[PATCH V5 11/13] mmc: block: Add CQE support

Adrian Hunter
2017-08-10T12:15:31Z

Add CQE support to the block driver, including:
- optionally using DCMD for flush requests
- manually issuing discard requests
- issuing read / write requests to the CQE
- supporting block-layer timeouts
- handling recovery
- supporting re-tuning

CQE offers 25% - 50% better random multi-threaded I/O. There is a slight
(e.g. 2%) drop in sequential read speed but no observable change to sequential
write.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
drivers/mmc/core/block.c | 195 ++++++++++++++++++++++++++++++++-
drivers/mmc/core/block.h | 7 ++
drivers/mmc/core/queue.c | 273 ++++++++++++++++++++++++++++++++++++++++++++++-
drivers/mmc/core/queue.h | 42 +++++++-
4 files changed, 510 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index d8677b28af5c..f1fc9a3b8b53 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -108,6 +108,7 @@ struct mmc_blk_data {
#define MMC_BLK_WRITE BIT(1)
#define MMC_BLK_DISCARD BIT(2)
#define MMC_BLK_SECDISCARD BIT(3)
+#define MMC_BLK_CQE_RECOVERY BIT(4)

/*
* Only set in main mmc_blk_data associated
@@ -1610,6 +1611,198 @@ static void mmc_blk_data_prep(struct mmc_queue *mq, struct mmc_queue_req *mqrq,
*do_data_tag_p = do_data_tag;
}

