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// SPDX-License-Identifier: GPL-2.0
/*
* Block driver for s390 storage class memory.
*
* Copyright IBM Corp. 2012
* Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
*/
#define KMSG_COMPONENT "scm_block"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <asm/eadm.h>
#include "scm_blk.h"
debug_info_t *scm_debug;
static int scm_major;
static mempool_t *aidaw_pool;
static DEFINE_SPINLOCK(list_lock);
static LIST_HEAD(inactive_requests);
static unsigned int nr_requests = 64;
static unsigned int nr_requests_per_io = 8;
static atomic_t nr_devices = ATOMIC_INIT(0);
module_param(nr_requests, uint, S_IRUGO);
MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
module_param(nr_requests_per_io, uint, S_IRUGO);
MODULE_PARM_DESC(nr_requests_per_io, "Number of requests per IO.");
MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
MODULE_LICENSE("GPL");
MODULE_ALIAS("scm:scmdev*");
static void __scm_free_rq(struct scm_request *scmrq)
{
struct aob_rq_header *aobrq = to_aobrq(scmrq);
free_page((unsigned long) scmrq->aob);
kfree(scmrq->request);
kfree(aobrq);
}
static void scm_free_rqs(void)
{
struct list_head *iter, *safe;
struct scm_request *scmrq;
spin_lock_irq(&list_lock);
list_for_each_safe(iter, safe, &inactive_requests) {
scmrq = list_entry(iter, struct scm_request, list);
list_del(&scmrq->list);
__scm_free_rq(scmrq);
}
spin_unlock_irq(&list_lock);
mempool_destroy(aidaw_pool);
}
static int __scm_alloc_rq(void)
{
struct aob_rq_header *aobrq;
struct scm_request *scmrq;
aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
if (!aobrq)
return -ENOMEM;
scmrq = (void *) aobrq->data;
scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
if (!scmrq->aob)
goto free;
scmrq->request = kcalloc(nr_requests_per_io, sizeof(scmrq->request[0]),
GFP_KERNEL);
if (!scmrq->request)
goto free;
INIT_LIST_HEAD(&scmrq->list);
spin_lock_irq(&list_lock);
list_add(&scmrq->list, &inactive_requests);
spin_unlock_irq(&list_lock);
return 0;
free:
__scm_free_rq(scmrq);
return -ENOMEM;
}
static int scm_alloc_rqs(unsigned int nrqs)
{
int ret = 0;
aidaw_pool = mempool_create_page_pool(max(nrqs/8, 1U), 0);
if (!aidaw_pool)
return -ENOMEM;
while (nrqs-- && !ret)
ret = __scm_alloc_rq();
return ret;
}
static struct scm_request *scm_request_fetch(void)
{
struct scm_request *scmrq = NULL;
spin_lock_irq(&list_lock);
if (list_empty(&inactive_requests))
goto out;
scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
list_del(&scmrq->list);
out:
spin_unlock_irq(&list_lock);
return scmrq;
}
static void scm_request_done(struct scm_request *scmrq)
{
unsigned long flags;
struct msb *msb;
u64 aidaw;
int i;
for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
msb = &scmrq->aob->msb[i];
aidaw = msb->data_addr;
if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
IS_ALIGNED(aidaw, PAGE_SIZE))
mempool_free(virt_to_page(aidaw), aidaw_pool);
}
spin_lock_irqsave(&list_lock, flags);
list_add(&scmrq->list, &inactive_requests);
spin_unlock_irqrestore(&list_lock, flags);
}
static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
{
return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
}
static inline struct aidaw *scm_aidaw_alloc(void)
{
struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
