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From: Avri Altman <avri.altman@wdc.com>
To: "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	Bart Van Assche <bvanassche@acm.org>,
	Daejun Park <daejun7.park@samsung.com>,
	Avri Altman <avri.altman@wdc.com>
Subject: [PATCH 2/4] scsi: ufshpb: Use a correct max multi chunk
Date: Sun,  8 Aug 2021 12:00:22 +0300	[thread overview]
Message-ID: <20210808090024.21721-3-avri.altman@wdc.com> (raw)
In-Reply-To: <20210808090024.21721-1-avri.altman@wdc.com>

In HPB2.0, if pre_req_min_tr_len < transfer_len < pre_req_max_tr_len
the driver is expected to send a HPB-WRITE-BUFFER companion to HPB-READ.

The upper bound should fit into a single byte, regardless of
bMAX_ DATA_SIZE_FOR_HPB_SINGLE_CMD which being an attribute (u32) can
be significantly larger.

To further illustrate the issue let us consider the following scenario:
 - SCSI_DEFAULT_MAX_SECTORS is 1024 limiting the IO chunks to 512KB
 - The OEM changes scsi_host_template .max_sectors to be 2048, which
   allows a 1M requests: transfer_len = 256
 - pre_req_max_tr_len = HPB_MULTI_CHUNK_HIGH = 256
 - ufshpb_is_supported_chunk returns true (256 <= 256)
 - WARN_ON_ONCE(256 > 256) doesn't warn
 - ufshpb_set_hpb_read_to_upiu cast transfer_len to u8: transfer_len = 0
 - the command is failing with illegal request

Fixes: 41d8a9333cc9 (scsi: ufs: ufshpb: Add HPB 2.0 support)
Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index c74a6c35a446..6df317dfe034 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -32,7 +32,7 @@
 /* hpb support chunk size */
 #define HPB_LEGACY_CHUNK_HIGH			1
 #define HPB_MULTI_CHUNK_LOW			7
-#define HPB_MULTI_CHUNK_HIGH			256
+#define HPB_MULTI_CHUNK_HIGH			255
 
 /* hpb vender defined opcode */
 #define UFSHPB_READ				0xF8
-- 
2.17.1


  parent reply	other threads:[~2021-08-08  9:01 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-08  9:00 [PATCH 0/4] scsi: ufs: Few HPB fixes Avri Altman
2021-08-08  9:00 ` [PATCH 1/4] scsi: ufshpb: re-wind the read timeout on every read Avri Altman
2021-08-08  9:00 ` Avri Altman [this message]
2021-08-08  9:00 ` [PATCH 3/4] scsi: ufshpb: Verify that num_inflight_map_req is non-negative Avri Altman
2021-08-08  9:00 ` [PATCH 4/4] scsi: ufshpb: Do not report victim error in HCM Avri Altman
2021-08-10  4:03 ` [PATCH 0/4] scsi: ufs: Few HPB fixes Martin K. Petersen
2021-08-17  3:17 ` Martin K. Petersen

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