+#define MMC_CQE_RETRIES 2
+
+void mmc_blk_cqe_complete_rq(struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = &mqrq->brq.mrq;
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+ struct mmc_host *host = mq->card->host;
+ unsigned long flags;
+ bool put_card;
+ int err;
+
+ mmc_cqe_post_req(host, mrq);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ mq->cqe_in_flight[mmc_cqe_issue_type(host, req)] -= 1;
+
+ put_card = mmc_cqe_tot_in_flight(mq) == 0;
+
+ if (mrq->cmd && mrq->cmd->error)
+ err = mrq->cmd->error;
+ else if (mrq->data && mrq->data->error)
+ err = mrq->data->error;
+ else
+ err = 0;
+
+ if (err) {
+ if (mqrq->retries++ < MMC_CQE_RETRIES)
+ blk_requeue_request(q, req);
+ else
+ __blk_end_request_all(req, BLK_STS_IOERR);
+ } else if (mrq->data) {
+ if (__blk_end_request(req, BLK_STS_OK, mrq->data->bytes_xfered))
+ blk_requeue_request(q, req);
+ } else {
+ __blk_end_request_all(req, BLK_STS_OK);
+ }
+
+ mmc_cqe_kick_queue(mq);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (put_card)
+ mmc_put_card(mq->card);
+}
+
+void mmc_blk_cqe_recovery(struct mmc_queue *mq)
+{
+ struct mmc_card *card = mq->card;
+ struct mmc_host *host = card->host;
+ int err;
+
+ mmc_get_card(card);
+
+ pr_debug("%s: CQE recovery start\n", mmc_hostname(host));
+
+ mq->cqe_in_recovery = true;
+
+ err = mmc_cqe_recovery(host);
+ if (err)
+ mmc_blk_reset(mq->blkdata, host, MMC_BLK_CQE_RECOVERY);
+ else
+ mmc_blk_reset_success(mq->blkdata, MMC_BLK_CQE_RECOVERY);
+
+ mq->cqe_in_recovery = false;
+
+ pr_debug("%s: CQE recovery done\n", mmc_hostname(host));
+
+ mmc_put_card(card);
+}
+
+static void mmc_blk_cqe_req_done(struct mmc_request *mrq)
+{
+ struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
+ brq.mrq);
+ struct request *req = mmc_queue_req_to_req(mqrq);
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+
+ /*
+ * Block layer timeouts race with completions which means the normal
+ * completion path cannot be used during recovery.
+ */
+ if (mq->cqe_in_recovery)
+ mmc_blk_cqe_complete_rq(req);
+ else
+ blk_complete_request(req);
+}
+
+static int mmc_blk_cqe_start_req(struct mmc_host *host, struct mmc_request *mrq)
+{
+ mrq->done = mmc_blk_cqe_req_done;
+ return mmc_cqe_start_req(host, mrq);
+}
+
+static struct mmc_request *mmc_blk_cqe_prep_dcmd(struct mmc_queue_req *mqrq,
+ struct request *req)
+{
+ struct mmc_blk_request *brq = &mqrq->brq;
+
+ memset(brq, 0, sizeof(*brq));
+
+ brq->mrq.cmd = &brq->cmd;
+ brq->mrq.tag = req->tag;
+
+ return &brq->mrq;
+}
+
+static int mmc_blk_cqe_issue_flush(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = mmc_blk_cqe_prep_dcmd(mqrq, req);
+
+ mrq->cmd->opcode = MMC_SWITCH;
+ mrq->cmd->arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+ (EXT_CSD_FLUSH_CACHE << 16) |
+ (1 << 8) |
+ EXT_CSD_CMD_SET_NORMAL;
+ mrq->cmd->flags = MMC_CMD_AC | MMC_RSP_R1B;
+
+ return mmc_blk_cqe_start_req(mq->card->host, mrq);
+}
+
+static int mmc_blk_cqe_issue_rw_rq(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+
+ mmc_blk_data_prep(mq, mqrq, 0, NULL, NULL);
+
+ return mmc_blk_cqe_start_req(mq->card->host, &mqrq->brq.mrq);
+}
+
+enum mmc_issued mmc_blk_cqe_issue_rq(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_blk_data *md = mq->blkdata;
+ struct mmc_card *card = md->queue.card;
+ struct mmc_host *host = card->host;
+ int ret;
+
+ ret = mmc_blk_part_switch(card, md);
+ if (ret)
+ return MMC_REQ_FAILED_TO_START;
+
+ switch (mmc_cqe_issue_type(host, req)) {
+ case MMC_ISSUE_SYNC:
+ ret = host->cqe_ops->cqe_wait_for_idle(host);
+ if (ret)
+ return MMC_REQ_BUSY;
+ switch (req_op(req)) {
+ case REQ_OP_DRV_IN:
+ case REQ_OP_DRV_OUT:
+ mmc_blk_issue_drv_op(mq, req);
+ break;
+ case REQ_OP_DISCARD:
+ mmc_blk_issue_discard_rq(mq, req);
+ break;
+ case REQ_OP_SECURE_ERASE:
+ mmc_blk_issue_secdiscard_rq(mq, req);
+ break;
+ case REQ_OP_FLUSH:
+ mmc_blk_issue_flush(mq, req);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return MMC_REQ_FAILED_TO_START;
+ }
+ return MMC_REQ_FINISHED;
+ case MMC_ISSUE_DCMD:
+ case MMC_ISSUE_ASYNC:
+ switch (req_op(req)) {
+ case REQ_OP_FLUSH:
+ ret = mmc_blk_cqe_issue_flush(mq, req);
+ break;
+ case REQ_OP_READ:
+ case REQ_OP_WRITE:
+ ret = mmc_blk_cqe_issue_rw_rq(mq, req);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ ret = -EINVAL;
+ }
+ if (!ret)
+ return MMC_REQ_STARTED;
+ return ret == -EBUSY ? MMC_REQ_BUSY : MMC_REQ_FAILED_TO_START;
+ default:
+ WARN_ON_ONCE(1);
+ return MMC_REQ_FAILED_TO_START;
+ }
+}
+
static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
struct mmc_card *card,
int disable_multi,
@@ -2033,7 +2226,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
INIT_LIST_HEAD(&md->part);
md->usage = 1;

- ret = mmc_init_queue(&md->queue, card, &md->lock, subname);
+ ret = mmc_init_queue(&md->queue, card, &md->lock, subname, area_type);
if (ret)
goto err_putdisk;

diff --git a/drivers/mmc/core/block.h b/drivers/mmc/core/block.h
index 860ca7c8df86..d7b3d7008b00 100644
--- a/drivers/mmc/core/block.h
+++ b/drivers/mmc/core/block.h
@@ -6,4 +6,11 @@

void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req);

