GNU Linux-libre 4.19.207-gnu1

[releases.git] / drivers / nvme / host / pci.c

/*
 * NVM Express device driver
 * Copyright (c) 2011-2014, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/aer.h>
#include <linux/async.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/blk-mq-pci.h>
#include <linux/dmi.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/once.h>
#include <linux/pci.h>
#include <linux/t10-pi.h>
#include <linux/types.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/sed-opal.h>

#include "nvme.h"

#define SQ_SIZE(depth)          (depth * sizeof(struct nvme_command))
#define CQ_SIZE(depth)          (depth * sizeof(struct nvme_completion))

#define SGES_PER_PAGE   (PAGE_SIZE / sizeof(struct nvme_sgl_desc))

/*
 * 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.
 */
#define NVME_MAX_KB_SZ  4096
#define NVME_MAX_SEGS   127

static int use_threaded_interrupts;
module_param(use_threaded_interrupts, int, 0);

static bool use_cmb_sqes = true;
module_param(use_cmb_sqes, bool, 0444);
MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");

static unsigned int max_host_mem_size_mb = 128;
module_param(max_host_mem_size_mb, uint, 0444);
MODULE_PARM_DESC(max_host_mem_size_mb,
        "Maximum Host Memory Buffer (HMB) size per controller (in MiB)");

static unsigned int sgl_threshold = SZ_32K;
module_param(sgl_threshold, uint, 0644);
MODULE_PARM_DESC(sgl_threshold,
                "Use SGLs when average request segment size is larger or equal to "
                "this size. Use 0 to disable SGLs.");

static int io_queue_depth_set(const char *val, const struct kernel_param *kp);
static const struct kernel_param_ops io_queue_depth_ops = {
        .set = io_queue_depth_set,
        .get = param_get_int,
};

static int io_queue_depth = 1024;
module_param_cb(io_queue_depth, &io_queue_depth_ops, &io_queue_depth, 0644);
MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2");

struct nvme_dev;
struct nvme_queue;

static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown);

/*
 * Represents an NVM Express device.  Each nvme_dev is a PCI function.
 */
struct nvme_dev {
        struct nvme_queue *queues;
        struct blk_mq_tag_set tagset;
        struct blk_mq_tag_set admin_tagset;
        u32 __iomem *dbs;
        struct device *dev;
        struct dma_pool *prp_page_pool;
        struct dma_pool *prp_small_pool;
        unsigned online_queues;
        unsigned max_qid;
        unsigned int num_vecs;
        int q_depth;
        u32 db_stride;
        void __iomem *bar;
        unsigned long bar_mapped_size;
        struct work_struct remove_work;
        struct mutex shutdown_lock;
        bool subsystem;
        void __iomem *cmb;
        pci_bus_addr_t cmb_bus_addr;
        u64 cmb_size;
        u32 cmbsz;
        u32 cmbloc;
        struct nvme_ctrl ctrl;
        struct completion ioq_wait;

        mempool_t *iod_mempool;

        /* shadow doorbell buffer support: */
        u32 *dbbuf_dbs;
        dma_addr_t dbbuf_dbs_dma_addr;
        u32 *dbbuf_eis;
        dma_addr_t dbbuf_eis_dma_addr;

        /* host memory buffer support: */
        u64 host_mem_size;
        u32 nr_host_mem_descs;
        dma_addr_t host_mem_descs_dma;
        struct nvme_host_mem_buf_desc *host_mem_descs;
        void **host_mem_desc_bufs;
};

static int io_queue_depth_set(const char *val, const struct kernel_param *kp)
{
        int n = 0, ret;

        ret = kstrtoint(val, 10, &n);
        if (ret != 0 || n < 2)
                return -EINVAL;

        return param_set_int(val, kp);
}

static inline unsigned int sq_idx(unsigned int qid, u32 stride)
{
        return qid * 2 * stride;
}

static inline unsigned int cq_idx(unsigned int qid, u32 stride)
{
        return (qid * 2 + 1) * stride;
}

static inline struct nvme_dev *to_nvme_dev(struct nvme_ctrl *ctrl)
{
        return container_of(ctrl, struct nvme_dev, ctrl);
}

/*
 * An NVM Express queue.  Each device has at least two (one for admin
 * commands and one for I/O commands).
 */
struct nvme_queue {
        struct device *q_dmadev;
        struct nvme_dev *dev;
        spinlock_t sq_lock;
        struct nvme_command *sq_cmds;
        struct nvme_command __iomem *sq_cmds_io;
        spinlock_t cq_lock ____cacheline_aligned_in_smp;
        volatile struct nvme_completion *cqes;
        struct blk_mq_tags **tags;
        dma_addr_t sq_dma_addr;
        dma_addr_t cq_dma_addr;
        u32 __iomem *q_db;
        u16 q_depth;
        s16 cq_vector;
        u16 sq_tail;
        u16 cq_head;
        u16 last_cq_head;
        u16 qid;
        u8 cq_phase;
        u32 *dbbuf_sq_db;
        u32 *dbbuf_cq_db;
        u32 *dbbuf_sq_ei;
        u32 *dbbuf_cq_ei;
};

/*
 * The nvme_iod describes the data in an I/O, including the list of PRP
 * entries.  You can't see it in this data structure because C doesn't let
 * me express that.  Use nvme_init_iod to ensure there's enough space
 * allocated to store the PRP list.
 */
struct nvme_iod {
        struct nvme_request req;
        struct nvme_queue *nvmeq;
        bool use_sgl;
        int aborted;
        int npages;             /* In the PRP list. 0 means small pool in use */
        int nents;              /* Used in scatterlist */
        int length;             /* Of data, in bytes */
        dma_addr_t first_dma;
        struct scatterlist meta_sg; /* metadata requires single contiguous buffer */
        struct scatterlist *sg;
        struct scatterlist inline_sg[0];
};

/*
 * Check we didin't inadvertently grow the command struct
 */
static inline void _nvme_check_size(void)
{
        BUILD_BUG_ON(sizeof(struct nvme_rw_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_cq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_create_sq) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_delete_queue) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_features) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_format_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_abort_cmd) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_command) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_id_ctrl) != NVME_IDENTIFY_DATA_SIZE);
        BUILD_BUG_ON(sizeof(struct nvme_id_ns) != NVME_IDENTIFY_DATA_SIZE);
        BUILD_BUG_ON(sizeof(struct nvme_lba_range_type) != 64);
        BUILD_BUG_ON(sizeof(struct nvme_smart_log) != 512);
        BUILD_BUG_ON(sizeof(struct nvme_dbbuf) != 64);
}

static inline unsigned int nvme_dbbuf_size(u32 stride)
{
        return ((num_possible_cpus() + 1) * 8 * stride);
}

static int nvme_dbbuf_dma_alloc(struct nvme_dev *dev)
{
        unsigned int mem_size = nvme_dbbuf_size(dev->db_stride);

        if (dev->dbbuf_dbs)
                return 0;

        dev->dbbuf_dbs = dma_alloc_coherent(dev->dev, mem_size,
                                            &dev->dbbuf_dbs_dma_addr,
                                            GFP_KERNEL);
        if (!dev->dbbuf_dbs)
                return -ENOMEM;
        dev->dbbuf_eis = dma_alloc_coherent(dev->dev, mem_size,
                                            &dev->dbbuf_eis_dma_addr,
                                            GFP_KERNEL);
        if (!dev->dbbuf_eis) {
                dma_free_coherent(dev->dev, mem_size,
                                  dev->dbbuf_dbs, dev->dbbuf_dbs_dma_addr);
                dev->dbbuf_dbs = NULL;
                return -ENOMEM;
        }

        return 0;
}

static void nvme_dbbuf_dma_free(struct nvme_dev *dev)
{
        unsigned int mem_size = nvme_dbbuf_size(dev->db_stride);

        if (dev->dbbuf_dbs) {
                dma_free_coherent(dev->dev, mem_size,
                                  dev->dbbuf_dbs, dev->dbbuf_dbs_dma_addr);
                dev->dbbuf_dbs = NULL;
        }
        if (dev->dbbuf_eis) {
                dma_free_coherent(dev->dev, mem_size,
                                  dev->dbbuf_eis, dev->dbbuf_eis_dma_addr);
                dev->dbbuf_eis = NULL;
        }
}

static void nvme_dbbuf_init(struct nvme_dev *dev,
                            struct nvme_queue *nvmeq, int qid)
{
        if (!dev->dbbuf_dbs || !qid)
                return;

        nvmeq->dbbuf_sq_db = &dev->dbbuf_dbs[sq_idx(qid, dev->db_stride)];
        nvmeq->dbbuf_cq_db = &dev->dbbuf_dbs[cq_idx(qid, dev->db_stride)];
        nvmeq->dbbuf_sq_ei = &dev->dbbuf_eis[sq_idx(qid, dev->db_stride)];
        nvmeq->dbbuf_cq_ei = &dev->dbbuf_eis[cq_idx(qid, dev->db_stride)];
}

static void nvme_dbbuf_free(struct nvme_queue *nvmeq)
{
        if (!nvmeq->qid)
                return;

        nvmeq->dbbuf_sq_db = NULL;
        nvmeq->dbbuf_cq_db = NULL;
        nvmeq->dbbuf_sq_ei = NULL;
        nvmeq->dbbuf_cq_ei = NULL;
}

static void nvme_dbbuf_set(struct nvme_dev *dev)
{
        struct nvme_command c;
        unsigned int i;

        if (!dev->dbbuf_dbs)
                return;

        memset(&c, 0, sizeof(c));
        c.dbbuf.opcode = nvme_admin_dbbuf;
        c.dbbuf.prp1 = cpu_to_le64(dev->dbbuf_dbs_dma_addr);
        c.dbbuf.prp2 = cpu_to_le64(dev->dbbuf_eis_dma_addr);

        if (nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0)) {
                dev_warn(dev->ctrl.device, "unable to set dbbuf\n");
                /* Free memory and continue on */
                nvme_dbbuf_dma_free(dev);

                for (i = 1; i <= dev->online_queues; i++)
                        nvme_dbbuf_free(&dev->queues[i]);
        }
}

static inline int nvme_dbbuf_need_event(u16 event_idx, u16 new_idx, u16 old)
{
        return (u16)(new_idx - event_idx - 1) < (u16)(new_idx - old);
}

/* Update dbbuf and return true if an MMIO is required */
static bool nvme_dbbuf_update_and_check_event(u16 value, u32 *dbbuf_db,
                                              volatile u32 *dbbuf_ei)
{
        if (dbbuf_db) {
                u16 old_value;

                /*
                 * Ensure that the queue is written before updating
                 * the doorbell in memory
                 */
                wmb();

                old_value = *dbbuf_db;
                *dbbuf_db = value;

                /*
                 * Ensure that the doorbell is updated before reading the event
                 * index from memory.  The controller needs to provide similar
                 * ordering to ensure the envent index is updated before reading
                 * the doorbell.
                 */
                mb();

                if (!nvme_dbbuf_need_event(*dbbuf_ei, value, old_value))
                        return false;
        }

        return true;
}

/*
 * Max size of iod being embedded in the request payload
 */
#define NVME_INT_PAGES          2
#define NVME_INT_BYTES(dev)     (NVME_INT_PAGES * (dev)->ctrl.page_size)