return page ? page_address(page) : NULL;
}
static inline unsigned long scm_aidaw_bytes(struct aidaw *aidaw)
{
unsigned long _aidaw = (unsigned long) aidaw;
unsigned long bytes = ALIGN(_aidaw, PAGE_SIZE) - _aidaw;
return (bytes / sizeof(*aidaw)) * PAGE_SIZE;
}
struct aidaw *scm_aidaw_fetch(struct scm_request *scmrq, unsigned int bytes)
{
struct aidaw *aidaw;
if (scm_aidaw_bytes(scmrq->next_aidaw) >= bytes)
return scmrq->next_aidaw;
aidaw = scm_aidaw_alloc();
if (aidaw)
memset(aidaw, 0, PAGE_SIZE);
return aidaw;
}
static int scm_request_prepare(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
struct scm_device *scmdev = bdev->gendisk->private_data;
int pos = scmrq->aob->request.msb_count;
struct msb *msb = &scmrq->aob->msb[pos];
struct request *req = scmrq->request[pos];
struct req_iterator iter;
struct aidaw *aidaw;
struct bio_vec bv;
aidaw = scm_aidaw_fetch(scmrq, blk_rq_bytes(req));
if (!aidaw)
return -ENOMEM;
msb->bs = MSB_BS_4K;
scmrq->aob->request.msb_count++;
msb->scm_addr = scmdev->address + ((u64) blk_rq_pos(req) << 9);
msb->oc = (rq_data_dir(req) == READ) ? MSB_OC_READ : MSB_OC_WRITE;
msb->flags |= MSB_FLAG_IDA;
msb->data_addr = (u64) aidaw;
rq_for_each_segment(bv, req, iter) {
WARN_ON(bv.bv_offset);
msb->blk_count += bv.bv_len >> 12;
aidaw->data_addr = (u64) page_address(bv.bv_page);
aidaw++;
}
scmrq->next_aidaw = aidaw;
return 0;
}
static inline void scm_request_set(struct scm_request *scmrq,
struct request *req)
{
scmrq->request[scmrq->aob->request.msb_count] = req;
}
static inline void scm_request_init(struct scm_blk_dev *bdev,
struct scm_request *scmrq)
{
struct aob_rq_header *aobrq = to_aobrq(scmrq);
struct aob *aob = scmrq->aob;
memset(scmrq->request, 0,
nr_requests_per_io * sizeof(scmrq->request[0]));
memset(aob, 0, sizeof(*aob));
aobrq->scmdev = bdev->scmdev;
aob->request.cmd_code = ARQB_CMD_MOVE;
aob->request.data = (u64) aobrq;
scmrq->bdev = bdev;
scmrq->retries = 4;
scmrq->error = BLK_STS_OK;
/* We don't use all msbs - place aidaws at the end of the aob page. */
scmrq->next_aidaw = (void *) &aob->msb[nr_requests_per_io];
}
static void scm_request_requeue(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
int i;
for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++)
blk_mq_requeue_request(scmrq->request[i], false);
atomic_dec(&bdev->queued_reqs);
scm_request_done(scmrq);
blk_mq_kick_requeue_list(bdev->rq);
}
static void scm_request_finish(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
blk_status_t *error;
int i;
for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
error = blk_mq_rq_to_pdu(scmrq->request[i]);
*error = scmrq->error;
if (likely(!blk_should_fake_timeout(scmrq->request[i]->q)))
blk_mq_complete_request(scmrq->request[i]);
}
atomic_dec(&bdev->queued_reqs);
scm_request_done(scmrq);
}
static void scm_request_start(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
atomic_inc(&bdev->queued_reqs);
if (eadm_start_aob(scmrq->aob)) {
SCM_LOG(5, "no subchannel");
scm_request_requeue(scmrq);
}
}
struct scm_queue {
struct scm_request *scmrq;
spinlock_t lock;
};
static blk_status_t scm_blk_request(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *qd)
{
struct scm_device *scmdev = hctx->queue->queuedata;
struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
struct scm_queue *sq = hctx->driver_data;
struct request *req = qd->rq;
struct scm_request *scmrq;
spin_lock(&sq->lock);
if (!scm_permit_request(bdev, req)) {
spin_unlock(&sq->lock);
return BLK_STS_RESOURCE;
}
scmrq = sq->scmrq;
if (!scmrq) {
scmrq = scm_request_fetch();
if (!scmrq) {
SCM_LOG(5, "no request");
spin_unlock(&sq->lock);
return BLK_STS_RESOURCE;
}
scm_request_init(bdev, scmrq);
sq->scmrq = scmrq;
}
scm_request_set(scmrq, req);
if (scm_request_prepare(scmrq)) {
SCM_LOG(5, "aidaw alloc failed");
scm_request_set(scmrq, NULL);
if (scmrq->aob->request.msb_count)
scm_request_start(scmrq);
sq->scmrq = NULL;
spin_unlock(&sq->lock);
return BLK_STS_RESOURCE;
}
blk_mq_start_request(req);
if (qd->last || scmrq->aob->request.msb_count == nr_requests_per_io) {
scm_request_start(scmrq);
sq->scmrq = NULL;
}
spin_unlock(&sq->lock);
return BLK_STS_OK;
}
static int scm_blk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
unsigned int idx)
{
struct scm_queue *qd = kzalloc(sizeof(*qd), GFP_KERNEL);
if (!qd)
return -ENOMEM;
spin_lock_init(&qd->lock);
hctx->driver_data = qd;
return 0;
}
static void scm_blk_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int idx)
{
struct scm_queue *qd = hctx->driver_data;
WARN_ON(qd->scmrq);
kfree(hctx->driver_data);
hctx->driver_data = NULL;
}
static void __scmrq_log_error(struct scm_request *scmrq)
{
struct aob *aob = scmrq->aob;
if (scmrq->error == BLK_STS_TIMEOUT)
SCM_LOG(1, "Request timeout");
else {
SCM_LOG(1, "Request error");
SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
}
if (scmrq->retries)
SCM_LOG(1, "Retry request");
else
pr_err("An I/O operation to SCM failed with rc=%d\n",
scmrq->error);
}
static void scm_blk_handle_error(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
unsigned long flags;
if (scmrq->error != BLK_STS_IOERR)
goto restart;
/* For -EIO the response block is valid. */
switch (scmrq->aob->response.eqc) {
case EQC_WR_PROHIBIT:
spin_lock_irqsave(&bdev->lock, flags);
if (bdev->state != SCM_WR_PROHIBIT)
pr_info("%lx: Write access to the SCM increment is suspended\n",
(unsigned long) bdev->scmdev->address);
bdev->state = SCM_WR_PROHIBIT;
spin_unlock_irqrestore(&bdev->lock, flags);
goto requeue;
default:
break;
}
restart:
if (!eadm_start_aob(scmrq->aob))
return;
requeue:
scm_request_requeue(scmrq);
}
void scm_blk_irq(struct scm_device *scmdev, void *data, blk_status_t error)
{
struct scm_request *scmrq = data;
scmrq->error = error;
if (error) {
__scmrq_log_error(scmrq);
if (scmrq->retries-- > 0) {
scm_blk_handle_error(scmrq);
return;
}
}
scm_request_finish(scmrq);
}
static void scm_blk_request_done(struct request *req)
{
blk_status_t *error = blk_mq_rq_to_pdu(req);
blk_mq_end_request(req, *error);
}
static const struct block_device_operations scm_blk_devops = {
.owner = THIS_MODULE,
};
static const struct blk_mq_ops scm_mq_ops = {
.queue_rq = scm_blk_request,
.complete = scm_blk_request_done,
.init_hctx = scm_blk_init_hctx,
.exit_hctx = scm_blk_exit_hctx,
};
int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
{
unsigned int devindex, nr_max_blk;
struct request_queue *rq;
int len, ret;
devindex = atomic_inc_return(&nr_devices) - 1;
/* scma..scmz + scmaa..scmzz */