+enum mmc_issued;
+
+enum mmc_issued mmc_blk_cqe_issue_rq(struct mmc_queue *mq,
+ struct request *req);
+void mmc_blk_cqe_complete_rq(struct request *rq);
+void mmc_blk_cqe_recovery(struct mmc_queue *mq);
+
#endif
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index affa7370ba82..0cb7b0e8ee58 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -36,10 +36,254 @@ static int mmc_prep_request(struct request_queue *q, struct request *req)
return BLKPREP_KILL;

req->rq_flags |= RQF_DONTPREP;
+ req_to_mmc_queue_req(req)->retries = 0;

return BLKPREP_OK;
}

+static void mmc_cqe_request_fn(struct request_queue *q)
+{
+ struct mmc_queue *mq = q->queuedata;
+ struct request *req;
+
+ if (!mq) {
+ while ((req = blk_fetch_request(q)) != NULL) {
+ req->rq_flags |= RQF_QUIET;
+ __blk_end_request_all(req, BLK_STS_IOERR);
+ }
+ return;
+ }
+
+ if (mq->asleep && !mq->cqe_busy)
+ wake_up_process(mq->thread);
+}
+
+static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
+{
+ /* Allow only 1 DCMD at a time */
+ return mq->cqe_in_flight[MMC_ISSUE_DCMD];
+}
+
+void mmc_cqe_kick_queue(struct mmc_queue *mq)
+{
+ if ((mq->cqe_busy & MMC_CQE_DCMD_BUSY) && !mmc_cqe_dcmd_busy(mq))
+ mq->cqe_busy &= ~MMC_CQE_DCMD_BUSY;
+
+ mq->cqe_busy &= ~MMC_CQE_QUEUE_FULL;
+
+ if (mq->asleep && !mq->cqe_busy)
+ __blk_run_queue(mq->queue);
+}
+
+static inline bool mmc_cqe_can_dcmd(struct mmc_host *host)
+{
+ return host->caps2 & MMC_CAP2_CQE_DCMD;
+}
+
+enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
+ struct request *req)
+{
+ switch (req_op(req)) {
+ case REQ_OP_DRV_IN:
+ case REQ_OP_DRV_OUT:
+ case REQ_OP_DISCARD:
+ case REQ_OP_SECURE_ERASE:
+ return MMC_ISSUE_SYNC;
+ case REQ_OP_FLUSH:
+ return mmc_cqe_can_dcmd(host) ? MMC_ISSUE_DCMD : MMC_ISSUE_SYNC;
+ default:
+ return MMC_ISSUE_ASYNC;
+ }
+}
+
+static void __mmc_cqe_recovery_notifier(struct mmc_queue *mq)
+{
+ if (!mq->cqe_recovery_needed) {
+ mq->cqe_recovery_needed = true;
+ wake_up_process(mq->thread);
+ }
+}
+
+static void mmc_cqe_recovery_notifier(struct mmc_host *host,
+ struct mmc_request *mrq)
+{
+ struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
+ brq.mrq);
+ struct request *req = mmc_queue_req_to_req(mqrq);
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __mmc_cqe_recovery_notifier(mq);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static int mmc_cqe_thread(void *d)
+{
+ struct mmc_queue *mq = d;
+ struct request_queue *q = mq->queue;
+ struct mmc_card *card = mq->card;
+ struct mmc_host *host = card->host;
+ unsigned long flags;
+ int get_put = 0;
+
+ current->flags |= PF_MEMALLOC;
+
+ down(&mq->thread_sem);
+ spin_lock_irqsave(q->queue_lock, flags);
+ while (1) {
+ struct request *req = NULL;
+ enum mmc_issue_type issue_type;
+ bool retune_ok = false;
+
+ if (mq->cqe_recovery_needed) {
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ mmc_blk_cqe_recovery(mq);
+ spin_lock_irqsave(q->queue_lock, flags);
+ mq->cqe_recovery_needed = false;
+ }
+
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (!kthread_should_stop())
+ req = blk_peek_request(q);
+
+ if (req) {
+ issue_type = mmc_cqe_issue_type(host, req);
+ switch (issue_type) {
+ case MMC_ISSUE_DCMD:
