Merge branch 'drm-vmwgfx-fixes' of ssh://people.freedesktop.org/~syeh/repos_linux...

[mirror_ubuntu-zesty-kernel.git] / drivers / scsi / cxlflash / superpipe.c

/*
 * CXL Flash Device Driver
 *
 * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
 *             Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
 *
 * Copyright (C) 2015 IBM Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/delay.h>
#include <linux/file.h>
#include <linux/syscalls.h>
#include <misc/cxl.h>
#include <asm/unaligned.h>

#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_eh.h>
#include <uapi/scsi/cxlflash_ioctl.h>

#include "sislite.h"
#include "common.h"
#include "vlun.h"
#include "superpipe.h"

struct cxlflash_global global;

/**
 * marshal_rele_to_resize() - translate release to resize structure
 * @rele:       Source structure from which to translate/copy.
 * @resize:     Destination structure for the translate/copy.
 */
static void marshal_rele_to_resize(struct dk_cxlflash_release *release,
                                   struct dk_cxlflash_resize *resize)
{
        resize->hdr = release->hdr;
        resize->context_id = release->context_id;
        resize->rsrc_handle = release->rsrc_handle;
}

/**
 * marshal_det_to_rele() - translate detach to release structure
 * @detach:     Destination structure for the translate/copy.
 * @rele:       Source structure from which to translate/copy.
 */
static void marshal_det_to_rele(struct dk_cxlflash_detach *detach,
                                struct dk_cxlflash_release *release)
{
        release->hdr = detach->hdr;
        release->context_id = detach->context_id;
}

/**
 * cxlflash_free_errpage() - frees resources associated with global error page
 */
void cxlflash_free_errpage(void)
{

        mutex_lock(&global.mutex);
        if (global.err_page) {
                __free_page(global.err_page);
                global.err_page = NULL;
        }
        mutex_unlock(&global.mutex);
}

/**
 * cxlflash_stop_term_user_contexts() - stops/terminates known user contexts
 * @cfg:        Internal structure associated with the host.
 *
 * When the host needs to go down, all users must be quiesced and their
 * memory freed. This is accomplished by putting the contexts in error
 * state which will notify the user and let them 'drive' the tear down.
 * Meanwhile, this routine camps until all user contexts have been removed.
 */
void cxlflash_stop_term_user_contexts(struct cxlflash_cfg *cfg)
{
        struct device *dev = &cfg->dev->dev;
        int i, found;

        cxlflash_mark_contexts_error(cfg);

        while (true) {
                found = false;

                for (i = 0; i < MAX_CONTEXT; i++)
                        if (cfg->ctx_tbl[i]) {
                                found = true;
                                break;
                        }

                if (!found && list_empty(&cfg->ctx_err_recovery))
                        return;

                dev_dbg(dev, "%s: Wait for user contexts to quiesce...\n",
                        __func__);
                wake_up_all(&cfg->reset_waitq);
                ssleep(1);
        }
}

/**
 * find_error_context() - locates a context by cookie on the error recovery list
 * @cfg:        Internal structure associated with the host.
 * @rctxid:     Desired context by id.
 * @file:       Desired context by file.
 *
 * Return: Found context on success, NULL on failure
 */
static struct ctx_info *find_error_context(struct cxlflash_cfg *cfg, u64 rctxid,
                                           struct file *file)
{
        struct ctx_info *ctxi;

        list_for_each_entry(ctxi, &cfg->ctx_err_recovery, list)
                if ((ctxi->ctxid == rctxid) || (ctxi->file == file))
                        return ctxi;

        return NULL;
}

/**
 * get_context() - obtains a validated and locked context reference
 * @cfg:        Internal structure associated with the host.
 * @rctxid:     Desired context (raw, un-decoded format).
 * @arg:        LUN information or file associated with request.
 * @ctx_ctrl:   Control information to 'steer' desired lookup.
 *
 * NOTE: despite the name pid, in linux, current->pid actually refers
 * to the lightweight process id (tid) and can change if the process is
 * multi threaded. The tgid remains constant for the process and only changes
 * when the process of fork. For all intents and purposes, think of tgid
 * as a pid in the traditional sense.
 *
 * Return: Validated context on success, NULL on failure
 */
struct ctx_info *get_context(struct cxlflash_cfg *cfg, u64 rctxid,
                             void *arg, enum ctx_ctrl ctx_ctrl)
{
        struct device *dev = &cfg->dev->dev;
        struct ctx_info *ctxi = NULL;
        struct lun_access *lun_access = NULL;
        struct file *file = NULL;
        struct llun_info *lli = arg;
        u64 ctxid = DECODE_CTXID(rctxid);
        int rc;
        pid_t pid = current->tgid, ctxpid = 0;

        if (ctx_ctrl & CTX_CTRL_FILE) {
                lli = NULL;
                file = (struct file *)arg;
        }

        if (ctx_ctrl & CTX_CTRL_CLONE)
                pid = current->parent->tgid;

        if (likely(ctxid < MAX_CONTEXT)) {
                while (true) {
                        mutex_lock(&cfg->ctx_tbl_list_mutex);
                        ctxi = cfg->ctx_tbl[ctxid];
                        if (ctxi)
                                if ((file && (ctxi->file != file)) ||
                                    (!file && (ctxi->ctxid != rctxid)))
                                        ctxi = NULL;

                        if ((ctx_ctrl & CTX_CTRL_ERR) ||
                            (!ctxi && (ctx_ctrl & CTX_CTRL_ERR_FALLBACK)))
                                ctxi = find_error_context(cfg, rctxid, file);
                        if (!ctxi) {
                                mutex_unlock(&cfg->ctx_tbl_list_mutex);
                                goto out;
                        }

                        /*
                         * Need to acquire ownership of the context while still
                         * under the table/list lock to serialize with a remove
                         * thread. Use the 'try' to avoid stalling the
                         * table/list lock for a single context.
                         *
                         * Note that the lock order is:
                         *
                         *      cfg->ctx_tbl_list_mutex -> ctxi->mutex
                         *
                         * Therefore release ctx_tbl_list_mutex before retrying.
                         */
                        rc = mutex_trylock(&ctxi->mutex);
                        mutex_unlock(&cfg->ctx_tbl_list_mutex);
                        if (rc)
                                break; /* got the context's lock! */
                }

                if (ctxi->unavail)
                        goto denied;

                ctxpid = ctxi->pid;
                if (likely(!(ctx_ctrl & CTX_CTRL_NOPID)))
                        if (pid != ctxpid)
                                goto denied;

                if (lli) {
                        list_for_each_entry(lun_access, &ctxi->luns, list)
                                if (lun_access->lli == lli)
                                        goto out;
                        goto denied;
                }
        }

out:
        dev_dbg(dev, "%s: rctxid=%016llX ctxinfo=%p ctxpid=%u pid=%u "
                "ctx_ctrl=%u\n", __func__, rctxid, ctxi, ctxpid, pid,
                ctx_ctrl);

        return ctxi;

denied:
        mutex_unlock(&ctxi->mutex);
        ctxi = NULL;
        goto out;
}

/**
 * put_context() - release a context that was retrieved from get_context()
 * @ctxi:       Context to release.
 *
 * For now, releasing the context equates to unlocking it's mutex.
 */
void put_context(struct ctx_info *ctxi)
{
        mutex_unlock(&ctxi->mutex);
}

/**
 * afu_attach() - attach a context to the AFU
 * @cfg:        Internal structure associated with the host.
 * @ctxi:       Context to attach.
 *
 * Upon setting the context capabilities, they must be confirmed with
 * a read back operation as the context might have been closed since
 * the mailbox was unlocked. When this occurs, registration is failed.
 *
 * Return: 0 on success, -errno on failure
 */
static int afu_attach(struct cxlflash_cfg *cfg, struct ctx_info *ctxi)
{
        struct device *dev = &cfg->dev->dev;
        struct afu *afu = cfg->afu;
        struct sisl_ctrl_map __iomem *ctrl_map = ctxi->ctrl_map;
        int rc = 0;
        u64 val;

        /* Unlock cap and restrict user to read/write cmds in translated mode */
        readq_be(&ctrl_map->mbox_r);
        val = (SISL_CTX_CAP_READ_CMD | SISL_CTX_CAP_WRITE_CMD);
        writeq_be(val, &ctrl_map->ctx_cap);
        val = readq_be(&ctrl_map->ctx_cap);
        if (val != (SISL_CTX_CAP_READ_CMD | SISL_CTX_CAP_WRITE_CMD)) {
                dev_err(dev, "%s: ctx may be closed val=%016llX\n",
                        __func__, val);
                rc = -EAGAIN;
                goto out;
        }

        /* Set up MMIO registers pointing to the RHT */
        writeq_be((u64)ctxi->rht_start, &ctrl_map->rht_start);
        val = SISL_RHT_CNT_ID((u64)MAX_RHT_PER_CONTEXT, (u64)(afu->ctx_hndl));
        writeq_be(val, &ctrl_map->rht_cnt_id);
out:
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

