Re: [SeaBIOS] [PATCH v2] block: add NVMe boot support

[Kevin O'Connor]

On Wed, Feb 01, 2017 at 09:55:33AM +0100, Julian Stecklina wrote:
> This patch enables SeaBIOS to boot from NVMe. Finding namespaces and
> basic I/O works. Testing has been done in qemu and so far it works with
> Grub, syslinux, and the FreeBSD loader. You need a recent Qemu (>=
> 2.7.0), because older versions have buggy NVMe support.
>
> The NVMe code is currently only enabled on Qemu due to lack of testing
> on real hardware.
>
> Signed-off-by: Julian Stecklina

Thanks Julian.  I have some comments below - most of them minor.
However, the use of panic() in a driver is a blocker - we don't want
any drivers to use panic as its use could cause a machine to be
inoperable.

[...]
> --- /dev/null
> +++ b/src/hw/nvme.c
> @@ -0,0 +1,651 @@
> +// Low level NVMe disk access
> +//
> +// Copyright 2017 Amazon.com, Inc. or its affiliates.
> +//
> +// This file may be distributed under the terms of the GNU LGPLv3 license.
>
> +#include "blockcmd.h"
> +#include "fw/paravirt.h" // runningOnQEMU
> +#include "malloc.h" // malloc_high
> +#include "output.h" // dprintf
> +#include "pci.h"
> +#include "pci_ids.h" // PCI_CLASS_STORAGE_NVME
> +#include "pci_regs.h" // PCI_BASE_ADDRESS_0
> +#include "pcidevice.h" // foreachpci
> +#include "stacks.h" // yield
> +#include "std/disk.h" // DISK_RET_
> +#include "string.h" // memset
> +#include "util.h" // boot_add_hd
> +#include "x86.h" // readl
>
> +#include "nvme.h"
> +#include "nvme-int.h"
>
> +static void *
> +zalloc_page_aligned(void *(*memalign)(u32 /* align */, u32 /* size */),
>                u32 size)
>
> +{
> void *res = memalign(NVME_PAGE_SIZE, size);
> if (res) memset(res, 0, size);
> return res;
>
> +}