+ if (mmc_cqe_dcmd_busy(mq)) {
+ mq->cqe_busy |= MMC_CQE_DCMD_BUSY;
+ req = NULL;
+ break;
+ }
+ /* Fall through */
+ case MMC_ISSUE_ASYNC:
+ if (blk_queue_start_tag(q, req)) {
+ mq->cqe_busy |= MMC_CQE_QUEUE_FULL;
+ req = NULL;
+ }
+ break;
+ default:
+ /*
+ * Timeouts are handled by mmc core, so set a
+ * large value to avoid races.
+ */
+ req->timeout = 600 * HZ;
+ blk_start_request(req);
+ break;
+ }
+ if (req) {
+ mq->cqe_in_flight[issue_type] += 1;
+ if (mmc_cqe_tot_in_flight(mq) == 1)
+ get_put += 1;
+ if (mmc_cqe_qcnt(mq) == 1)
+ retune_ok = true;
+ }
+ }
+
+ mq->asleep = !req;
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (req) {
+ enum mmc_issued issued;
+
+ set_current_state(TASK_RUNNING);
+
+ if (get_put) {
+ get_put = 0;
+ mmc_get_card(card);
+ }
+
+ if (host->need_retune && retune_ok &&
+ !host->hold_retune)
+ host->retune_now = true;
+ else
+ host->retune_now = false;
+
+ issued = mmc_blk_cqe_issue_rq(mq, req);
+
+ cond_resched();
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ switch (issued) {
+ case MMC_REQ_STARTED:
+ break;
+ case MMC_REQ_BUSY:
+ blk_requeue_request(q, req);
+ goto finished;
+ case MMC_REQ_FAILED_TO_START:
+ __blk_end_request_all(req, BLK_STS_IOERR);
+ /* Fall through */
+ case MMC_REQ_FINISHED:
+finished:
+ mq->cqe_in_flight[issue_type] -= 1;
+ if (mmc_cqe_tot_in_flight(mq) == 0)
+ get_put = -1;
+ }
+ } else {
+ if (get_put < 0) {
+ get_put = 0;
+ mmc_put_card(card);
+ }
+ /*
+ * Do not stop with requests in flight in case recovery
+ * is needed.
+ */
+ if (kthread_should_stop() &&
+ !mmc_cqe_tot_in_flight(mq)) {
+ set_current_state(TASK_RUNNING);
+ break;
+ }
+ up(&mq->thread_sem);
+ schedule();
+ down(&mq->thread_sem);
+ spin_lock_irqsave(q->queue_lock, flags);
+ }
+ } /* loop */
+ up(&mq->thread_sem);
+
+ return 0;
+}
+
+static enum blk_eh_timer_return __mmc_cqe_timed_out(struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = &mqrq->brq.mrq;
+ struct mmc_queue *mq = req->q->queuedata;
+ struct mmc_host *host = mq->card->host;
+ enum mmc_issue_type issue_type = mmc_cqe_issue_type(host, req);
+ bool recovery_needed = false;
+
+ switch (issue_type) {
+ case MMC_ISSUE_ASYNC:
+ case MMC_ISSUE_DCMD:
+ if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) {
+ if (recovery_needed)
+ __mmc_cqe_recovery_notifier(mq);
+ return BLK_EH_RESET_TIMER;
+ }
+ /* No timeout */
+ return BLK_EH_HANDLED;
+ default:
+ /* Timeout is handled by mmc core */
+ return BLK_EH_RESET_TIMER;
+ }
+}
+
+static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
+{
+ struct mmc_queue *mq = req->q->queuedata;
+
+ if (mq->cqe_recovery_needed)
+ return BLK_EH_RESET_TIMER;
+
+ return __mmc_cqe_timed_out(req);
+}
+
static int mmc_queue_thread(void *d)
{
struct mmc_queue *mq = d;
@@ -233,11 +477,12 @@ static void mmc_exit_request(struct request_queue *q, struct request *req)
* Initialise a MMC card request queue.
*/
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
- spinlock_t *lock, const char *subname)
+ spinlock_t *lock, const char *subname, int area_type)
{
struct mmc_host *host = card->host;
u64 limit = BLK_BOUNCE_HIGH;
int ret = -ENOMEM;
+ bool use_cqe = host->cqe_enabled && area_type != MMC_BLK_DATA_AREA_RPMB;

