FROMLIST: scsi: ufs: Introduce HPB feature

This is a patch for the HPB initialization and adds HPB function calls to
UFS core driver.

NAND flash-based storage devices, including UFS, have mechanisms to
translate logical addresses of IO requests to the corresponding physical
addresses of the flash storage.
In UFS, Logical-address-to-Physical-address (L2P) map data, which is
required to identify the physical address for the requested IOs, can only
be partially stored in SRAM from NAND flash. Due to this partial loading,
accessing the flash address area where the L2P information for that address
is not loaded in the SRAM can result in serious performance degradation.

The basic concept of HPB is to cache L2P mapping entries in host system
memory so that both physical block address (PBA) and logical block address
(LBA) can be delivered in HPB read command.
The HPB READ command allows to read data faster than a read command in UFS
since it provides the physical address (HPB Entry) of the desired logical
block in addition to its logical address. The UFS device can access the
physical block in NAND directly without searching and uploading L2P mapping
table. This improves read performance because the NAND read operation for
uploading L2P mapping table is removed.

In HPB initialization, the host checks if the UFS device supports HPB
feature and retrieves related device capabilities. Then, some HPB
parameters are configured in the device.

We measured the total start-up time of popular applications and observed
the difference by enabling the HPB.
Popular applications are 12 game apps and 24 non-game apps. Each target
applications were launched in order. The cycle consists of running 36
applications in sequence. We repeated the cycle for observing performance
improvement by L2P mapping cache hit in HPB.

The Following is experiment environment:
 - kernel version: 4.4.0
 - RAM: 8GB
 - UFS 2.1 (64GB)

Result:
+-------+----------+----------+-------+
| cycle | baseline | with HPB | diff  |
+-------+----------+----------+-------+
| 1     | 272.4    | 264.9    | -7.5  |
| 2     | 250.4    | 248.2    | -2.2  |
| 3     | 226.2    | 215.6    | -10.6 |
| 4     | 230.6    | 214.8    | -15.8 |
| 5     | 232.0    | 218.1    | -13.9 |
| 6     | 231.9    | 212.6    | -19.3 |
+-------+----------+----------+-------+

We also measured HPB performance using iozone.
Here is my iozone script:
iozone -r 4k -+n -i2 -ecI -t 16 -l 16 -u 16
-s $IO_RANGE/16 -F mnt/tmp_1 mnt/tmp_2 mnt/tmp_3 mnt/tmp_4 mnt/tmp_5
mnt/tmp_6 mnt/tmp_7 mnt/tmp_8 mnt/tmp_9 mnt/tmp_10 mnt/tmp_11 mnt/tmp_12
mnt/tmp_13 mnt/tmp_14 mnt/tmp_15 mnt/tmp_16

Result:
+----------+--------+---------+
| IO range | HPB on | HPB off |
+----------+--------+---------+
|   1 GB   | 294.8  | 300.87  |
|   4 GB   | 293.51 | 179.35  |
|   8 GB   | 294.85 | 162.52  |
|  16 GB   | 293.45 | 156.26  |
|  32 GB   | 277.4  | 153.25  |
+----------+--------+---------+

Bug: 183467926
Bug: 170940265
Bug: 183454255

Link: https://lore.kernel.org/linux-scsi/20210616070812epcms2p4650ce5cd78056dce9162482e59bb74dd@epcms2p4/



Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Can Guo <cang@codeaurora.org>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Acked-by: Avri Altman <Avri.Altman@wdc.com>
Tested-by: Bean Huo <beanhuo@micron.com>
Tested-by: Can Guo <cang@codeaurora.org>
Tested-by: Stanley Chu <stanley.chu@mediatek.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daejun Park <daejun7.park@samsung.com>
Change-Id: Ib198ff9844fc78c718d1c8e2a98fa13cc7b05f35