/*
 * QEMU NVM Express Controller
 *
 * Copyright (c) 2012, Intel Corporation
 *
 * Written by Keith Busch <keith.busch@intel.com>
 *
 * This code is licensed under the GNU GPL v2 or later.
 */

/**
 * Reference Specs: http://www.nvmexpress.org, 1.1, 1.0e
 *
 *  http://www.nvmexpress.org/resources/
 */

/**
 * Usage: add options:
 *      -drive file=<file>,if=none,id=<drive_id>
 *      -device nvme,drive=<drive_id>,serial=<serial>,id=<id[optional]>
 */

#include "qemu/osdep.h"
#include "hw/block/block.h"
#include "hw/hw.h"
#include "hw/pci/msix.h"
#include "hw/pci/pci.h"
#include "sysemu/sysemu.h"
#include "qapi/error.h"
#include "qapi/visitor.h"
#include "sysemu/block-backend.h"

#include "nvme.h"

static void nvme_process_sq(void *opaque);

static int nvme_check_sqid(NvmeCtrl *n, uint16_t sqid)
{
    return sqid < n->num_queues && n->sq[sqid] != NULL ? 0 : -1;
}

static int nvme_check_cqid(NvmeCtrl *n, uint16_t cqid)
{
    return cqid < n->num_queues && n->cq[cqid] != NULL ? 0 : -1;
}

static void nvme_inc_cq_tail(NvmeCQueue *cq)
{
    cq->tail++;
    if (cq->tail >= cq->size) {
        cq->tail = 0;
        cq->phase = !cq->phase;
    }
}

static void nvme_inc_sq_head(NvmeSQueue *sq)
{
    sq->head = (sq->head + 1) % sq->size;
}

static uint8_t nvme_cq_full(NvmeCQueue *cq)
{
    return (cq->tail + 1) % cq->size == cq->head;
}

static uint8_t nvme_sq_empty(NvmeSQueue *sq)
{
    return sq->head == sq->tail;
}

static void nvme_isr_notify(NvmeCtrl *n, NvmeCQueue *cq)
{
    if (cq->irq_enabled) {
        if (msix_enabled(&(n->parent_obj))) {
            msix_notify(&(n->parent_obj), cq->vector);
        } else {
            pci_irq_pulse(&n->parent_obj);
        }
    }
}

static uint16_t nvme_map_prp(QEMUSGList *qsg, uint64_t prp1, uint64_t prp2,
    uint32_t len, NvmeCtrl *n)
{
    hwaddr trans_len = n->page_size - (prp1 % n->page_size);
    trans_len = MIN(len, trans_len);
    int num_prps = (len >> n->page_bits) + 1;

    if (!prp1) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }

    pci_dma_sglist_init(qsg, &n->parent_obj, num_prps);
    qemu_sglist_add(qsg, prp1, trans_len);
    len -= trans_len;
    if (len) {
        if (!prp2) {
            goto unmap;
        }
        if (len > n->page_size) {
            uint64_t prp_list[n->max_prp_ents];
            uint32_t nents, prp_trans;
            int i = 0;

            nents = (len + n->page_size - 1) >> n->page_bits;
            prp_trans = MIN(n->max_prp_ents, nents) * sizeof(uint64_t);
            pci_dma_read(&n->parent_obj, prp2, (void *)prp_list, prp_trans);
            while (len != 0) {
                uint64_t prp_ent = le64_to_cpu(prp_list[i]);

                if (i == n->max_prp_ents - 1 && len > n->page_size) {
                    if (!prp_ent || prp_ent & (n->page_size - 1)) {
                        goto unmap;
                    }

                    i = 0;
                    nents = (len + n->page_size - 1) >> n->page_bits;
                    prp_trans = MIN(n->max_prp_ents, nents) * sizeof(uint64_t);
                    pci_dma_read(&n->parent_obj, prp_ent, (void *)prp_list,
                        prp_trans);
                    prp_ent = le64_to_cpu(prp_list[i]);
                }

                if (!prp_ent || prp_ent & (n->page_size - 1)) {
                    goto unmap;
                }

                trans_len = MIN(len, n->page_size);
                qemu_sglist_add(qsg, prp_ent, trans_len);
                len -= trans_len;
                i++;
            }
        } else {
            if (prp2 & (n->page_size - 1)) {
                goto unmap;
            }
            qemu_sglist_add(qsg, prp2, len);
        }
    }
    return NVME_SUCCESS;