/**
 * read_cap16() - issues a SCSI READ_CAP16 command
 * @sdev:       SCSI device associated with LUN.
 * @lli:        LUN destined for capacity request.
 *
 * The READ_CAP16 can take quite a while to complete. Should an EEH occur while
 * in scsi_execute(), the EEH handler will attempt to recover. As part of the
 * recovery, the handler drains all currently running ioctls, waiting until they
 * have completed before proceeding with a reset. As this routine is used on the
 * ioctl path, this can create a condition where the EEH handler becomes stuck,
 * infinitely waiting for this ioctl thread. To avoid this behavior, temporarily
 * unmark this thread as an ioctl thread by releasing the ioctl read semaphore.
 * This will allow the EEH handler to proceed with a recovery while this thread
 * is still running. Once the scsi_execute() returns, reacquire the ioctl read
 * semaphore and check the adapter state in case it changed while inside of
 * scsi_execute(). The state check will wait if the adapter is still being
 * recovered or return a failure if the recovery failed. In the event that the
 * adapter reset failed, simply return the failure as the ioctl would be unable
 * to continue.
 *
 * Note that the above puts a requirement on this routine to only be called on
 * an ioctl thread.
 *
 * Return: 0 on success, -errno on failure
 */
static int read_cap16(struct scsi_device *sdev, struct llun_info *lli)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct glun_info *gli = lli->parent;
        u8 *cmd_buf = NULL;
        u8 *scsi_cmd = NULL;
        u8 *sense_buf = NULL;
        int rc = 0;
        int result = 0;
        int retry_cnt = 0;
        u32 to = CMD_TIMEOUT * HZ;

retry:
        cmd_buf = kzalloc(CMD_BUFSIZE, GFP_KERNEL);
        scsi_cmd = kzalloc(MAX_COMMAND_SIZE, GFP_KERNEL);
        sense_buf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
        if (unlikely(!cmd_buf || !scsi_cmd || !sense_buf)) {
                rc = -ENOMEM;
                goto out;
        }

        scsi_cmd[0] = SERVICE_ACTION_IN_16;     /* read cap(16) */
        scsi_cmd[1] = SAI_READ_CAPACITY_16;     /* service action */
        put_unaligned_be32(CMD_BUFSIZE, &scsi_cmd[10]);

        dev_dbg(dev, "%s: %ssending cmd(0x%x)\n", __func__,
                retry_cnt ? "re" : "", scsi_cmd[0]);

        /* Drop the ioctl read semahpore across lengthy call */
        up_read(&cfg->ioctl_rwsem);
        result = scsi_execute(sdev, scsi_cmd, DMA_FROM_DEVICE, cmd_buf,
                              CMD_BUFSIZE, sense_buf, to, CMD_RETRIES, 0, NULL);
        down_read(&cfg->ioctl_rwsem);
        rc = check_state(cfg);
        if (rc) {
                dev_err(dev, "%s: Failed state! result=0x08%X\n",
                        __func__, result);
                rc = -ENODEV;
                goto out;
        }

        if (driver_byte(result) == DRIVER_SENSE) {
                result &= ~(0xFF<<24); /* DRIVER_SENSE is not an error */
                if (result & SAM_STAT_CHECK_CONDITION) {
                        struct scsi_sense_hdr sshdr;

                        scsi_normalize_sense(sense_buf, SCSI_SENSE_BUFFERSIZE,
                                            &sshdr);
                        switch (sshdr.sense_key) {
                        case NO_SENSE:
                        case RECOVERED_ERROR:
                                /* fall through */
                        case NOT_READY:
                                result &= ~SAM_STAT_CHECK_CONDITION;
                                break;
                        case UNIT_ATTENTION:
                                switch (sshdr.asc) {
                                case 0x29: /* Power on Reset or Device Reset */
                                        /* fall through */
                                case 0x2A: /* Device capacity changed */
                                case 0x3F: /* Report LUNs changed */
                                        /* Retry the command once more */
                                        if (retry_cnt++ < 1) {
                                                kfree(cmd_buf);
                                                kfree(scsi_cmd);
                                                kfree(sense_buf);
                                                goto retry;
                                        }
                                }
                                break;
                        default:
                                break;
                        }
                }
        }

        if (result) {
                dev_err(dev, "%s: command failed, result=0x%x\n",
                        __func__, result);
                rc = -EIO;
                goto out;
        }

        /*
         * Read cap was successful, grab values from the buffer;
         * note that we don't need to worry about unaligned access
         * as the buffer is allocated on an aligned boundary.
         */
        mutex_lock(&gli->mutex);
        gli->max_lba = be64_to_cpu(*((__be64 *)&cmd_buf[0]));
        gli->blk_len = be32_to_cpu(*((__be32 *)&cmd_buf[8]));
        mutex_unlock(&gli->mutex);

out:
        kfree(cmd_buf);
        kfree(scsi_cmd);
        kfree(sense_buf);

        dev_dbg(dev, "%s: maxlba=%lld blklen=%d rc=%d\n",
                __func__, gli->max_lba, gli->blk_len, rc);
        return rc;
}

/**
 * get_rhte() - obtains validated resource handle table entry reference
 * @ctxi:       Context owning the resource handle.
 * @rhndl:      Resource handle associated with entry.
 * @lli:        LUN associated with request.
 *
 * Return: Validated RHTE on success, NULL on failure
 */
struct sisl_rht_entry *get_rhte(struct ctx_info *ctxi, res_hndl_t rhndl,
                                struct llun_info *lli)
{
        struct sisl_rht_entry *rhte = NULL;

        if (unlikely(!ctxi->rht_start)) {
                pr_debug("%s: Context does not have allocated RHT!\n",
                         __func__);
                goto out;
        }

        if (unlikely(rhndl >= MAX_RHT_PER_CONTEXT)) {
                pr_debug("%s: Bad resource handle! (%d)\n", __func__, rhndl);
                goto out;
        }

        if (unlikely(ctxi->rht_lun[rhndl] != lli)) {
                pr_debug("%s: Bad resource handle LUN! (%d)\n",
                         __func__, rhndl);
                goto out;
        }

        rhte = &ctxi->rht_start[rhndl];
        if (unlikely(rhte->nmask == 0)) {
                pr_debug("%s: Unopened resource handle! (%d)\n",
                         __func__, rhndl);
                rhte = NULL;
                goto out;
        }

out:
        return rhte;
}

/**
 * rhte_checkout() - obtains free/empty resource handle table entry
 * @ctxi:       Context owning the resource handle.
 * @lli:        LUN associated with request.
 *
 * Return: Free RHTE on success, NULL on failure
 */
struct sisl_rht_entry *rhte_checkout(struct ctx_info *ctxi,
                                     struct llun_info *lli)
{
        struct sisl_rht_entry *rhte = NULL;
        int i;

        /* Find a free RHT entry */
        for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
                if (ctxi->rht_start[i].nmask == 0) {
                        rhte = &ctxi->rht_start[i];
                        ctxi->rht_out++;
                        break;
                }

        if (likely(rhte))
                ctxi->rht_lun[i] = lli;

        pr_debug("%s: returning rhte=%p (%d)\n", __func__, rhte, i);
        return rhte;
}

/**
 * rhte_checkin() - releases a resource handle table entry
 * @ctxi:       Context owning the resource handle.
 * @rhte:       RHTE to release.
 */
void rhte_checkin(struct ctx_info *ctxi,
                  struct sisl_rht_entry *rhte)
{
        u32 rsrc_handle = rhte - ctxi->rht_start;

        rhte->nmask = 0;
        rhte->fp = 0;
        ctxi->rht_out--;
        ctxi->rht_lun[rsrc_handle] = NULL;
        ctxi->rht_needs_ws[rsrc_handle] = false;
}

/**
 * rhte_format1() - populates a RHTE for format 1
 * @rhte:       RHTE to populate.
 * @lun_id:     LUN ID of LUN associated with RHTE.
 * @perm:       Desired permissions for RHTE.
 * @port_sel:   Port selection mask
 */
static void rht_format1(struct sisl_rht_entry *rhte, u64 lun_id, u32 perm,
                        u32 port_sel)
{
        /*
         * Populate the Format 1 RHT entry for direct access (physical
         * LUN) using the synchronization sequence defined in the
         * SISLite specification.
         */
        struct sisl_rht_entry_f1 dummy = { 0 };
        struct sisl_rht_entry_f1 *rhte_f1 = (struct sisl_rht_entry_f1 *)rhte;

        memset(rhte_f1, 0, sizeof(*rhte_f1));
        rhte_f1->fp = SISL_RHT_FP(1U, 0);
        dma_wmb(); /* Make setting of format bit visible */

        rhte_f1->lun_id = lun_id;
        dma_wmb(); /* Make setting of LUN id visible */

