1 files changed, 387 insertions, 259 deletions

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 8ff12e415cb5..071efec25346 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -7,7 +7,7 @@
 #include <linux/acpi.h>
 #include <linux/async.h>
 #include <linux/blkdev.h>
-#include <linux/blk-mq.h>
+#include <linux/blk-mq-dma.h>
 #include <linux/blk-integrity.h>
 #include <linux/dmi.h>
 #include <linux/init.h>
@@ -27,7 +27,6 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/sed-opal.h>
-#include <linux/pci-p2pdma.h>
 
 #include "trace.h"
 #include "nvme.h"
@@ -39,20 +38,17 @@
 #define NVME_SMALL_POOL_SIZE	256
 
 /*
- * These can be higher, but we need to ensure that any command doesn't
- * require an sg allocation that needs more than a page of data.
+ * Arbitrary upper bound.
  */
-#define NVME_MAX_KB_SZ	8192
+#define NVME_MAX_BYTES		SZ_8M
 #define NVME_MAX_NR_DESCRIPTORS	5
 
 /*
- * For data SGLs we support a single descriptors worth of SGL entries, but for
- * now we also limit it to avoid an allocation larger than PAGE_SIZE for the
- * scatterlist.
+ * For data SGLs we support a single descriptors worth of SGL entries.
+ * For PRPs, segments don't matter at all.
  */
 #define NVME_MAX_SEGS \
-	min(NVME_CTRL_PAGE_SIZE / sizeof(struct nvme_sgl_desc), \
-	    (PAGE_SIZE / sizeof(struct scatterlist)))
+	(NVME_CTRL_PAGE_SIZE / sizeof(struct nvme_sgl_desc))
 
 /*
  * For metadata SGLs, only the small descriptor is supported, and the first
@@ -61,6 +57,21 @@
 #define NVME_MAX_META_SEGS \
 	((NVME_SMALL_POOL_SIZE / sizeof(struct nvme_sgl_desc)) - 1)
 
+/*
+ * The last entry is used to link to the next descriptor.
+ */
+#define PRPS_PER_PAGE \
+	(((NVME_CTRL_PAGE_SIZE / sizeof(__le64))) - 1)
+
+/*
+ * I/O could be non-aligned both at the beginning and end.
+ */
+#define MAX_PRP_RANGE \
+	(NVME_MAX_BYTES + 2 * (NVME_CTRL_PAGE_SIZE - 1))
+
+static_assert(MAX_PRP_RANGE / NVME_CTRL_PAGE_SIZE <=
+	(1 /* prp1 */ + NVME_MAX_NR_DESCRIPTORS * PRPS_PER_PAGE));
+
 static int use_threaded_interrupts;
 module_param(use_threaded_interrupts, int, 0444);
 
@@ -97,7 +108,7 @@ static int io_queue_count_set(const char *val, const struct kernel_param *kp)
 	int ret;
 
 	ret = kstrtouint(val, 10, &n);
-	if (ret != 0 || n > num_possible_cpus())
+	if (ret != 0 || n > blk_mq_num_possible_queues(0))
 		return -EINVAL;
 	return param_set_uint(val, kp);
 }
@@ -162,7 +173,7 @@ struct nvme_dev {
 	bool hmb;
 	struct sg_table *hmb_sgt;
 
-	mempool_t *iod_mempool;
+	mempool_t *dmavec_mempool;
 	mempool_t *iod_meta_mempool;
 
 	/* shadow doorbell buffer support: */
@@ -246,7 +257,15 @@ enum nvme_iod_flags {
 	IOD_ABORTED		= 1U << 0,
 
 	/* uses the small descriptor pool */
-	IOD_SMALL_DESCRIPTOR		= 1U << 1,
+	IOD_SMALL_DESCRIPTOR	= 1U << 1,
+
+	/* single segment dma mapping */
+	IOD_SINGLE_SEGMENT	= 1U << 2,
+};
+
+struct nvme_dma_vec {
+	dma_addr_t addr;
+	unsigned int len;
 };
 
 /*
@@ -257,13 +276,16 @@ struct nvme_iod {
 	struct nvme_command cmd;
 	u8 flags;
 	u8 nr_descriptors;
-	unsigned int dma_len;	/* length of single DMA segment mapping */
-	dma_addr_t first_dma;
+
+	unsigned int total_len;
+	struct dma_iova_state dma_state;
+	void *descriptors[NVME_MAX_NR_DESCRIPTORS];
+	struct nvme_dma_vec *dma_vecs;
+	unsigned int nr_dma_vecs;
+
 	dma_addr_t meta_dma;
-	struct sg_table sgt;
 	struct sg_table meta_sgt;
 	struct nvme_sgl_desc *meta_descriptor;
-	void *descriptors[NVME_MAX_NR_DESCRIPTORS];
 };
 
 static inline unsigned int nvme_dbbuf_size(struct nvme_dev *dev)
@@ -406,18 +428,6 @@ static bool nvme_dbbuf_update_and_check_event(u16 value, __le32 *dbbuf_db,
 	return true;
 }
 
-/*
- * Will slightly overestimate the number of pages needed.  This is OK
- * as it only leads to a small amount of wasted memory for the lifetime of
- * the I/O.
- */
-static __always_inline int nvme_pci_npages_prp(void)
-{
-	unsigned max_bytes = (NVME_MAX_KB_SZ * 1024) + NVME_CTRL_PAGE_SIZE;
-	unsigned nprps = DIV_ROUND_UP(max_bytes, NVME_CTRL_PAGE_SIZE);
-	return DIV_ROUND_UP(8 * nprps, NVME_CTRL_PAGE_SIZE - 8);
-}
-
 static struct nvme_descriptor_pools *
 nvme_setup_descriptor_pools(struct nvme_dev *dev, unsigned numa_node)
 {
@@ -578,32 +588,49 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx)
 	spin_unlock(&nvmeq->sq_lock);
 }
 