 unmap:
    qemu_sglist_destroy(qsg);
    return NVME_INVALID_FIELD | NVME_DNR;
}

static uint16_t nvme_dma_read_prp(NvmeCtrl *n, uint8_t *ptr, uint32_t len,
    uint64_t prp1, uint64_t prp2)
{
    QEMUSGList qsg;

    if (nvme_map_prp(&qsg, prp1, prp2, len, n)) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    if (dma_buf_read(ptr, len, &qsg)) {
        qemu_sglist_destroy(&qsg);
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    qemu_sglist_destroy(&qsg);
    return NVME_SUCCESS;
}

static void nvme_post_cqes(void *opaque)
{
    NvmeCQueue *cq = opaque;
    NvmeCtrl *n = cq->ctrl;
    NvmeRequest *req, *next;

    QTAILQ_FOREACH_SAFE(req, &cq->req_list, entry, next) {
        NvmeSQueue *sq;
        hwaddr addr;

        if (nvme_cq_full(cq)) {
            break;
        }

        QTAILQ_REMOVE(&cq->req_list, req, entry);
        sq = req->sq;
        req->cqe.status = cpu_to_le16((req->status << 1) | cq->phase);
        req->cqe.sq_id = cpu_to_le16(sq->sqid);
        req->cqe.sq_head = cpu_to_le16(sq->head);
        addr = cq->dma_addr + cq->tail * n->cqe_size;
        nvme_inc_cq_tail(cq);
        pci_dma_write(&n->parent_obj, addr, (void *)&req->cqe,
            sizeof(req->cqe));
        QTAILQ_INSERT_TAIL(&sq->req_list, req, entry);
    }
    nvme_isr_notify(n, cq);
}

static void nvme_enqueue_req_completion(NvmeCQueue *cq, NvmeRequest *req)
{
    assert(cq->cqid == req->sq->cqid);
    QTAILQ_REMOVE(&req->sq->out_req_list, req, entry);
    QTAILQ_INSERT_TAIL(&cq->req_list, req, entry);
    timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
}

static void nvme_rw_cb(void *opaque, int ret)
{
    NvmeRequest *req = opaque;
    NvmeSQueue *sq = req->sq;
    NvmeCtrl *n = sq->ctrl;
    NvmeCQueue *cq = n->cq[sq->cqid];

    if (!ret) {
        block_acct_done(blk_get_stats(n->conf.blk), &req->acct);
        req->status = NVME_SUCCESS;
    } else {
        block_acct_failed(blk_get_stats(n->conf.blk), &req->acct);
        req->status = NVME_INTERNAL_DEV_ERROR;
    }
    if (req->has_sg) {
        qemu_sglist_destroy(&req->qsg);
    }
    nvme_enqueue_req_completion(cq, req);
}

static uint16_t nvme_flush(NvmeCtrl *n, NvmeNamespace *ns, NvmeCmd *cmd,
    NvmeRequest *req)
{
    req->has_sg = false;
    block_acct_start(blk_get_stats(n->conf.blk), &req->acct, 0,
         BLOCK_ACCT_FLUSH);
    req->aiocb = blk_aio_flush(n->conf.blk, nvme_rw_cb, req);

    return NVME_NO_COMPLETE;
}

static uint16_t nvme_rw(NvmeCtrl *n, NvmeNamespace *ns, NvmeCmd *cmd,
    NvmeRequest *req)
{
    NvmeRwCmd *rw = (NvmeRwCmd *)cmd;
    uint32_t nlb  = le32_to_cpu(rw->nlb) + 1;
    uint64_t slba = le64_to_cpu(rw->slba);
    uint64_t prp1 = le64_to_cpu(rw->prp1);
    uint64_t prp2 = le64_to_cpu(rw->prp2);

    uint8_t lba_index  = NVME_ID_NS_FLBAS_INDEX(ns->id_ns.flbas);
    uint8_t data_shift = ns->id_ns.lbaf[lba_index].ds;
    uint64_t data_size = (uint64_t)nlb << data_shift;
    uint64_t data_offset = slba << data_shift;
    int is_write = rw->opcode == NVME_CMD_WRITE ? 1 : 0;
    enum BlockAcctType acct = is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ;

    if ((slba + nlb) > ns->id_ns.nsze) {
        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
        return NVME_LBA_RANGE | NVME_DNR;
    }

    if (nvme_map_prp(&req->qsg, prp1, prp2, data_size, n)) {
        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
        return NVME_INVALID_FIELD | NVME_DNR;
    }

    assert((nlb << data_shift) == req->qsg.size);