        /*
         * Use a dummy RHT Format 1 entry to build the second dword
         * of the entry that must be populated in a single write when
         * enabled (valid bit set to TRUE).
         */
        dummy.valid = 0x80;
        dummy.fp = SISL_RHT_FP(1U, perm);
        dummy.port_sel = port_sel;
        rhte_f1->dw = dummy.dw;

        dma_wmb(); /* Make remaining RHT entry fields visible */
}

/**
 * cxlflash_lun_attach() - attaches a user to a LUN and manages the LUN's mode
 * @gli:        LUN to attach.
 * @mode:       Desired mode of the LUN.
 * @locked:     Mutex status on current thread.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_lun_attach(struct glun_info *gli, enum lun_mode mode, bool locked)
{
        int rc = 0;

        if (!locked)
                mutex_lock(&gli->mutex);

        if (gli->mode == MODE_NONE)
                gli->mode = mode;
        else if (gli->mode != mode) {
                pr_debug("%s: LUN operating in mode %d, requested mode %d\n",
                         __func__, gli->mode, mode);
                rc = -EINVAL;
                goto out;
        }

        gli->users++;
        WARN_ON(gli->users <= 0);
out:
        pr_debug("%s: Returning rc=%d gli->mode=%u gli->users=%u\n",
                 __func__, rc, gli->mode, gli->users);
        if (!locked)
                mutex_unlock(&gli->mutex);
        return rc;
}

/**
 * cxlflash_lun_detach() - detaches a user from a LUN and resets the LUN's mode
 * @gli:        LUN to detach.
 *
 * When resetting the mode, terminate block allocation resources as they
 * are no longer required (service is safe to call even when block allocation
 * resources were not present - such as when transitioning from physical mode).
 * These resources will be reallocated when needed (subsequent transition to
 * virtual mode).
 */
void cxlflash_lun_detach(struct glun_info *gli)
{
        mutex_lock(&gli->mutex);
        WARN_ON(gli->mode == MODE_NONE);
        if (--gli->users == 0) {
                gli->mode = MODE_NONE;
                cxlflash_ba_terminate(&gli->blka.ba_lun);
        }
        pr_debug("%s: gli->users=%u\n", __func__, gli->users);
        WARN_ON(gli->users < 0);
        mutex_unlock(&gli->mutex);
}

/**
 * _cxlflash_disk_release() - releases the specified resource entry
 * @sdev:       SCSI device associated with LUN.
 * @ctxi:       Context owning resources.
 * @release:    Release ioctl data structure.
 *
 * For LUNs in virtual mode, the virtual LUN associated with the specified
 * resource handle is resized to 0 prior to releasing the RHTE. Note that the
 * AFU sync should _not_ be performed when the context is sitting on the error
 * recovery list. A context on the error recovery list is not known to the AFU
 * due to reset. When the context is recovered, it will be reattached and made
 * known again to the AFU.
 *
 * Return: 0 on success, -errno on failure
 */
int _cxlflash_disk_release(struct scsi_device *sdev,
                           struct ctx_info *ctxi,
                           struct dk_cxlflash_release *release)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct afu *afu = cfg->afu;
        bool put_ctx = false;

        struct dk_cxlflash_resize size;
        res_hndl_t rhndl = release->rsrc_handle;

        int rc = 0;
        u64 ctxid = DECODE_CTXID(release->context_id),
            rctxid = release->context_id;

        struct sisl_rht_entry *rhte;
        struct sisl_rht_entry_f1 *rhte_f1;

        dev_dbg(dev, "%s: ctxid=%llu rhndl=0x%llx gli->mode=%u gli->users=%u\n",
                __func__, ctxid, release->rsrc_handle, gli->mode, gli->users);

        if (!ctxi) {
                ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
                if (unlikely(!ctxi)) {
                        dev_dbg(dev, "%s: Bad context! (%llu)\n",
                                __func__, ctxid);
                        rc = -EINVAL;
                        goto out;
                }

                put_ctx = true;
        }

        rhte = get_rhte(ctxi, rhndl, lli);
        if (unlikely(!rhte)) {
                dev_dbg(dev, "%s: Bad resource handle! (%d)\n",
                        __func__, rhndl);
                rc = -EINVAL;
                goto out;
        }

        /*
         * Resize to 0 for virtual LUNS by setting the size
         * to 0. This will clear LXT_START and LXT_CNT fields
         * in the RHT entry and properly sync with the AFU.
         *
         * Afterwards we clear the remaining fields.
         */
        switch (gli->mode) {
        case MODE_VIRTUAL:
                marshal_rele_to_resize(release, &size);
                size.req_size = 0;
                rc = _cxlflash_vlun_resize(sdev, ctxi, &size);
                if (rc) {
                        dev_dbg(dev, "%s: resize failed rc %d\n", __func__, rc);
                        goto out;
                }

                break;
        case MODE_PHYSICAL:
                /*
                 * Clear the Format 1 RHT entry for direct access
                 * (physical LUN) using the synchronization sequence
                 * defined in the SISLite specification.
                 */
                rhte_f1 = (struct sisl_rht_entry_f1 *)rhte;

                rhte_f1->valid = 0;
                dma_wmb(); /* Make revocation of RHT entry visible */

                rhte_f1->lun_id = 0;
                dma_wmb(); /* Make clearing of LUN id visible */

                rhte_f1->dw = 0;
                dma_wmb(); /* Make RHT entry bottom-half clearing visible */

                if (!ctxi->err_recovery_active)
                        cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
                break;
        default:
                WARN(1, "Unsupported LUN mode!");
                goto out;
        }

        rhte_checkin(ctxi, rhte);
        cxlflash_lun_detach(gli);

out:
        if (put_ctx)
                put_context(ctxi);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

int cxlflash_disk_release(struct scsi_device *sdev,
                          struct dk_cxlflash_release *release)
{
        return _cxlflash_disk_release(sdev, NULL, release);
}

/**
 * destroy_context() - releases a context
 * @cfg:        Internal structure associated with the host.
 * @ctxi:       Context to release.
 *
 * This routine is safe to be called with a a non-initialized context.
 * Also note that the routine conditionally checks for the existence
 * of the context control map before clearing the RHT registers and
 * context capabilities because it is possible to destroy a context
 * while the context is in the error state (previous mapping was
 * removed [so there is no need to worry about clearing] and context
 * is waiting for a new mapping).
 */
static void destroy_context(struct cxlflash_cfg *cfg,
                            struct ctx_info *ctxi)
{
        struct afu *afu = cfg->afu;

        if (ctxi->initialized) {
                WARN_ON(!list_empty(&ctxi->luns));

                /* Clear RHT registers and drop all capabilities for context */
                if (afu->afu_map && ctxi->ctrl_map) {
                        writeq_be(0, &ctxi->ctrl_map->rht_start);
                        writeq_be(0, &ctxi->ctrl_map->rht_cnt_id);
                        writeq_be(0, &ctxi->ctrl_map->ctx_cap);
                }
        }

        /* Free memory associated with context */
        free_page((ulong)ctxi->rht_start);
        kfree(ctxi->rht_needs_ws);
        kfree(ctxi->rht_lun);
        kfree(ctxi);
}

/**
 * create_context() - allocates and initializes a context
 * @cfg:        Internal structure associated with the host.
 *
 * Return: Allocated context on success, NULL on failure
 */
static struct ctx_info *create_context(struct cxlflash_cfg *cfg)
{
        struct device *dev = &cfg->dev->dev;
        struct ctx_info *ctxi = NULL;
        struct llun_info **lli = NULL;
        u8 *ws = NULL;
        struct sisl_rht_entry *rhte;

        ctxi = kzalloc(sizeof(*ctxi), GFP_KERNEL);
        lli = kzalloc((MAX_RHT_PER_CONTEXT * sizeof(*lli)), GFP_KERNEL);
        ws = kzalloc((MAX_RHT_PER_CONTEXT * sizeof(*ws)), GFP_KERNEL);
        if (unlikely(!ctxi || !lli || !ws)) {
                dev_err(dev, "%s: Unable to allocate context!\n", __func__);
                goto err;
        }

        rhte = (struct sisl_rht_entry *)get_zeroed_page(GFP_KERNEL);
        if (unlikely(!rhte)) {
                dev_err(dev, "%s: Unable to allocate RHT!\n", __func__);
                goto err;
        }

        ctxi->rht_lun = lli;
        ctxi->rht_needs_ws = ws;
        ctxi->rht_start = rhte;
out:
        return ctxi;

err:
        kfree(ws);
        kfree(lli);
        kfree(ctxi);
        ctxi = NULL;
        goto out;
}

/**
 * init_context() - initializes a previously allocated context
 * @ctxi:       Previously allocated context
 * @cfg:        Internal structure associated with the host.
 * @ctx:        Previously obtained CXL context reference.
 * @ctxid:      Previously obtained process element associated with CXL context.
 * @file:       Previously obtained file associated with CXL context.
 * @perms:      User-specified permissions.
 */
static void init_context(struct ctx_info *ctxi, struct cxlflash_cfg *cfg,
                         struct cxl_context *ctx, int ctxid, struct file *file,
                         u32 perms)
{
        struct afu *afu = cfg->afu;

        ctxi->rht_perms = perms;
        ctxi->ctrl_map = &afu->afu_map->ctrls[ctxid].ctrl;
        ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
        ctxi->pid = current->tgid; /* tgid = pid */
        ctxi->ctx = ctx;
        ctxi->cfg = cfg;
        ctxi->file = file;
        ctxi->initialized = true;
        mutex_init(&ctxi->mutex);
        kref_init(&ctxi->kref);
        INIT_LIST_HEAD(&ctxi->luns);
        INIT_LIST_HEAD(&ctxi->list); /* initialize for list_empty() */
}