-static inline bool nvme_pci_metadata_use_sgls(struct nvme_dev *dev,
-					      struct request *req)
+enum nvme_use_sgl {
+	SGL_UNSUPPORTED,
+	SGL_SUPPORTED,
+	SGL_FORCED,
+};
+
+static inline bool nvme_pci_metadata_use_sgls(struct request *req)
 {
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct nvme_dev *dev = nvmeq->dev;
+
 	if (!nvme_ctrl_meta_sgl_supported(&dev->ctrl))
 		return false;
 	return req->nr_integrity_segments > 1 ||
 		nvme_req(req)->flags & NVME_REQ_USERCMD;
 }
 
-static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
-				     int nseg)
+static inline enum nvme_use_sgl nvme_pci_use_sgls(struct nvme_dev *dev,
+		struct request *req)
 {
 	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
-	unsigned int avg_seg_size;
 
-	avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req), nseg);
+	if (nvmeq->qid && nvme_ctrl_sgl_supported(&dev->ctrl)) {
+		if (nvme_req(req)->flags & NVME_REQ_USERCMD)
+			return SGL_FORCED;
+		if (req->nr_integrity_segments > 1)
+			return SGL_FORCED;
+		return SGL_SUPPORTED;
+	}
 
-	if (!nvme_ctrl_sgl_supported(&dev->ctrl))
-		return false;
-	if (!nvmeq->qid)
-		return false;
-	if (nvme_pci_metadata_use_sgls(dev, req))
-		return true;
-	if (!sgl_threshold || avg_seg_size < sgl_threshold)
-		return nvme_req(req)->flags & NVME_REQ_USERCMD;
-	return true;
+	return SGL_UNSUPPORTED;
+}
+
+static unsigned int nvme_pci_avg_seg_size(struct request *req)
+{
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	unsigned int nseg;
+
+	if (blk_rq_dma_map_coalesce(&iod->dma_state))
+		nseg = 1;
+	else
+		nseg = blk_rq_nr_phys_segments(req);
+	return DIV_ROUND_UP(blk_rq_payload_bytes(req), nseg);
 }
 
 static inline struct dma_pool *nvme_dma_pool(struct nvme_queue *nvmeq,
@@ -614,11 +641,25 @@ static inline struct dma_pool *nvme_dma_pool(struct nvme_queue *nvmeq,
 	return nvmeq->descriptor_pools.large;
 }
 
-static void nvme_free_descriptors(struct nvme_queue *nvmeq, struct request *req)
+static inline bool nvme_pci_cmd_use_sgl(struct nvme_command *cmd)
+{
+	return cmd->common.flags &
+		(NVME_CMD_SGL_METABUF | NVME_CMD_SGL_METASEG);
+}
+
+static inline dma_addr_t nvme_pci_first_desc_dma_addr(struct nvme_command *cmd)
 {
+	if (nvme_pci_cmd_use_sgl(cmd))
+		return le64_to_cpu(cmd->common.dptr.sgl.addr);
+	return le64_to_cpu(cmd->common.dptr.prp2);
+}
+
+static void nvme_free_descriptors(struct request *req)
+{
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
 	const int last_prp = NVME_CTRL_PAGE_SIZE / sizeof(__le64) - 1;
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	dma_addr_t dma_addr = iod->first_dma;
+	dma_addr_t dma_addr = nvme_pci_first_desc_dma_addr(&iod->cmd);
 	int i;
 
 	if (iod->nr_descriptors == 1) {
@@ -637,68 +678,130 @@ static void nvme_free_descriptors(struct nvme_queue *nvmeq, struct request *req)
 	}
 }
 
-static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_queue *nvmeq,
-			    struct request *req)
+static void nvme_free_prps(struct request *req)
+{
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	unsigned int i;
+
+	for (i = 0; i < iod->nr_dma_vecs; i++)
+		dma_unmap_page(nvmeq->dev->dev, iod->dma_vecs[i].addr,
+				iod->dma_vecs[i].len, rq_dma_dir(req));
+	mempool_free(iod->dma_vecs, nvmeq->dev->dmavec_mempool);
+}
+
+static void nvme_free_sgls(struct request *req)
+{
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct device *dma_dev = nvmeq->dev->dev;
+	dma_addr_t sqe_dma_addr = le64_to_cpu(iod->cmd.common.dptr.sgl.addr);
+	unsigned int sqe_dma_len = le32_to_cpu(iod->cmd.common.dptr.sgl.length);
+	struct nvme_sgl_desc *sg_list = iod->descriptors[0];
+	enum dma_data_direction dir = rq_dma_dir(req);
+
+	if (iod->nr_descriptors) {
+		unsigned int nr_entries = sqe_dma_len / sizeof(*sg_list), i;
+
+		for (i = 0; i < nr_entries; i++)
+			dma_unmap_page(dma_dev, le64_to_cpu(sg_list[i].addr),
+				le32_to_cpu(sg_list[i].length), dir);
+	} else {
+		dma_unmap_page(dma_dev, sqe_dma_addr, sqe_dma_len, dir);
+	}
+}
+
+static void nvme_unmap_data(struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct device *dma_dev = nvmeq->dev->dev;
 