    req->has_sg = true;
    dma_acct_start(n->conf.blk, &req->acct, &req->qsg, acct);
    req->aiocb = is_write ?
        dma_blk_write(n->conf.blk, &req->qsg, data_offset, BDRV_SECTOR_SIZE,
                      nvme_rw_cb, req) :
        dma_blk_read(n->conf.blk, &req->qsg, data_offset, BDRV_SECTOR_SIZE,
                     nvme_rw_cb, req);

    return NVME_NO_COMPLETE;
}

static uint16_t nvme_io_cmd(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
{
    NvmeNamespace *ns;
    uint32_t nsid = le32_to_cpu(cmd->nsid);

    if (nsid == 0 || nsid > n->num_namespaces) {
        return NVME_INVALID_NSID | NVME_DNR;
    }

    ns = &n->namespaces[nsid - 1];
    switch (cmd->opcode) {
    case NVME_CMD_FLUSH:
        return nvme_flush(n, ns, cmd, req);
    case NVME_CMD_WRITE:
    case NVME_CMD_READ:
        return nvme_rw(n, ns, cmd, req);
    default:
        return NVME_INVALID_OPCODE | NVME_DNR;
    }
}

static void nvme_free_sq(NvmeSQueue *sq, NvmeCtrl *n)
{
    n->sq[sq->sqid] = NULL;
    timer_del(sq->timer);
    timer_free(sq->timer);
    g_free(sq->io_req);
    if (sq->sqid) {
        g_free(sq);
    }
}

static uint16_t nvme_del_sq(NvmeCtrl *n, NvmeCmd *cmd)
{
    NvmeDeleteQ *c = (NvmeDeleteQ *)cmd;
    NvmeRequest *req, *next;
    NvmeSQueue *sq;
    NvmeCQueue *cq;
    uint16_t qid = le16_to_cpu(c->qid);

    if (!qid || nvme_check_sqid(n, qid)) {
        return NVME_INVALID_QID | NVME_DNR;
    }

    sq = n->sq[qid];
    while (!QTAILQ_EMPTY(&sq->out_req_list)) {
        req = QTAILQ_FIRST(&sq->out_req_list);
        assert(req->aiocb);
        blk_aio_cancel(req->aiocb);
    }
    if (!nvme_check_cqid(n, sq->cqid)) {
        cq = n->cq[sq->cqid];
        QTAILQ_REMOVE(&cq->sq_list, sq, entry);

        nvme_post_cqes(cq);
        QTAILQ_FOREACH_SAFE(req, &cq->req_list, entry, next) {
            if (req->sq == sq) {
                QTAILQ_REMOVE(&cq->req_list, req, entry);
                QTAILQ_INSERT_TAIL(&sq->req_list, req, entry);
            }
        }
    }

    nvme_free_sq(sq, n);
    return NVME_SUCCESS;
}

static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, uint64_t dma_addr,
    uint16_t sqid, uint16_t cqid, uint16_t size)
{
    int i;
    NvmeCQueue *cq;

    sq->ctrl = n;
    sq->dma_addr = dma_addr;
    sq->sqid = sqid;
    sq->size = size;
    sq->cqid = cqid;
    sq->head = sq->tail = 0;
    sq->io_req = g_new(NvmeRequest, sq->size);

    QTAILQ_INIT(&sq->req_list);
    QTAILQ_INIT(&sq->out_req_list);
    for (i = 0; i < sq->size; i++) {
        sq->io_req[i].sq = sq;
        QTAILQ_INSERT_TAIL(&(sq->req_list), &sq->io_req[i], entry);
    }
    sq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_process_sq, sq);

    assert(n->cq[cqid]);
    cq = n->cq[cqid];
    QTAILQ_INSERT_TAIL(&(cq->sq_list), sq, entry);
    n->sq[sqid] = sq;
}

static uint16_t nvme_create_sq(NvmeCtrl *n, NvmeCmd *cmd)
{
    NvmeSQueue *sq;
    NvmeCreateSq *c = (NvmeCreateSq *)cmd;

    uint16_t cqid = le16_to_cpu(c->cqid);
    uint16_t sqid = le16_to_cpu(c->sqid);
    uint16_t qsize = le16_to_cpu(c->qsize);
    uint16_t qflags = le16_to_cpu(c->sq_flags);
    uint64_t prp1 = le64_to_cpu(c->prp1);

