Re: [PATCH v19 3/3] scsi: ufs: Prepare HPB read for cached sub-region

From: Can Guo
Date: Thu Feb 04 2021 - 22:30:49 EST

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On 2021-01-29 13:30, Daejun Park wrote:

This patch changes the read I/O to the HPB read I/O.

If the logical address of the read I/O belongs to active sub-region, the
HPB driver modifies the read I/O command to HPB read. It modifies the UPIU
command of UFS instead of modifying the existing SCSI command.

In the HPB version 1.0, the maximum read I/O size that can be converted to
HPB read is 4KB.

The dirty map of the active sub-region prevents an incorrect HPB read that
has stale physical page number which is updated by previous write I/O.

Reviewed-by: Can Guo <cang@xxxxxxxxxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Acked-by: Avri Altman <Avri.Altman@xxxxxxx>
Tested-by: Bean Huo <beanhuo@xxxxxxxxxx>
Signed-off-by: Daejun Park <daejun7.park@xxxxxxxxxxx>
---
drivers/scsi/ufs/ufshcd.c | 2 +
drivers/scsi/ufs/ufshpb.c | 234 ++++++++++++++++++++++++++++++++++++++
drivers/scsi/ufs/ufshpb.h | 2 +
3 files changed, 238 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 52e48de8d27c..37cb343e9ec1 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -2653,6 +2653,8 @@ static int ufshcd_queuecommand(struct Scsi_Host
*host, struct scsi_cmnd *cmd)

lrbp->req_abort_skip = false;

+ ufshpb_prep(hba, lrbp);
+
ufshcd_comp_scsi_upiu(hba, lrbp);

err = ufshcd_map_sg(hba, lrbp);
diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 48edfdd0f606..73e7b3ed04a4 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -31,6 +31,29 @@ bool ufshpb_is_allowed(struct ufs_hba *hba)
return !(hba->ufshpb_dev.hpb_disabled);
}

+static int ufshpb_is_valid_srgn(struct ufshpb_region *rgn,
+ struct ufshpb_subregion *srgn)
+{
+ return rgn->rgn_state != HPB_RGN_INACTIVE &&
+ srgn->srgn_state == HPB_SRGN_VALID;
+}
+
+static bool ufshpb_is_read_cmd(struct scsi_cmnd *cmd)
+{
+ return req_op(cmd->request) == REQ_OP_READ;
+}
+
+static bool ufshpb_is_write_or_discard_cmd(struct scsi_cmnd *cmd)
+{
+ return op_is_write(req_op(cmd->request)) ||
+ op_is_discard(req_op(cmd->request));
+}
+
+static bool ufshpb_is_support_chunk(int transfer_len)
+{
+ return transfer_len <= HPB_MULTI_CHUNK_HIGH;
+}
+
static bool ufshpb_is_general_lun(int lun)
{
return lun < UFS_UPIU_MAX_UNIT_NUM_ID;
@@ -98,6 +121,217 @@ static void ufshpb_set_state(struct ufshpb_lu
*hpb, int state)
atomic_set(&hpb->hpb_state, state);
}