-	if (iod->dma_len) {
-		dma_unmap_page(dev->dev, iod->first_dma, iod->dma_len,
-			       rq_dma_dir(req));
+	if (iod->flags & IOD_SINGLE_SEGMENT) {
+		static_assert(offsetof(union nvme_data_ptr, prp1) ==
+				offsetof(union nvme_data_ptr, sgl.addr));
+		dma_unmap_page(dma_dev, le64_to_cpu(iod->cmd.common.dptr.prp1),
+				iod->total_len, rq_dma_dir(req));
 		return;
 	}
 
-	WARN_ON_ONCE(!iod->sgt.nents);
+	if (!blk_rq_dma_unmap(req, dma_dev, &iod->dma_state, iod->total_len)) {
+		if (nvme_pci_cmd_use_sgl(&iod->cmd))
+			nvme_free_sgls(req);
+		else
+			nvme_free_prps(req);
+	}
 
-	dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0);
-	nvme_free_descriptors(nvmeq, req);
-	mempool_free(iod->sgt.sgl, dev->iod_mempool);
+	if (iod->nr_descriptors)
+		nvme_free_descriptors(req);
 }
 
-static void nvme_print_sgl(struct scatterlist *sgl, int nents)
+static bool nvme_pci_prp_iter_next(struct request *req, struct device *dma_dev,
+		struct blk_dma_iter *iter)
 {
-	int i;
-	struct scatterlist *sg;
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 
-	for_each_sg(sgl, sg, nents, i) {
-		dma_addr_t phys = sg_phys(sg);
-		pr_warn("sg[%d] phys_addr:%pad offset:%d length:%d "
-			"dma_address:%pad dma_length:%d\n",
-			i, &phys, sg->offset, sg->length, &sg_dma_address(sg),
-			sg_dma_len(sg));
+	if (iter->len)
+		return true;
+	if (!blk_rq_dma_map_iter_next(req, dma_dev, &iod->dma_state, iter))
+		return false;
+	if (!dma_use_iova(&iod->dma_state) && dma_need_unmap(dma_dev)) {
+		iod->dma_vecs[iod->nr_dma_vecs].addr = iter->addr;
+		iod->dma_vecs[iod->nr_dma_vecs].len = iter->len;
+		iod->nr_dma_vecs++;
 	}
+	return true;
 }
 
-static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq,
-		struct request *req, struct nvme_rw_command *cmnd)
+static blk_status_t nvme_pci_setup_data_prp(struct request *req,
+		struct blk_dma_iter *iter)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	int length = blk_rq_payload_bytes(req);
-	struct scatterlist *sg = iod->sgt.sgl;
-	int dma_len = sg_dma_len(sg);
-	u64 dma_addr = sg_dma_address(sg);
-	int offset = dma_addr & (NVME_CTRL_PAGE_SIZE - 1);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	unsigned int length = blk_rq_payload_bytes(req);
+	dma_addr_t prp1_dma, prp2_dma = 0;
+	unsigned int prp_len, i;
 	__le64 *prp_list;
-	dma_addr_t prp_dma;
-	int i;
 
-	length -= (NVME_CTRL_PAGE_SIZE - offset);
-	if (length <= 0) {
-		iod->first_dma = 0;
-		goto done;
+	if (!dma_use_iova(&iod->dma_state) && dma_need_unmap(nvmeq->dev->dev)) {
+		iod->dma_vecs = mempool_alloc(nvmeq->dev->dmavec_mempool,
+				GFP_ATOMIC);
+		if (!iod->dma_vecs)
+			return BLK_STS_RESOURCE;
+		iod->dma_vecs[0].addr = iter->addr;
+		iod->dma_vecs[0].len = iter->len;
+		iod->nr_dma_vecs = 1;
 	}
 
-	dma_len -= (NVME_CTRL_PAGE_SIZE - offset);
-	if (dma_len) {
-		dma_addr += (NVME_CTRL_PAGE_SIZE - offset);
-	} else {
-		sg = sg_next(sg);
-		dma_addr = sg_dma_address(sg);
-		dma_len = sg_dma_len(sg);
+	/*
+	 * PRP1 always points to the start of the DMA transfers.
+	 *
+	 * This is the only PRP (except for the list entries) that could be
+	 * non-aligned.
+	 */
+	prp1_dma = iter->addr;
+	prp_len = min(length, NVME_CTRL_PAGE_SIZE -
+			(iter->addr & (NVME_CTRL_PAGE_SIZE - 1)));
+	iod->total_len += prp_len;
+	iter->addr += prp_len;
+	iter->len -= prp_len;
+	length -= prp_len;
+	if (!length)
+		goto done;
+
+	if (!nvme_pci_prp_iter_next(req, nvmeq->dev->dev, iter)) {
+		if (WARN_ON_ONCE(!iter->status))
+			goto bad_sgl;
+		goto done;
 	}
 
+	/*
+	 * PRP2 is usually a list, but can point to data if all data to be
+	 * transferred fits into PRP1 + PRP2:
+	 */
 	if (length <= NVME_CTRL_PAGE_SIZE) {
-		iod->first_dma = dma_addr;
+		prp2_dma = iter->addr;
+		iod->total_len += length;
 		goto done;
 	}
 