if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT;
@@ -247,7 +492,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
if (!mq->queue)
return -ENOMEM;
mq->queue->queue_lock = lock;
- mq->queue->request_fn = mmc_request_fn;
+ mq->queue->request_fn = use_cqe ? mmc_cqe_request_fn : mmc_request_fn;
mq->queue->init_rq_fn = mmc_init_request;
mq->queue->exit_rq_fn = mmc_exit_request;
mq->queue->cmd_size = sizeof(struct mmc_queue_req);
@@ -259,6 +504,24 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
return ret;
}

+ if (use_cqe) {
+ int q_depth = card->ext_csd.cmdq_depth;
+
+ if (q_depth > host->cqe_qdepth)
+ q_depth = host->cqe_qdepth;
+
+ ret = blk_queue_init_tags(mq->queue, q_depth, NULL,
+ BLK_TAG_ALLOC_FIFO);
+ if (ret)
+ goto cleanup_queue;
+
+ blk_queue_softirq_done(mq->queue, mmc_blk_cqe_complete_rq);
+ blk_queue_rq_timed_out(mq->queue, mmc_cqe_timed_out);
+ blk_queue_rq_timeout(mq->queue, 60 * HZ);
+
+ host->cqe_recovery_notifier = mmc_cqe_recovery_notifier;
+ }
+
blk_queue_prep_rq(mq->queue, mmc_prep_request);
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, mq->queue);
@@ -280,9 +543,9 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,

sema_init(&mq->thread_sem, 1);

- mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d%s",
- host->index, subname ? subname : "");
-
+ mq->thread = kthread_run(use_cqe ? mmc_cqe_thread : mmc_queue_thread,
+ mq, "mmcqd/%d%s", host->index,
+ subname ? subname : "");
if (IS_ERR(mq->thread)) {
ret = PTR_ERR(mq->thread);
goto cleanup_queue;
diff --git a/drivers/mmc/core/queue.h b/drivers/mmc/core/queue.h
index 361b46408e0f..8e9273d977c0 100644
--- a/drivers/mmc/core/queue.h
+++ b/drivers/mmc/core/queue.h
@@ -7,6 +7,20 @@
#include <linux/mmc/core.h>
#include <linux/mmc/host.h>

+enum mmc_issued {
+ MMC_REQ_STARTED,
+ MMC_REQ_BUSY,
+ MMC_REQ_FAILED_TO_START,
+ MMC_REQ_FINISHED,
+};
+
+enum mmc_issue_type {
+ MMC_ISSUE_SYNC,
+ MMC_ISSUE_DCMD,
+ MMC_ISSUE_ASYNC,
+ MMC_ISSUE_MAX,
+};
+
static inline struct mmc_queue_req *req_to_mmc_queue_req(struct request *rq)
{
return blk_mq_rq_to_pdu(rq);
@@ -53,6 +67,7 @@ struct mmc_queue_req {
int drv_op_result;
struct mmc_blk_ioc_data **idata;
unsigned int ioc_count;
+ int retries;
};

struct mmc_queue {
@@ -70,10 +85,17 @@ struct mmc_queue {
* associated mmc_queue_req data.
*/
int qcnt;
+ /* Following are defined for a Command Queue Engine */
+ int cqe_in_flight[MMC_ISSUE_MAX];
+ unsigned int cqe_busy;
+ bool cqe_recovery_needed;
+ bool cqe_in_recovery;
+#define MMC_CQE_DCMD_BUSY BIT(0)
+#define MMC_CQE_QUEUE_FULL BIT(1)
};

extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t *,
- const char *);
+ const char *, int);
extern void mmc_cleanup_queue(struct mmc_queue *);
extern void mmc_queue_suspend(struct mmc_queue *);
extern void mmc_queue_resume(struct mmc_queue *);
@@ -85,4 +107,22 @@ extern unsigned int mmc_queue_map_sg(struct mmc_queue *,

extern int mmc_access_rpmb(struct mmc_queue *);

+void mmc_cqe_kick_queue(struct mmc_queue *mq);
+
+enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
+ struct request *req);
+
+static inline int mmc_cqe_tot_in_flight(struct mmc_queue *mq)
+{
+ return mq->cqe_in_flight[MMC_ISSUE_SYNC] +
+ mq->cqe_in_flight[MMC_ISSUE_DCMD] +
+ mq->cqe_in_flight[MMC_ISSUE_ASYNC];
+}
+
+static inline int mmc_cqe_qcnt(struct mmc_queue *mq)
+{
+ return mq->cqe_in_flight[MMC_ISSUE_DCMD] +
+ mq->cqe_in_flight[MMC_ISSUE_ASYNC];
+}
+
#endif
--
1.9.1