memalign_high() and memalign_tmp() are thin wrappers around _malloc()
- see malloc.h.  Instead of passing pointers to these thin wrapper
functions it would be preferable to pass the malloc zone and call
_malloc() directly.
> +static void
> +nvme_init_queue_common(struct nvme_ctrl *ctrl, struct nvme_queue *q, u16 q_idx,
>                   u16 length)
>
> +{
> memset(q, 0, sizeof(*q));
> q->dbl = (u32 *)((char *)ctrl->reg + 0x1000 + q_idx * ctrl->doorbell_stride);
> dprintf(3, " q %p q_idx %u dbl %p\n", q, q_idx, q->dbl);
> q->mask = length - 1;
>
> +}
>
> +static void
> +nvme_init_sq(struct nvme_ctrl *ctrl, struct nvme_sq *sq, u16 q_idx, u16 length,
>         struct nvme_cq *cq)
>
> +{
> nvme_init_queue_common(ctrl, &sq->common, q_idx, length);
> sq->sqe = zalloc_page_aligned(memalign_high, sizeof(*sq->sqe) * length);
> dprintf(3, "sq %p q_idx %u sqe %p\n", sq, q_idx, sq->sqe);
> sq->cq   = cq;
> sq->head = 0;
> sq->tail = 0;
>
> +}
>
> +static void
> +nvme_init_cq(struct nvme_ctrl *ctrl, struct nvme_cq *cq, u16 q_idx, u16 length)
> +{
> nvme_init_queue_common(ctrl, &cq->common, q_idx, length);
> cq->cqe = zalloc_page_aligned(memalign_high, sizeof(*cq->cqe) * length);
> cq->head = 0;
> /* All CQE phase bits are initialized to zero. This means initially we wait
>   for the host controller to set these to 1. */
> cq->phase = 1;
>
> +}
>
> +static int
> +nvme_poll_cq(struct nvme_cq *cq)
> +{
> u32 dw3 = readl(&cq->cqe[cq->head].dword[3]);
> return (!!(dw3 & NVME_CQE_DW3_P) == cq->phase);
>
> +}
>
> +static int
> +nvme_is_cqe_success(struct nvme_cqe const *cqe)
> +{
> return (cqe->status & 0xFF) >> 1 == 0;
>
> +}
>
> +static struct nvme_cqe
> +nvme_error_cqe(void)
> +{
> struct nvme_cqe r;
> /* 0xFF is a vendor specific status code != success. Should be okay for
>   indicating failure. */
> memset(&r, 0xFF, sizeof(r));
> return r;
>
> +}
>
> +static struct nvme_cqe
> +nvme_consume_cqe(struct nvme_sq *sq)
> +{
> struct nvme_cq *cq = sq->cq;
> if (!nvme_poll_cq(cq)) {
>    /* Cannot consume a completion queue entry, if there is none ready. */
>    return nvme_error_cqe();
> }
> struct nvme_cqe *cqe = &cq->cqe[cq->head];
> u16 cq_next_head = (cq->head + 1) & cq->common.mask;
> dprintf(4, "cq %p head %u -> %u\n", cq, cq->head, cq_next_head);
> if (cq_next_head < cq->head) {
>    dprintf(3, "cq %p wrap\n", cq);
>    cq->phase = ~cq->phase;
> }
> cq->head = cq_next_head;
> /* Update the submission queue head. */
> if (cqe->sq_head != sq->head) {
>    sq->head = cqe->sq_head;
>    dprintf(4, "sq %p advanced to %u\n", sq, cqe->sq_head);
> }
> /* Tell the controller that we consumed the completion. */
> writel(cq->common.dbl, cq->head);
> return *cqe;
>
> +}
>
> +static struct nvme_cqe
> +nvme_wait(struct nvme_sq *sq)
> +{
> static const unsigned nvme_timeout = 500 /* ms */;
> u32 to = timer_calc(nvme_timeout);
> while (!nvme_poll_cq(sq->cq)) {
>    yield();
>    if (timer_check(to)) {
>        warn_timeout();
>        return nvme_error_cqe();
>    }
> }
> return nvme_consume_cqe(sq);
>
> +}
>
> +/* Returns the next submission queue entry (or NULL if the queue is full). It
> also fills out Command Dword 0 and clears the rest. */
>
> +static struct nvme_sqe *
> +nvme_get_next_sqe(struct nvme_sq *sq, u8 opc, void *metadata, void *data)
> +{
> if (((sq->head + 1) & sq->common.mask) == sq->tail) {
>    dprintf(3, "submission queue is full");
>    return NULL;
> }
> struct nvme_sqe *sqe = &sq->sqe[sq->tail];
> dprintf(4, "sq %p next_sqe %u\n", sq, sq->tail);
> memset(sqe, 0, sizeof(*sqe));
> sqe->cdw0 = opc | (sq->tail << 16 /* CID */);
> sqe->mptr = (u32)metadata;
> sqe->dptr_prp1 = (u32)data;
> if (sqe->dptr_prp1 & (NVME_PAGE_SIZE - 1)) {
>    /* Data buffer not page aligned. */
>    panic("data buffer not page aligned: %p\n", data);
>    warn_internalerror();

Can't call panic().
> }
> return sqe;
>
> +}
>
> +/* Call this after you've filled out an sqe that you've got from nvme_get_next_sqe. */
> +static void
> +nvme_commit_sqe(struct nvme_sq *sq)
> +{
> dprintf(4, "sq %p commit_sqe %u\n", sq, sq->tail);
> sq->tail = (sq->tail + 1) & sq->common.mask;
> writel(sq->common.dbl, sq->tail);
>
> +}
>
> +/* Perform an identify command on the admin queue and return the resulting
> buffer. This may be a NULL pointer, if something failed. This function
> cannot be used after initialization, because it uses buffers in tmp zone. */
>
> +static union nvme_identify *
> +nvme_admin_identify(struct nvme_ctrl *ctrl, u8 cns, u32 nsid)
> +{
> union nvme_identify *identify_buf = zalloc_page_aligned(memalign_tmp, 4096);
> if (!identify_buf) {
>    /* Could not allocate identify buffer. */
>    warn_internalerror();
>    return NULL;
> }
> struct nvme_sqe *cmd_identify;
> cmd_identify = nvme_get_next_sqe(&ctrl->admin_sq,
>                                 NVME_SQE_OPC_ADMIN_IDENTIFY, NULL,
>                                 identify_buf);
> if (!cmd_identify) { panic("admin queue full\n"); }