@@ -707,58 +810,80 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_queue *nvmeq,
 		iod->flags |= IOD_SMALL_DESCRIPTOR;
 
 	prp_list = dma_pool_alloc(nvme_dma_pool(nvmeq, iod), GFP_ATOMIC,
-			&prp_dma);
-	if (!prp_list)
-		return BLK_STS_RESOURCE;
+			&prp2_dma);
+	if (!prp_list) {
+		iter->status = BLK_STS_RESOURCE;
+		goto done;
+	}
 	iod->descriptors[iod->nr_descriptors++] = prp_list;
-	iod->first_dma = prp_dma;
+
 	i = 0;
 	for (;;) {
+		prp_list[i++] = cpu_to_le64(iter->addr);
+		prp_len = min(length, NVME_CTRL_PAGE_SIZE);
+		if (WARN_ON_ONCE(iter->len < prp_len))
+			goto bad_sgl;
+
+		iod->total_len += prp_len;
+		iter->addr += prp_len;
+		iter->len -= prp_len;
+		length -= prp_len;
+		if (!length)
+			break;
+
+		if (!nvme_pci_prp_iter_next(req, nvmeq->dev->dev, iter)) {
+			if (WARN_ON_ONCE(!iter->status))
+				goto bad_sgl;
+			goto done;
+		}
+
+		/*
+		 * If we've filled the entire descriptor, allocate a new that is
+		 * pointed to be the last entry in the previous PRP list.  To
+		 * accommodate for that move the last actual entry to the new
+		 * descriptor.
+		 */
 		if (i == NVME_CTRL_PAGE_SIZE >> 3) {
 			__le64 *old_prp_list = prp_list;
+			dma_addr_t prp_list_dma;
 
 			prp_list = dma_pool_alloc(nvmeq->descriptor_pools.large,
-					GFP_ATOMIC, &prp_dma);
-			if (!prp_list)
-				goto free_prps;
+					GFP_ATOMIC, &prp_list_dma);
+			if (!prp_list) {
+				iter->status = BLK_STS_RESOURCE;
+				goto done;
+			}
 			iod->descriptors[iod->nr_descriptors++] = prp_list;
+
 			prp_list[0] = old_prp_list[i - 1];
-			old_prp_list[i - 1] = cpu_to_le64(prp_dma);
+			old_prp_list[i - 1] = cpu_to_le64(prp_list_dma);
 			i = 1;
 		}
-		prp_list[i++] = cpu_to_le64(dma_addr);
-		dma_len -= NVME_CTRL_PAGE_SIZE;
-		dma_addr += NVME_CTRL_PAGE_SIZE;
-		length -= NVME_CTRL_PAGE_SIZE;
-		if (length <= 0)
-			break;
-		if (dma_len > 0)
-			continue;
-		if (unlikely(dma_len < 0))
-			goto bad_sgl;
-		sg = sg_next(sg);
-		dma_addr = sg_dma_address(sg);
-		dma_len = sg_dma_len(sg);
 	}
+
 done:
-	cmnd->dptr.prp1 = cpu_to_le64(sg_dma_address(iod->sgt.sgl));
-	cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma);
-	return BLK_STS_OK;
-free_prps:
-	nvme_free_descriptors(nvmeq, req);
-	return BLK_STS_RESOURCE;
+	/*
+	 * nvme_unmap_data uses the DPT field in the SQE to tear down the
+	 * mapping, so initialize it even for failures.
+	 */
+	iod->cmd.common.dptr.prp1 = cpu_to_le64(prp1_dma);
+	iod->cmd.common.dptr.prp2 = cpu_to_le64(prp2_dma);
+	if (unlikely(iter->status))
+		nvme_unmap_data(req);
+	return iter->status;
+
 bad_sgl:
-	WARN(DO_ONCE(nvme_print_sgl, iod->sgt.sgl, iod->sgt.nents),
-			"Invalid SGL for payload:%d nents:%d\n",
-			blk_rq_payload_bytes(req), iod->sgt.nents);
+	dev_err_once(nvmeq->dev->dev,
+		"Incorrectly formed request for payload:%d nents:%d\n",
+		blk_rq_payload_bytes(req), blk_rq_nr_phys_segments(req));
 	return BLK_STS_IOERR;
 }
 
 static void nvme_pci_sgl_set_data(struct nvme_sgl_desc *sge,
-		struct scatterlist *sg)
+		struct blk_dma_iter *iter)
 {
-	sge->addr = cpu_to_le64(sg_dma_address(sg));
-	sge->length = cpu_to_le32(sg_dma_len(sg));
+	sge->addr = cpu_to_le64(iter->addr);
+	sge->length = cpu_to_le32(iter->len);
 	sge->type = NVME_SGL_FMT_DATA_DESC << 4;
 }
 
@@ -770,21 +895,22 @@ static void nvme_pci_sgl_set_seg(struct nvme_sgl_desc *sge,
 	sge->type = NVME_SGL_FMT_LAST_SEG_DESC << 4;
 }
 
-static blk_status_t nvme_pci_setup_sgls(struct nvme_queue *nvmeq,
-		struct request *req, struct nvme_rw_command *cmd)
+static blk_status_t nvme_pci_setup_data_sgl(struct request *req,
+		struct blk_dma_iter *iter)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	unsigned int entries = blk_rq_nr_phys_segments(req);
 	struct nvme_sgl_desc *sg_list;
-	struct scatterlist *sg = iod->sgt.sgl;
-	unsigned int entries = iod->sgt.nents;
 	dma_addr_t sgl_dma;
-	int i = 0;
+	unsigned int mapped = 0;
 
-	/* setting the transfer type as SGL */
-	cmd->flags = NVME_CMD_SGL_METABUF;
+	/* set the transfer type as SGL */
+	iod->cmd.common.flags = NVME_CMD_SGL_METABUF;
 