/*
 * 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 int nvme_npages(unsigned size, struct nvme_dev *dev)
{
        unsigned nprps = DIV_ROUND_UP(size + dev->ctrl.page_size,
                                      dev->ctrl.page_size);
        return DIV_ROUND_UP(8 * nprps, PAGE_SIZE - 8);
}

/*
 * Calculates the number of pages needed for the SGL segments. For example a 4k
 * page can accommodate 256 SGL descriptors.
 */
static int nvme_pci_npages_sgl(unsigned int num_seg)
{
        return DIV_ROUND_UP(num_seg * sizeof(struct nvme_sgl_desc), PAGE_SIZE);
}

static unsigned int nvme_pci_iod_alloc_size(struct nvme_dev *dev,
                unsigned int size, unsigned int nseg, bool use_sgl)
{
        size_t alloc_size;

        if (use_sgl)
                alloc_size = sizeof(__le64 *) * nvme_pci_npages_sgl(nseg);
        else
                alloc_size = sizeof(__le64 *) * nvme_npages(size, dev);

        return alloc_size + sizeof(struct scatterlist) * nseg;
}

static unsigned int nvme_pci_cmd_size(struct nvme_dev *dev, bool use_sgl)
{
        unsigned int alloc_size = nvme_pci_iod_alloc_size(dev,
                                    NVME_INT_BYTES(dev), NVME_INT_PAGES,
                                    use_sgl);

        return sizeof(struct nvme_iod) + alloc_size;
}

static int nvme_admin_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                                unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = &dev->queues[0];

        WARN_ON(hctx_idx != 0);
        WARN_ON(dev->admin_tagset.tags[0] != hctx->tags);
        WARN_ON(nvmeq->tags);

        hctx->driver_data = nvmeq;
        nvmeq->tags = &dev->admin_tagset.tags[0];
        return 0;
}

static void nvme_admin_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
        struct nvme_queue *nvmeq = hctx->driver_data;

        nvmeq->tags = NULL;
}

static int nvme_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
                          unsigned int hctx_idx)
{
        struct nvme_dev *dev = data;
        struct nvme_queue *nvmeq = &dev->queues[hctx_idx + 1];

        if (!nvmeq->tags)
                nvmeq->tags = &dev->tagset.tags[hctx_idx];

        WARN_ON(dev->tagset.tags[hctx_idx] != hctx->tags);
        hctx->driver_data = nvmeq;
        return 0;
}

static int nvme_init_request(struct blk_mq_tag_set *set, struct request *req,
                unsigned int hctx_idx, unsigned int numa_node)
{
        struct nvme_dev *dev = set->driver_data;
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        int queue_idx = (set == &dev->tagset) ? hctx_idx + 1 : 0;
        struct nvme_queue *nvmeq = &dev->queues[queue_idx];

        BUG_ON(!nvmeq);
        iod->nvmeq = nvmeq;

        nvme_req(req)->ctrl = &dev->ctrl;
        return 0;
}

static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
{
        struct nvme_dev *dev = set->driver_data;

        return blk_mq_pci_map_queues(set, to_pci_dev(dev->dev),
                        dev->num_vecs > 1 ? 1 /* admin queue */ : 0);
}

/**
 * nvme_submit_cmd() - Copy a command into a queue and ring the doorbell
 * @nvmeq: The queue to use
 * @cmd: The command to send
 */
static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd)
{
        spin_lock(&nvmeq->sq_lock);
        if (nvmeq->sq_cmds_io)
                memcpy_toio(&nvmeq->sq_cmds_io[nvmeq->sq_tail], cmd,
                                sizeof(*cmd));
        else
                memcpy(&nvmeq->sq_cmds[nvmeq->sq_tail], cmd, sizeof(*cmd));

        if (++nvmeq->sq_tail == nvmeq->q_depth)
                nvmeq->sq_tail = 0;
        if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail,
                        nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei))
                writel(nvmeq->sq_tail, nvmeq->q_db);
        spin_unlock(&nvmeq->sq_lock);
}

static void **nvme_pci_iod_list(struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        return (void **)(iod->sg + blk_rq_nr_phys_segments(req));
}

static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        int nseg = blk_rq_nr_phys_segments(req);
        unsigned int avg_seg_size;

        if (nseg == 0)
                return false;

        avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req), nseg);

        if (!(dev->ctrl.sgls & ((1 << 0) | (1 << 1))))
                return false;
        if (!iod->nvmeq->qid)
                return false;
        if (!sgl_threshold || avg_seg_size < sgl_threshold)
                return false;
        return true;
}

static blk_status_t nvme_init_iod(struct request *rq, struct nvme_dev *dev)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(rq);
        int nseg = blk_rq_nr_phys_segments(rq);
        unsigned int size = blk_rq_payload_bytes(rq);

        iod->use_sgl = nvme_pci_use_sgls(dev, rq);

        if (nseg > NVME_INT_PAGES || size > NVME_INT_BYTES(dev)) {
                iod->sg = mempool_alloc(dev->iod_mempool, GFP_ATOMIC);
                if (!iod->sg)
                        return BLK_STS_RESOURCE;
        } else {
                iod->sg = iod->inline_sg;
        }

        iod->aborted = 0;
        iod->npages = -1;
        iod->nents = 0;
        iod->length = size;

        return BLK_STS_OK;
}

static void nvme_free_iod(struct nvme_dev *dev, struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        const int last_prp = dev->ctrl.page_size / sizeof(__le64) - 1;
        dma_addr_t dma_addr = iod->first_dma, next_dma_addr;

        int i;

        if (iod->npages == 0)
                dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
                        dma_addr);

        for (i = 0; i < iod->npages; i++) {
                void *addr = nvme_pci_iod_list(req)[i];

                if (iod->use_sgl) {
                        struct nvme_sgl_desc *sg_list = addr;

                        next_dma_addr =
                            le64_to_cpu((sg_list[SGES_PER_PAGE - 1]).addr);
                } else {
                        __le64 *prp_list = addr;

                        next_dma_addr = le64_to_cpu(prp_list[last_prp]);
                }

                dma_pool_free(dev->prp_page_pool, addr, dma_addr);
                dma_addr = next_dma_addr;
        }

        if (iod->sg != iod->inline_sg)
                mempool_free(iod->sg, dev->iod_mempool);
}

static void nvme_print_sgl(struct scatterlist *sgl, int nents)
{
        int i;
        struct scatterlist *sg;

        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));
        }
}

static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
                struct request *req, struct nvme_rw_command *cmnd)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct dma_pool *pool;
        int length = blk_rq_payload_bytes(req);
        struct scatterlist *sg = iod->sg;
        int dma_len = sg_dma_len(sg);
        u64 dma_addr = sg_dma_address(sg);
        u32 page_size = dev->ctrl.page_size;
        int offset = dma_addr & (page_size - 1);
        __le64 *prp_list;
        void **list = nvme_pci_iod_list(req);
        dma_addr_t prp_dma;
        int nprps, i;

        length -= (page_size - offset);
        if (length <= 0) {
                iod->first_dma = 0;
                goto done;
        }

        dma_len -= (page_size - offset);
        if (dma_len) {
                dma_addr += (page_size - offset);
        } else {
                sg = sg_next(sg);
                dma_addr = sg_dma_address(sg);
                dma_len = sg_dma_len(sg);
        }

        if (length <= page_size) {
                iod->first_dma = dma_addr;
                goto done;
        }

        nprps = DIV_ROUND_UP(length, page_size);
        if (nprps <= (256 / 8)) {
                pool = dev->prp_small_pool;
                iod->npages = 0;
        } else {
                pool = dev->prp_page_pool;
                iod->npages = 1;
        }

        prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
        if (!prp_list) {
                iod->first_dma = dma_addr;
                iod->npages = -1;
                return BLK_STS_RESOURCE;
        }
        list[0] = prp_list;
        iod->first_dma = prp_dma;
        i = 0;
        for (;;) {
                if (i == page_size >> 3) {
                        __le64 *old_prp_list = prp_list;
                        prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
                        if (!prp_list)
                                return BLK_STS_RESOURCE;
                        list[iod->npages++] = prp_list;
                        prp_list[0] = old_prp_list[i - 1];
                        old_prp_list[i - 1] = cpu_to_le64(prp_dma);
                        i = 1;
                }
                prp_list[i++] = cpu_to_le64(dma_addr);
                dma_len -= page_size;
                dma_addr += page_size;
                length -= 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->sg));
        cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma);

        return BLK_STS_OK;

 bad_sgl:
        WARN(DO_ONCE(nvme_print_sgl, iod->sg, iod->nents),
                        "Invalid SGL for payload:%d nents:%d\n",
                        blk_rq_payload_bytes(req), iod->nents);
        return BLK_STS_IOERR;
}

static void nvme_pci_sgl_set_data(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 void nvme_pci_sgl_set_seg(struct nvme_sgl_desc *sge,
                dma_addr_t dma_addr, int entries)
{
        sge->addr = cpu_to_le64(dma_addr);
        if (entries < SGES_PER_PAGE) {
                sge->length = cpu_to_le32(entries * sizeof(*sge));
                sge->type = NVME_SGL_FMT_LAST_SEG_DESC << 4;
        } else {
                sge->length = cpu_to_le32(PAGE_SIZE);
                sge->type = NVME_SGL_FMT_SEG_DESC << 4;
        }
}

static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
                struct request *req, struct nvme_rw_command *cmd, int entries)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct dma_pool *pool;
        struct nvme_sgl_desc *sg_list;
        struct scatterlist *sg = iod->sg;
        dma_addr_t sgl_dma;
        int i = 0;

        /* setting the transfer type as SGL */
        cmd->flags = NVME_CMD_SGL_METABUF;

        if (entries == 1) {
                nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);
                return BLK_STS_OK;
        }

        if (entries <= (256 / sizeof(struct nvme_sgl_desc))) {
                pool = dev->prp_small_pool;
                iod->npages = 0;
        } else {
                pool = dev->prp_page_pool;
                iod->npages = 1;
        }

        sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
        if (!sg_list) {
                iod->npages = -1;
                return BLK_STS_RESOURCE;
        }

        nvme_pci_iod_list(req)[0] = sg_list;
        iod->first_dma = sgl_dma;

        nvme_pci_sgl_set_seg(&cmd->dptr.sgl, sgl_dma, entries);

        do {
                if (i == SGES_PER_PAGE) {
                        struct nvme_sgl_desc *old_sg_desc = sg_list;
                        struct nvme_sgl_desc *link = &old_sg_desc[i - 1];

                        sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
                        if (!sg_list)
                                return BLK_STS_RESOURCE;