    if (!cqid || nvme_check_cqid(n, cqid)) {
        return NVME_INVALID_CQID | NVME_DNR;
    }
    if (!sqid || !nvme_check_sqid(n, sqid)) {
        return NVME_INVALID_QID | NVME_DNR;
    }
    if (!qsize || qsize > NVME_CAP_MQES(n->bar.cap)) {
        return NVME_MAX_QSIZE_EXCEEDED | NVME_DNR;
    }
    if (!prp1 || prp1 & (n->page_size - 1)) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    if (!(NVME_SQ_FLAGS_PC(qflags))) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    sq = g_malloc0(sizeof(*sq));
    nvme_init_sq(sq, n, prp1, sqid, cqid, qsize + 1);
    return NVME_SUCCESS;
}

static void nvme_free_cq(NvmeCQueue *cq, NvmeCtrl *n)
{
    n->cq[cq->cqid] = NULL;
    timer_del(cq->timer);
    timer_free(cq->timer);
    msix_vector_unuse(&n->parent_obj, cq->vector);
    if (cq->cqid) {
        g_free(cq);
    }
}

static uint16_t nvme_del_cq(NvmeCtrl *n, NvmeCmd *cmd)
{
    NvmeDeleteQ *c = (NvmeDeleteQ *)cmd;
    NvmeCQueue *cq;
    uint16_t qid = le16_to_cpu(c->qid);

    if (!qid || nvme_check_cqid(n, qid)) {
        return NVME_INVALID_CQID | NVME_DNR;
    }

    cq = n->cq[qid];
    if (!QTAILQ_EMPTY(&cq->sq_list)) {
        return NVME_INVALID_QUEUE_DEL;
    }
    nvme_free_cq(cq, n);
    return NVME_SUCCESS;
}

static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
    uint16_t cqid, uint16_t vector, uint16_t size, uint16_t irq_enabled)
{
    cq->ctrl = n;
    cq->cqid = cqid;
    cq->size = size;
    cq->dma_addr = dma_addr;
    cq->phase = 1;
    cq->irq_enabled = irq_enabled;
    cq->vector = vector;
    cq->head = cq->tail = 0;
    QTAILQ_INIT(&cq->req_list);
    QTAILQ_INIT(&cq->sq_list);
    msix_vector_use(&n->parent_obj, cq->vector);
    n->cq[cqid] = cq;
    cq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_post_cqes, cq);
}

static uint16_t nvme_create_cq(NvmeCtrl *n, NvmeCmd *cmd)
{
    NvmeCQueue *cq;
    NvmeCreateCq *c = (NvmeCreateCq *)cmd;
    uint16_t cqid = le16_to_cpu(c->cqid);
    uint16_t vector = le16_to_cpu(c->irq_vector);
    uint16_t qsize = le16_to_cpu(c->qsize);
    uint16_t qflags = le16_to_cpu(c->cq_flags);
    uint64_t prp1 = le64_to_cpu(c->prp1);

    if (!cqid || !nvme_check_cqid(n, cqid)) {
        return NVME_INVALID_CQID | NVME_DNR;
    }
    if (!qsize || qsize > NVME_CAP_MQES(n->bar.cap)) {
        return NVME_MAX_QSIZE_EXCEEDED | NVME_DNR;
    }
    if (!prp1) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    if (vector > n->num_queues) {
        return NVME_INVALID_IRQ_VECTOR | NVME_DNR;
    }
    if (!(NVME_CQ_FLAGS_PC(qflags))) {
        return NVME_INVALID_FIELD | NVME_DNR;
    }

    cq = g_malloc0(sizeof(*cq));
    nvme_init_cq(cq, n, prp1, cqid, vector, qsize + 1,
        NVME_CQ_FLAGS_IEN(qflags));
    return NVME_SUCCESS;
}

static uint16_t nvme_identify_ctrl(NvmeCtrl *n, NvmeIdentify *c)
{
    uint64_t prp1 = le64_to_cpu(c->prp1);
    uint64_t prp2 = le64_to_cpu(c->prp2);

    return nvme_dma_read_prp(n, (uint8_t *)&n->id_ctrl, sizeof(n->id_ctrl),
        prp1, prp2);
}

static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeIdentify *c)
{
    NvmeNamespace *ns;
    uint32_t nsid = le32_to_cpu(c->nsid);
    uint64_t prp1 = le64_to_cpu(c->prp1);
    uint64_t prp2 = le64_to_cpu(c->prp2);

    if (nsid == 0 || nsid > n->num_namespaces) {
        return NVME_INVALID_NSID | NVME_DNR;
    }

    ns = &n->namespaces[nsid - 1];
    return nvme_dma_read_prp(n, (uint8_t *)&ns->id_ns, sizeof(ns->id_ns),
        prp1, prp2);
}