/**
 * remove_context() - context kref release handler
 * @kref:       Kernel reference associated with context to be removed.
 *
 * When a context no longer has any references it can safely be removed
 * from global access and destroyed. Note that it is assumed the thread
 * relinquishing access to the context holds its mutex.
 */
static void remove_context(struct kref *kref)
{
        struct ctx_info *ctxi = container_of(kref, struct ctx_info, kref);
        struct cxlflash_cfg *cfg = ctxi->cfg;
        u64 ctxid = DECODE_CTXID(ctxi->ctxid);

        /* Remove context from table/error list */
        WARN_ON(!mutex_is_locked(&ctxi->mutex));
        ctxi->unavail = true;
        mutex_unlock(&ctxi->mutex);
        mutex_lock(&cfg->ctx_tbl_list_mutex);
        mutex_lock(&ctxi->mutex);

        if (!list_empty(&ctxi->list))
                list_del(&ctxi->list);
        cfg->ctx_tbl[ctxid] = NULL;
        mutex_unlock(&cfg->ctx_tbl_list_mutex);
        mutex_unlock(&ctxi->mutex);

        /* Context now completely uncoupled/unreachable */
        destroy_context(cfg, ctxi);
}

/**
 * _cxlflash_disk_detach() - detaches a LUN from a context
 * @sdev:       SCSI device associated with LUN.
 * @ctxi:       Context owning resources.
 * @detach:     Detach ioctl data structure.
 *
 * As part of the detach, all per-context resources associated with the LUN
 * are cleaned up. When detaching the last LUN for a context, the context
 * itself is cleaned up and released.
 *
 * Return: 0 on success, -errno on failure
 */
static int _cxlflash_disk_detach(struct scsi_device *sdev,
                                 struct ctx_info *ctxi,
                                 struct dk_cxlflash_detach *detach)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct lun_access *lun_access, *t;
        struct dk_cxlflash_release rel;
        bool put_ctx = false;

        int i;
        int rc = 0;
        u64 ctxid = DECODE_CTXID(detach->context_id),
            rctxid = detach->context_id;

        dev_dbg(dev, "%s: ctxid=%llu\n", __func__, ctxid);

        if (!ctxi) {
                ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
                if (unlikely(!ctxi)) {
                        dev_dbg(dev, "%s: Bad context! (%llu)\n",
                                __func__, ctxid);
                        rc = -EINVAL;
                        goto out;
                }

                put_ctx = true;
        }

        /* Cleanup outstanding resources tied to this LUN */
        if (ctxi->rht_out) {
                marshal_det_to_rele(detach, &rel);
                for (i = 0; i < MAX_RHT_PER_CONTEXT; i++) {
                        if (ctxi->rht_lun[i] == lli) {
                                rel.rsrc_handle = i;
                                _cxlflash_disk_release(sdev, ctxi, &rel);
                        }

                        /* No need to loop further if we're done */
                        if (ctxi->rht_out == 0)
                                break;
                }
        }

        /* Take our LUN out of context, free the node */
        list_for_each_entry_safe(lun_access, t, &ctxi->luns, list)
                if (lun_access->lli == lli) {
                        list_del(&lun_access->list);
                        kfree(lun_access);
                        lun_access = NULL;
                        break;
                }

        /*
         * Release the context reference and the sdev reference that
         * bound this LUN to the context.
         */
        if (kref_put(&ctxi->kref, remove_context))
                put_ctx = false;
        scsi_device_put(sdev);
out:
        if (put_ctx)
                put_context(ctxi);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;
}

static int cxlflash_disk_detach(struct scsi_device *sdev,
                                struct dk_cxlflash_detach *detach)
{
        return _cxlflash_disk_detach(sdev, NULL, detach);
}

/**
 * cxlflash_cxl_release() - release handler for adapter file descriptor
 * @inode:      File-system inode associated with fd.
 * @file:       File installed with adapter file descriptor.
 *
 * This routine is the release handler for the fops registered with
 * the CXL services on an initial attach for a context. It is called
 * when a close (explicity by the user or as part of a process tear
 * down) is performed on the adapter file descriptor returned to the
 * user. The user should be aware that explicitly performing a close
 * considered catastrophic and subsequent usage of the superpipe API
 * with previously saved off tokens will fail.
 *
 * This routine derives the context reference and calls detach for
 * each LUN associated with the context.The final detach operation
 * causes the context itself to be freed. With exception to when the
 * CXL process element (context id) lookup fails (a case that should
 * theoretically never occur), every call into this routine results
 * in a complete freeing of a context.
 *
 * Return: 0 on success
 */
static int cxlflash_cxl_release(struct inode *inode, struct file *file)
{
        struct cxl_context *ctx = cxl_fops_get_context(file);
        struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
                                                cxl_fops);
        struct device *dev = &cfg->dev->dev;
        struct ctx_info *ctxi = NULL;
        struct dk_cxlflash_detach detach = { { 0 }, 0 };
        struct lun_access *lun_access, *t;
        enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
        int ctxid;

        ctxid = cxl_process_element(ctx);
        if (unlikely(ctxid < 0)) {
                dev_err(dev, "%s: Context %p was closed! (%d)\n",
                        __func__, ctx, ctxid);
                goto out;
        }

        ctxi = get_context(cfg, ctxid, file, ctrl);
        if (unlikely(!ctxi)) {
                ctxi = get_context(cfg, ctxid, file, ctrl | CTX_CTRL_CLONE);
                if (!ctxi) {
                        dev_dbg(dev, "%s: Context %d already free!\n",
                                __func__, ctxid);
                        goto out_release;
                }

                dev_dbg(dev, "%s: Another process owns context %d!\n",
                        __func__, ctxid);
                put_context(ctxi);
                goto out;
        }

        dev_dbg(dev, "%s: close for context %d\n", __func__, ctxid);

        detach.context_id = ctxi->ctxid;
        list_for_each_entry_safe(lun_access, t, &ctxi->luns, list)
                _cxlflash_disk_detach(lun_access->sdev, ctxi, &detach);
out_release:
        cxl_fd_release(inode, file);
out:
        dev_dbg(dev, "%s: returning\n", __func__);
        return 0;
}

/**
 * unmap_context() - clears a previously established mapping
 * @ctxi:       Context owning the mapping.
 *
 * This routine is used to switch between the error notification page
 * (dummy page of all 1's) and the real mapping (established by the CXL
 * fault handler).
 */
static void unmap_context(struct ctx_info *ctxi)
{
        unmap_mapping_range(ctxi->file->f_mapping, 0, 0, 1);
}

/**
 * get_err_page() - obtains and allocates the error notification page
 *
 * Return: error notification page on success, NULL on failure
 */
static struct page *get_err_page(void)
{
        struct page *err_page = global.err_page;

        if (unlikely(!err_page)) {
                err_page = alloc_page(GFP_KERNEL);
                if (unlikely(!err_page)) {
                        pr_err("%s: Unable to allocate err_page!\n", __func__);
                        goto out;
                }

                memset(page_address(err_page), -1, PAGE_SIZE);

                /* Serialize update w/ other threads to avoid a leak */
                mutex_lock(&global.mutex);
                if (likely(!global.err_page))
                        global.err_page = err_page;
                else {
                        __free_page(err_page);
                        err_page = global.err_page;
                }
                mutex_unlock(&global.mutex);
        }

out:
        pr_debug("%s: returning err_page=%p\n", __func__, err_page);
        return err_page;
}

/**
 * cxlflash_mmap_fault() - mmap fault handler for adapter file descriptor
 * @vma:        VM area associated with mapping.
 * @vmf:        VM fault associated with current fault.
 *
 * To support error notification via MMIO, faults are 'caught' by this routine
 * that was inserted before passing back the adapter file descriptor on attach.
 * When a fault occurs, this routine evaluates if error recovery is active and
 * if so, installs the error page to 'notify' the user about the error state.
 * During normal operation, the fault is simply handled by the original fault
 * handler that was installed by CXL services as part of initializing the
 * adapter file descriptor. The VMA's page protection bits are toggled to
 * indicate cached/not-cached depending on the memory backing the fault.
 *
 * Return: 0 on success, VM_FAULT_SIGBUS on failure
 */
static int cxlflash_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct file *file = vma->vm_file;
        struct cxl_context *ctx = cxl_fops_get_context(file);
        struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
                                                cxl_fops);
        struct device *dev = &cfg->dev->dev;
        struct ctx_info *ctxi = NULL;
        struct page *err_page = NULL;
        enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
        int rc = 0;
        int ctxid;

        ctxid = cxl_process_element(ctx);
        if (unlikely(ctxid < 0)) {
                dev_err(dev, "%s: Context %p was closed! (%d)\n",
                        __func__, ctx, ctxid);
                goto err;
        }

        ctxi = get_context(cfg, ctxid, file, ctrl);
        if (unlikely(!ctxi)) {
                dev_dbg(dev, "%s: Bad context! (%d)\n", __func__, ctxid);
                goto err;
        }

        dev_dbg(dev, "%s: fault for context %d\n", __func__, ctxid);

        if (likely(!ctxi->err_recovery_active)) {
                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
                rc = ctxi->cxl_mmap_vmops->fault(vma, vmf);
        } else {
                dev_dbg(dev, "%s: err recovery active, use err_page!\n",
                        __func__);

                err_page = get_err_page();
                if (unlikely(!err_page)) {
                        dev_err(dev, "%s: Could not obtain error page!\n",
                                __func__);
                        rc = VM_FAULT_RETRY;
                        goto out;
                }

                get_page(err_page);
                vmf->page = err_page;
                vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
        }

out:
        if (likely(ctxi))
                put_context(ctxi);
        dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
        return rc;

err:
        rc = VM_FAULT_SIGBUS;
        goto out;
}

/*
 * Local MMAP vmops to 'catch' faults
 */
static const struct vm_operations_struct cxlflash_mmap_vmops = {
        .fault = cxlflash_mmap_fault,
};

