linux-kernel - [PATCH 05/12] block: Introduce PCI P2P flags for request and request queue

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Message-Id: <20180104190137.7654-6-logang@deltatee.com>
Date:   Thu,  4 Jan 2018 12:01:30 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-block@...r.kernel.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Keith Busch <keith.busch@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Max Gurtovoy <maxg@...lanox.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH 05/12] block: Introduce PCI P2P flags for request and request queue

QUEUE_FLAG_PCI_P2P is introduced meaning a driver's request queue
supports targeting P2P memory.

REQ_PCI_P2P is introduced to indicate a particular bio request is
directed to/from PCI P2P memory. A request with this flag is not
accepted unless the corresponding queues have the QUEUE_FLAG_PCI_P2P
flag set.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 block/blk-core.c          |  3 +++
 include/linux/blk_types.h | 18 +++++++++++++++++-
 include/linux/blkdev.h    |  2 ++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index b8881750a3ac..f347c25731ff 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2141,6 +2141,9 @@ generic_make_request_checks(struct bio *bio)
 	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
 		goto not_supported;
 
+	if ((bio->bi_opf & REQ_PCI_P2P) && !blk_queue_pci_p2p(q))
+		goto not_supported;
+
 	if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
 		goto end_io;
 
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 9e7d8bd776d2..8e1b4d643478 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -228,6 +228,10 @@ enum req_flag_bits {
 	__REQ_BACKGROUND,	/* background IO */
 	__REQ_NOWAIT,           /* Don't wait if request will block */
 
+#ifdef CONFIG_PCI_P2P
+	__REQ_PCI_P2P,		/* request is to/from P2P memory */
+#endif
+
 	/* command specific flags for REQ_OP_WRITE_ZEROES: */
 	__REQ_NOUNMAP,		/* do not free blocks when zeroing */
 
@@ -252,6 +256,18 @@ enum req_flag_bits {
 #define REQ_BACKGROUND		(1ULL << __REQ_BACKGROUND)
 #define REQ_NOWAIT		(1ULL << __REQ_NOWAIT)
 
+#ifdef CONFIG_PCI_P2P
+/*
+ * Currently SGLs do not support mixed P2P and regular memory so
+ * requests with P2P memory must not be merged.
+ */
+#define REQ_PCI_P2P		(1ULL << __REQ_PCI_P2P)
+#define REQ_IS_PCI_P2P(req)	((req)->cmd_flags & REQ_PCI_P2P)
+#else
+#define REQ_PCI_P2P		0
+#define REQ_IS_PCI_P2P(req)	0
+#endif /* CONFIG_PCI_P2P */
+
 #define REQ_NOUNMAP		(1ULL << __REQ_NOUNMAP)
 
 #define REQ_DRV			(1ULL << __REQ_DRV)
@@ -260,7 +276,7 @@ enum req_flag_bits {
 	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
 
 #define REQ_NOMERGE_FLAGS \
-	(REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA)
+	(REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA | REQ_PCI_P2P)
 
 #define bio_op(bio) \
 	((bio)->bi_opf & REQ_OP_MASK)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0ce8a372d506..877b71dd1122 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -651,6 +651,7 @@ struct request_queue {
 #define QUEUE_FLAG_SCSI_PASSTHROUGH 27	/* queue supports SCSI commands */
 #define QUEUE_FLAG_QUIESCED    28	/* queue has been quiesced */
 #define QUEUE_FLAG_PREEMPT_ONLY	29	/* only process REQ_PREEMPT requests */
+#define QUEUE_FLAG_PCI_P2P     30	/* device supports pci p2p requests */
 
 #define QUEUE_FLAG_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
 				 (1 << QUEUE_FLAG_SAME_COMP)	|	\
@@ -746,6 +747,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 #define blk_queue_dax(q)	test_bit(QUEUE_FLAG_DAX, &(q)->queue_flags)
 #define blk_queue_scsi_passthrough(q)	\
 	test_bit(QUEUE_FLAG_SCSI_PASSTHROUGH, &(q)->queue_flags)
+#define blk_queue_pci_p2p(q)	test_bit(QUEUE_FLAG_PCI_P2P, &(q)->queue_flags)
 
 #define blk_noretry_request(rq) \
 	((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
-- 
2.11.0