static uint16_t nvme_identify_nslist(NvmeCtrl *n, NvmeIdentify *c)
{
    static const int data_len = 4096;
    uint32_t min_nsid = le32_to_cpu(c->nsid);
    uint64_t prp1 = le64_to_cpu(c->prp1);
    uint64_t prp2 = le64_to_cpu(c->prp2);
    uint32_t *list;
    uint16_t ret;
    int i, j = 0;

    list = g_malloc0(data_len);
    for (i = 0; i < n->num_namespaces; i++) {
        if (i < min_nsid) {
            continue;
        }
        list[j++] = cpu_to_le32(i + 1);
        if (j == data_len / sizeof(uint32_t)) {
            break;
        }
    }
    ret = nvme_dma_read_prp(n, (uint8_t *)list, data_len, prp1, prp2);
    g_free(list);
    return ret;
}


static uint16_t nvme_identify(NvmeCtrl *n, NvmeCmd *cmd)
{
    NvmeIdentify *c = (NvmeIdentify *)cmd;

    switch (le32_to_cpu(c->cns)) {
    case 0x00:
        return nvme_identify_ns(n, c);
    case 0x01:
        return nvme_identify_ctrl(n, c);
    case 0x02:
        return nvme_identify_nslist(n, c);
    default:
        return NVME_INVALID_FIELD | NVME_DNR;
    }
}

static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
{
    uint32_t dw10 = le32_to_cpu(cmd->cdw10);
    uint32_t result;

    switch (dw10) {
    case NVME_VOLATILE_WRITE_CACHE:
        result = blk_enable_write_cache(n->conf.blk);
        break;
    case NVME_NUMBER_OF_QUEUES:
        result = cpu_to_le32((n->num_queues - 1) | ((n->num_queues - 1) << 16));
        break;
    default:
        return NVME_INVALID_FIELD | NVME_DNR;
    }

    req->cqe.result = result;
    return NVME_SUCCESS;
}

static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
{
    uint32_t dw10 = le32_to_cpu(cmd->cdw10);
    uint32_t dw11 = le32_to_cpu(cmd->cdw11);

    switch (dw10) {
    case NVME_VOLATILE_WRITE_CACHE:
        blk_set_enable_write_cache(n->conf.blk, dw11 & 1);
        break;
    case NVME_NUMBER_OF_QUEUES:
        req->cqe.result =
            cpu_to_le32((n->num_queues - 1) | ((n->num_queues - 1) << 16));
        break;
    default:
        return NVME_INVALID_FIELD | NVME_DNR;
    }
    return NVME_SUCCESS;
}

static uint16_t nvme_admin_cmd(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
{
    switch (cmd->opcode) {
    case NVME_ADM_CMD_DELETE_SQ:
        return nvme_del_sq(n, cmd);
    case NVME_ADM_CMD_CREATE_SQ:
        return nvme_create_sq(n, cmd);
    case NVME_ADM_CMD_DELETE_CQ:
        return nvme_del_cq(n, cmd);
    case NVME_ADM_CMD_CREATE_CQ:
        return nvme_create_cq(n, cmd);
    case NVME_ADM_CMD_IDENTIFY:
        return nvme_identify(n, cmd);
    case NVME_ADM_CMD_SET_FEATURES:
        return nvme_set_feature(n, cmd, req);
    case NVME_ADM_CMD_GET_FEATURES:
        return nvme_get_feature(n, cmd, req);
    default:
        return NVME_INVALID_OPCODE | NVME_DNR;
    }
}

static void nvme_process_sq(void *opaque)
{
    NvmeSQueue *sq = opaque;
    NvmeCtrl *n = sq->ctrl;
    NvmeCQueue *cq = n->cq[sq->cqid];

    uint16_t status;
    hwaddr addr;
    NvmeCmd cmd;
    NvmeRequest *req;

    while (!(nvme_sq_empty(sq) || QTAILQ_EMPTY(&sq->req_list))) {
        addr = sq->dma_addr + sq->head * n->sqe_size;
        pci_dma_read(&n->parent_obj, addr, (void *)&cmd, sizeof(cmd));
        nvme_inc_sq_head(sq);

        req = QTAILQ_FIRST(&sq->req_list);
        QTAILQ_REMOVE(&sq->req_list, req, entry);
        QTAILQ_INSERT_TAIL(&sq->out_req_list, req, entry);
        memset(&req->cqe, 0, sizeof(req->cqe));
        req->cqe.cid = cmd.cid;