/**
 * cxlflash_cxl_mmap() - mmap handler for adapter file descriptor
 * @file:       File installed with adapter file descriptor.
 * @vma:        VM area associated with mapping.
 *
 * Installs local mmap vmops to 'catch' faults for error notification support.
 *
 * Return: 0 on success, -errno on failure
 */
static int cxlflash_cxl_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct cxl_context *ctx = cxl_fops_get_context(file);
        struct cxlflash_cfg *cfg = container_of(file->f_op, struct cxlflash_cfg,
                                                cxl_fops);
        struct device *dev = &cfg->dev->dev;
        struct ctx_info *ctxi = NULL;
        enum ctx_ctrl ctrl = CTX_CTRL_ERR_FALLBACK | CTX_CTRL_FILE;
        int ctxid;
        int rc = 0;

        ctxid = cxl_process_element(ctx);
        if (unlikely(ctxid < 0)) {
                dev_err(dev, "%s: Context %p was closed! (%d)\n",
                        __func__, ctx, ctxid);
                rc = -EIO;
                goto out;
        }

        ctxi = get_context(cfg, ctxid, file, ctrl);
        if (unlikely(!ctxi)) {
                dev_dbg(dev, "%s: Bad context! (%d)\n", __func__, ctxid);
                rc = -EIO;
                goto out;
        }

        dev_dbg(dev, "%s: mmap for context %d\n", __func__, ctxid);

        rc = cxl_fd_mmap(file, vma);
        if (likely(!rc)) {
                /* Insert ourself in the mmap fault handler path */
                ctxi->cxl_mmap_vmops = vma->vm_ops;
                vma->vm_ops = &cxlflash_mmap_vmops;
        }

out:
        if (likely(ctxi))
                put_context(ctxi);
        return rc;
}

const struct file_operations cxlflash_cxl_fops = {
        .owner = THIS_MODULE,
        .mmap = cxlflash_cxl_mmap,
        .release = cxlflash_cxl_release,
};

/**
 * cxlflash_mark_contexts_error() - move contexts to error state and list
 * @cfg:        Internal structure associated with the host.
 *
 * A context is only moved over to the error list when there are no outstanding
 * references to it. This ensures that a running operation has completed.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_mark_contexts_error(struct cxlflash_cfg *cfg)
{
        int i, rc = 0;
        struct ctx_info *ctxi = NULL;

        mutex_lock(&cfg->ctx_tbl_list_mutex);

        for (i = 0; i < MAX_CONTEXT; i++) {
                ctxi = cfg->ctx_tbl[i];
                if (ctxi) {
                        mutex_lock(&ctxi->mutex);
                        cfg->ctx_tbl[i] = NULL;
                        list_add(&ctxi->list, &cfg->ctx_err_recovery);
                        ctxi->err_recovery_active = true;
                        ctxi->ctrl_map = NULL;
                        unmap_context(ctxi);
                        mutex_unlock(&ctxi->mutex);
                }
        }

        mutex_unlock(&cfg->ctx_tbl_list_mutex);
        return rc;
}

/*
 * Dummy NULL fops
 */
static const struct file_operations null_fops = {
        .owner = THIS_MODULE,
};

/**
 * check_state() - checks and responds to the current adapter state
 * @cfg:        Internal structure associated with the host.
 *
 * This routine can block and should only be used on process context.
 * It assumes that the caller is an ioctl thread and holding the ioctl
 * read semaphore. This is temporarily let up across the wait to allow
 * for draining actively running ioctls. Also note that when waking up
 * from waiting in reset, the state is unknown and must be checked again
 * before proceeding.
 *
 * Return: 0 on success, -errno on failure
 */
int check_state(struct cxlflash_cfg *cfg)
{
        struct device *dev = &cfg->dev->dev;
        int rc = 0;

retry:
        switch (cfg->state) {
        case STATE_RESET:
                dev_dbg(dev, "%s: Reset state, going to wait...\n", __func__);
                up_read(&cfg->ioctl_rwsem);
                rc = wait_event_interruptible(cfg->reset_waitq,
                                              cfg->state != STATE_RESET);
                down_read(&cfg->ioctl_rwsem);
                if (unlikely(rc))
                        break;
                goto retry;
        case STATE_FAILTERM:
                dev_dbg(dev, "%s: Failed/Terminating!\n", __func__);
                rc = -ENODEV;
                break;
        default:
                break;
        }

        return rc;
}

/**
 * cxlflash_disk_attach() - attach a LUN to a context
 * @sdev:       SCSI device associated with LUN.
 * @attach:     Attach ioctl data structure.
 *
 * Creates a context and attaches LUN to it. A LUN can only be attached
 * one time to a context (subsequent attaches for the same context/LUN pair
 * are not supported). Additional LUNs can be attached to a context by
 * specifying the 'reuse' flag defined in the cxlflash_ioctl.h header.
 *
 * Return: 0 on success, -errno on failure
 */
static int cxlflash_disk_attach(struct scsi_device *sdev,
                                struct dk_cxlflash_attach *attach)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct afu *afu = cfg->afu;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct cxl_ioctl_start_work *work;
        struct ctx_info *ctxi = NULL;
        struct lun_access *lun_access = NULL;
        int rc = 0;
        u32 perms;
        int ctxid = -1;
        u64 rctxid = 0UL;
        struct file *file = NULL;

        struct cxl_context *ctx = NULL;

        int fd = -1;

        if (attach->num_interrupts > 4) {
                dev_dbg(dev, "%s: Cannot support this many interrupts %llu\n",
                        __func__, attach->num_interrupts);
                rc = -EINVAL;
                goto out;
        }

        if (gli->max_lba == 0) {
                dev_dbg(dev, "%s: No capacity info for this LUN (%016llX)\n",
                        __func__, lli->lun_id[sdev->channel]);
                rc = read_cap16(sdev, lli);
                if (rc) {
                        dev_err(dev, "%s: Invalid device! (%d)\n",
                                __func__, rc);
                        rc = -ENODEV;
                        goto out;
                }
                dev_dbg(dev, "%s: LBA = %016llX\n", __func__, gli->max_lba);
                dev_dbg(dev, "%s: BLK_LEN = %08X\n", __func__, gli->blk_len);
        }

        if (attach->hdr.flags & DK_CXLFLASH_ATTACH_REUSE_CONTEXT) {
                rctxid = attach->context_id;
                ctxi = get_context(cfg, rctxid, NULL, 0);
                if (!ctxi) {
                        dev_dbg(dev, "%s: Bad context! (%016llX)\n",
                                __func__, rctxid);
                        rc = -EINVAL;
                        goto out;
                }

                list_for_each_entry(lun_access, &ctxi->luns, list)
                        if (lun_access->lli == lli) {
                                dev_dbg(dev, "%s: Already attached!\n",
                                        __func__);
                                rc = -EINVAL;
                                goto out;
                        }
        }

        rc = scsi_device_get(sdev);
        if (unlikely(rc)) {
                dev_err(dev, "%s: Unable to get sdev reference!\n", __func__);
                goto out;
        }

        lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
        if (unlikely(!lun_access)) {
                dev_err(dev, "%s: Unable to allocate lun_access!\n", __func__);
                rc = -ENOMEM;
                goto err;
        }

        lun_access->lli = lli;
        lun_access->sdev = sdev;

        /* Non-NULL context indicates reuse (another context reference) */
        if (ctxi) {
                dev_dbg(dev, "%s: Reusing context for LUN! (%016llX)\n",
                        __func__, rctxid);
                kref_get(&ctxi->kref);
                list_add(&lun_access->list, &ctxi->luns);
                goto out_attach;
        }

        ctxi = create_context(cfg);
        if (unlikely(!ctxi)) {
                dev_err(dev, "%s: Failed to create context! (%d)\n",
                        __func__, ctxid);
                goto err;
        }

        ctx = cxl_dev_context_init(cfg->dev);
        if (IS_ERR_OR_NULL(ctx)) {
                dev_err(dev, "%s: Could not initialize context %p\n",
                        __func__, ctx);
                rc = -ENODEV;
                goto err;
        }

        work = &ctxi->work;
        work->num_interrupts = attach->num_interrupts;
        work->flags = CXL_START_WORK_NUM_IRQS;

        rc = cxl_start_work(ctx, work);
        if (unlikely(rc)) {
                dev_dbg(dev, "%s: Could not start context rc=%d\n",
                        __func__, rc);
                goto err;
        }

        ctxid = cxl_process_element(ctx);
        if (unlikely((ctxid >= MAX_CONTEXT) || (ctxid < 0))) {
                dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
                rc = -EPERM;
                goto err;
        }

        file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
        if (unlikely(fd < 0)) {
                rc = -ENODEV;
                dev_err(dev, "%s: Could not get file descriptor\n", __func__);
                goto err;
        }