-	if (entries == 1) {
-		nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);
+	if (entries == 1 || blk_rq_dma_map_coalesce(&iod->dma_state)) {
+		nvme_pci_sgl_set_data(&iod->cmd.common.dptr.sgl, iter);
+		iod->total_len += iter->len;
 		return BLK_STS_OK;
 	}
 
@@ -796,119 +922,104 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_queue *nvmeq,
 	if (!sg_list)
 		return BLK_STS_RESOURCE;
 	iod->descriptors[iod->nr_descriptors++] = sg_list;
-	iod->first_dma = sgl_dma;
 
-	nvme_pci_sgl_set_seg(&cmd->dptr.sgl, sgl_dma, entries);
 	do {
-		nvme_pci_sgl_set_data(&sg_list[i++], sg);
-		sg = sg_next(sg);
-	} while (--entries > 0);
+		if (WARN_ON_ONCE(mapped == entries)) {
+			iter->status = BLK_STS_IOERR;
+			break;
+		}
+		nvme_pci_sgl_set_data(&sg_list[mapped++], iter);
+		iod->total_len += iter->len;
+	} while (blk_rq_dma_map_iter_next(req, nvmeq->dev->dev, &iod->dma_state,
+				iter));
 
-	return BLK_STS_OK;
+	nvme_pci_sgl_set_seg(&iod->cmd.common.dptr.sgl, sgl_dma, mapped);
+	if (unlikely(iter->status))
+		nvme_free_sgls(req);
+	return iter->status;
 }
 
-static blk_status_t nvme_setup_prp_simple(struct nvme_dev *dev,
-		struct request *req, struct nvme_rw_command *cmnd,
-		struct bio_vec *bv)
+static blk_status_t nvme_pci_setup_data_simple(struct request *req,
+		enum nvme_use_sgl use_sgl)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	unsigned int offset = bv->bv_offset & (NVME_CTRL_PAGE_SIZE - 1);
-	unsigned int first_prp_len = NVME_CTRL_PAGE_SIZE - offset;
-
-	iod->first_dma = dma_map_bvec(dev->dev, bv, rq_dma_dir(req), 0);
-	if (dma_mapping_error(dev->dev, iod->first_dma))
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct bio_vec bv = req_bvec(req);
+	unsigned int prp1_offset = bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1);
+	bool prp_possible = prp1_offset + bv.bv_len <= NVME_CTRL_PAGE_SIZE * 2;
+	dma_addr_t dma_addr;
+
+	if (!use_sgl && !prp_possible)
+		return BLK_STS_AGAIN;
+	if (is_pci_p2pdma_page(bv.bv_page))
+		return BLK_STS_AGAIN;
+
+	dma_addr = dma_map_bvec(nvmeq->dev->dev, &bv, rq_dma_dir(req), 0);
+	if (dma_mapping_error(nvmeq->dev->dev, dma_addr))
 		return BLK_STS_RESOURCE;
-	iod->dma_len = bv->bv_len;
-
-	cmnd->dptr.prp1 = cpu_to_le64(iod->first_dma);
-	if (bv->bv_len > first_prp_len)
-		cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma + first_prp_len);
-	else
-		cmnd->dptr.prp2 = 0;
-	return BLK_STS_OK;
-}
-
-static blk_status_t nvme_setup_sgl_simple(struct nvme_dev *dev,
-		struct request *req, struct nvme_rw_command *cmnd,
-		struct bio_vec *bv)
-{
-	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	iod->total_len = bv.bv_len;
+	iod->flags |= IOD_SINGLE_SEGMENT;
+
+	if (use_sgl == SGL_FORCED || !prp_possible) {
+		iod->cmd.common.flags = NVME_CMD_SGL_METABUF;
+		iod->cmd.common.dptr.sgl.addr = cpu_to_le64(dma_addr);
+		iod->cmd.common.dptr.sgl.length = cpu_to_le32(bv.bv_len);
+		iod->cmd.common.dptr.sgl.type = NVME_SGL_FMT_DATA_DESC << 4;
+	} else {
+		unsigned int first_prp_len = NVME_CTRL_PAGE_SIZE - prp1_offset;
 
-	iod->first_dma = dma_map_bvec(dev->dev, bv, rq_dma_dir(req), 0);
-	if (dma_mapping_error(dev->dev, iod->first_dma))
-		return BLK_STS_RESOURCE;
-	iod->dma_len = bv->bv_len;
+		iod->cmd.common.dptr.prp1 = cpu_to_le64(dma_addr);
+		iod->cmd.common.dptr.prp2 = 0;
+		if (bv.bv_len > first_prp_len)
+			iod->cmd.common.dptr.prp2 =
+				cpu_to_le64(dma_addr + first_prp_len);
+	}
 
-	cmnd->flags = NVME_CMD_SGL_METABUF;
-	cmnd->dptr.sgl.addr = cpu_to_le64(iod->first_dma);
-	cmnd->dptr.sgl.length = cpu_to_le32(iod->dma_len);
-	cmnd->dptr.sgl.type = NVME_SGL_FMT_DATA_DESC << 4;
 	return BLK_STS_OK;
 }
 
-static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
-		struct nvme_command *cmnd)
+static blk_status_t nvme_map_data(struct request *req)
 {
-	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	blk_status_t ret = BLK_STS_RESOURCE;
-	int rc;
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct nvme_dev *dev = nvmeq->dev;
+	enum nvme_use_sgl use_sgl = nvme_pci_use_sgls(dev, req);
+	struct blk_dma_iter iter;
+	blk_status_t ret;
 