        status = sq->sqid ? nvme_io_cmd(n, &cmd, req) :
            nvme_admin_cmd(n, &cmd, req);
        if (status != NVME_NO_COMPLETE) {
            req->status = status;
            nvme_enqueue_req_completion(cq, req);
        }
    }
}

static void nvme_clear_ctrl(NvmeCtrl *n)
{
    int i;

    for (i = 0; i < n->num_queues; i++) {
        if (n->sq[i] != NULL) {
            nvme_free_sq(n->sq[i], n);
        }
    }
    for (i = 0; i < n->num_queues; i++) {
        if (n->cq[i] != NULL) {
            nvme_free_cq(n->cq[i], n);
        }
    }

    blk_flush(n->conf.blk);
    n->bar.cc = 0;
}

static int nvme_start_ctrl(NvmeCtrl *n)
{
    uint32_t page_bits = NVME_CC_MPS(n->bar.cc) + 12;
    uint32_t page_size = 1 << page_bits;

    if (n->cq[0] || n->sq[0] || !n->bar.asq || !n->bar.acq ||
            n->bar.asq & (page_size - 1) || n->bar.acq & (page_size - 1) ||
            NVME_CC_MPS(n->bar.cc) < NVME_CAP_MPSMIN(n->bar.cap) ||
            NVME_CC_MPS(n->bar.cc) > NVME_CAP_MPSMAX(n->bar.cap) ||
            NVME_CC_IOCQES(n->bar.cc) < NVME_CTRL_CQES_MIN(n->id_ctrl.cqes) ||
            NVME_CC_IOCQES(n->bar.cc) > NVME_CTRL_CQES_MAX(n->id_ctrl.cqes) ||
            NVME_CC_IOSQES(n->bar.cc) < NVME_CTRL_SQES_MIN(n->id_ctrl.sqes) ||
            NVME_CC_IOSQES(n->bar.cc) > NVME_CTRL_SQES_MAX(n->id_ctrl.sqes) ||
            !NVME_AQA_ASQS(n->bar.aqa) || !NVME_AQA_ACQS(n->bar.aqa)) {
        return -1;
    }

    n->page_bits = page_bits;
    n->page_size = page_size;
    n->max_prp_ents = n->page_size / sizeof(uint64_t);
    n->cqe_size = 1 << NVME_CC_IOCQES(n->bar.cc);
    n->sqe_size = 1 << NVME_CC_IOSQES(n->bar.cc);
    nvme_init_cq(&n->admin_cq, n, n->bar.acq, 0, 0,
        NVME_AQA_ACQS(n->bar.aqa) + 1, 1);
    nvme_init_sq(&n->admin_sq, n, n->bar.asq, 0, 0,
        NVME_AQA_ASQS(n->bar.aqa) + 1);

    return 0;
}

static void nvme_write_bar(NvmeCtrl *n, hwaddr offset, uint64_t data,
    unsigned size)
{
    switch (offset) {
    case 0xc:
        n->bar.intms |= data & 0xffffffff;
        n->bar.intmc = n->bar.intms;
        break;
    case 0x10:
        n->bar.intms &= ~(data & 0xffffffff);
        n->bar.intmc = n->bar.intms;
        break;
    case 0x14:
        /* Windows first sends data, then sends enable bit */
        if (!NVME_CC_EN(data) && !NVME_CC_EN(n->bar.cc) &&
            !NVME_CC_SHN(data) && !NVME_CC_SHN(n->bar.cc))
        {
            n->bar.cc = data;
        }

        if (NVME_CC_EN(data) && !NVME_CC_EN(n->bar.cc)) {
            n->bar.cc = data;
            if (nvme_start_ctrl(n)) {
                n->bar.csts = NVME_CSTS_FAILED;
            } else {
                n->bar.csts = NVME_CSTS_READY;
            }
        } else if (!NVME_CC_EN(data) && NVME_CC_EN(n->bar.cc)) {
            nvme_clear_ctrl(n);
            n->bar.csts &= ~NVME_CSTS_READY;
        }
        if (NVME_CC_SHN(data) && !(NVME_CC_SHN(n->bar.cc))) {
                nvme_clear_ctrl(n);
                n->bar.cc = data;
                n->bar.csts |= NVME_CSTS_SHST_COMPLETE;
        } else if (!NVME_CC_SHN(data) && NVME_CC_SHN(n->bar.cc)) {
                n->bar.csts &= ~NVME_CSTS_SHST_COMPLETE;
                n->bar.cc = data;
        }
        break;
    case 0x24:
        n->bar.aqa = data & 0xffffffff;
        break;
    case 0x28:
        n->bar.asq = data;
        break;
    case 0x2c:
        n->bar.asq |= data << 32;
        break;
    case 0x30:
        n->bar.acq = data;
        break;
    case 0x34:
        n->bar.acq |= data << 32;
        break;
    default:
        break;
    }
}