        /* Translate read/write O_* flags from fcntl.h to AFU permission bits */
        perms = SISL_RHT_PERM(attach->hdr.flags + 1);

        /* Context mutex is locked upon return */
        init_context(ctxi, cfg, ctx, ctxid, file, perms);

        rc = afu_attach(cfg, ctxi);
        if (unlikely(rc)) {
                dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
                goto err;
        }

        /*
         * No error paths after this point. Once the fd is installed it's
         * visible to user space and can't be undone safely on this thread.
         * There is no need to worry about a deadlock here because no one
         * knows about us yet; we can be the only one holding our mutex.
         */
        list_add(&lun_access->list, &ctxi->luns);
        mutex_lock(&cfg->ctx_tbl_list_mutex);
        mutex_lock(&ctxi->mutex);
        cfg->ctx_tbl[ctxid] = ctxi;
        mutex_unlock(&cfg->ctx_tbl_list_mutex);
        fd_install(fd, file);

out_attach:
        if (fd != -1)
                attach->hdr.return_flags = DK_CXLFLASH_APP_CLOSE_ADAP_FD;
        else
                attach->hdr.return_flags = 0;

        attach->context_id = ctxi->ctxid;
        attach->block_size = gli->blk_len;
        attach->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
        attach->last_lba = gli->max_lba;
        attach->max_xfer = sdev->host->max_sectors * MAX_SECTOR_UNIT;
        attach->max_xfer /= gli->blk_len;

out:
        attach->adap_fd = fd;

        if (ctxi)
                put_context(ctxi);

        dev_dbg(dev, "%s: returning ctxid=%d fd=%d bs=%lld rc=%d llba=%lld\n",
                __func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
        return rc;

err:
        /* Cleanup CXL context; okay to 'stop' even if it was not started */
        if (!IS_ERR_OR_NULL(ctx)) {
                cxl_stop_context(ctx);
                cxl_release_context(ctx);
                ctx = NULL;
        }

        /*
         * Here, we're overriding the fops with a dummy all-NULL fops because
         * fput() calls the release fop, which will cause us to mistakenly
         * call into the CXL code. Rather than try to add yet more complexity
         * to that routine (cxlflash_cxl_release) we should try to fix the
         * issue here.
         */
        if (fd > 0) {
                file->f_op = &null_fops;
                fput(file);
                put_unused_fd(fd);
                fd = -1;
                file = NULL;
        }

        /* Cleanup our context */
        if (ctxi) {
                destroy_context(cfg, ctxi);
                ctxi = NULL;
        }

        kfree(lun_access);
        scsi_device_put(sdev);
        goto out;
}

/**
 * recover_context() - recovers a context in error
 * @cfg:        Internal structure associated with the host.
 * @ctxi:       Context to release.
 * @adap_fd:    Adapter file descriptor associated with new/recovered context.
 *
 * Restablishes the state for a context-in-error.
 *
 * Return: 0 on success, -errno on failure
 */
static int recover_context(struct cxlflash_cfg *cfg,
                           struct ctx_info *ctxi,
                           int *adap_fd)
{
        struct device *dev = &cfg->dev->dev;
        int rc = 0;
        int fd = -1;
        int ctxid = -1;
        struct file *file;
        struct cxl_context *ctx;
        struct afu *afu = cfg->afu;

        ctx = cxl_dev_context_init(cfg->dev);
        if (IS_ERR_OR_NULL(ctx)) {
                dev_err(dev, "%s: Could not initialize context %p\n",
                        __func__, ctx);
                rc = -ENODEV;
                goto out;
        }

        rc = cxl_start_work(ctx, &ctxi->work);
        if (unlikely(rc)) {
                dev_dbg(dev, "%s: Could not start context rc=%d\n",
                        __func__, rc);
                goto err1;
        }

        ctxid = cxl_process_element(ctx);
        if (unlikely((ctxid >= MAX_CONTEXT) || (ctxid < 0))) {
                dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
                rc = -EPERM;
                goto err2;
        }

        file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
        if (unlikely(fd < 0)) {
                rc = -ENODEV;
                dev_err(dev, "%s: Could not get file descriptor\n", __func__);
                goto err2;
        }

        /* Update with new MMIO area based on updated context id */
        ctxi->ctrl_map = &afu->afu_map->ctrls[ctxid].ctrl;

        rc = afu_attach(cfg, ctxi);
        if (rc) {
                dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
                goto err3;
        }

        /*
         * No error paths after this point. Once the fd is installed it's
         * visible to user space and can't be undone safely on this thread.
         */
        ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
        ctxi->ctx = ctx;
        ctxi->file = file;

        /*
         * Put context back in table (note the reinit of the context list);
         * we must first drop the context's mutex and then acquire it in
         * order with the table/list mutex to avoid a deadlock - safe to do
         * here because no one can find us at this moment in time.
         */
        mutex_unlock(&ctxi->mutex);
        mutex_lock(&cfg->ctx_tbl_list_mutex);
        mutex_lock(&ctxi->mutex);
        list_del_init(&ctxi->list);
        cfg->ctx_tbl[ctxid] = ctxi;
        mutex_unlock(&cfg->ctx_tbl_list_mutex);
        fd_install(fd, file);
        *adap_fd = fd;
out:
        dev_dbg(dev, "%s: returning ctxid=%d fd=%d rc=%d\n",
                __func__, ctxid, fd, rc);
        return rc;

err3:
        fput(file);
        put_unused_fd(fd);
err2:
        cxl_stop_context(ctx);
err1:
        cxl_release_context(ctx);
        goto out;
}

/**
 * cxlflash_afu_recover() - initiates AFU recovery
 * @sdev:       SCSI device associated with LUN.
 * @recover:    Recover ioctl data structure.
 *
 * Only a single recovery is allowed at a time to avoid exhausting CXL
 * resources (leading to recovery failure) in the event that we're up
 * against the maximum number of contexts limit. For similar reasons,
 * a context recovery is retried if there are multiple recoveries taking
 * place at the same time and the failure was due to CXL services being
 * unable to keep up.
 *
 * As this routine is called on ioctl context, it holds the ioctl r/w
 * semaphore that is used to drain ioctls in recovery scenarios. The
 * implementation to achieve the pacing described above (a local mutex)
 * requires that the ioctl r/w semaphore be dropped and reacquired to
 * avoid a 3-way deadlock when multiple process recoveries operate in
 * parallel.
 *
 * Because a user can detect an error condition before the kernel, it is
 * quite possible for this routine to act as the kernel's EEH detection
 * source (MMIO read of mbox_r). Because of this, there is a window of
 * time where an EEH might have been detected but not yet 'serviced'
 * (callback invoked, causing the device to enter reset state). To avoid
 * looping in this routine during that window, a 1 second sleep is in place
 * between the time the MMIO failure is detected and the time a wait on the
 * reset wait queue is attempted via check_state().
 *
 * Return: 0 on success, -errno on failure
 */
static int cxlflash_afu_recover(struct scsi_device *sdev,
                                struct dk_cxlflash_recover_afu *recover)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct afu *afu = cfg->afu;
        struct ctx_info *ctxi = NULL;
        struct mutex *mutex = &cfg->ctx_recovery_mutex;
        u64 ctxid = DECODE_CTXID(recover->context_id),
            rctxid = recover->context_id;
        long reg;
        int lretry = 20; /* up to 2 seconds */
        int new_adap_fd = -1;
        int rc = 0;

        atomic_inc(&cfg->recovery_threads);
        up_read(&cfg->ioctl_rwsem);
        rc = mutex_lock_interruptible(mutex);
        down_read(&cfg->ioctl_rwsem);
        if (rc)
                goto out;
        rc = check_state(cfg);
        if (rc) {
                dev_err(dev, "%s: Failed state! rc=%d\n", __func__, rc);
                rc = -ENODEV;
                goto out;
        }

        dev_dbg(dev, "%s: reason 0x%016llX rctxid=%016llX\n",
                __func__, recover->reason, rctxid);

retry:
        /* Ensure that this process is attached to the context */
        ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
        if (unlikely(!ctxi)) {
                dev_dbg(dev, "%s: Bad context! (%llu)\n", __func__, ctxid);
                rc = -EINVAL;
                goto out;
        }

        if (ctxi->err_recovery_active) {
retry_recover:
                rc = recover_context(cfg, ctxi, &new_adap_fd);
                if (unlikely(rc)) {
                        dev_err(dev, "%s: Recovery failed for context %llu (rc=%d)\n",
                                __func__, ctxid, rc);
                        if ((rc == -ENODEV) &&
                            ((atomic_read(&cfg->recovery_threads) > 1) ||
                             (lretry--))) {
                                dev_dbg(dev, "%s: Going to try again!\n",
                                        __func__);
                                mutex_unlock(mutex);
                                msleep(100);
                                rc = mutex_lock_interruptible(mutex);
                                if (rc)
                                        goto out;
                                goto retry_recover;
                        }

