linux-kernel - [PATCH 3/3] IB/ehca: Make sure user pages are from hugetlb before using MR large pages

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Date:	Thu, 13 Sep 2007 18:16:20 +0200
From:	Joachim Fenkes <fenkes@...ibm.com>
To:	"LinuxPPC-Dev" <linuxppc-dev@...abs.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"OF-General" <general@...ts.openfabrics.org>,
	Roland Dreier <rolandd@...co.com>,
	"OF-EWG" <ewg@...ts.openfabrics.org>
Cc:	"Hoang-Nam Nguyen" <hnguyen@...ibm.com>,
	Christoph Raisch <raisch@...ibm.com>,
	Stefan Roscher <stefan.roscher@...ibm.com>
Subject: [PATCH 3/3] IB/ehca: Make sure user pages are from hugetlb before using MR large pages

...because, on virtualized hardware like System p, we can't be sure that the
physical pages behind them are contiguous.

Signed-off-by: Joachim Fenkes <fenkes@...ibm.com>
---
 drivers/infiniband/hw/ehca/ehca_mrmw.c |   25 +++++++++++++++----------
 1 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/hw/ehca/ehca_mrmw.c b/drivers/infiniband/hw/ehca/ehca_mrmw.c
index 4c8f3b3..4ba8b7c 100644
--- a/drivers/infiniband/hw/ehca/ehca_mrmw.c
+++ b/drivers/infiniband/hw/ehca/ehca_mrmw.c
@@ -51,6 +51,7 @@
 
 #define NUM_CHUNKS(length, chunk_size) \
 	(((length) + (chunk_size - 1)) / (chunk_size))
+
 /* max number of rpages (per hcall register_rpages) */
 #define MAX_RPAGES 512
 
@@ -64,6 +65,11 @@ enum ehca_mr_pgsize {
 	EHCA_MR_PGSIZE16M = 0x1000000L
 };
 
+#define EHCA_MR_PGSHIFT4K  12
+#define EHCA_MR_PGSHIFT64K 16
+#define EHCA_MR_PGSHIFT1M  20
+#define EHCA_MR_PGSHIFT16M 24
+
 static u32 ehca_encode_hwpage_size(u32 pgsize)
 {
 	u32 idx = 0;
@@ -347,17 +353,16 @@ struct ib_mr *ehca_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 	/* select proper hw_pgsize */
 	if (ehca_mr_largepage &&
 	    (shca->hca_cap_mr_pgsize & HCA_CAP_MR_PGSIZE_16M)) {
-		if (length <= EHCA_MR_PGSIZE4K
-		    && PAGE_SIZE == EHCA_MR_PGSIZE4K)
-			hwpage_size = EHCA_MR_PGSIZE4K;
-		else if (length <= EHCA_MR_PGSIZE64K)
-			hwpage_size = EHCA_MR_PGSIZE64K;
-		else if (length <= EHCA_MR_PGSIZE1M)
-			hwpage_size = EHCA_MR_PGSIZE1M;
-		else
-			hwpage_size = EHCA_MR_PGSIZE16M;
+		int page_shift = PAGE_SHIFT;
+		if (e_mr->umem->hugetlb) {
+			/* determine page_shift, clamp between 4K and 16M */
+			page_shift = (fls64(length - 1) + 3) & ~3;
+			page_shift = min(max(page_shift, EHCA_MR_PGSHIFT4K),
+					 EHCA_MR_PGSHIFT16M);
+		}
+		hwpage_size = 1UL << page_shift;
 	} else
-		hwpage_size = EHCA_MR_PGSIZE4K;
+		hwpage_size = EHCA_MR_PGSIZE4K; /* ehca1 only supports 4k */
 	ehca_dbg(pd->device, "hwpage_size=%lx", hwpage_size);
 
 reg_user_mr_fallback:
-- 
1.5.2


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