                        i = 0;
                        nvme_pci_iod_list(req)[iod->npages++] = sg_list;
                        sg_list[i++] = *link;
                        nvme_pci_sgl_set_seg(link, sgl_dma, entries);
                }

                nvme_pci_sgl_set_data(&sg_list[i++], sg);
                sg = sg_next(sg);
        } while (--entries > 0);

        return BLK_STS_OK;
}

static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
                struct nvme_command *cmnd)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct request_queue *q = req->q;
        enum dma_data_direction dma_dir = rq_data_dir(req) ?
                        DMA_TO_DEVICE : DMA_FROM_DEVICE;
        blk_status_t ret = BLK_STS_IOERR;
        int nr_mapped;

        sg_init_table(iod->sg, blk_rq_nr_phys_segments(req));
        iod->nents = blk_rq_map_sg(q, req, iod->sg);
        if (!iod->nents)
                goto out;

        ret = BLK_STS_RESOURCE;
        nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
                        DMA_ATTR_NO_WARN);
        if (!nr_mapped)
                goto out;

        if (iod->use_sgl)
                ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped);
        else
                ret = nvme_pci_setup_prps(dev, req, &cmnd->rw);

        if (ret != BLK_STS_OK)
                goto out_unmap;

        ret = BLK_STS_IOERR;
        if (blk_integrity_rq(req)) {
                if (blk_rq_count_integrity_sg(q, req->bio) != 1)
                        goto out_unmap;

                sg_init_table(&iod->meta_sg, 1);
                if (blk_rq_map_integrity_sg(q, req->bio, &iod->meta_sg) != 1)
                        goto out_unmap;

                if (!dma_map_sg(dev->dev, &iod->meta_sg, 1, dma_dir))
                        goto out_unmap;
        }

        if (blk_integrity_rq(req))
                cmnd->rw.metadata = cpu_to_le64(sg_dma_address(&iod->meta_sg));
        return BLK_STS_OK;

out_unmap:
        dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
out:
        return ret;
}

static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        enum dma_data_direction dma_dir = rq_data_dir(req) ?
                        DMA_TO_DEVICE : DMA_FROM_DEVICE;

        if (iod->nents) {
                dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
                if (blk_integrity_rq(req))
                        dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
        }

        nvme_cleanup_cmd(req);
        nvme_free_iod(dev, req);
}

/*
 * NOTE: ns is NULL when called on the admin queue.
 */
static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
                         const struct blk_mq_queue_data *bd)
{
        struct nvme_ns *ns = hctx->queue->queuedata;
        struct nvme_queue *nvmeq = hctx->driver_data;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *req = bd->rq;
        struct nvme_command cmnd;
        blk_status_t ret;

        /*
         * We should not need to do this, but we're still using this to
         * ensure we can drain requests on a dying queue.
         */
        if (unlikely(nvmeq->cq_vector < 0))
                return BLK_STS_IOERR;

        ret = nvme_setup_cmd(ns, req, &cmnd);
        if (ret)
                return ret;

        ret = nvme_init_iod(req, dev);
        if (ret)
                goto out_free_cmd;

        if (blk_rq_nr_phys_segments(req)) {
                ret = nvme_map_data(dev, req, &cmnd);
                if (ret)
                        goto out_cleanup_iod;
        }

        blk_mq_start_request(req);
        nvme_submit_cmd(nvmeq, &cmnd);
        return BLK_STS_OK;
out_cleanup_iod:
        nvme_free_iod(dev, req);
out_free_cmd:
        nvme_cleanup_cmd(req);
        return ret;
}

static void nvme_pci_complete_rq(struct request *req)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);

        nvme_unmap_data(iod->nvmeq->dev, req);
        nvme_complete_rq(req);
}

/* We read the CQE phase first to check if the rest of the entry is valid */
static inline bool nvme_cqe_pending(struct nvme_queue *nvmeq)
{
        return (le16_to_cpu(nvmeq->cqes[nvmeq->cq_head].status) & 1) ==
                        nvmeq->cq_phase;
}

static inline void nvme_ring_cq_doorbell(struct nvme_queue *nvmeq)
{
        u16 head = nvmeq->cq_head;

        if (nvme_dbbuf_update_and_check_event(head, nvmeq->dbbuf_cq_db,
                                              nvmeq->dbbuf_cq_ei))
                writel(head, nvmeq->q_db + nvmeq->dev->db_stride);
}

static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
{
        volatile struct nvme_completion *cqe = &nvmeq->cqes[idx];
        struct request *req;

        if (unlikely(cqe->command_id >= nvmeq->q_depth)) {
                dev_warn(nvmeq->dev->ctrl.device,
                        "invalid id %d completed on queue %d\n",
                        cqe->command_id, le16_to_cpu(cqe->sq_id));
                return;
        }

        /*
         * AEN requests are special as they don't time out and can
         * survive any kind of queue freeze and often don't respond to
         * aborts.  We don't even bother to allocate a struct request
         * for them but rather special case them here.
         */
        if (unlikely(nvmeq->qid == 0 &&
                        cqe->command_id >= NVME_AQ_BLK_MQ_DEPTH)) {
                nvme_complete_async_event(&nvmeq->dev->ctrl,
                                cqe->status, &cqe->result);
                return;
        }

        req = blk_mq_tag_to_rq(*nvmeq->tags, cqe->command_id);
        nvme_end_request(req, cqe->status, cqe->result);
}

static void nvme_complete_cqes(struct nvme_queue *nvmeq, u16 start, u16 end)
{
        while (start != end) {
                nvme_handle_cqe(nvmeq, start);
                if (++start == nvmeq->q_depth)
                        start = 0;
        }
}

static inline void nvme_update_cq_head(struct nvme_queue *nvmeq)
{
        if (nvmeq->cq_head == nvmeq->q_depth - 1) {
                nvmeq->cq_head = 0;
                nvmeq->cq_phase = !nvmeq->cq_phase;
        } else {
                nvmeq->cq_head++;
        }
}

static inline bool nvme_process_cq(struct nvme_queue *nvmeq, u16 *start,
                u16 *end, int tag)
{
        bool found = false;

        *start = nvmeq->cq_head;
        while (!found && nvme_cqe_pending(nvmeq)) {
                if (nvmeq->cqes[nvmeq->cq_head].command_id == tag)
                        found = true;
                nvme_update_cq_head(nvmeq);
        }
        *end = nvmeq->cq_head;

        if (*start != *end)
                nvme_ring_cq_doorbell(nvmeq);
        return found;
}

static irqreturn_t nvme_irq(int irq, void *data)
{
        struct nvme_queue *nvmeq = data;
        irqreturn_t ret = IRQ_NONE;
        u16 start, end;

        spin_lock(&nvmeq->cq_lock);
        if (nvmeq->cq_head != nvmeq->last_cq_head)
                ret = IRQ_HANDLED;
        nvme_process_cq(nvmeq, &start, &end, -1);
        nvmeq->last_cq_head = nvmeq->cq_head;
        spin_unlock(&nvmeq->cq_lock);

        if (start != end) {
                nvme_complete_cqes(nvmeq, start, end);
                return IRQ_HANDLED;
        }

        return ret;
}

static irqreturn_t nvme_irq_check(int irq, void *data)
{
        struct nvme_queue *nvmeq = data;
        if (nvme_cqe_pending(nvmeq))
                return IRQ_WAKE_THREAD;
        return IRQ_NONE;
}

static int __nvme_poll(struct nvme_queue *nvmeq, unsigned int tag)
{
        u16 start, end;
        bool found;

        if (!nvme_cqe_pending(nvmeq))
                return 0;

        spin_lock_irq(&nvmeq->cq_lock);
        found = nvme_process_cq(nvmeq, &start, &end, tag);
        spin_unlock_irq(&nvmeq->cq_lock);

        nvme_complete_cqes(nvmeq, start, end);
        return found;
}

static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
{
        struct nvme_queue *nvmeq = hctx->driver_data;

        return __nvme_poll(nvmeq, tag);
}

static void nvme_pci_submit_async_event(struct nvme_ctrl *ctrl)
{
        struct nvme_dev *dev = to_nvme_dev(ctrl);
        struct nvme_queue *nvmeq = &dev->queues[0];
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.common.opcode = nvme_admin_async_event;
        c.common.command_id = NVME_AQ_BLK_MQ_DEPTH;
        nvme_submit_cmd(nvmeq, &c);
}

static int adapter_delete_queue(struct nvme_dev *dev, u8 opcode, u16 id)
{
        struct nvme_command c;

        memset(&c, 0, sizeof(c));
        c.delete_queue.opcode = opcode;
        c.delete_queue.qid = cpu_to_le16(id);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_alloc_cq(struct nvme_dev *dev, u16 qid,
                struct nvme_queue *nvmeq, s16 vector)
{
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG | NVME_CQ_IRQ_ENABLED;

        /*
         * Note: we (ab)use the fact that the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_cq.opcode = nvme_admin_create_cq;
        c.create_cq.prp1 = cpu_to_le64(nvmeq->cq_dma_addr);
        c.create_cq.cqid = cpu_to_le16(qid);
        c.create_cq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_cq.cq_flags = cpu_to_le16(flags);
        c.create_cq.irq_vector = cpu_to_le16(vector);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_alloc_sq(struct nvme_dev *dev, u16 qid,
                                                struct nvme_queue *nvmeq)
{
        struct nvme_ctrl *ctrl = &dev->ctrl;
        struct nvme_command c;
        int flags = NVME_QUEUE_PHYS_CONTIG;

        /*
         * Some drives have a bug that auto-enables WRRU if MEDIUM isn't
         * set. Since URGENT priority is zeroes, it makes all queues
         * URGENT.
         */
        if (ctrl->quirks & NVME_QUIRK_MEDIUM_PRIO_SQ)
                flags |= NVME_SQ_PRIO_MEDIUM;

        /*
         * Note: we (ab)use the fact that the prp fields survive if no data
         * is attached to the request.
         */
        memset(&c, 0, sizeof(c));
        c.create_sq.opcode = nvme_admin_create_sq;
        c.create_sq.prp1 = cpu_to_le64(nvmeq->sq_dma_addr);
        c.create_sq.sqid = cpu_to_le16(qid);
        c.create_sq.qsize = cpu_to_le16(nvmeq->q_depth - 1);
        c.create_sq.sq_flags = cpu_to_le16(flags);
        c.create_sq.cqid = cpu_to_le16(qid);

        return nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
}

static int adapter_delete_cq(struct nvme_dev *dev, u16 cqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_cq, cqid);
}

static int adapter_delete_sq(struct nvme_dev *dev, u16 sqid)
{
        return adapter_delete_queue(dev, nvme_admin_delete_sq, sqid);
}

static void abort_endio(struct request *req, blk_status_t error)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = iod->nvmeq;

        dev_warn(nvmeq->dev->ctrl.device,
                 "Abort status: 0x%x", nvme_req(req)->status);
        atomic_inc(&nvmeq->dev->ctrl.abort_limit);
        blk_mq_free_request(req);
}

static bool nvme_should_reset(struct nvme_dev *dev, u32 csts)
{

        /* If true, indicates loss of adapter communication, possibly by a
         * NVMe Subsystem reset.
         */
        bool nssro = dev->subsystem && (csts & NVME_CSTS_NSSRO);