Can't call panic().
> cmd_identify->nsid = nsid;
> cmd_identify->dword[10] = cns;
> nvme_commit_sqe(&ctrl->admin_sq);
> struct nvme_cqe cqe = nvme_wait(&ctrl->admin_sq);
> if (!nvme_is_cqe_success(&cqe)) {
>    free(identify_buf);
>    return NULL;
> }
> return identify_buf;
>
> +}
>
> +static struct nvme_identify_ctrl *
> +nvme_admin_identify_ctrl(struct nvme_ctrl *ctrl)
> +{
> return &nvme_admin_identify(ctrl, NVME_ADMIN_IDENTIFY_CNS_ID_CTRL, 0)->ctrl;
>
> +}
>
> +static struct nvme_identify_ns_list *
> +nvme_admin_identify_get_ns_list(struct nvme_ctrl *ctrl)
> +{
> return &nvme_admin_identify(ctrl, NVME_ADMIN_IDENTIFY_CNS_GET_NS_LIST,
>                            0)->ns_list;
>
> +}
>
> +static struct nvme_identify_ns *
> +nvme_admin_identify_ns(struct nvme_ctrl *ctrl, u32 ns_id)
> +{
> return &nvme_admin_identify(ctrl, NVME_ADMIN_IDENTIFY_CNS_ID_NS,
>                            ns_id)->ns;
>
> +}
>
> +static void
> +nvme_probe_ns(struct nvme_ctrl *ctrl, struct nvme_namespace *ns, u32 ns_id)
> +{
> ns->ctrl  = ctrl;
> ns->ns_id = ns_id;
> struct nvme_identify_ns *id = nvme_admin_identify_ns(ctrl, ns_id);
> if (!id) {
>    dprintf(2, "NVMe couldn't identify namespace %u.\n", ns_id);
>    goto free_buffer;
> }
> u8 current_lba_format = id->flbas & 0xF;
> if (current_lba_format > id->nlbaf) {
>    dprintf(2, "NVMe NS %u: current LBA format %u is beyond what the "
>            " namespace supports (%u)?\n",
>            ns_id, current_lba_format, id->nlbaf + 1);
>    goto free_buffer;
> }
> ns->lba_count = id->nsze;
> struct nvme_lba_format *fmt = &id->lbaf[current_lba_format];
> ns->block_size    = 1U << fmt->lbads;
> ns->metadata_size = fmt->ms;
> if (ns->block_size > NVME_PAGE_SIZE) {
>    /* If we see devices that trigger this path, we need to increase our
>       buffer size. */
>    warn_internalerror();
>    goto free_buffer;
> }
> ns->drive.cntl_id   = ns - ctrl->ns;
> ns->drive.removable = 0;
> ns->drive.type      = DTYPE_NVME;
> ns->drive.blksize   = ns->block_size;
> ns->drive.sectors   = ns->lba_count;
> ns->dma_buffer = zalloc_page_aligned(memalign_high, NVME_PAGE_SIZE);
> char *desc = znprintf(MAXDESCSIZE, "NVMe NS %u: %llu MiB (%llu %u-byte "
>                      "blocks + %u-byte metadata)\n",
>                      ns_id, (ns->lba_count * ns->block_size) >> 20,
>                      ns->lba_count, ns->block_size, ns->metadata_size);
> dprintf(3, "%s", desc);
> boot_add_hd(&ns->drive, desc, bootprio_find_pci_device(ctrl->pci));
> free_buffer:
> free (id);
> }
>
> +/* Returns 0 on success. */
> +static int
> +nvme_create_io_cq(struct nvme_ctrl *ctrl, struct nvme_cq *cq, u16 q_idx)
> +{
> struct nvme_sqe *cmd_create_cq;
> nvme_init_cq(ctrl, cq, q_idx, NVME_PAGE_SIZE / sizeof(struct nvme_cqe));
> cmd_create_cq = nvme_get_next_sqe(&ctrl->admin_sq,
>                                  NVME_SQE_OPC_ADMIN_CREATE_IO_CQ, NULL,
>                                  cq->cqe);
> if (!cmd_create_cq) {
>    return -1;
> }
> cmd_create_cq->dword[10] = (cq->common.mask << 16) | (q_idx >> 1);
> cmd_create_cq->dword[11] = 1 /* physically contiguous */;
> nvme_commit_sqe(&ctrl->admin_sq);
> struct nvme_cqe cqe = nvme_wait(&ctrl->admin_sq);
> if (!nvme_is_cqe_success(&cqe)) {
>    dprintf(2, "create io cq failed: %08x %08x %08x %08x\n",
>            cqe.dword[0], cqe.dword[1], cqe.dword[2], cqe.dword[3]);
>    return -1;
> }
> return 0;
>
> +}
>
> +/* Returns 0 on success. */
> +static int
> +nvme_create_io_sq(struct nvme_ctrl *ctrl, struct nvme_sq *sq, u16 q_idx, struct nvme_cq *cq)
> +{
> struct nvme_sqe *cmd_create_sq;
> nvme_init_sq(ctrl, sq, q_idx, NVME_PAGE_SIZE / sizeof(struct nvme_cqe), cq);
> cmd_create_sq = nvme_get_next_sqe(&ctrl->admin_sq,
>                                  NVME_SQE_OPC_ADMIN_CREATE_IO_SQ, NULL,
>                                  sq->sqe);
> if (!cmd_create_sq) {