+static void ufshpb_set_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
+ int srgn_idx, int srgn_offset, int cnt)
+{
+ struct ufshpb_region *rgn;
+ struct ufshpb_subregion *srgn;
+ int set_bit_len;
+ int bitmap_len = hpb->entries_per_srgn;
+
+next_srgn:
+ rgn = hpb->rgn_tbl + rgn_idx;
+ srgn = rgn->srgn_tbl + srgn_idx;
+
+ if ((srgn_offset + cnt) > bitmap_len)
+ set_bit_len = bitmap_len - srgn_offset;
+ else
+ set_bit_len = cnt;
+
+ if (rgn->rgn_state != HPB_RGN_INACTIVE &&
+ srgn->srgn_state == HPB_SRGN_VALID)
+ bitmap_set(srgn->mctx->ppn_dirty, srgn_offset, set_bit_len);
+
+ srgn_offset = 0;
+ if (++srgn_idx == hpb->srgns_per_rgn) {
+ srgn_idx = 0;
+ rgn_idx++;
+ }
+
+ cnt -= set_bit_len;
+ if (cnt > 0)
+ goto next_srgn;
+
+ WARN_ON(cnt < 0);
+}
+
+static bool ufshpb_test_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
+ int srgn_idx, int srgn_offset, int cnt)
+{
+ struct ufshpb_region *rgn;
+ struct ufshpb_subregion *srgn;
+ int bitmap_len = hpb->entries_per_srgn;
+ int bit_len;
+
+next_srgn:
+ rgn = hpb->rgn_tbl + rgn_idx;
+ srgn = rgn->srgn_tbl + srgn_idx;
+
+ if (!ufshpb_is_valid_srgn(rgn, srgn))
+ return true;
+
+ /*
+ * If the region state is active, mctx must be allocated.
+ * In this case, check whether the region is evicted or
+ * mctx allcation fail.
+ */
+ WARN_ON(!srgn->mctx);
+
+ if ((srgn_offset + cnt) > bitmap_len)
+ bit_len = bitmap_len - srgn_offset;
+ else
+ bit_len = cnt;
+
+ if (find_next_bit(srgn->mctx->ppn_dirty,
+ bit_len, srgn_offset) >= srgn_offset)
+ return true;
+
+ srgn_offset = 0;
+ if (++srgn_idx == hpb->srgns_per_rgn) {
+ srgn_idx = 0;
+ rgn_idx++;
+ }
+
+ cnt -= bit_len;
+ if (cnt > 0)
+ goto next_srgn;
+
+ return false;
+}
+
+static u64 ufshpb_get_ppn(struct ufshpb_lu *hpb,
+ struct ufshpb_map_ctx *mctx, int pos, int *error)
+{
+ u64 *ppn_table;
+ struct page *page;
+ int index, offset;
+
+ index = pos / (PAGE_SIZE / HPB_ENTRY_SIZE);
+ offset = pos % (PAGE_SIZE / HPB_ENTRY_SIZE);
+
+ page = mctx->m_page[index];
+ if (unlikely(!page)) {
+ *error = -ENOMEM;
+ dev_err(&hpb->sdev_ufs_lu->sdev_dev,
+ "error. cannot find page in mctx\n");
+ return 0;
+ }
+
+ ppn_table = page_address(page);
+ if (unlikely(!ppn_table)) {
+ *error = -ENOMEM;
+ dev_err(&hpb->sdev_ufs_lu->sdev_dev,
+ "error. cannot get ppn_table\n");
+ return 0;
+ }
+
+ return ppn_table[offset];
+}
+
+static void
+ufshpb_get_pos_from_lpn(struct ufshpb_lu *hpb, unsigned long lpn, int *rgn_idx,
+ int *srgn_idx, int *offset)
+{
+ int rgn_offset;
+
+ *rgn_idx = lpn >> hpb->entries_per_rgn_shift;
+ rgn_offset = lpn & hpb->entries_per_rgn_mask;
+ *srgn_idx = rgn_offset >> hpb->entries_per_srgn_shift;
+ *offset = rgn_offset & hpb->entries_per_srgn_mask;
+}
+
+static void
+ufshpb_set_hpb_read_to_upiu(struct ufshpb_lu *hpb, struct ufshcd_lrb *lrbp,
+ u32 lpn, u64 ppn, unsigned int transfer_len)
+{
+ unsigned char *cdb = lrbp->cmd->cmnd;
+
+ cdb[0] = UFSHPB_READ;
+
+ put_unaligned_be64(ppn, &cdb[6]);

You are assuming the HPB entries read out by "HPB Read Buffer" cmd are in Little
Endian, which is why you are using put_unaligned_be64 here. However, this assumption
is not right for all the other flash vendors - HPB entries read out by "HPB Read Buffer"
cmd may come in Big Endian, if so, their random read performance are screwed.

Actually, I have seen at least two flash vendors acting so. I had to modify this line
to get the code work properly on my setups.

Meanwhile, in your cover letter, you mentioned that the performance data is collected
on a UFS2.1 device. Please re-collect the data on a real UFS3.1 device and let me
know the part number. Otherwise, the data is not quite convincing to us.

Regards,
Can Guo.