        /* If there is a reset/reinit ongoing, we shouldn't reset again. */
        switch (dev->ctrl.state) {
        case NVME_CTRL_RESETTING:
        case NVME_CTRL_CONNECTING:
                return false;
        default:
                break;
        }

        /* We shouldn't reset unless the controller is on fatal error state
         * _or_ if we lost the communication with it.
         */
        if (!(csts & NVME_CSTS_CFS) && !nssro)
                return false;

        return true;
}

static void nvme_warn_reset(struct nvme_dev *dev, u32 csts)
{
        /* Read a config register to help see what died. */
        u16 pci_status;
        int result;

        result = pci_read_config_word(to_pci_dev(dev->dev), PCI_STATUS,
                                      &pci_status);
        if (result == PCIBIOS_SUCCESSFUL)
                dev_warn(dev->ctrl.device,
                         "controller is down; will reset: CSTS=0x%x, PCI_STATUS=0x%hx\n",
                         csts, pci_status);
        else
                dev_warn(dev->ctrl.device,
                         "controller is down; will reset: CSTS=0x%x, PCI_STATUS read failed (%d)\n",
                         csts, result);
}

static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
{
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_queue *nvmeq = iod->nvmeq;
        struct nvme_dev *dev = nvmeq->dev;
        struct request *abort_req;
        struct nvme_command cmd;
        bool shutdown = false;
        u32 csts = readl(dev->bar + NVME_REG_CSTS);

        /* If PCI error recovery process is happening, we cannot reset or
         * the recovery mechanism will surely fail.
         */
        mb();
        if (pci_channel_offline(to_pci_dev(dev->dev)))
                return BLK_EH_RESET_TIMER;

        /*
         * Reset immediately if the controller is failed
         */
        if (nvme_should_reset(dev, csts)) {
                nvme_warn_reset(dev, csts);
                nvme_dev_disable(dev, false);
                nvme_reset_ctrl(&dev->ctrl);
                return BLK_EH_DONE;
        }

        /*
         * Did we miss an interrupt?
         */
        if (__nvme_poll(nvmeq, req->tag)) {
                dev_warn(dev->ctrl.device,
                         "I/O %d QID %d timeout, completion polled\n",
                         req->tag, nvmeq->qid);
                return BLK_EH_DONE;
        }

        /*
         * Shutdown immediately if controller times out while starting. The
         * reset work will see the pci device disabled when it gets the forced
         * cancellation error. All outstanding requests are completed on
         * shutdown, so we return BLK_EH_DONE.
         */
        switch (dev->ctrl.state) {
        case NVME_CTRL_DELETING:
                shutdown = true;
        case NVME_CTRL_CONNECTING:
        case NVME_CTRL_RESETTING:
                dev_warn_ratelimited(dev->ctrl.device,
                         "I/O %d QID %d timeout, disable controller\n",
                         req->tag, nvmeq->qid);
                nvme_dev_disable(dev, shutdown);
                nvme_req(req)->flags |= NVME_REQ_CANCELLED;
                return BLK_EH_DONE;
        default:
                break;
        }

        /*
         * Shutdown the controller immediately and schedule a reset if the
         * command was already aborted once before and still hasn't been
         * returned to the driver, or if this is the admin queue.
         */
        if (!nvmeq->qid || iod->aborted) {
                dev_warn(dev->ctrl.device,
                         "I/O %d QID %d timeout, reset controller\n",
                         req->tag, nvmeq->qid);
                nvme_dev_disable(dev, false);
                nvme_reset_ctrl(&dev->ctrl);

                nvme_req(req)->flags |= NVME_REQ_CANCELLED;
                return BLK_EH_DONE;
        }

        if (atomic_dec_return(&dev->ctrl.abort_limit) < 0) {
                atomic_inc(&dev->ctrl.abort_limit);
                return BLK_EH_RESET_TIMER;
        }
        iod->aborted = 1;

        memset(&cmd, 0, sizeof(cmd));
        cmd.abort.opcode = nvme_admin_abort_cmd;
        cmd.abort.cid = req->tag;
        cmd.abort.sqid = cpu_to_le16(nvmeq->qid);

        dev_warn(nvmeq->dev->ctrl.device,
                "I/O %d QID %d timeout, aborting\n",
                 req->tag, nvmeq->qid);

        abort_req = nvme_alloc_request(dev->ctrl.admin_q, &cmd,
                        BLK_MQ_REQ_NOWAIT, NVME_QID_ANY);
        if (IS_ERR(abort_req)) {
                atomic_inc(&dev->ctrl.abort_limit);
                return BLK_EH_RESET_TIMER;
        }

        abort_req->timeout = ADMIN_TIMEOUT;
        abort_req->end_io_data = NULL;
        blk_execute_rq_nowait(abort_req->q, NULL, abort_req, 0, abort_endio);

        /*
         * The aborted req will be completed on receiving the abort req.
         * We enable the timer again. If hit twice, it'll cause a device reset,
         * as the device then is in a faulty state.
         */
        return BLK_EH_RESET_TIMER;
}

static void nvme_free_queue(struct nvme_queue *nvmeq)
{
        dma_free_coherent(nvmeq->q_dmadev, CQ_SIZE(nvmeq->q_depth),
                                (void *)nvmeq->cqes, nvmeq->cq_dma_addr);
        if (nvmeq->sq_cmds)
                dma_free_coherent(nvmeq->q_dmadev, SQ_SIZE(nvmeq->q_depth),
                                        nvmeq->sq_cmds, nvmeq->sq_dma_addr);
}

static void nvme_free_queues(struct nvme_dev *dev, int lowest)
{
        int i;

        for (i = dev->ctrl.queue_count - 1; i >= lowest; i--) {
                dev->ctrl.queue_count--;
                nvme_free_queue(&dev->queues[i]);
        }
}

/**
 * nvme_suspend_queue - put queue into suspended state
 * @nvmeq - queue to suspend
 */
static int nvme_suspend_queue(struct nvme_queue *nvmeq)
{
        int vector;

        spin_lock_irq(&nvmeq->cq_lock);
        if (nvmeq->cq_vector == -1) {
                spin_unlock_irq(&nvmeq->cq_lock);
                return 1;
        }
        vector = nvmeq->cq_vector;
        nvmeq->dev->online_queues--;
        nvmeq->cq_vector = -1;
        spin_unlock_irq(&nvmeq->cq_lock);

        /*
         * Ensure that nvme_queue_rq() sees it ->cq_vector == -1 without
         * having to grab the lock.
         */
        mb();

        if (!nvmeq->qid && nvmeq->dev->ctrl.admin_q)
                blk_mq_quiesce_queue(nvmeq->dev->ctrl.admin_q);

        pci_free_irq(to_pci_dev(nvmeq->dev->dev), vector, nvmeq);

        return 0;
}

static void nvme_disable_admin_queue(struct nvme_dev *dev, bool shutdown)
{
        struct nvme_queue *nvmeq = &dev->queues[0];
        u16 start, end;

        if (shutdown)
                nvme_shutdown_ctrl(&dev->ctrl);
        else
                nvme_disable_ctrl(&dev->ctrl, dev->ctrl.cap);

        spin_lock_irq(&nvmeq->cq_lock);
        nvme_process_cq(nvmeq, &start, &end, -1);
        spin_unlock_irq(&nvmeq->cq_lock);

        nvme_complete_cqes(nvmeq, start, end);
}

static int nvme_cmb_qdepth(struct nvme_dev *dev, int nr_io_queues,
                                int entry_size)
{
        int q_depth = dev->q_depth;
        unsigned q_size_aligned = roundup(q_depth * entry_size,
                                          dev->ctrl.page_size);

        if (q_size_aligned * nr_io_queues > dev->cmb_size) {
                u64 mem_per_q = div_u64(dev->cmb_size, nr_io_queues);
                mem_per_q = round_down(mem_per_q, dev->ctrl.page_size);
                q_depth = div_u64(mem_per_q, entry_size);

                /*
                 * Ensure the reduced q_depth is above some threshold where it
                 * would be better to map queues in system memory with the
                 * original depth
                 */
                if (q_depth < 64)
                        return -ENOMEM;
        }

        return q_depth;
}

static int nvme_alloc_sq_cmds(struct nvme_dev *dev, struct nvme_queue *nvmeq,
                                int qid, int depth)
{
        /* CMB SQEs will be mapped before creation */
        if (qid && dev->cmb && use_cmb_sqes && (dev->cmbsz & NVME_CMBSZ_SQS))
                return 0;

        nvmeq->sq_cmds = dma_alloc_coherent(dev->dev, SQ_SIZE(depth),
                                            &nvmeq->sq_dma_addr, GFP_KERNEL);
        if (!nvmeq->sq_cmds)
                return -ENOMEM;
        return 0;
}

static int nvme_alloc_queue(struct nvme_dev *dev, int qid, int depth)
{
        struct nvme_queue *nvmeq = &dev->queues[qid];

        if (dev->ctrl.queue_count > qid)
                return 0;

        nvmeq->cqes = dma_zalloc_coherent(dev->dev, CQ_SIZE(depth),
                                          &nvmeq->cq_dma_addr, GFP_KERNEL);
        if (!nvmeq->cqes)
                goto free_nvmeq;

        if (nvme_alloc_sq_cmds(dev, nvmeq, qid, depth))
                goto free_cqdma;

        nvmeq->q_dmadev = dev->dev;
        nvmeq->dev = dev;
        spin_lock_init(&nvmeq->sq_lock);
        spin_lock_init(&nvmeq->cq_lock);
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        nvmeq->q_depth = depth;
        nvmeq->qid = qid;
        nvmeq->cq_vector = -1;
        dev->ctrl.queue_count++;

        return 0;

 free_cqdma:
        dma_free_coherent(dev->dev, CQ_SIZE(depth), (void *)nvmeq->cqes,
                                                        nvmeq->cq_dma_addr);
 free_nvmeq:
        return -ENOMEM;
}

static int queue_request_irq(struct nvme_queue *nvmeq)
{
        struct pci_dev *pdev = to_pci_dev(nvmeq->dev->dev);
        int nr = nvmeq->dev->ctrl.instance;

        if (use_threaded_interrupts) {
                return pci_request_irq(pdev, nvmeq->cq_vector, nvme_irq_check,
                                nvme_irq, nvmeq, "nvme%dq%d", nr, nvmeq->qid);
        } else {
                return pci_request_irq(pdev, nvmeq->cq_vector, nvme_irq,
                                NULL, nvmeq, "nvme%dq%d", nr, nvmeq->qid);
        }
}

static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
{
        struct nvme_dev *dev = nvmeq->dev;

        spin_lock_irq(&nvmeq->cq_lock);
        nvmeq->sq_tail = 0;
        nvmeq->cq_head = 0;
        nvmeq->cq_phase = 1;
        nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
        memset((void *)nvmeq->cqes, 0, CQ_SIZE(nvmeq->q_depth));
        nvme_dbbuf_init(dev, nvmeq, qid);
        dev->online_queues++;
        spin_unlock_irq(&nvmeq->cq_lock);
}

static int nvme_create_queue(struct nvme_queue *nvmeq, int qid)
{
        struct nvme_dev *dev = nvmeq->dev;
        int result;
        s16 vector;

        if (dev->cmb && use_cmb_sqes && (dev->cmbsz & NVME_CMBSZ_SQS)) {
                unsigned offset = (qid - 1) * roundup(SQ_SIZE(nvmeq->q_depth),
                                                      dev->ctrl.page_size);
                nvmeq->sq_dma_addr = dev->cmb_bus_addr + offset;
                nvmeq->sq_cmds_io = dev->cmb + offset;
        }

