linux-kernel - [PATCH 18/36] HMM: add new HMM page table flag (select flag).

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Message-Id: <1432236705-4209-19-git-send-email-j.glisse@gmail.com>
Date:	Thu, 21 May 2015 15:31:27 -0400
From:	j.glisse@...il.com
To:	akpm@...ux-foundation.org
Cc:	<linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	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>,
	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>,
	Laurent Morichetti <Laurent.Morichetti@....com>,
	Alexander Deucher <Alexander.Deucher@....com>,
	Oded Gabbay <Oded.Gabbay@....com>,
	Jérôme Glisse <jglisse@...hat.com>
Subject: [PATCH 18/36] HMM: add new HMM page table flag (select flag).

From: Jérôme Glisse <jglisse@...hat.com>

When migrating memory the same array for HMM page table entry might be
use with several different devices. Add a new select flag so current
device driver callback can know which entry are selected for the device.

Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
---
 include/linux/hmm_pt.h | 6 ++++--
 mm/hmm.c               | 5 ++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/hmm_pt.h b/include/linux/hmm_pt.h
index 26cfe5e..36f7e00 100644
--- a/include/linux/hmm_pt.h
+++ b/include/linux/hmm_pt.h
@@ -77,8 +77,9 @@ static inline unsigned long hmm_pde_pfn(dma_addr_t pde)
 #define HMM_PTE_VALID_DEV_BIT	0
 #define HMM_PTE_VALID_DMA_BIT	1
 #define HMM_PTE_VALID_PFN_BIT	2
-#define HMM_PTE_WRITE_BIT	3
-#define HMM_PTE_DIRTY_BIT	4
+#define HMM_PTE_SELECT		3
+#define HMM_PTE_WRITE_BIT	4
+#define HMM_PTE_DIRTY_BIT	5
 /*
  * Reserve some bits for device driver private flags. Note that thus can only
  * be manipulated using the hmm_pte_*_bit() sets of helpers.
@@ -170,6 +171,7 @@ static inline bool hmm_pte_test_and_set_bit(dma_addr_t *ptep,
 HMM_PTE_BIT_HELPER(valid_dev, HMM_PTE_VALID_DEV_BIT)
 HMM_PTE_BIT_HELPER(valid_dma, HMM_PTE_VALID_DMA_BIT)
 HMM_PTE_BIT_HELPER(valid_pfn, HMM_PTE_VALID_PFN_BIT)
+HMM_PTE_BIT_HELPER(select, HMM_PTE_SELECT)
 HMM_PTE_BIT_HELPER(dirty, HMM_PTE_DIRTY_BIT)
 HMM_PTE_BIT_HELPER(write, HMM_PTE_WRITE_BIT)
 
diff --git a/mm/hmm.c b/mm/hmm.c
index 2143a58..761905a 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -757,6 +757,7 @@ static int hmm_mirror_fault_hpmd(struct hmm_mirror *mirror,
 			hmm_pte[i] = hmm_pte_from_pfn(pfn);
 			if (pmd_write(*pmdp))
 				hmm_pte_set_write(&hmm_pte[i]);
+			hmm_pte_set_select(&hmm_pte[i]);
 		} while (addr = next, pfn++, i++, addr != hmm_end);
 		hmm_pt_iter_directory_unlock(iter, &mirror->pt);
 		mirror_fault->addr = addr;
@@ -826,6 +827,7 @@ static int hmm_mirror_fault_pmd(pmd_t *pmdp,
 			hmm_pte[i] = hmm_pte_from_pfn(pte_pfn(*ptep));
 			if (pte_write(*ptep))
 				hmm_pte_set_write(&hmm_pte[i]);
+			hmm_pte_set_select(&hmm_pte[i]);
 		} while (addr = next, ptep++, i++, addr != hmm_end);
 		hmm_pt_iter_directory_unlock(iter, &mirror->pt);
 		pte_unmap(ptep - 1);
@@ -864,7 +866,8 @@ static int hmm_mirror_dma_map(struct hmm_mirror *mirror,
 
 again:
 			pte = ACCESS_ONCE(hmm_pte[i]);
-			if (!hmm_pte_test_valid_pfn(&pte)) {
+			if (!hmm_pte_test_valid_pfn(&pte) ||
+			    !hmm_pte_test_select(&pte)) {
 				if (!hmm_pte_test_valid_dma(&pte)) {
 					ret = -ENOENT;
 					break;
-- 
1.9.3

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