+	/*
+	 * Try to skip the DMA iterator for single segment requests, as that
+	 * significantly improves performances for small I/O sizes.
+	 */
 	if (blk_rq_nr_phys_segments(req) == 1) {
-		struct bio_vec bv = req_bvec(req);
-
-		if (!is_pci_p2pdma_page(bv.bv_page)) {
-			if (!nvme_pci_metadata_use_sgls(dev, req) &&
-			    (bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) +
-			     bv.bv_len <= NVME_CTRL_PAGE_SIZE * 2)
-				return nvme_setup_prp_simple(dev, req,
-							     &cmnd->rw, &bv);
-
-			if (nvmeq->qid && sgl_threshold &&
-			    nvme_ctrl_sgl_supported(&dev->ctrl))
-				return nvme_setup_sgl_simple(dev, req,
-							     &cmnd->rw, &bv);
-		}
+		ret = nvme_pci_setup_data_simple(req, use_sgl);
+		if (ret != BLK_STS_AGAIN)
+			return ret;
 	}
 
-	iod->dma_len = 0;
-	iod->sgt.sgl = mempool_alloc(dev->iod_mempool, GFP_ATOMIC);
-	if (!iod->sgt.sgl)
-		return BLK_STS_RESOURCE;
-	sg_init_table(iod->sgt.sgl, blk_rq_nr_phys_segments(req));
-	iod->sgt.orig_nents = blk_rq_map_sg(req, iod->sgt.sgl);
-	if (!iod->sgt.orig_nents)
-		goto out_free_sg;
-
-	rc = dma_map_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req),
-			     DMA_ATTR_NO_WARN);
-	if (rc) {
-		if (rc == -EREMOTEIO)
-			ret = BLK_STS_TARGET;
-		goto out_free_sg;
-	}
+	if (!blk_rq_dma_map_iter_start(req, dev->dev, &iod->dma_state, &iter))
+		return iter.status;
 
-	if (nvme_pci_use_sgls(dev, req, iod->sgt.nents))
-		ret = nvme_pci_setup_sgls(nvmeq, req, &cmnd->rw);
-	else
-		ret = nvme_pci_setup_prps(nvmeq, req, &cmnd->rw);
-	if (ret != BLK_STS_OK)
-		goto out_unmap_sg;
-	return BLK_STS_OK;
+	if (use_sgl == SGL_FORCED ||
+	    (use_sgl == SGL_SUPPORTED &&
+	     (sgl_threshold && nvme_pci_avg_seg_size(req) >= sgl_threshold)))
+		return nvme_pci_setup_data_sgl(req, &iter);
+	return nvme_pci_setup_data_prp(req, &iter);
+}
 
-out_unmap_sg:
-	dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0);
-out_free_sg:
-	mempool_free(iod->sgt.sgl, dev->iod_mempool);
-	return ret;
+static void nvme_pci_sgl_set_data_sg(struct nvme_sgl_desc *sge,
+		struct scatterlist *sg)
+{
+	sge->addr = cpu_to_le64(sg_dma_address(sg));
+	sge->length = cpu_to_le32(sg_dma_len(sg));
+	sge->type = NVME_SGL_FMT_DATA_DESC << 4;
 }
 
-static blk_status_t nvme_pci_setup_meta_sgls(struct nvme_dev *dev,
-					     struct request *req)
+static blk_status_t nvme_pci_setup_meta_sgls(struct request *req)
 {
 	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct nvme_dev *dev = nvmeq->dev;
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	struct nvme_rw_command *cmnd = &iod->cmd.rw;
 	struct nvme_sgl_desc *sg_list;
 	struct scatterlist *sgl, *sg;
 	unsigned int entries;
@@ -939,19 +1050,19 @@ static blk_status_t nvme_pci_setup_meta_sgls(struct nvme_dev *dev,
 	iod->meta_descriptor = sg_list;
 	iod->meta_dma = sgl_dma;
 
-	cmnd->flags = NVME_CMD_SGL_METASEG;
-	cmnd->metadata = cpu_to_le64(sgl_dma);
+	iod->cmd.common.flags = NVME_CMD_SGL_METASEG;
+	iod->cmd.common.metadata = cpu_to_le64(sgl_dma);
 
 	sgl = iod->meta_sgt.sgl;
 	if (entries == 1) {
-		nvme_pci_sgl_set_data(sg_list, sgl);
+		nvme_pci_sgl_set_data_sg(sg_list, sgl);
 		return BLK_STS_OK;
 	}
 
 	sgl_dma += sizeof(*sg_list);
 	nvme_pci_sgl_set_seg(sg_list, sgl_dma, entries);
 	for_each_sg(sgl, sg, entries, i)
-		nvme_pci_sgl_set_data(&sg_list[i + 1], sg);
+		nvme_pci_sgl_set_data_sg(&sg_list[i + 1], sg);
 
 	return BLK_STS_OK;
 
@@ -962,38 +1073,37 @@ out_free_sg:
 	return BLK_STS_RESOURCE;
 }
 
-static blk_status_t nvme_pci_setup_meta_mptr(struct nvme_dev *dev,
-					     struct request *req)
+static blk_status_t nvme_pci_setup_meta_mptr(struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
 	struct bio_vec bv = rq_integrity_vec(req);
-	struct nvme_command *cmnd = &iod->cmd;
 