        /*
         * A queue's vector matches the queue identifier unless the controller
         * has only one vector available.
         */
        vector = dev->num_vecs == 1 ? 0 : qid;
        result = adapter_alloc_cq(dev, qid, nvmeq, vector);
        if (result)
                return result;

        result = adapter_alloc_sq(dev, qid, nvmeq);
        if (result < 0)
                return result;
        else if (result)
                goto release_cq;

        /*
         * Set cq_vector after alloc cq/sq, otherwise nvme_suspend_queue will
         * invoke free_irq for it and cause a 'Trying to free already-free IRQ
         * xxx' warning if the create CQ/SQ command times out.
         */
        nvmeq->cq_vector = vector;
        nvme_init_queue(nvmeq, qid);
        result = queue_request_irq(nvmeq);
        if (result < 0)
                goto release_sq;

        return result;

release_sq:
        nvmeq->cq_vector = -1;
        dev->online_queues--;
        adapter_delete_sq(dev, qid);
release_cq:
        adapter_delete_cq(dev, qid);
        return result;
}

static const struct blk_mq_ops nvme_mq_admin_ops = {
        .queue_rq       = nvme_queue_rq,
        .complete       = nvme_pci_complete_rq,
        .init_hctx      = nvme_admin_init_hctx,
        .exit_hctx      = nvme_admin_exit_hctx,
        .init_request   = nvme_init_request,
        .timeout        = nvme_timeout,
};

static const struct blk_mq_ops nvme_mq_ops = {
        .queue_rq       = nvme_queue_rq,
        .complete       = nvme_pci_complete_rq,
        .init_hctx      = nvme_init_hctx,
        .init_request   = nvme_init_request,
        .map_queues     = nvme_pci_map_queues,
        .timeout        = nvme_timeout,
        .poll           = nvme_poll,
};

static void nvme_dev_remove_admin(struct nvme_dev *dev)
{
        if (dev->ctrl.admin_q && !blk_queue_dying(dev->ctrl.admin_q)) {
                /*
                 * If the controller was reset during removal, it's possible
                 * user requests may be waiting on a stopped queue. Start the
                 * queue to flush these to completion.
                 */
                blk_mq_unquiesce_queue(dev->ctrl.admin_q);
                blk_cleanup_queue(dev->ctrl.admin_q);
                blk_mq_free_tag_set(&dev->admin_tagset);
        }
}

static int nvme_alloc_admin_tags(struct nvme_dev *dev)
{
        if (!dev->ctrl.admin_q) {
                dev->admin_tagset.ops = &nvme_mq_admin_ops;
                dev->admin_tagset.nr_hw_queues = 1;

                dev->admin_tagset.queue_depth = NVME_AQ_MQ_TAG_DEPTH;
                dev->admin_tagset.timeout = ADMIN_TIMEOUT;
                dev->admin_tagset.numa_node = dev_to_node(dev->dev);
                dev->admin_tagset.cmd_size = nvme_pci_cmd_size(dev, false);
                dev->admin_tagset.flags = BLK_MQ_F_NO_SCHED;
                dev->admin_tagset.driver_data = dev;

                if (blk_mq_alloc_tag_set(&dev->admin_tagset))
                        return -ENOMEM;
                dev->ctrl.admin_tagset = &dev->admin_tagset;

                dev->ctrl.admin_q = blk_mq_init_queue(&dev->admin_tagset);
                if (IS_ERR(dev->ctrl.admin_q)) {
                        blk_mq_free_tag_set(&dev->admin_tagset);
                        return -ENOMEM;
                }
                if (!blk_get_queue(dev->ctrl.admin_q)) {
                        nvme_dev_remove_admin(dev);
                        dev->ctrl.admin_q = NULL;
                        return -ENODEV;
                }
        } else
                blk_mq_unquiesce_queue(dev->ctrl.admin_q);

        return 0;
}

static unsigned long db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
{
        return NVME_REG_DBS + ((nr_io_queues + 1) * 8 * dev->db_stride);
}

static int nvme_remap_bar(struct nvme_dev *dev, unsigned long size)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (size <= dev->bar_mapped_size)
                return 0;
        if (size > pci_resource_len(pdev, 0))
                return -ENOMEM;
        if (dev->bar)
                iounmap(dev->bar);
        dev->bar = ioremap(pci_resource_start(pdev, 0), size);
        if (!dev->bar) {
                dev->bar_mapped_size = 0;
                return -ENOMEM;
        }
        dev->bar_mapped_size = size;
        dev->dbs = dev->bar + NVME_REG_DBS;

        return 0;
}

static int nvme_pci_configure_admin_queue(struct nvme_dev *dev)
{
        int result;
        u32 aqa;
        struct nvme_queue *nvmeq;

        result = nvme_remap_bar(dev, db_bar_size(dev, 0));
        if (result < 0)
                return result;

        dev->subsystem = readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 1, 0) ?
                                NVME_CAP_NSSRC(dev->ctrl.cap) : 0;

        if (dev->subsystem &&
            (readl(dev->bar + NVME_REG_CSTS) & NVME_CSTS_NSSRO))
                writel(NVME_CSTS_NSSRO, dev->bar + NVME_REG_CSTS);

        result = nvme_disable_ctrl(&dev->ctrl, dev->ctrl.cap);
        if (result < 0)
                return result;

        result = nvme_alloc_queue(dev, 0, NVME_AQ_DEPTH);
        if (result)
                return result;

        nvmeq = &dev->queues[0];
        aqa = nvmeq->q_depth - 1;
        aqa |= aqa << 16;

        writel(aqa, dev->bar + NVME_REG_AQA);
        lo_hi_writeq(nvmeq->sq_dma_addr, dev->bar + NVME_REG_ASQ);
        lo_hi_writeq(nvmeq->cq_dma_addr, dev->bar + NVME_REG_ACQ);

        result = nvme_enable_ctrl(&dev->ctrl, dev->ctrl.cap);
        if (result)
                return result;

        nvmeq->cq_vector = 0;
        nvme_init_queue(nvmeq, 0);
        result = queue_request_irq(nvmeq);
        if (result) {
                nvmeq->cq_vector = -1;
                return result;
        }

        return result;
}

static int nvme_create_io_queues(struct nvme_dev *dev)
{
        unsigned i, max;
        int ret = 0;

        for (i = dev->ctrl.queue_count; i <= dev->max_qid; i++) {
                if (nvme_alloc_queue(dev, i, dev->q_depth)) {
                        ret = -ENOMEM;
                        break;
                }
        }

        max = min(dev->max_qid, dev->ctrl.queue_count - 1);
        for (i = dev->online_queues; i <= max; i++) {
                ret = nvme_create_queue(&dev->queues[i], i);
                if (ret)
                        break;
        }

        /*
         * Ignore failing Create SQ/CQ commands, we can continue with less
         * than the desired amount of queues, and even a controller without
         * I/O queues can still be used to issue admin commands.  This might
         * be useful to upgrade a buggy firmware for example.
         */
        return ret >= 0 ? 0 : ret;
}

static ssize_t nvme_cmb_show(struct device *dev,
                             struct device_attribute *attr,
                             char *buf)
{
        struct nvme_dev *ndev = to_nvme_dev(dev_get_drvdata(dev));

        return scnprintf(buf, PAGE_SIZE, "cmbloc : x%08x\ncmbsz  : x%08x\n",
                       ndev->cmbloc, ndev->cmbsz);
}
static DEVICE_ATTR(cmb, S_IRUGO, nvme_cmb_show, NULL);

static u64 nvme_cmb_size_unit(struct nvme_dev *dev)
{
        u8 szu = (dev->cmbsz >> NVME_CMBSZ_SZU_SHIFT) & NVME_CMBSZ_SZU_MASK;

        return 1ULL << (12 + 4 * szu);
}

static u32 nvme_cmb_size(struct nvme_dev *dev)
{
        return (dev->cmbsz >> NVME_CMBSZ_SZ_SHIFT) & NVME_CMBSZ_SZ_MASK;
}

static void nvme_map_cmb(struct nvme_dev *dev)
{
        u64 size, offset;
        resource_size_t bar_size;
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int bar;

        if (dev->cmb_size)
                return;

        dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
        if (!dev->cmbsz)
                return;
        dev->cmbloc = readl(dev->bar + NVME_REG_CMBLOC);

        if (!use_cmb_sqes)
                return;

        size = nvme_cmb_size_unit(dev) * nvme_cmb_size(dev);
        offset = nvme_cmb_size_unit(dev) * NVME_CMB_OFST(dev->cmbloc);
        bar = NVME_CMB_BIR(dev->cmbloc);
        bar_size = pci_resource_len(pdev, bar);

        if (offset > bar_size)
                return;

        /*
         * Controllers may support a CMB size larger than their BAR,
         * for example, due to being behind a bridge. Reduce the CMB to
         * the reported size of the BAR
         */
        if (size > bar_size - offset)
                size = bar_size - offset;

        dev->cmb = ioremap_wc(pci_resource_start(pdev, bar) + offset, size);
        if (!dev->cmb)
                return;
        dev->cmb_bus_addr = pci_bus_address(pdev, bar) + offset;
        dev->cmb_size = size;

        if (sysfs_add_file_to_group(&dev->ctrl.device->kobj,
                                    &dev_attr_cmb.attr, NULL))
                dev_warn(dev->ctrl.device,
                         "failed to add sysfs attribute for CMB\n");
}

static inline void nvme_release_cmb(struct nvme_dev *dev)
{
        if (dev->cmb) {
                iounmap(dev->cmb);
                dev->cmb = NULL;
                sysfs_remove_file_from_group(&dev->ctrl.device->kobj,
                                             &dev_attr_cmb.attr, NULL);
                dev->cmbsz = 0;
        }
}

static int nvme_set_host_mem(struct nvme_dev *dev, u32 bits)
{
        u64 dma_addr = dev->host_mem_descs_dma;
        struct nvme_command c;
        int ret;

        memset(&c, 0, sizeof(c));
        c.features.opcode       = nvme_admin_set_features;
        c.features.fid          = cpu_to_le32(NVME_FEAT_HOST_MEM_BUF);
        c.features.dword11      = cpu_to_le32(bits);
        c.features.dword12      = cpu_to_le32(dev->host_mem_size >>
                                              ilog2(dev->ctrl.page_size));
        c.features.dword13      = cpu_to_le32(lower_32_bits(dma_addr));
        c.features.dword14      = cpu_to_le32(upper_32_bits(dma_addr));
        c.features.dword15      = cpu_to_le32(dev->nr_host_mem_descs);

        ret = nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
        if (ret) {
                dev_warn(dev->ctrl.device,
                         "failed to set host mem (err %d, flags %#x).\n",
                         ret, bits);
        }
        return ret;
}