static uint64_t nvme_mmio_read(void *opaque, hwaddr addr, unsigned size)
{
    NvmeCtrl *n = (NvmeCtrl *)opaque;
    uint8_t *ptr = (uint8_t *)&n->bar;
    uint64_t val = 0;

    if (addr < sizeof(n->bar)) {
        memcpy(&val, ptr + addr, size);
    }
    return val;
}

static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val)
{
    uint32_t qid;

    if (addr & ((1 << 2) - 1)) {
        return;
    }

    if (((addr - 0x1000) >> 2) & 1) {
        uint16_t new_head = val & 0xffff;
        int start_sqs;
        NvmeCQueue *cq;

        qid = (addr - (0x1000 + (1 << 2))) >> 3;
        if (nvme_check_cqid(n, qid)) {
            return;
        }

        cq = n->cq[qid];
        if (new_head >= cq->size) {
            return;
        }

        start_sqs = nvme_cq_full(cq) ? 1 : 0;
        cq->head = new_head;
        if (start_sqs) {
            NvmeSQueue *sq;
            QTAILQ_FOREACH(sq, &cq->sq_list, entry) {
                timer_mod(sq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
            }
            timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
        }

        if (cq->tail != cq->head) {
            nvme_isr_notify(n, cq);
        }
    } else {
        uint16_t new_tail = val & 0xffff;
        NvmeSQueue *sq;

        qid = (addr - 0x1000) >> 3;
        if (nvme_check_sqid(n, qid)) {
            return;
        }

        sq = n->sq[qid];
        if (new_tail >= sq->size) {
            return;
        }

        sq->tail = new_tail;
        timer_mod(sq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 500);
    }
}

static void nvme_mmio_write(void *opaque, hwaddr addr, uint64_t data,
    unsigned size)
{
    NvmeCtrl *n = (NvmeCtrl *)opaque;
    if (addr < sizeof(n->bar)) {
        nvme_write_bar(n, addr, data, size);
    } else if (addr >= 0x1000) {
        nvme_process_db(n, addr, data);
    }
}

static const MemoryRegionOps nvme_mmio_ops = {
    .read = nvme_mmio_read,
    .write = nvme_mmio_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
    .impl = {
        .min_access_size = 2,
        .max_access_size = 8,
    },
};

static int nvme_init(PCIDevice *pci_dev)
{
    NvmeCtrl *n = NVME(pci_dev);
    NvmeIdCtrl *id = &n->id_ctrl;

    int i;
    int64_t bs_size;
    uint8_t *pci_conf;

    if (!n->conf.blk) {
        return -1;
    }

    bs_size = blk_getlength(n->conf.blk);
    if (bs_size < 0) {
        return -1;
    }

    blkconf_serial(&n->conf, &n->serial);
    if (!n->serial) {
        return -1;
    }
    blkconf_blocksizes(&n->conf);
    blkconf_apply_backend_options(&n->conf);

    pci_conf = pci_dev->config;
    pci_conf[PCI_INTERRUPT_PIN] = 1;
    pci_config_set_prog_interface(pci_dev->config, 0x2);
    pci_config_set_class(pci_dev->config, PCI_CLASS_STORAGE_EXPRESS);
    pcie_endpoint_cap_init(&n->parent_obj, 0x80);

    n->num_namespaces = 1;
    n->num_queues = 64;
    n->reg_size = pow2ceil(0x1004 + 2 * (n->num_queues + 1) * 4);
    n->ns_size = bs_size / (uint64_t)n->num_namespaces;

    n->namespaces = g_new0(NvmeNamespace, n->num_namespaces);
    n->sq = g_new0(NvmeSQueue *, n->num_queues);
    n->cq = g_new0(NvmeCQueue *, n->num_queues);

    memory_region_init_io(&n->iomem, OBJECT(n), &nvme_mmio_ops, n,
                          "nvme", n->reg_size);
    pci_register_bar(&n->parent_obj, 0,
        PCI_BASE_ADDRESS_SPACE_MEMORY | PCI_BASE_ADDRESS_MEM_TYPE_64,
        &n->iomem);
    msix_init_exclusive_bar(&n->parent_obj, n->num_queues, 4);