-	iod->meta_dma = dma_map_bvec(dev->dev, &bv, rq_dma_dir(req), 0);
-	if (dma_mapping_error(dev->dev, iod->meta_dma))
+	iod->meta_dma = dma_map_bvec(nvmeq->dev->dev, &bv, rq_dma_dir(req), 0);
+	if (dma_mapping_error(nvmeq->dev->dev, iod->meta_dma))
 		return BLK_STS_IOERR;
-	cmnd->rw.metadata = cpu_to_le64(iod->meta_dma);
+	iod->cmd.common.metadata = cpu_to_le64(iod->meta_dma);
 	return BLK_STS_OK;
 }
 
-static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req)
+static blk_status_t nvme_map_metadata(struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 
 	if ((iod->cmd.common.flags & NVME_CMD_SGL_METABUF) &&
-	    nvme_pci_metadata_use_sgls(dev, req))
-		return nvme_pci_setup_meta_sgls(dev, req);
-	return nvme_pci_setup_meta_mptr(dev, req);
+	    nvme_pci_metadata_use_sgls(req))
+		return nvme_pci_setup_meta_sgls(req);
+	return nvme_pci_setup_meta_mptr(req);
 }
 
-static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
+static blk_status_t nvme_prep_rq(struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 	blk_status_t ret;
 
 	iod->flags = 0;
 	iod->nr_descriptors = 0;
-	iod->sgt.nents = 0;
+	iod->total_len = 0;
 	iod->meta_sgt.nents = 0;
 
 	ret = nvme_setup_cmd(req->q->queuedata, req);
@@ -1001,13 +1111,13 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
 		return ret;
 
 	if (blk_rq_nr_phys_segments(req)) {
-		ret = nvme_map_data(dev, req, &iod->cmd);
+		ret = nvme_map_data(req);
 		if (ret)
 			goto out_free_cmd;
 	}
 
 	if (blk_integrity_rq(req)) {
-		ret = nvme_map_metadata(dev, req);
+		ret = nvme_map_metadata(req);
 		if (ret)
 			goto out_unmap_data;
 	}
@@ -1016,7 +1126,7 @@ static blk_status_t nvme_prep_rq(struct nvme_dev *dev, struct request *req)
 	return BLK_STS_OK;
 out_unmap_data:
 	if (blk_rq_nr_phys_segments(req))
-		nvme_unmap_data(dev, req->mq_hctx->driver_data, req);
+		nvme_unmap_data(req);
 out_free_cmd:
 	nvme_cleanup_cmd(req);
 	return ret;
@@ -1041,7 +1151,7 @@ static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
 	if (unlikely(!nvme_check_ready(&dev->ctrl, req, true)))
 		return nvme_fail_nonready_command(&dev->ctrl, req);
 
-	ret = nvme_prep_rq(dev, req);
+	ret = nvme_prep_rq(req);
 	if (unlikely(ret))
 		return ret;
 	spin_lock(&nvmeq->sq_lock);
@@ -1079,7 +1189,7 @@ static bool nvme_prep_rq_batch(struct nvme_queue *nvmeq, struct request *req)
 	if (unlikely(!nvme_check_ready(&nvmeq->dev->ctrl, req, true)))
 		return false;
 
-	return nvme_prep_rq(nvmeq->dev, req) == BLK_STS_OK;
+	return nvme_prep_rq(req) == BLK_STS_OK;
 }
 
 static void nvme_queue_rqs(struct rq_list *rqlist)
@@ -1105,11 +1215,11 @@ static void nvme_queue_rqs(struct rq_list *rqlist)
 	*rqlist = requeue_list;
 }
 
-static __always_inline void nvme_unmap_metadata(struct nvme_dev *dev,
-						struct nvme_queue *nvmeq,
-						struct request *req)
+static __always_inline void nvme_unmap_metadata(struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
+	struct nvme_dev *dev = nvmeq->dev;
 
 	if (!iod->meta_sgt.nents) {
 		dma_unmap_page(dev->dev, iod->meta_dma,
@@ -1126,14 +1236,10 @@ static __always_inline void nvme_unmap_metadata(struct nvme_dev *dev,
 
 static __always_inline void nvme_pci_unmap_rq(struct request *req)
 {
-	struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
-	struct nvme_dev *dev = nvmeq->dev;
-
 	if (blk_integrity_rq(req))
-		nvme_unmap_metadata(dev, nvmeq, req);
-
+		nvme_unmap_metadata(req);
 	if (blk_rq_nr_phys_segments(req))
-		nvme_unmap_data(dev, nvmeq, req);
+		nvme_unmap_data(req);
 }
 
 static void nvme_pci_complete_rq(struct request *req)
@@ -1958,8 +2064,28 @@ static int nvme_pci_configure_admin_queue(struct nvme_dev *dev)
 	 * might be pointing at!
 	 */
 	result = nvme_disable_ctrl(&dev->ctrl, false);
-	if (result < 0)
-		return result;
+	if (result < 0) {
+		struct pci_dev *pdev = to_pci_dev(dev->dev);
+
+		/*
+		 * The NVMe Controller Reset method did not get an expected
+		 * CSTS.RDY transition, so something with the device appears to
+		 * be stuck. Use the lower level and bigger hammer PCIe
+		 * Function Level Reset to attempt restoring the device to its
+		 * initial state, and try again.
+		 */
+		result = pcie_reset_flr(pdev, false);
+		if (result < 0)
+			return result;
+
+		pci_restore_state(pdev);
+		result = nvme_disable_ctrl(&dev->ctrl, false);
+		if (result < 0)
+			return result;
+
+		dev_info(dev->ctrl.device,
+			"controller reset completed after pcie flr\n");
+	}
 
 	result = nvme_alloc_queue(dev, 0, NVME_AQ_DEPTH);
 	if (result)
@@ -2101,8 +2227,6 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	if ((dev->cmbsz & (NVME_CMBSZ_WDS | NVME_CMBSZ_RDS)) ==
 			(NVME_CMBSZ_WDS | NVME_CMBSZ_RDS))
 		pci_p2pmem_publish(pdev, true);
-
-	nvme_update_attrs(dev);
 }
 
 static int nvme_set_host_mem(struct nvme_dev *dev, u32 bits)
@@ -2333,7 +2457,7 @@ static ssize_t cmb_show(struct device *dev, struct device_attribute *attr,
 {
 	struct nvme_dev *ndev = to_nvme_dev(dev_get_drvdata(dev));
 
