Merge patch series "Add Command Duration Limits support"

Niklas Cassel <nks@flawful.org> says:

This series adds support for Command Duration Limits.
The series is based on linux tag: v6.4-rc1
The series can also be found in git: https://github.com/floatious/linux/commits/cdl-v7

=================
CDL in ATA / SCSI
=================
Command Duration Limits is defined in:
T13 ATA Command Set - 5 (ACS-5) and
T10 SCSI Primary Commands - 6 (SPC-6) respectively
(a simpler version of CDL is defined in T10 SPC-5).

CDL defines Duration Limits Descriptors (DLD).
7 DLDs for read commands and 7 DLDs for write commands.
Simply put, a DLD contains a limit and a policy.

A command can specify that a certain limit should be applied by setting
the DLD index field (3 bits, so 0-7) in the command itself.

The DLD index points to one of the 7 DLDs.
DLD index 0 means no descriptor, so no limit.
DLD index 1-7 means DLD 1-7.

A DLD can have a few different policies, but the two major ones are:
-Policy 0xF (abort), command will be completed with command aborted error
(ATA) or status CHECK CONDITION (SCSI), with sense data indicating that
the command timed out.
-Policy 0xD (complete-unavailable), command will be completed without
error (ATA) or status GOOD (SCSI), with sense data indicating that the
command timed out. Note that the command will not have transferred any
data to/from the device when the command timed out, even though the
command returned success.

Regardless of the CDL policy, in case of a CDL timeout, the I/O will
result in a -ETIME error to user-space.

The DLDs are defined in the CDL log page(s) and are readable and writable.
Reading and writing the CDL DLDs are outside the scope of the kernel.
If a user wants to read or write the descriptors, they can do so using a
user-space application that sends passthrough commands, such as cdl-tools:
https://github.com/westerndigitalcorporation/cdl-tools

================================
The introduction of ioprio hints
================================
What the kernel does provide, is a method to let I/O use one of the CDL DLDs
defined in the device. Note that the kernel will simply forward the DLD index
to the device, so the kernel currently does not know, nor does it need to know,
how the DLDs are defined inside the device.

The way that the CDL DLD index is supplied to the kernel is by introducing a
new 10 bit "ioprio hint" field within the existing 16 bit ioprio definition.

Currently, only 6 out of the 16 ioprio bits are in use, the remaining 10 bits
are unused, and are currently explicitly disallowed to be set by the kernel.

For now, we only add ioprio hints representing CDL DLD index 1-7. Additional
ioprio hints for other QoS features could be defined in the future.

A theoretical future work could be to make an I/O scheduler aware of these
hints. E.g. for CDL, an I/O scheduler could make use of the duration limit
in each descriptor, and take that information into account while scheduling
commands. Right now, the ioprio hints will be ignored by the I/O schedulers.

==============================
How to use CDL from user-space
==============================
Since CDL is mutually exclusive with NCQ priority
(see ncq_prio_enable and sas_ncq_prio_enable in
Documentation/ABI/testing/sysfs-block-device),
CDL has to be explicitly enabled using:
echo 1 > /sys/block/$bdev/device/cdl_enable

Since the ioprio hints are supplied through the existing I/O priority API,
it should be simple for an application to make use of the ioprio hints.

It simply has to reuse one of the new macros defined in
include/uapi/linux/ioprio.h: IOPRIO_PRIO_HINT() or IOPRIO_PRIO_VALUE_HINT(),
and supply one of the new hints defined in include/uapi/linux/ioprio.h:
IOPRIO_HINT_DEV_DURATION_LIMIT_[1-7], which indicates that the I/O should
use the corresponding CDL DLD index 1-7.

By reusing the I/O priority API, the user can both define a DLD to use per
AIO (io_uring sqe->ioprio or libaio iocb->aio_reqprio) or per-thread
(ioprio_set()).

=======
Testing
=======
With the following fio patches:
https://github.com/floatious/fio/commits/cdl

fio adds support for ioprio hints, such that CDL can be tested using e.g.:
fio --ioengine=io_uring --cmdprio_percentage=10 --cmdprio_hint=DLD_index

A simple way to test is to use a DLD with a very short duration limit,
and send large reads. Regardless of the CDL policy, in case of a CDL
timeout, the I/O will result in a -ETIME error to user-space.

We also provide a CDL test suite located in the cdl-tools repo, see:
https://github.com/westerndigitalcorporation/cdl-tools#testing-a-system-command-duration-limits-support

We have tested this patch series using:
-real hardware
-the following QEMU implementation:
https://github.com/floatious/qemu/tree/cdl
(NOTE: the QEMU implementation requires you to define the CDL policy at compile
time, so you currently need to recompile QEMU when switching between policies.)

