	Roland Dreier <roland@...estorage.com>,
	Ben Sander <ben.sander@....com>,
	Greg Stoner <Greg.Stoner@....com>,
	John Bridgman <John.Bridgman@....com>,
	Michael Mantor <Michael.Mantor@....com>,
	Paul Blinzer <Paul.Blinzer@....com>,
	Leonid Shamis <Leonid.Shamis@....com>,
	Laurent Morichetti <Laurent.Morichetti@....com>,
	Alexander Deucher <Alexander.Deucher@....com>,
	Jérôme Glisse <jglisse@...hat.com>
Subject: [PATCH v12 12/29] HMM: add dirty range helper (toggle dirty bit inside mirror page table) v2.

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: Jérôme Glisse <jglisse@...hat.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 548f0c5..dc37e49 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -945,6 +945,44 @@ 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.
-- 
2.4.3