                        goto out;
                }

                ctxi->err_recovery_active = false;
                recover->context_id = ctxi->ctxid;
                recover->adap_fd = new_adap_fd;
                recover->mmio_size = sizeof(afu->afu_map->hosts[0].harea);
                recover->hdr.return_flags = DK_CXLFLASH_APP_CLOSE_ADAP_FD |
                        DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET;
                goto out;
        }

        /* Test if in error state */
        reg = readq_be(&afu->ctrl_map->mbox_r);
        if (reg == -1) {
                dev_dbg(dev, "%s: MMIO fail, wait for recovery.\n", __func__);

                /*
                 * Before checking the state, put back the context obtained with
                 * get_context() as it is no longer needed and sleep for a short
                 * period of time (see prolog notes).
                 */
                put_context(ctxi);
                ctxi = NULL;
                ssleep(1);
                rc = check_state(cfg);
                if (unlikely(rc))
                        goto out;
                goto retry;
        }

        dev_dbg(dev, "%s: MMIO working, no recovery required!\n", __func__);
out:
        if (likely(ctxi))
                put_context(ctxi);
        mutex_unlock(mutex);
        atomic_dec_if_positive(&cfg->recovery_threads);
        return rc;
}

/**
 * process_sense() - evaluates and processes sense data
 * @sdev:       SCSI device associated with LUN.
 * @verify:     Verify ioctl data structure.
 *
 * Return: 0 on success, -errno on failure
 */
static int process_sense(struct scsi_device *sdev,
                         struct dk_cxlflash_verify *verify)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        u64 prev_lba = gli->max_lba;
        struct scsi_sense_hdr sshdr = { 0 };
        int rc = 0;

        rc = scsi_normalize_sense((const u8 *)&verify->sense_data,
                                  DK_CXLFLASH_VERIFY_SENSE_LEN, &sshdr);
        if (!rc) {
                dev_err(dev, "%s: Failed to normalize sense data!\n", __func__);
                rc = -EINVAL;
                goto out;
        }

        switch (sshdr.sense_key) {
        case NO_SENSE:
        case RECOVERED_ERROR:
                /* fall through */
        case NOT_READY:
                break;
        case UNIT_ATTENTION:
                switch (sshdr.asc) {
                case 0x29: /* Power on Reset or Device Reset */
                        /* fall through */
                case 0x2A: /* Device settings/capacity changed */
                        rc = read_cap16(sdev, lli);
                        if (rc) {
                                rc = -ENODEV;
                                break;
                        }
                        if (prev_lba != gli->max_lba)
                                dev_dbg(dev, "%s: Capacity changed old=%lld "
                                        "new=%lld\n", __func__, prev_lba,
                                        gli->max_lba);
                        break;
                case 0x3F: /* Report LUNs changed, Rescan. */
                        scsi_scan_host(cfg->host);
                        break;
                default:
                        rc = -EIO;
                        break;
                }
                break;
        default:
                rc = -EIO;
                break;
        }
out:
        dev_dbg(dev, "%s: sense_key %x asc %x ascq %x rc %d\n", __func__,
                sshdr.sense_key, sshdr.asc, sshdr.ascq, rc);
        return rc;
}

/**
 * cxlflash_disk_verify() - verifies a LUN is the same and handle size changes
 * @sdev:       SCSI device associated with LUN.
 * @verify:     Verify ioctl data structure.
 *
 * Return: 0 on success, -errno on failure
 */
static int cxlflash_disk_verify(struct scsi_device *sdev,
                                struct dk_cxlflash_verify *verify)
{
        int rc = 0;
        struct ctx_info *ctxi = NULL;
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;
        struct sisl_rht_entry *rhte = NULL;
        res_hndl_t rhndl = verify->rsrc_handle;
        u64 ctxid = DECODE_CTXID(verify->context_id),
            rctxid = verify->context_id;
        u64 last_lba = 0;

        dev_dbg(dev, "%s: ctxid=%llu rhndl=%016llX, hint=%016llX, "
                "flags=%016llX\n", __func__, ctxid, verify->rsrc_handle,
                verify->hint, verify->hdr.flags);

        ctxi = get_context(cfg, rctxid, lli, 0);
        if (unlikely(!ctxi)) {
                dev_dbg(dev, "%s: Bad context! (%llu)\n", __func__, ctxid);
                rc = -EINVAL;
                goto out;
        }

        rhte = get_rhte(ctxi, rhndl, lli);
        if (unlikely(!rhte)) {
                dev_dbg(dev, "%s: Bad resource handle! (%d)\n",
                        __func__, rhndl);
                rc = -EINVAL;
                goto out;
        }

        /*
         * Look at the hint/sense to see if it requires us to redrive
         * inquiry (i.e. the Unit attention is due to the WWN changing).
         */
        if (verify->hint & DK_CXLFLASH_VERIFY_HINT_SENSE) {
                /* Can't hold mutex across process_sense/read_cap16,
                 * since we could have an intervening EEH event.
                 */
                ctxi->unavail = true;
                mutex_unlock(&ctxi->mutex);
                rc = process_sense(sdev, verify);
                if (unlikely(rc)) {
                        dev_err(dev, "%s: Failed to validate sense data (%d)\n",
                                __func__, rc);
                        mutex_lock(&ctxi->mutex);
                        ctxi->unavail = false;
                        goto out;
                }
                mutex_lock(&ctxi->mutex);
                ctxi->unavail = false;
        }

        switch (gli->mode) {
        case MODE_PHYSICAL:
                last_lba = gli->max_lba;
                break;
        case MODE_VIRTUAL:
                /* Cast lxt_cnt to u64 for multiply to be treated as 64bit op */
                last_lba = ((u64)rhte->lxt_cnt * MC_CHUNK_SIZE * gli->blk_len);
                last_lba /= CXLFLASH_BLOCK_SIZE;
                last_lba--;
                break;
        default:
                WARN(1, "Unsupported LUN mode!");
        }

        verify->last_lba = last_lba;

out:
        if (likely(ctxi))
                put_context(ctxi);
        dev_dbg(dev, "%s: returning rc=%d llba=%llX\n",
                __func__, rc, verify->last_lba);
        return rc;
}

/**
 * decode_ioctl() - translates an encoded ioctl to an easily identifiable string
 * @cmd:        The ioctl command to decode.
 *
 * Return: A string identifying the decoded ioctl.
 */
static char *decode_ioctl(int cmd)
{
        switch (cmd) {
        case DK_CXLFLASH_ATTACH:
                return __stringify_1(DK_CXLFLASH_ATTACH);
        case DK_CXLFLASH_USER_DIRECT:
                return __stringify_1(DK_CXLFLASH_USER_DIRECT);
        case DK_CXLFLASH_USER_VIRTUAL:
                return __stringify_1(DK_CXLFLASH_USER_VIRTUAL);
        case DK_CXLFLASH_VLUN_RESIZE:
                return __stringify_1(DK_CXLFLASH_VLUN_RESIZE);
        case DK_CXLFLASH_RELEASE:
                return __stringify_1(DK_CXLFLASH_RELEASE);
        case DK_CXLFLASH_DETACH:
                return __stringify_1(DK_CXLFLASH_DETACH);
        case DK_CXLFLASH_VERIFY:
                return __stringify_1(DK_CXLFLASH_VERIFY);
        case DK_CXLFLASH_VLUN_CLONE:
                return __stringify_1(DK_CXLFLASH_VLUN_CLONE);
        case DK_CXLFLASH_RECOVER_AFU:
                return __stringify_1(DK_CXLFLASH_RECOVER_AFU);
        case DK_CXLFLASH_MANAGE_LUN:
                return __stringify_1(DK_CXLFLASH_MANAGE_LUN);
        }

        return "UNKNOWN";
}

/**
 * cxlflash_disk_direct_open() - opens a direct (physical) disk
 * @sdev:       SCSI device associated with LUN.
 * @arg:        UDirect ioctl data structure.
 *
 * On successful return, the user is informed of the resource handle
 * to be used to identify the direct lun and the size (in blocks) of
 * the direct lun in last LBA format.
 *
 * Return: 0 on success, -errno on failure
 */
static int cxlflash_disk_direct_open(struct scsi_device *sdev, void *arg)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct afu *afu = cfg->afu;
        struct llun_info *lli = sdev->hostdata;
        struct glun_info *gli = lli->parent;

        struct dk_cxlflash_udirect *pphys = (struct dk_cxlflash_udirect *)arg;

        u64 ctxid = DECODE_CTXID(pphys->context_id),
            rctxid = pphys->context_id;
        u64 lun_size = 0;
        u64 last_lba = 0;
        u64 rsrc_handle = -1;
        u32 port = CHAN2PORT(sdev->channel);

        int rc = 0;

        struct ctx_info *ctxi = NULL;
        struct sisl_rht_entry *rhte = NULL;

        pr_debug("%s: ctxid=%llu ls=0x%llx\n", __func__, ctxid, lun_size);