static void nvme_free_host_mem(struct nvme_dev *dev)
{
        int i;

        for (i = 0; i < dev->nr_host_mem_descs; i++) {
                struct nvme_host_mem_buf_desc *desc = &dev->host_mem_descs[i];
                size_t size = le32_to_cpu(desc->size) * dev->ctrl.page_size;

                dma_free_attrs(dev->dev, size, dev->host_mem_desc_bufs[i],
                               le64_to_cpu(desc->addr),
                               DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
        }

        kfree(dev->host_mem_desc_bufs);
        dev->host_mem_desc_bufs = NULL;
        dma_free_coherent(dev->dev,
                        dev->nr_host_mem_descs * sizeof(*dev->host_mem_descs),
                        dev->host_mem_descs, dev->host_mem_descs_dma);
        dev->host_mem_descs = NULL;
        dev->nr_host_mem_descs = 0;
}

static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
                u32 chunk_size)
{
        struct nvme_host_mem_buf_desc *descs;
        u32 max_entries, len;
        dma_addr_t descs_dma;
        int i = 0;
        void **bufs;
        u64 size, tmp;

        tmp = (preferred + chunk_size - 1);
        do_div(tmp, chunk_size);
        max_entries = tmp;

        if (dev->ctrl.hmmaxd && dev->ctrl.hmmaxd < max_entries)
                max_entries = dev->ctrl.hmmaxd;

        descs = dma_zalloc_coherent(dev->dev, max_entries * sizeof(*descs),
                        &descs_dma, GFP_KERNEL);
        if (!descs)
                goto out;

        bufs = kcalloc(max_entries, sizeof(*bufs), GFP_KERNEL);
        if (!bufs)
                goto out_free_descs;

        for (size = 0; size < preferred && i < max_entries; size += len) {
                dma_addr_t dma_addr;

                len = min_t(u64, chunk_size, preferred - size);
                bufs[i] = dma_alloc_attrs(dev->dev, len, &dma_addr, GFP_KERNEL,
                                DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
                if (!bufs[i])
                        break;

                descs[i].addr = cpu_to_le64(dma_addr);
                descs[i].size = cpu_to_le32(len / dev->ctrl.page_size);
                i++;
        }

        if (!size)
                goto out_free_bufs;

        dev->nr_host_mem_descs = i;
        dev->host_mem_size = size;
        dev->host_mem_descs = descs;
        dev->host_mem_descs_dma = descs_dma;
        dev->host_mem_desc_bufs = bufs;
        return 0;

out_free_bufs:
        while (--i >= 0) {
                size_t size = le32_to_cpu(descs[i].size) * dev->ctrl.page_size;

                dma_free_attrs(dev->dev, size, bufs[i],
                               le64_to_cpu(descs[i].addr),
                               DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
        }

        kfree(bufs);
out_free_descs:
        dma_free_coherent(dev->dev, max_entries * sizeof(*descs), descs,
                        descs_dma);
out:
        dev->host_mem_descs = NULL;
        return -ENOMEM;
}

static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
{
        u32 chunk_size;

        /* start big and work our way down */
        for (chunk_size = min_t(u64, preferred, PAGE_SIZE * MAX_ORDER_NR_PAGES);
             chunk_size >= max_t(u32, dev->ctrl.hmminds * 4096, PAGE_SIZE * 2);
             chunk_size /= 2) {
                if (!__nvme_alloc_host_mem(dev, preferred, chunk_size)) {
                        if (!min || dev->host_mem_size >= min)
                                return 0;
                        nvme_free_host_mem(dev);
                }
        }

        return -ENOMEM;
}

static int nvme_setup_host_mem(struct nvme_dev *dev)
{
        u64 max = (u64)max_host_mem_size_mb * SZ_1M;
        u64 preferred = (u64)dev->ctrl.hmpre * 4096;
        u64 min = (u64)dev->ctrl.hmmin * 4096;
        u32 enable_bits = NVME_HOST_MEM_ENABLE;
        int ret;

        preferred = min(preferred, max);
        if (min > max) {
                dev_warn(dev->ctrl.device,
                        "min host memory (%lld MiB) above limit (%d MiB).\n",
                        min >> ilog2(SZ_1M), max_host_mem_size_mb);
                nvme_free_host_mem(dev);
                return 0;
        }

        /*
         * If we already have a buffer allocated check if we can reuse it.
         */
        if (dev->host_mem_descs) {
                if (dev->host_mem_size >= min)
                        enable_bits |= NVME_HOST_MEM_RETURN;
                else
                        nvme_free_host_mem(dev);
        }

        if (!dev->host_mem_descs) {
                if (nvme_alloc_host_mem(dev, min, preferred)) {
                        dev_warn(dev->ctrl.device,
                                "failed to allocate host memory buffer.\n");
                        return 0; /* controller must work without HMB */
                }

                dev_info(dev->ctrl.device,
                        "allocated %lld MiB host memory buffer.\n",
                        dev->host_mem_size >> ilog2(SZ_1M));
        }

        ret = nvme_set_host_mem(dev, enable_bits);
        if (ret)
                nvme_free_host_mem(dev);
        return ret;
}

static int nvme_setup_io_queues(struct nvme_dev *dev)
{
        struct nvme_queue *adminq = &dev->queues[0];
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int result, nr_io_queues;
        unsigned long size;

        struct irq_affinity affd = {
                .pre_vectors = 1
        };

        nr_io_queues = num_possible_cpus();
        result = nvme_set_queue_count(&dev->ctrl, &nr_io_queues);
        if (result < 0)
                return result;

        if (nr_io_queues == 0)
                return 0;

        if (dev->cmb && (dev->cmbsz & NVME_CMBSZ_SQS)) {
                result = nvme_cmb_qdepth(dev, nr_io_queues,
                                sizeof(struct nvme_command));
                if (result > 0)
                        dev->q_depth = result;
                else
                        nvme_release_cmb(dev);
        }

        do {
                size = db_bar_size(dev, nr_io_queues);
                result = nvme_remap_bar(dev, size);
                if (!result)
                        break;
                if (!--nr_io_queues)
                        return -ENOMEM;
        } while (1);
        adminq->q_db = dev->dbs;

        /* Deregister the admin queue's interrupt */
        pci_free_irq(pdev, 0, adminq);

        /*
         * If we enable msix early due to not intx, disable it again before
         * setting up the full range we need.
         */
        pci_free_irq_vectors(pdev);
        result = pci_alloc_irq_vectors_affinity(pdev, 1, nr_io_queues + 1,
                        PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
        if (result <= 0)
                return -EIO;
        dev->num_vecs = result;
        dev->max_qid = max(result - 1, 1);

        /*
         * Should investigate if there's a performance win from allocating
         * more queues than interrupt vectors; it might allow the submission
         * path to scale better, even if the receive path is limited by the
         * number of interrupts.
         */

        result = queue_request_irq(adminq);
        if (result) {
                adminq->cq_vector = -1;
                return result;
        }
        return nvme_create_io_queues(dev);
}

static void nvme_del_queue_end(struct request *req, blk_status_t error)
{
        struct nvme_queue *nvmeq = req->end_io_data;

        blk_mq_free_request(req);
        complete(&nvmeq->dev->ioq_wait);
}

static void nvme_del_cq_end(struct request *req, blk_status_t error)
{
        struct nvme_queue *nvmeq = req->end_io_data;
        u16 start, end;

        if (!error) {
                unsigned long flags;

                spin_lock_irqsave(&nvmeq->cq_lock, flags);
                nvme_process_cq(nvmeq, &start, &end, -1);
                spin_unlock_irqrestore(&nvmeq->cq_lock, flags);

                nvme_complete_cqes(nvmeq, start, end);
        }

        nvme_del_queue_end(req, error);
}

static int nvme_delete_queue(struct nvme_queue *nvmeq, u8 opcode)
{
        struct request_queue *q = nvmeq->dev->ctrl.admin_q;
        struct request *req;
        struct nvme_command cmd;

        memset(&cmd, 0, sizeof(cmd));
        cmd.delete_queue.opcode = opcode;
        cmd.delete_queue.qid = cpu_to_le16(nvmeq->qid);

        req = nvme_alloc_request(q, &cmd, BLK_MQ_REQ_NOWAIT, NVME_QID_ANY);
        if (IS_ERR(req))
                return PTR_ERR(req);

        req->timeout = ADMIN_TIMEOUT;
        req->end_io_data = nvmeq;

        blk_execute_rq_nowait(q, NULL, req, false,
                        opcode == nvme_admin_delete_cq ?
                                nvme_del_cq_end : nvme_del_queue_end);
        return 0;
}

static void nvme_disable_io_queues(struct nvme_dev *dev)
{
        int pass, queues = dev->online_queues - 1;
        unsigned long timeout;
        u8 opcode = nvme_admin_delete_sq;

        for (pass = 0; pass < 2; pass++) {
                int sent = 0, i = queues;

                reinit_completion(&dev->ioq_wait);
 retry:
                timeout = ADMIN_TIMEOUT;
                for (; i > 0; i--, sent++)
                        if (nvme_delete_queue(&dev->queues[i], opcode))
                                break;

                while (sent--) {
                        timeout = wait_for_completion_io_timeout(&dev->ioq_wait, timeout);
                        if (timeout == 0)
                                return;
                        if (i)
                                goto retry;
                }
                opcode = nvme_admin_delete_cq;
        }
}

/*
 * return error value only when tagset allocation failed
 */
static int nvme_dev_add(struct nvme_dev *dev)
{
        int ret;

        if (!dev->ctrl.tagset) {
                dev->tagset.ops = &nvme_mq_ops;
                dev->tagset.nr_hw_queues = dev->online_queues - 1;
                dev->tagset.timeout = NVME_IO_TIMEOUT;
                dev->tagset.numa_node = dev_to_node(dev->dev);
                dev->tagset.queue_depth =
                                min_t(int, dev->q_depth, BLK_MQ_MAX_DEPTH) - 1;
                dev->tagset.cmd_size = nvme_pci_cmd_size(dev, false);
                if ((dev->ctrl.sgls & ((1 << 0) | (1 << 1))) && sgl_threshold) {
                        dev->tagset.cmd_size = max(dev->tagset.cmd_size,
                                        nvme_pci_cmd_size(dev, true));
                }
                dev->tagset.flags = BLK_MQ_F_SHOULD_MERGE;
                dev->tagset.driver_data = dev;

                ret = blk_mq_alloc_tag_set(&dev->tagset);
                if (ret) {
                        dev_warn(dev->ctrl.device,
                                "IO queues tagset allocation failed %d\n", ret);
                        return ret;
                }
                dev->ctrl.tagset = &dev->tagset;

                nvme_dbbuf_set(dev);
        } else {
                blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);

                /* Free previously allocated queues that are no longer usable */
                nvme_free_queues(dev, dev->online_queues);
        }

        return 0;
}

static int nvme_pci_enable(struct nvme_dev *dev)
{
        int result = -ENOMEM;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_enable_device_mem(pdev))
                return result;

        pci_set_master(pdev);

        if (dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(64)) &&
            dma_set_mask_and_coherent(dev->dev, DMA_BIT_MASK(32)))
                goto disable;

        if (readl(dev->bar + NVME_REG_CSTS) == -1) {
                result = -ENODEV;
                goto disable;
        }