>    return -1;
> }
> cmd_create_sq->dword[10] = (sq->common.mask << 16) | (q_idx >> 1);
> cmd_create_sq->dword[11] = (q_idx >> 1) << 16 | 1 /* contiguous */;
> dprintf(3, "sq %p create dword10 %08x dword11 %08x\n", sq,
>        cmd_create_sq->dword[10], cmd_create_sq->dword[11]);
> nvme_commit_sqe(&ctrl->admin_sq);
> struct nvme_cqe cqe = nvme_wait(&ctrl->admin_sq);
> if (!nvme_is_cqe_success(&cqe)) {
>    dprintf(2, "create io sq failed: %08x %08x %08x %08x\n",
>            cqe.dword[0], cqe.dword[1], cqe.dword[2], cqe.dword[3]);
>    return -1;
> }
> return 0;
>
> +}
>
> +/* Reads count sectors into buf. Returns DISK_RET_*. The buffer cannot cross
> page boundaries. */
>
> +static int
> +nvme_io_readwrite(struct nvme_namespace *ns, u64 lba, char *buf, u16 count,
>              int write)
>
> +{
> u32 buf_addr = (u32)buf;
> if ((buf_addr & 0x3) ||
>    ((buf_addr & ~(NVME_PAGE_SIZE - 1)) !=
>     ((buf_addr + ns->block_size * count - 1) & ~(NVME_PAGE_SIZE - 1)))) {
>    /* Buffer is misaligned or crosses page boundary */
>    warn_internalerror();
>    return DISK_RET_EBADTRACK;
> }
> struct nvme_sqe *io_read = nvme_get_next_sqe(&ns->ctrl->io_sq,
>                                             write ? NVME_SQE_OPC_IO_WRITE
>                                                   : NVME_SQE_OPC_IO_READ,
>                                             NULL, buf);
> io_read->nsid = ns->ns_id;
> io_read->dword[10] = (u32)lba;
> io_read->dword[11] = (u32)(lba >> 32);
> io_read->dword[12] = (1U << 31 /* limited retry */) | (count - 1);
> nvme_commit_sqe(&ns->ctrl->io_sq);
> struct nvme_cqe cqe = nvme_wait(&ns->ctrl->io_sq);
> if (!nvme_is_cqe_success(&cqe)) {
>    dprintf(2, "read io: %08x %08x %08x %08x\n",
>            cqe.dword[0], cqe.dword[1], cqe.dword[2], cqe.dword[3]);
>    return DISK_RET_EBADTRACK;
> }
> return DISK_RET_SUCCESS;
>
> +}
>
> +static int
> +nvme_create_io_queues(struct nvme_ctrl *ctrl)
> +{
> if (nvme_create_io_cq(ctrl, &ctrl->io_cq, 3))
>    return -1;
> if (nvme_create_io_sq(ctrl, &ctrl->io_sq, 2, &ctrl->io_cq))
>    return -1;
> return 0;
>
> +}
>
> +/* Waits for CSTS.RDY to match rdy. Returns 0 on success. */
> +static int
> +nvme_wait_csts_rdy(struct nvme_ctrl *ctrl, unsigned rdy)
> +{
> u32 const max_to = 500 /* ms */ * ((ctrl->reg->cap >> 24) & 0xFFU);
> u32 to = timer_calc(max_to);
> u32 csts;
> while (rdy != ((csts = ctrl->reg->csts) & NVME_CSTS_RDY)) {
>    yield();
>    if (csts & NVME_CSTS_FATAL) {
>        dprintf(3, "NVMe fatal error during controller shutdown\n");
>        return -1;
>    }
>    if (timer_check(to)) {
>        warn_timeout();
>        return -1;
>    }
> }
> return 0;
>
> +}
>
> +static void
> +nvme_controller_enable(struct nvme_ctrl *ctrl)
> +{
> pci_enable_busmaster(ctrl->pci);
> /* Turn the controller off. */
> ctrl->reg->cc = 0;
> if (nvme_wait_csts_rdy(ctrl, 0)) {
>    dprintf(2, "NVMe fatal error during controller shutdown\n");
>    return;
> }
> ctrl->doorbell_stride = 4U << ((ctrl->reg->cap >> 32) & 0xF);
> nvme_init_cq(ctrl, &ctrl->admin_cq, 1,
>             NVME_PAGE_SIZE / sizeof(struct nvme_cqe));
> nvme_init_sq(ctrl, &ctrl->admin_sq, 0,
>             NVME_PAGE_SIZE / sizeof(struct nvme_sqe), &ctrl->admin_cq);
> ctrl->reg->aqa = ctrl->admin_cq.common.mask << 16
>    | ctrl->admin_sq.common.mask;
> /* Create the admin queue pair */
> if (!ctrl->admin_sq.sqe || !ctrl->admin_cq.cqe) goto out_of_memory;
> ctrl->reg->asq = (u32)ctrl->admin_sq.sqe;
> ctrl->reg->acq = (u32)ctrl->admin_cq.cqe;
> dprintf(3, "  admin submission queue: %p\n", ctrl->admin_sq.sqe);
> dprintf(3, "  admin completion queue: %p\n", ctrl->admin_cq.cqe);
> ctrl->reg->cc = NVME_CC_EN | (NVME_CQE_SIZE_LOG << 20)
>    | (NVME_SQE_SIZE_LOG << 16 /* IOSQES */);
> if (nvme_wait_csts_rdy(ctrl, 1)) {
>    dprintf(2, "NVMe fatal error while enabling controller\n");
>    return;