-	return sysfs_emit(buf, "cmbloc : x%08x\ncmbsz  : x%08x\n",
+	return sysfs_emit(buf, "cmbloc : 0x%08x\ncmbsz  : 0x%08x\n",
 		       ndev->cmbloc, ndev->cmbsz);
 }
 static DEVICE_ATTR_RO(cmb);
@@ -2520,7 +2644,8 @@ static unsigned int nvme_max_io_queues(struct nvme_dev *dev)
 	 */
 	if (dev->ctrl.quirks & NVME_QUIRK_SHARED_TAGS)
 		return 1;
-	return num_possible_cpus() + dev->nr_write_queues + dev->nr_poll_queues;
+	return blk_mq_num_possible_queues(0) + dev->nr_write_queues +
+		dev->nr_poll_queues;
 }
 
 static int nvme_setup_io_queues(struct nvme_dev *dev)
@@ -2915,13 +3040,13 @@ static int nvme_disable_prepare_reset(struct nvme_dev *dev, bool shutdown)
 static int nvme_pci_alloc_iod_mempool(struct nvme_dev *dev)
 {
 	size_t meta_size = sizeof(struct scatterlist) * (NVME_MAX_META_SEGS + 1);
-	size_t alloc_size = sizeof(struct scatterlist) * NVME_MAX_SEGS;
+	size_t alloc_size = sizeof(struct nvme_dma_vec) * NVME_MAX_SEGS;
 
-	dev->iod_mempool = mempool_create_node(1,
+	dev->dmavec_mempool = mempool_create_node(1,
 			mempool_kmalloc, mempool_kfree,
 			(void *)alloc_size, GFP_KERNEL,
 			dev_to_node(dev->dev));
-	if (!dev->iod_mempool)
+	if (!dev->dmavec_mempool)
 		return -ENOMEM;
 
 	dev->iod_meta_mempool = mempool_create_node(1,
@@ -2930,10 +3055,9 @@ static int nvme_pci_alloc_iod_mempool(struct nvme_dev *dev)
 			dev_to_node(dev->dev));
 	if (!dev->iod_meta_mempool)
 		goto free;
-
 	return 0;
 free:
-	mempool_destroy(dev->iod_mempool);
+	mempool_destroy(dev->dmavec_mempool);
 	return -ENOMEM;
 }
 
@@ -3010,6 +3134,8 @@ static void nvme_reset_work(struct work_struct *work)
 	if (result < 0)
 		goto out;
 
+	nvme_update_attrs(dev);
+
 	result = nvme_setup_io_queues(dev);
 	if (result)
 		goto out;
@@ -3272,7 +3398,8 @@ static struct nvme_dev *nvme_pci_alloc_dev(struct pci_dev *pdev,
 	 * over a single page.
 	 */
 	dev->ctrl.max_hw_sectors = min_t(u32,
-		NVME_MAX_KB_SZ << 1, dma_opt_mapping_size(&pdev->dev) >> 9);
+			NVME_MAX_BYTES >> SECTOR_SHIFT,
+			dma_opt_mapping_size(&pdev->dev) >> 9);
 	dev->ctrl.max_segments = NVME_MAX_SEGS;
 	dev->ctrl.max_integrity_segments = 1;
 	return dev;
@@ -3343,6 +3470,8 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (result < 0)
 		goto out_disable;
 
+	nvme_update_attrs(dev);
+
 	result = nvme_setup_io_queues(dev);
 	if (result)
 		goto out_disable;
@@ -3378,7 +3507,7 @@ out_disable:
 	nvme_dbbuf_dma_free(dev);
 	nvme_free_queues(dev, 0);
 out_release_iod_mempool:
-	mempool_destroy(dev->iod_mempool);
+	mempool_destroy(dev->dmavec_mempool);
 	mempool_destroy(dev->iod_meta_mempool);
 out_dev_unmap:
 	nvme_dev_unmap(dev);
@@ -3442,7 +3571,7 @@ static void nvme_remove(struct pci_dev *pdev)
 	nvme_dev_remove_admin(dev);
 	nvme_dbbuf_dma_free(dev);
 	nvme_free_queues(dev, 0);
-	mempool_destroy(dev->iod_mempool);
+	mempool_destroy(dev->dmavec_mempool);
 	mempool_destroy(dev->iod_meta_mempool);
 	nvme_release_descriptor_pools(dev);
 	nvme_dev_unmap(dev);
@@ -3845,7 +3974,6 @@ static int __init nvme_init(void)
 	BUILD_BUG_ON(sizeof(struct nvme_create_sq) != 64);
 	BUILD_BUG_ON(sizeof(struct nvme_delete_queue) != 64);
 	BUILD_BUG_ON(IRQ_AFFINITY_MAX_SETS < 2);
-	BUILD_BUG_ON(nvme_pci_npages_prp() > NVME_MAX_NR_DESCRIPTORS);
 
 	return pci_register_driver(&nvme_driver);
 }