+ cdb[14] = transfer_len;
+
+ lrbp->cmd->cmd_len = UFS_CDB_SIZE;
+}
+
+/*
+ * This function will set up HPB read command using host-side L2P map data.
+ * In HPB v1.0, maximum size of HPB read command is 4KB.
+ */
+void ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
+{
+ struct ufshpb_lu *hpb;
+ struct ufshpb_region *rgn;
+ struct ufshpb_subregion *srgn;
+ struct scsi_cmnd *cmd = lrbp->cmd;
+ u32 lpn;
+ u64 ppn;
+ unsigned long flags;
+ int transfer_len, rgn_idx, srgn_idx, srgn_offset;
+ int err = 0;
+
+ hpb = ufshpb_get_hpb_data(cmd->device);
+ if (!hpb)
+ return;
+
+ if (ufshpb_get_state(hpb) != HPB_PRESENT) {
+ dev_notice(&hpb->sdev_ufs_lu->sdev_dev,
+ "%s: ufshpb state is not PRESENT", __func__);
+ return;
+ }
+
+ if (!ufshpb_is_write_or_discard_cmd(cmd) &&
+ !ufshpb_is_read_cmd(cmd))
+ return;
+
+ transfer_len = sectors_to_logical(cmd->device, blk_rq_sectors(cmd->request));
+ if (unlikely(!transfer_len))
+ return;
+
+ lpn = sectors_to_logical(cmd->device, blk_rq_pos(cmd->request));
+ ufshpb_get_pos_from_lpn(hpb, lpn, &rgn_idx, &srgn_idx, &srgn_offset);
+ rgn = hpb->rgn_tbl + rgn_idx;
+ srgn = rgn->srgn_tbl + srgn_idx;
+
+ /* If command type is WRITE or DISCARD, set bitmap as drity */
+ if (ufshpb_is_write_or_discard_cmd(cmd)) {
+ spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+ ufshpb_set_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
+ transfer_len);
+ spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+ return;
+ }
+
+ if (!ufshpb_is_support_chunk(transfer_len))
+ return;
+
+ spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+ if (ufshpb_test_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
+ transfer_len)) {
+ hpb->stats.miss_cnt++;
+ spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+ return;
+ }
+
+ ppn = ufshpb_get_ppn(hpb, srgn->mctx, srgn_offset, &err);
+ spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+ if (unlikely(err)) {
+ /*
+ * In this case, the region state is active,
+ * but the ppn table is not allocated.
+ * Make sure that ppn table must be allocated on
+ * active state.
+ */
+ WARN_ON(true);
+ dev_err(hba->dev, "ufshpb_get_ppn failed. err %d\n", err);
+ return;
+ }
+
+ ufshpb_set_hpb_read_to_upiu(hpb, lrbp, lpn, ppn, transfer_len);
+
+ hpb->stats.hit_cnt++;
+}
+
static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
struct ufshpb_subregion *srgn)
{
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index e40b016971ac..2c43a03b66b6 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -198,6 +198,7 @@ struct ufs_hba;
struct ufshcd_lrb;

#ifndef CONFIG_SCSI_UFS_HPB
+static void ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp) {}
static void ufshpb_rsp_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp) {}
static void ufshpb_resume(struct ufs_hba *hba) {}
static void ufshpb_suspend(struct ufs_hba *hba) {}
@@ -211,6 +212,7 @@ static bool ufshpb_is_allowed(struct ufs_hba *hba)
{ return false; }
static void ufshpb_get_geo_info(struct ufs_hba *hba, u8 *geo_buf) {}
static void ufshpb_get_dev_info(struct ufs_hba *hba, u8 *desc_buf) {}
#else
+void ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp);
void ufshpb_rsp_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp);
void ufshpb_resume(struct ufs_hba *hba);
void ufshpb_suspend(struct ufs_hba *hba);

Next message: Darrick J. Wong: "Re: [PATCH] xfs: fix unused variable build warning in xfs_log.c"
Previous message: Jason Wang: "Re: [PATCH v3 09/13] vhost/vdpa: remove vhost_vdpa_config_validate()"
Next in thread: Bean Huo: "Re: [PATCH v19 3/3] scsi: ufs: Prepare HPB read for cached sub-region"
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