Shouldn't this free the allocated memory on failure (ie, goto failed)?
> }
> /* The admin queue is set up and the controller is ready. Let's figure out
>   what namespaces we have. */
> struct nvme_identify_ctrl *identify = nvme_admin_identify_ctrl(ctrl);
> if (!identify) {
>    dprintf(2, "NVMe couldn't identify controller.\n");
>    goto failed;
> }
> /* TODO Print model/serial info. */
> dprintf(3, "NVMe has %u namespace%s.\n",
>        identify->nn, (identify->nn == 1) ? "" : "s");
> ctrl->ns_count = identify->nn;
> free(identify);
> if ((ctrl->ns_count == 0) || nvme_create_io_queues(ctrl)) {
>    /* No point to continue, if the controller says it doesn't have
>       namespaces or we couldn't create I/O queues. */
>    goto failed;
> }
> ctrl->ns = malloc_fseg(sizeof(*ctrl->ns) * ctrl->ns_count);
> if (!ctrl->ns) goto out_of_memory;
> memset(ctrl->ns, 0, sizeof(*ctrl->ns) * ctrl->ns_count);
> struct nvme_identify_ns_list *ns_list = nvme_admin_identify_get_ns_list(ctrl);
> if (!ns_list) {
>    dprintf(2, "NVMe couldn't get namespace list.\n");
>    goto failed;
> }
> /* Populate namespace IDs */
> int ns_idx;
> for (ns_idx = 0;
>     ns_idx < ARRAY_SIZE(ns_list->ns_id)
>         && ns_idx < ctrl->ns_count
>         && ns_list->ns_id[ns_idx];
>     ns_idx++) {
>    nvme_probe_ns(ctrl, &ctrl->ns[ns_idx], ns_list->ns_id[ns_idx]);
> }
> free(ns_list);
> /* If for some reason the namespace list gives us fewer namespaces, we just
>   go along. */
> if (ns_idx != ctrl->ns_count) {
>    dprintf(2, "NVMe namespace list has only %u namespaces?\n", ns_idx);
>    ctrl->ns_count = ns_idx;
> }
> dprintf(3, "NVMe initialization complete!\n");
> return;
> out_of_memory:
> warn_noalloc();
> failed:
> free(ctrl->admin_sq.sqe);
> free(ctrl->admin_cq.cqe);
> free(ctrl->ns);
> return;
>
> +}
>
> +/* Initialize an NVMe controller and detect its drives. */
> +static void
> +nvme_controller_setup(void *opaque)
> +{
> struct pci_device *pci = opaque;
> if (create_bounce_buf() < 0)
>    return;