if (devindex > 701) {
ret = -ENODEV;
goto out;
}
bdev->scmdev = scmdev;
bdev->state = SCM_OPER;
spin_lock_init(&bdev->lock);
atomic_set(&bdev->queued_reqs, 0);
bdev->tag_set.ops = &scm_mq_ops;
bdev->tag_set.cmd_size = sizeof(blk_status_t);
bdev->tag_set.nr_hw_queues = nr_requests;
bdev->tag_set.queue_depth = nr_requests_per_io * nr_requests;
bdev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
bdev->tag_set.numa_node = NUMA_NO_NODE;
ret = blk_mq_alloc_tag_set(&bdev->tag_set);
if (ret)
goto out;
bdev->gendisk = blk_mq_alloc_disk(&bdev->tag_set, scmdev);
if (IS_ERR(bdev->gendisk)) {
ret = PTR_ERR(bdev->gendisk);
goto out_tag;
}
rq = bdev->rq = bdev->gendisk->queue;
nr_max_blk = min(scmdev->nr_max_block,
(unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
blk_queue_logical_block_size(rq, 1 << 12);
blk_queue_max_hw_sectors(rq, nr_max_blk << 3); /* 8 * 512 = blk_size */
blk_queue_max_segments(rq, nr_max_blk);
blk_queue_flag_set(QUEUE_FLAG_NONROT, rq);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, rq);
bdev->gendisk->private_data = scmdev;
bdev->gendisk->fops = &scm_blk_devops;
bdev->gendisk->major = scm_major;
bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
bdev->gendisk->minors = SCM_NR_PARTS;
len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
if (devindex > 25) {
len += snprintf(bdev->gendisk->disk_name + len,
DISK_NAME_LEN - len, "%c",
'a' + (devindex / 26) - 1);
devindex = devindex % 26;
}
snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
'a' + devindex);
/* 512 byte sectors */
set_capacity(bdev->gendisk, scmdev->size >> 9);
ret = device_add_disk(&scmdev->dev, bdev->gendisk, NULL);
if (ret)
goto out_cleanup_disk;
return 0;
out_cleanup_disk:
blk_cleanup_disk(bdev->gendisk);
out_tag:
blk_mq_free_tag_set(&bdev->tag_set);
out:
atomic_dec(&nr_devices);
return ret;
}
void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
{
del_gendisk(bdev->gendisk);
blk_cleanup_disk(bdev->gendisk);
blk_mq_free_tag_set(&bdev->tag_set);
}
void scm_blk_set_available(struct scm_blk_dev *bdev)
{
unsigned long flags;
spin_lock_irqsave(&bdev->lock, flags);
if (bdev->state == SCM_WR_PROHIBIT)
pr_info("%lx: Write access to the SCM increment is restored\n",
(unsigned long) bdev->scmdev->address);
bdev->state = SCM_OPER;
spin_unlock_irqrestore(&bdev->lock, flags);
}
static bool __init scm_blk_params_valid(void)
{
if (!nr_requests_per_io || nr_requests_per_io > 64)
return false;
return true;
}
static int __init scm_blk_init(void)
{
int ret = -EINVAL;
if (!scm_blk_params_valid())
goto out;
ret = register_blkdev(0, "scm");
if (ret < 0)
goto out;
scm_major = ret;
ret = scm_alloc_rqs(nr_requests);
if (ret)
goto out_free;
scm_debug = debug_register("scm_log", 16, 1, 16);
if (!scm_debug) {
ret = -ENOMEM;
goto out_free;
}
debug_register_view(scm_debug, &debug_hex_ascii_view);
debug_set_level(scm_debug, 2);
ret = scm_drv_init();
if (ret)
goto out_dbf;
return ret;
out_dbf:
debug_unregister(scm_debug);
out_free:
scm_free_rqs();
unregister_blkdev(scm_major, "scm");
out:
return ret;
}
module_init(scm_blk_init);
static void __exit scm_blk_cleanup(void)
{
scm_drv_cleanup();
debug_unregister(scm_debug);
scm_free_rqs();
unregister_blkdev(scm_major, "scm");
}
module_exit(scm_blk_cleanup);