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.

Tested-by: Bean Huo <bean...@micron.com>
Signed-off-by: Daejun Park <daejun7.p...@samsung.com>
---
 drivers/scsi/ufs/ufshpb.c | 227 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 227 insertions(+)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 25cd7153f102..fe24b2277621 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -46,6 +46,22 @@ static inline int ufshpb_is_valid_srgn(struct ufshpb_region 
*rgn,
                srgn->srgn_state == HPB_SRGN_VALID;
 }
 
+static inline bool ufshpb_is_read_cmd(struct scsi_cmnd *cmd)
+{
+       return req_op(cmd->request) == REQ_OP_READ;
+}
+
+static inline bool ufshpb_is_write_discard_cmd(struct scsi_cmnd *cmd)
+{
+       return op_is_write(req_op(cmd->request)) ||
+              op_is_discard(req_op(cmd->request));
+}
+
+static inline bool ufshpb_is_support_chunk(int transfer_len)
+{
+       return transfer_len <= HPB_MULTI_CHUNK_HIGH;
+}
+
 static inline bool ufshpb_is_general_lun(int lun)
 {
        return lun < UFS_UPIU_MAX_UNIT_NUM_ID;
@@ -112,8 +128,219 @@ static inline void ufshpb_set_state(struct ufshpb_lu 
*hpb, int state)
        atomic_set(&hpb->hpb_state, state);
 }
 
+static inline u32 ufshpb_get_lpn(struct scsi_cmnd *cmnd)
+{
+       return blk_rq_pos(cmnd->request) >>
+               (ilog2(cmnd->device->sector_size) - 9);
+}
+
+static inline unsigned int ufshpb_get_len(struct scsi_cmnd *cmnd)
+{
+       return blk_rq_sectors(cmnd->request) >>
+               (ilog2(cmnd->device->sector_size) - 9);
+}
+
+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 inline 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->ucd_req_ptr->sc.cdb;
+
+       cdb[0] = UFSHPB_READ;
+
+       put_unaligned_be64(ppn, &cdb[6]);
+       cdb[14] = transfer_len;
+}
+
+/* routine : READ10 -> HPB_READ  */
 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);
+       if (!hpb)
+               return;
+
+       WARN_ON(hpb->lun != cmd->device->lun);
+       if (!ufshpb_is_write_discard_cmd(cmd) &&
+           !ufshpb_is_read_cmd(cmd))
+               return;
+
+       transfer_len = ufshpb_get_len(cmd);
+       if (unlikely(!transfer_len))
+               return;
+
+       lpn = ufshpb_get_lpn(cmd);
+       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_discard_cmd(cmd)) {
+               spin_lock_irqsave(&hpb->hpb_state_lock, flags);
+               ufshpb_set_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
+                                transfer_len);
+               spin_unlock_irqrestore(&hpb->hpb_state_lock, flags);
+               return;
+       }
+
+       WARN_ON(!ufshpb_is_read_cmd(cmd));
+
+       if (!ufshpb_is_support_chunk(transfer_len))
+               return;
+
+       spin_lock_irqsave(&hpb->hpb_state_lock, flags);
+       if (ufshpb_test_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
+                                  transfer_len)) {
+               atomic_inc(&hpb->stats.miss_cnt);
+               spin_unlock_irqrestore(&hpb->hpb_state_lock, flags);
+               return;
+       }
+
+       ppn = ufshpb_get_ppn(hpb, srgn->mctx, srgn_offset, &err);
+       spin_unlock_irqrestore(&hpb->hpb_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);
+
+       atomic_inc(&hpb->stats.hit_cnt);
 }
 
 static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
-- 
2.17.1


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