The bounce buffer isn't used anywhere in the code, so it's not
necessary to create it.
> struct nvme_reg volatile *reg = pci_enable_membar(pci, PCI_BASE_ADDRESS_0);
> if (!reg)
>    return;
> u32 version = reg->vs;
> dprintf(3, "Found NVMe controller with version %u.%u.%u.\n",
>        version >> 16, (version >> 8) & 0xFF, version & 0xFF);
> dprintf(3, "  Capabilities %016llx\n", reg->cap);
> if (version < 0x00010100U) {
>    dprintf(3, "Need at least 1.1.0! Skipping.\n");
>    return;
> }
> if (~reg->cap & NVME_CAP_CSS_NVME) {
>    dprintf(3, "Controller doesn't speak NVMe command set. Skipping.\n");
>    return;
> }
> struct nvme_ctrl *ctrl = malloc_high(sizeof(*ctrl));
> if (!ctrl) {
>    warn_noalloc();
>    return;
> }
> memset(ctrl, 0, sizeof(*ctrl));
> ctrl->reg = reg;
> ctrl->pci = pci;
> nvme_controller_enable(ctrl);

Shouldn't ctrl be free'd on failure?
> +}
>
> +// Locate and init NVMe controllers
> +static void
> +nvme_scan(void)
> +{
> // Scan PCI bus for ATA adapters
> struct pci_device *pci;
> foreachpci(pci) {
>    if (pci->class != PCI_CLASS_STORAGE_NVME)
>        continue;
>    if (pci->prog_if != 2 /* as of NVM 1.0e */) {
>        dprintf(3, "Found incompatble NVMe: prog-if=%02x\n", pci->prog_if);
>        continue;
>    }
>    run_thread(nvme_controller_setup, pci);
> }
>
> +}
>
> +static int
> +nvme_cmd_readwrite(struct nvme_namespace *ns, struct disk_op_s *op, int write)
> +{
> int res = DISK_RET_SUCCESS;
> u16 const max_blocks = NVME_PAGE_SIZE / ns->block_size;
> u16 i;
> for (i = 0; i < op->count || res != DISK_RET_SUCCESS;) {
>    u16 blocks_remaining = op->count - i;
>    u16 blocks = blocks_remaining < max_blocks ? blocks_remaining
>                                               : max_blocks;
>    char *op_buf = op->buf_fl + i * ns->block_size;
>    if (write) {
>        memcpy(ns->dma_buffer, op_buf, blocks * ns->block_size);
>    }
>    res = nvme_io_readwrite(ns, op->lba + i, ns->dma_buffer, blocks, write);
>    dprintf(3, "ns %u %s lba %llu+%u: %d\n", ns->ns_id, write ? "write"
>                                                              : "read",
>            op->lba + i, blocks, res);
>    if (!write && res == DISK_RET_SUCCESS) {
>        memcpy(op_buf, ns->dma_buffer, blocks * ns->block_size);
>    }
>    i += blocks;
> }
> return res;
>
> +}
>
> +int
> +nvme_process_op(struct disk_op_s *op)
> +{
> if (!CONFIG_NVME || !runningOnQEMU())
>    return DISK_RET_SUCCESS;
> struct nvme_namespace *ns = container_of(op->drive_gf, struct nvme_namespace,
>                                         drive);
> switch (op->command) {
> case CMD_READ:
> case CMD_WRITE:
>    return nvme_cmd_readwrite(ns, op, op->command == CMD_WRITE);
> default:
>    return default_process_op(op);
> }
>
> +}
>
> +void
> +nvme_setup(void)
> +{
> ASSERT32FLAT();
> if (!CONFIG_NVME)
>    return;

With the driver set to require QEMU_HARDWARE, this test should be:
  if (!CONFIG_NVME || !runningOnQEMU()) return;
to make sure the code is actually running on QEMU.
> dprintf(3, "init nvme\n");
> nvme_scan();
>
> +}
>
> +/* EOF */

-Kevin