        /*
         * Some devices and/or platforms don't advertise or work with INTx
         * interrupts. Pre-enable a single MSIX or MSI vec for setup. We'll
         * adjust this later.
         */
        result = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
        if (result < 0)
                return result;

        dev->ctrl.cap = lo_hi_readq(dev->bar + NVME_REG_CAP);

        dev->q_depth = min_t(int, NVME_CAP_MQES(dev->ctrl.cap) + 1,
                                io_queue_depth);
        dev->db_stride = 1 << NVME_CAP_STRIDE(dev->ctrl.cap);
        dev->dbs = dev->bar + 4096;

        /*
         * Temporary fix for the Apple controller found in the MacBook8,1 and
         * some MacBook7,1 to avoid controller resets and data loss.
         */
        if (pdev->vendor == PCI_VENDOR_ID_APPLE && pdev->device == 0x2001) {
                dev->q_depth = 2;
                dev_warn(dev->ctrl.device, "detected Apple NVMe controller, "
                        "set queue depth=%u to work around controller resets\n",
                        dev->q_depth);
        } else if (pdev->vendor == PCI_VENDOR_ID_SAMSUNG &&
                   (pdev->device == 0xa821 || pdev->device == 0xa822) &&
                   NVME_CAP_MQES(dev->ctrl.cap) == 0) {
                dev->q_depth = 64;
                dev_err(dev->ctrl.device, "detected PM1725 NVMe controller, "
                        "set queue depth=%u\n", dev->q_depth);
        }

        nvme_map_cmb(dev);

        pci_enable_pcie_error_reporting(pdev);
        pci_save_state(pdev);
        return 0;

 disable:
        pci_disable_device(pdev);
        return result;
}

static void nvme_dev_unmap(struct nvme_dev *dev)
{
        if (dev->bar)
                iounmap(dev->bar);
        pci_release_mem_regions(to_pci_dev(dev->dev));
}

static void nvme_pci_disable(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        pci_free_irq_vectors(pdev);

        if (pci_is_enabled(pdev)) {
                pci_disable_pcie_error_reporting(pdev);
                pci_disable_device(pdev);
        }
}

static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
{
        int i;
        bool dead = true;
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        mutex_lock(&dev->shutdown_lock);
        if (pci_is_enabled(pdev)) {
                u32 csts = readl(dev->bar + NVME_REG_CSTS);

                if (dev->ctrl.state == NVME_CTRL_LIVE ||
                    dev->ctrl.state == NVME_CTRL_RESETTING)
                        nvme_start_freeze(&dev->ctrl);
                dead = !!((csts & NVME_CSTS_CFS) || !(csts & NVME_CSTS_RDY) ||
                        pdev->error_state  != pci_channel_io_normal);
        }

        /*
         * Give the controller a chance to complete all entered requests if
         * doing a safe shutdown.
         */
        if (!dead) {
                if (shutdown)
                        nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT);
        }

        nvme_stop_queues(&dev->ctrl);

        if (!dead && dev->ctrl.queue_count > 0) {
                nvme_disable_io_queues(dev);
                nvme_disable_admin_queue(dev, shutdown);
        }
        for (i = dev->ctrl.queue_count - 1; i >= 0; i--)
                nvme_suspend_queue(&dev->queues[i]);

        nvme_pci_disable(dev);

        blk_mq_tagset_busy_iter(&dev->tagset, nvme_cancel_request, &dev->ctrl);
        blk_mq_tagset_busy_iter(&dev->admin_tagset, nvme_cancel_request, &dev->ctrl);

        /*
         * The driver will not be starting up queues again if shutting down so
         * must flush all entered requests to their failed completion to avoid
         * deadlocking blk-mq hot-cpu notifier.
         */
        if (shutdown) {
                nvme_start_queues(&dev->ctrl);
                if (dev->ctrl.admin_q && !blk_queue_dying(dev->ctrl.admin_q))
                        blk_mq_unquiesce_queue(dev->ctrl.admin_q);
        }
        mutex_unlock(&dev->shutdown_lock);
}

static int nvme_setup_prp_pools(struct nvme_dev *dev)
{
        dev->prp_page_pool = dma_pool_create("prp list page", dev->dev,
                                                PAGE_SIZE, PAGE_SIZE, 0);
        if (!dev->prp_page_pool)
                return -ENOMEM;

        /* Optimisation for I/Os between 4k and 128k */
        dev->prp_small_pool = dma_pool_create("prp list 256", dev->dev,
                                                256, 256, 0);
        if (!dev->prp_small_pool) {
                dma_pool_destroy(dev->prp_page_pool);
                return -ENOMEM;
        }
        return 0;
}

static void nvme_release_prp_pools(struct nvme_dev *dev)
{
        dma_pool_destroy(dev->prp_page_pool);
        dma_pool_destroy(dev->prp_small_pool);
}

static void nvme_pci_free_ctrl(struct nvme_ctrl *ctrl)
{
        struct nvme_dev *dev = to_nvme_dev(ctrl);

        nvme_dbbuf_dma_free(dev);
        put_device(dev->dev);
        if (dev->tagset.tags)
                blk_mq_free_tag_set(&dev->tagset);
        if (dev->ctrl.admin_q)
                blk_put_queue(dev->ctrl.admin_q);
        kfree(dev->queues);
        free_opal_dev(dev->ctrl.opal_dev);
        mempool_destroy(dev->iod_mempool);
        kfree(dev);
}

static void nvme_remove_dead_ctrl(struct nvme_dev *dev, int status)
{
        dev_warn(dev->ctrl.device, "Removing after probe failure status: %d\n", status);

        nvme_get_ctrl(&dev->ctrl);
        nvme_dev_disable(dev, false);
        nvme_kill_queues(&dev->ctrl);
        if (!queue_work(nvme_wq, &dev->remove_work))
                nvme_put_ctrl(&dev->ctrl);
}

static void nvme_reset_work(struct work_struct *work)
{
        struct nvme_dev *dev =
                container_of(work, struct nvme_dev, ctrl.reset_work);
        bool was_suspend = !!(dev->ctrl.ctrl_config & NVME_CC_SHN_NORMAL);
        int result;
        enum nvme_ctrl_state new_state = NVME_CTRL_LIVE;

        if (dev->ctrl.state != NVME_CTRL_RESETTING) {
                dev_warn(dev->ctrl.device, "ctrl state %d is not RESETTING\n",
                         dev->ctrl.state);
                result = -ENODEV;
                goto out;
        }

        /*
         * If we're called to reset a live controller first shut it down before
         * moving on.
         */
        if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
                nvme_dev_disable(dev, false);

        mutex_lock(&dev->shutdown_lock);
        result = nvme_pci_enable(dev);
        if (result)
                goto out_unlock;

        result = nvme_pci_configure_admin_queue(dev);
        if (result)
                goto out_unlock;

        result = nvme_alloc_admin_tags(dev);
        if (result)
                goto out_unlock;

        /*
         * Limit the max command size to prevent iod->sg allocations going
         * over a single page.
         */
        dev->ctrl.max_hw_sectors = NVME_MAX_KB_SZ << 1;
        dev->ctrl.max_segments = NVME_MAX_SEGS;
        mutex_unlock(&dev->shutdown_lock);

        /*
         * Introduce CONNECTING state from nvme-fc/rdma transports to mark the
         * initializing procedure here.
         */
        if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_CONNECTING)) {
                dev_warn(dev->ctrl.device,
                        "failed to mark controller CONNECTING\n");
                result = -EBUSY;
                goto out;
        }

        result = nvme_init_identify(&dev->ctrl);
        if (result)
                goto out;

        if (dev->ctrl.oacs & NVME_CTRL_OACS_SEC_SUPP) {
                if (!dev->ctrl.opal_dev)
                        dev->ctrl.opal_dev =
                                init_opal_dev(&dev->ctrl, &nvme_sec_submit);
                else if (was_suspend)
                        opal_unlock_from_suspend(dev->ctrl.opal_dev);
        } else {
                free_opal_dev(dev->ctrl.opal_dev);
                dev->ctrl.opal_dev = NULL;
        }

        if (dev->ctrl.oacs & NVME_CTRL_OACS_DBBUF_SUPP) {
                result = nvme_dbbuf_dma_alloc(dev);
                if (result)
                        dev_warn(dev->dev,
                                 "unable to allocate dma for dbbuf\n");
        }

        if (dev->ctrl.hmpre) {
                result = nvme_setup_host_mem(dev);
                if (result < 0)
                        goto out;
        }

        result = nvme_setup_io_queues(dev);
        if (result)
                goto out;

        /*
         * Keep the controller around but remove all namespaces if we don't have
         * any working I/O queue.
         */
        if (dev->online_queues < 2) {
                dev_warn(dev->ctrl.device, "IO queues not created\n");
                nvme_kill_queues(&dev->ctrl);
                nvme_remove_namespaces(&dev->ctrl);
                new_state = NVME_CTRL_ADMIN_ONLY;
        } else {
                nvme_start_queues(&dev->ctrl);
                nvme_wait_freeze(&dev->ctrl);
                /* hit this only when allocate tagset fails */
                if (nvme_dev_add(dev))
                        new_state = NVME_CTRL_ADMIN_ONLY;
                nvme_unfreeze(&dev->ctrl);
        }