        rc = cxlflash_lun_attach(gli, MODE_PHYSICAL, false);
        if (unlikely(rc)) {
                dev_dbg(dev, "%s: Failed to attach to LUN! (PHYSICAL)\n",
                        __func__);
                goto out;
        }

        ctxi = get_context(cfg, rctxid, lli, 0);
        if (unlikely(!ctxi)) {
                dev_dbg(dev, "%s: Bad context! (%llu)\n", __func__, ctxid);
                rc = -EINVAL;
                goto err1;
        }

        rhte = rhte_checkout(ctxi, lli);
        if (unlikely(!rhte)) {
                dev_dbg(dev, "%s: too many opens for this context\n", __func__);
                rc = -EMFILE;   /* too many opens  */
                goto err1;
        }

        rsrc_handle = (rhte - ctxi->rht_start);

        rht_format1(rhte, lli->lun_id[sdev->channel], ctxi->rht_perms, port);
        cxlflash_afu_sync(afu, ctxid, rsrc_handle, AFU_LW_SYNC);

        last_lba = gli->max_lba;
        pphys->hdr.return_flags = 0;
        pphys->last_lba = last_lba;
        pphys->rsrc_handle = rsrc_handle;

out:
        if (likely(ctxi))
                put_context(ctxi);
        dev_dbg(dev, "%s: returning handle 0x%llx rc=%d llba %lld\n",
                __func__, rsrc_handle, rc, last_lba);
        return rc;

err1:
        cxlflash_lun_detach(gli);
        goto out;
}

/**
 * ioctl_common() - common IOCTL handler for driver
 * @sdev:       SCSI device associated with LUN.
 * @cmd:        IOCTL command.
 *
 * Handles common fencing operations that are valid for multiple ioctls. Always
 * allow through ioctls that are cleanup oriented in nature, even when operating
 * in a failed/terminating state.
 *
 * Return: 0 on success, -errno on failure
 */
static int ioctl_common(struct scsi_device *sdev, int cmd)
{
        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct llun_info *lli = sdev->hostdata;
        int rc = 0;

        if (unlikely(!lli)) {
                dev_dbg(dev, "%s: Unknown LUN\n", __func__);
                rc = -EINVAL;
                goto out;
        }

        rc = check_state(cfg);
        if (unlikely(rc) && (cfg->state == STATE_FAILTERM)) {
                switch (cmd) {
                case DK_CXLFLASH_VLUN_RESIZE:
                case DK_CXLFLASH_RELEASE:
                case DK_CXLFLASH_DETACH:
                        dev_dbg(dev, "%s: Command override! (%d)\n",
                                __func__, rc);
                        rc = 0;
                        break;
                }
        }
out:
        return rc;
}

/**
 * cxlflash_ioctl() - IOCTL handler for driver
 * @sdev:       SCSI device associated with LUN.
 * @cmd:        IOCTL command.
 * @arg:        Userspace ioctl data structure.
 *
 * A read/write semaphore is used to implement a 'drain' of currently
 * running ioctls. The read semaphore is taken at the beginning of each
 * ioctl thread and released upon concluding execution. Additionally the
 * semaphore should be released and then reacquired in any ioctl execution
 * path which will wait for an event to occur that is outside the scope of
 * the ioctl (i.e. an adapter reset). To drain the ioctls currently running,
 * a thread simply needs to acquire the write semaphore.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
{
        typedef int (*sioctl) (struct scsi_device *, void *);

        struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
        struct device *dev = &cfg->dev->dev;
        struct afu *afu = cfg->afu;
        struct dk_cxlflash_hdr *hdr;
        char buf[sizeof(union cxlflash_ioctls)];
        size_t size = 0;
        bool known_ioctl = false;
        int idx;
        int rc = 0;
        struct Scsi_Host *shost = sdev->host;
        sioctl do_ioctl = NULL;

        static const struct {
                size_t size;
                sioctl ioctl;
        } ioctl_tbl[] = {       /* NOTE: order matters here */
        {sizeof(struct dk_cxlflash_attach), (sioctl)cxlflash_disk_attach},
        {sizeof(struct dk_cxlflash_udirect), cxlflash_disk_direct_open},
        {sizeof(struct dk_cxlflash_release), (sioctl)cxlflash_disk_release},
        {sizeof(struct dk_cxlflash_detach), (sioctl)cxlflash_disk_detach},
        {sizeof(struct dk_cxlflash_verify), (sioctl)cxlflash_disk_verify},
        {sizeof(struct dk_cxlflash_recover_afu), (sioctl)cxlflash_afu_recover},
        {sizeof(struct dk_cxlflash_manage_lun), (sioctl)cxlflash_manage_lun},
        {sizeof(struct dk_cxlflash_uvirtual), cxlflash_disk_virtual_open},
        {sizeof(struct dk_cxlflash_resize), (sioctl)cxlflash_vlun_resize},
        {sizeof(struct dk_cxlflash_clone), (sioctl)cxlflash_disk_clone},
        };

        /* Hold read semaphore so we can drain if needed */
        down_read(&cfg->ioctl_rwsem);

        /* Restrict command set to physical support only for internal LUN */
        if (afu->internal_lun)
                switch (cmd) {
                case DK_CXLFLASH_RELEASE:
                case DK_CXLFLASH_USER_VIRTUAL:
                case DK_CXLFLASH_VLUN_RESIZE:
                case DK_CXLFLASH_VLUN_CLONE:
                        dev_dbg(dev, "%s: %s not supported for lun_mode=%d\n",
                                __func__, decode_ioctl(cmd), afu->internal_lun);
                        rc = -EINVAL;
                        goto cxlflash_ioctl_exit;
                }

        switch (cmd) {
        case DK_CXLFLASH_ATTACH:
        case DK_CXLFLASH_USER_DIRECT:
        case DK_CXLFLASH_RELEASE:
        case DK_CXLFLASH_DETACH:
        case DK_CXLFLASH_VERIFY:
        case DK_CXLFLASH_RECOVER_AFU:
        case DK_CXLFLASH_USER_VIRTUAL:
        case DK_CXLFLASH_VLUN_RESIZE:
        case DK_CXLFLASH_VLUN_CLONE:
                dev_dbg(dev, "%s: %s (%08X) on dev(%d/%d/%d/%llu)\n",
                        __func__, decode_ioctl(cmd), cmd, shost->host_no,
                        sdev->channel, sdev->id, sdev->lun);
                rc = ioctl_common(sdev, cmd);
                if (unlikely(rc))
                        goto cxlflash_ioctl_exit;

                /* fall through */

        case DK_CXLFLASH_MANAGE_LUN:
                known_ioctl = true;
                idx = _IOC_NR(cmd) - _IOC_NR(DK_CXLFLASH_ATTACH);
                size = ioctl_tbl[idx].size;
                do_ioctl = ioctl_tbl[idx].ioctl;

                if (likely(do_ioctl))
                        break;

                /* fall through */
        default:
                rc = -EINVAL;
                goto cxlflash_ioctl_exit;
        }

        if (unlikely(copy_from_user(&buf, arg, size))) {
                dev_err(dev, "%s: copy_from_user() fail! "
                        "size=%lu cmd=%d (%s) arg=%p\n",
                        __func__, size, cmd, decode_ioctl(cmd), arg);
                rc = -EFAULT;
                goto cxlflash_ioctl_exit;
        }

        hdr = (struct dk_cxlflash_hdr *)&buf;
        if (hdr->version != DK_CXLFLASH_VERSION_0) {
                dev_dbg(dev, "%s: Version %u not supported for %s\n",
                        __func__, hdr->version, decode_ioctl(cmd));
                rc = -EINVAL;
                goto cxlflash_ioctl_exit;
        }

        if (hdr->rsvd[0] || hdr->rsvd[1] || hdr->rsvd[2] || hdr->return_flags) {
                dev_dbg(dev, "%s: Reserved/rflags populated!\n", __func__);
                rc = -EINVAL;
                goto cxlflash_ioctl_exit;
        }

        rc = do_ioctl(sdev, (void *)&buf);
        if (likely(!rc))
                if (unlikely(copy_to_user(arg, &buf, size))) {
                        dev_err(dev, "%s: copy_to_user() fail! "
                                "size=%lu cmd=%d (%s) arg=%p\n",
                                __func__, size, cmd, decode_ioctl(cmd), arg);
                        rc = -EFAULT;
                }

        /* fall through to exit */

cxlflash_ioctl_exit:
        up_read(&cfg->ioctl_rwsem);
        if (unlikely(rc && known_ioctl))
                dev_err(dev, "%s: ioctl %s (%08X) on dev(%d/%d/%d/%llu) "
                        "returned rc %d\n", __func__,
                        decode_ioctl(cmd), cmd, shost->host_no,
                        sdev->channel, sdev->id, sdev->lun, rc);
        else
                dev_dbg(dev, "%s: ioctl %s (%08X) on dev(%d/%d/%d/%llu) "
                        "returned rc %d\n", __func__, decode_ioctl(cmd),
                        cmd, shost->host_no, sdev->channel, sdev->id,
                        sdev->lun, rc);
        return rc;
}