    id->vid = cpu_to_le16(pci_get_word(pci_conf + PCI_VENDOR_ID));
    id->ssvid = cpu_to_le16(pci_get_word(pci_conf + PCI_SUBSYSTEM_VENDOR_ID));
    strpadcpy((char *)id->mn, sizeof(id->mn), "QEMU NVMe Ctrl", ' ');
    strpadcpy((char *)id->fr, sizeof(id->fr), "1.0", ' ');
    strpadcpy((char *)id->sn, sizeof(id->sn), n->serial, ' ');
    id->rab = 6;
    id->ieee[0] = 0x00;
    id->ieee[1] = 0x02;
    id->ieee[2] = 0xb3;
    id->oacs = cpu_to_le16(0);
    id->frmw = 7 << 1;
    id->lpa = 1 << 0;
    id->sqes = (0x6 << 4) | 0x6;
    id->cqes = (0x4 << 4) | 0x4;
    id->nn = cpu_to_le32(n->num_namespaces);
    id->psd[0].mp = cpu_to_le16(0x9c4);
    id->psd[0].enlat = cpu_to_le32(0x10);
    id->psd[0].exlat = cpu_to_le32(0x4);
    if (blk_enable_write_cache(n->conf.blk)) {
        id->vwc = 1;
    }

    n->bar.cap = 0;
    NVME_CAP_SET_MQES(n->bar.cap, 0x7ff);
    NVME_CAP_SET_CQR(n->bar.cap, 1);
    NVME_CAP_SET_AMS(n->bar.cap, 1);
    NVME_CAP_SET_TO(n->bar.cap, 0xf);
    NVME_CAP_SET_CSS(n->bar.cap, 1);
    NVME_CAP_SET_MPSMAX(n->bar.cap, 4);

    n->bar.vs = 0x00010100;
    n->bar.intmc = n->bar.intms = 0;

    for (i = 0; i < n->num_namespaces; i++) {
        NvmeNamespace *ns = &n->namespaces[i];
        NvmeIdNs *id_ns = &ns->id_ns;
        id_ns->nsfeat = 0;
        id_ns->nlbaf = 0;
        id_ns->flbas = 0;
        id_ns->mc = 0;
        id_ns->dpc = 0;
        id_ns->dps = 0;
        id_ns->lbaf[0].ds = BDRV_SECTOR_BITS;
        id_ns->ncap  = id_ns->nuse = id_ns->nsze =
            cpu_to_le64(n->ns_size >>
                id_ns->lbaf[NVME_ID_NS_FLBAS_INDEX(ns->id_ns.flbas)].ds);
    }
    return 0;
}

static void nvme_exit(PCIDevice *pci_dev)
{
    NvmeCtrl *n = NVME(pci_dev);

    nvme_clear_ctrl(n);
    g_free(n->namespaces);
    g_free(n->cq);
    g_free(n->sq);
    msix_uninit_exclusive_bar(pci_dev);
}

static Property nvme_props[] = {
    DEFINE_BLOCK_PROPERTIES(NvmeCtrl, conf),
    DEFINE_PROP_STRING("serial", NvmeCtrl, serial),
    DEFINE_PROP_END_OF_LIST(),
};

static const VMStateDescription nvme_vmstate = {
    .name = "nvme",
    .unmigratable = 1,
};

static void nvme_class_init(ObjectClass *oc, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(oc);
    PCIDeviceClass *pc = PCI_DEVICE_CLASS(oc);

    pc->init = nvme_init;
    pc->exit = nvme_exit;
    pc->class_id = PCI_CLASS_STORAGE_EXPRESS;
    pc->vendor_id = PCI_VENDOR_ID_INTEL;
    pc->device_id = 0x5845;
    pc->revision = 2;
    pc->is_express = 1;

    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
    dc->desc = "Non-Volatile Memory Express";
    dc->props = nvme_props;
    dc->vmsd = &nvme_vmstate;
}

static void nvme_instance_init(Object *obj)
{
    NvmeCtrl *s = NVME(obj);

    device_add_bootindex_property(obj, &s->conf.bootindex,
                                  "bootindex", "/namespace@1,0",
                                  DEVICE(obj), &error_abort);
}

static const TypeInfo nvme_info = {
    .name          = "nvme",
    .parent        = TYPE_PCI_DEVICE,
    .instance_size = sizeof(NvmeCtrl),
    .class_init    = nvme_class_init,
    .instance_init = nvme_instance_init,
};

static void nvme_register_types(void)
{
    type_register_static(&nvme_info);
}

type_init(nvme_register_types)