        /*
         * If only admin queue live, keep it to do further investigation or
         * recovery.
         */
        if (!nvme_change_ctrl_state(&dev->ctrl, new_state)) {
                dev_warn(dev->ctrl.device,
                        "failed to mark controller state %d\n", new_state);
                result = -ENODEV;
                goto out;
        }

        nvme_start_ctrl(&dev->ctrl);
        return;

 out_unlock:
        mutex_unlock(&dev->shutdown_lock);
 out:
        nvme_remove_dead_ctrl(dev, result);
}

static void nvme_remove_dead_ctrl_work(struct work_struct *work)
{
        struct nvme_dev *dev = container_of(work, struct nvme_dev, remove_work);
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_get_drvdata(pdev))
                device_release_driver(&pdev->dev);
        nvme_put_ctrl(&dev->ctrl);
}

static int nvme_pci_reg_read32(struct nvme_ctrl *ctrl, u32 off, u32 *val)
{
        *val = readl(to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val)
{
        writel(val, to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val)
{
        *val = lo_hi_readq(to_nvme_dev(ctrl)->bar + off);
        return 0;
}

static int nvme_pci_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
{
        struct pci_dev *pdev = to_pci_dev(to_nvme_dev(ctrl)->dev);

        return snprintf(buf, size, "%s", dev_name(&pdev->dev));
}

static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
        .name                   = "pcie",
        .module                 = THIS_MODULE,
        .flags                  = NVME_F_METADATA_SUPPORTED,
        .reg_read32             = nvme_pci_reg_read32,
        .reg_write32            = nvme_pci_reg_write32,
        .reg_read64             = nvme_pci_reg_read64,
        .free_ctrl              = nvme_pci_free_ctrl,
        .submit_async_event     = nvme_pci_submit_async_event,
        .get_address            = nvme_pci_get_address,
};

static int nvme_dev_map(struct nvme_dev *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev->dev);

        if (pci_request_mem_regions(pdev, "nvme"))
                return -ENODEV;

        if (nvme_remap_bar(dev, NVME_REG_DBS + 4096))
                goto release;

        return 0;
  release:
        pci_release_mem_regions(pdev);
        return -ENODEV;
}

static unsigned long check_vendor_combination_bug(struct pci_dev *pdev)
{
        if (pdev->vendor == 0x144d && pdev->device == 0xa802) {
                /*
                 * Several Samsung devices seem to drop off the PCIe bus
                 * randomly when APST is on and uses the deepest sleep state.
                 * This has been observed on a Samsung "SM951 NVMe SAMSUNG
                 * 256GB", a "PM951 NVMe SAMSUNG 512GB", and a "Samsung SSD
                 * 950 PRO 256GB", but it seems to be restricted to two Dell
                 * laptops.
                 */
                if (dmi_match(DMI_SYS_VENDOR, "Dell Inc.") &&
                    (dmi_match(DMI_PRODUCT_NAME, "XPS 15 9550") ||
                     dmi_match(DMI_PRODUCT_NAME, "Precision 5510")))
                        return NVME_QUIRK_NO_DEEPEST_PS;
        } else if (pdev->vendor == 0x144d && pdev->device == 0xa804) {
                /*
                 * Samsung SSD 960 EVO drops off the PCIe bus after system
                 * suspend on a Ryzen board, ASUS PRIME B350M-A, as well as
                 * within few minutes after bootup on a Coffee Lake board -
                 * ASUS PRIME Z370-A
                 */
                if (dmi_match(DMI_BOARD_VENDOR, "ASUSTeK COMPUTER INC.") &&
                    (dmi_match(DMI_BOARD_NAME, "PRIME B350M-A") ||
                     dmi_match(DMI_BOARD_NAME, "PRIME Z370-A")))
                        return NVME_QUIRK_NO_APST;
        }

        return 0;
}

static void nvme_async_probe(void *data, async_cookie_t cookie)
{
        struct nvme_dev *dev = data;

        flush_work(&dev->ctrl.reset_work);
        flush_work(&dev->ctrl.scan_work);
        nvme_put_ctrl(&dev->ctrl);
}

static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int node, result = -ENOMEM;
        struct nvme_dev *dev;
        unsigned long quirks = id->driver_data;
        size_t alloc_size;

        node = dev_to_node(&pdev->dev);
        if (node == NUMA_NO_NODE)
                set_dev_node(&pdev->dev, first_memory_node);

        dev = kzalloc_node(sizeof(*dev), GFP_KERNEL, node);
        if (!dev)
                return -ENOMEM;

        dev->queues = kcalloc_node(num_possible_cpus() + 1,
                        sizeof(struct nvme_queue), GFP_KERNEL, node);
        if (!dev->queues)
                goto free;

        dev->dev = get_device(&pdev->dev);
        pci_set_drvdata(pdev, dev);

        result = nvme_dev_map(dev);
        if (result)
                goto put_pci;

        INIT_WORK(&dev->ctrl.reset_work, nvme_reset_work);
        INIT_WORK(&dev->remove_work, nvme_remove_dead_ctrl_work);
        mutex_init(&dev->shutdown_lock);
        init_completion(&dev->ioq_wait);

        result = nvme_setup_prp_pools(dev);
        if (result)
                goto unmap;

        quirks |= check_vendor_combination_bug(pdev);

        /*
         * Double check that our mempool alloc size will cover the biggest
         * command we support.
         */
        alloc_size = nvme_pci_iod_alloc_size(dev, NVME_MAX_KB_SZ,
                                                NVME_MAX_SEGS, true);
        WARN_ON_ONCE(alloc_size > PAGE_SIZE);

        dev->iod_mempool = mempool_create_node(1, mempool_kmalloc,
                                                mempool_kfree,
                                                (void *) alloc_size,
                                                GFP_KERNEL, node);
        if (!dev->iod_mempool) {
                result = -ENOMEM;
                goto release_pools;
        }

        result = nvme_init_ctrl(&dev->ctrl, &pdev->dev, &nvme_pci_ctrl_ops,
                        quirks);
        if (result)
                goto release_mempool;

        dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));

        nvme_reset_ctrl(&dev->ctrl);
        nvme_get_ctrl(&dev->ctrl);
        async_schedule(nvme_async_probe, dev);

        return 0;

 release_mempool:
        mempool_destroy(dev->iod_mempool);
 release_pools:
        nvme_release_prp_pools(dev);
 unmap:
        nvme_dev_unmap(dev);
 put_pci:
        put_device(dev->dev);
 free:
        kfree(dev->queues);
        kfree(dev);
        return result;
}

static void nvme_reset_prepare(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        nvme_dev_disable(dev, false);
}

static void nvme_reset_done(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        nvme_reset_ctrl_sync(&dev->ctrl);
}

static void nvme_shutdown(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);
        nvme_dev_disable(dev, true);
}

/*
 * The driver's remove may be called on a device in a partially initialized
 * state. This function must not have any dependencies on the device state in
 * order to proceed.
 */
static void nvme_remove(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
        pci_set_drvdata(pdev, NULL);

        if (!pci_device_is_present(pdev)) {
                nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DEAD);
                nvme_dev_disable(dev, true);
        }

        flush_work(&dev->ctrl.reset_work);
        nvme_stop_ctrl(&dev->ctrl);
        nvme_remove_namespaces(&dev->ctrl);
        nvme_dev_disable(dev, true);
        nvme_release_cmb(dev);
        nvme_free_host_mem(dev);
        nvme_dev_remove_admin(dev);
        nvme_free_queues(dev, 0);
        nvme_uninit_ctrl(&dev->ctrl);
        nvme_release_prp_pools(dev);
        nvme_dev_unmap(dev);
        nvme_put_ctrl(&dev->ctrl);
}

#ifdef CONFIG_PM_SLEEP
static int nvme_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        nvme_dev_disable(ndev, true);
        return 0;
}

static int nvme_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct nvme_dev *ndev = pci_get_drvdata(pdev);

        nvme_reset_ctrl(&ndev->ctrl);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(nvme_dev_pm_ops, nvme_suspend, nvme_resume);

static pci_ers_result_t nvme_error_detected(struct pci_dev *pdev,
                                                pci_channel_state_t state)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        /*
         * A frozen channel requires a reset. When detected, this method will
         * shutdown the controller to quiesce. The controller will be restarted
         * after the slot reset through driver's slot_reset callback.
         */
        switch (state) {
        case pci_channel_io_normal:
                return PCI_ERS_RESULT_CAN_RECOVER;
        case pci_channel_io_frozen:
                dev_warn(dev->ctrl.device,
                        "frozen state error detected, reset controller\n");
                nvme_dev_disable(dev, false);
                return PCI_ERS_RESULT_NEED_RESET;
        case pci_channel_io_perm_failure:
                dev_warn(dev->ctrl.device,
                        "failure state error detected, request disconnect\n");
                return PCI_ERS_RESULT_DISCONNECT;
        }
        return PCI_ERS_RESULT_NEED_RESET;
}

static pci_ers_result_t nvme_slot_reset(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        dev_info(dev->ctrl.device, "restart after slot reset\n");
        pci_restore_state(pdev);
        nvme_reset_ctrl(&dev->ctrl);
        return PCI_ERS_RESULT_RECOVERED;
}

static void nvme_error_resume(struct pci_dev *pdev)
{
        struct nvme_dev *dev = pci_get_drvdata(pdev);

        flush_work(&dev->ctrl.reset_work);
        pci_cleanup_aer_uncorrect_error_status(pdev);
}

static const struct pci_error_handlers nvme_err_handler = {
        .error_detected = nvme_error_detected,
        .slot_reset     = nvme_slot_reset,
        .resume         = nvme_error_resume,
        .reset_prepare  = nvme_reset_prepare,
        .reset_done     = nvme_reset_done,
};

static const struct pci_device_id nvme_id_table[] = {
        { PCI_VDEVICE(INTEL, 0x0953),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DEALLOCATE_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x0a53),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DEALLOCATE_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x0a54),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DEALLOCATE_ZEROES, },
        { PCI_VDEVICE(INTEL, 0x0a55),
                .driver_data = NVME_QUIRK_STRIPE_SIZE |
                                NVME_QUIRK_DEALLOCATE_ZEROES, },
        { PCI_VDEVICE(INTEL, 0xf1a5),   /* Intel 600P/P3100 */
                .driver_data = NVME_QUIRK_NO_DEEPEST_PS |
                                NVME_QUIRK_MEDIUM_PRIO_SQ },
        { PCI_VDEVICE(INTEL, 0x5845),   /* Qemu emulated controller */
                .driver_data = NVME_QUIRK_IDENTIFY_CNS, },
        { PCI_DEVICE(0x1bb1, 0x0100),   /* Seagate Nytro Flash Storage */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x1c58, 0x0003),   /* HGST adapter */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x1c58, 0x0023),   /* WDC SN200 adapter */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x1c5f, 0x0540),   /* Memblaze Pblaze4 adapter */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x144d, 0xa821),   /* Samsung PM1725 */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x144d, 0xa822),   /* Samsung PM1725a */
                .driver_data = NVME_QUIRK_DELAY_BEFORE_CHK_RDY, },
        { PCI_DEVICE(0x1d1d, 0x1f1f),   /* LighNVM qemu device */
                .driver_data = NVME_QUIRK_LIGHTNVM, },
        { PCI_DEVICE(0x1d1d, 0x2807),   /* CNEX WL */
                .driver_data = NVME_QUIRK_LIGHTNVM, },
        { PCI_DEVICE(0x1d1d, 0x2601),   /* CNEX Granby */
                .driver_data = NVME_QUIRK_LIGHTNVM, },
        { PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },
        { PCI_DEVICE(0x2646, 0x2263),   /* KINGSTON A2000 NVMe SSD  */
                .driver_data = NVME_QUIRK_NO_DEEPEST_PS, },
        { PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2001) },
        { PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2003) },
        { 0, }
};
MODULE_DEVICE_TABLE(pci, nvme_id_table);

static struct pci_driver nvme_driver = {
        .name           = "nvme",
        .id_table       = nvme_id_table,
        .probe          = nvme_probe,
        .remove         = nvme_remove,
        .shutdown       = nvme_shutdown,
        .driver         = {
                .pm     = &nvme_dev_pm_ops,
        },
        .sriov_configure = pci_sriov_configure_simple,
        .err_handler    = &nvme_err_handler,
};

static int __init nvme_init(void)
{
        return pci_register_driver(&nvme_driver);
}

static void __exit nvme_exit(void)
{
        pci_unregister_driver(&nvme_driver);
        flush_workqueue(nvme_wq);
        _nvme_check_size();
}

MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.0");
module_init(nvme_init);
module_exit(nvme_exit);