===================
Further information
===================
For further information about CDL, see Damien's slides:

Presented at SDC 2021:
https://www.snia.org/sites/default/files/SDC/2021/pdfs/SNIA-SDC21-LeMoal-Be-On-Time-command-duration-limits-Feature-Support-in%20Linux.pdf

Presented at Lund Linux Con 2022:
https://drive.google.com/file/d/1I6ChFc0h4JY9qZdO1bY5oCAdYCSZVqWw/view?usp=sharing

================
Changes since V6
================
-Rebased series on v6.4-rc1.
-Picked up Reviewed-by tags from Hannes (Thank you Hannes!)
-Picked up Reviewed-by tag from Christoph (Thank you Christoph!)
-Changed KernelVersion from 6.4 to 6.5 for new sysfs attributes.

For older change logs, see previous patch series versions:
https://lore.kernel.org/linux-scsi/20230406113252.41211-1-nks@flawful.org/
https://lore.kernel.org/linux-scsi/20230404182428.715140-1-nks@flawful.org/
https://lore.kernel.org/linux-scsi/20230309215516.3800571-1-niklas.cassel@wdc.com/
https://lore.kernel.org/linux-scsi/20230124190308.127318-1-niklas.cassel@wdc.com/
https://lore.kernel.org/linux-scsi/20230112140412.667308-1-niklas.cassel@wdc.com/
https://lore.kernel.org/linux-scsi/20221208105947.2399894-1-niklas.cassel@wdc.com/

Link: https://lore.kernel.org/r/20230511011356.227789-1-nks@flawful.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

3 files changed, 45 insertions, 14 deletions

diff --git a/include/linux/ata.h b/include/linux/ata.h
index c224dbddb9b2..792e10a09787 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -322,15 +322,21 @@ enum {
 	ATA_LOG_SATA_NCQ	= 0x10,
 	ATA_LOG_NCQ_NON_DATA	= 0x12,
 	ATA_LOG_NCQ_SEND_RECV	= 0x13,
+	ATA_LOG_CDL		= 0x18,
+	ATA_LOG_CDL_SIZE	= ATA_SECT_SIZE,
 	ATA_LOG_IDENTIFY_DEVICE	= 0x30,
+	ATA_LOG_SENSE_NCQ	= 0x0F,
+	ATA_LOG_SENSE_NCQ_SIZE	= ATA_SECT_SIZE * 2,
 	ATA_LOG_CONCURRENT_POSITIONING_RANGES = 0x47,
 
 	/* Identify device log pages: */
+	ATA_LOG_SUPPORTED_CAPABILITIES	= 0x03,
+	ATA_LOG_CURRENT_SETTINGS  = 0x04,
 	ATA_LOG_SECURITY	  = 0x06,
 	ATA_LOG_SATA_SETTINGS	  = 0x08,
 	ATA_LOG_ZONED_INFORMATION = 0x09,
 
-	/* Identify device SATA settings log:*/
+	/* Identify device SATA settings log: */
 	ATA_LOG_DEVSLP_OFFSET	  = 0x30,
 	ATA_LOG_DEVSLP_SIZE	  = 0x08,
 	ATA_LOG_DEVSLP_MDAT	  = 0x00,
@@ -415,6 +421,8 @@ enum {
 	SETFEATURES_SATA_ENABLE = 0x10, /* Enable use of SATA feature */
 	SETFEATURES_SATA_DISABLE = 0x90, /* Disable use of SATA feature */
 
+	SETFEATURES_CDL		= 0x0d, /* Enable/disable cmd duration limits */
+
 	/* SETFEATURE Sector counts for SATA features */
 	SATA_FPDMA_OFFSET	= 0x01,	/* FPDMA non-zero buffer offsets */
 	SATA_FPDMA_AA		= 0x02, /* FPDMA Setup FIS Auto-Activate */
@@ -425,6 +433,7 @@ enum {
 	SATA_DEVSLP		= 0x09,	/* Device Sleep */
 
 	SETFEATURE_SENSE_DATA	= 0xC3, /* Sense Data Reporting feature */
+	SETFEATURE_SENSE_DATA_SUCC_NCQ = 0xC4, /* Sense Data for successful NCQ commands */
 
 	/* feature values for SET_MAX */
 	ATA_SET_MAX_ADDR	= 0x00,
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 936e898016f8..bb573f87c8d1 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -171,6 +171,12 @@ typedef u16 blk_short_t;
  */
 #define BLK_STS_OFFLINE		((__force blk_status_t)17)
 
+/*
+ * BLK_STS_DURATION_LIMIT is returned from the driver when the target device
+ * aborted the command because it exceeded one of its Command Duration Limits.
+ */
+#define BLK_STS_DURATION_LIMIT	((__force blk_status_t)18)
+
 /**
  * blk_path_error - returns true if error may be path related
  * @error: status the request was completed with
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 311cd93377c7..5c8ef33b0af2 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -94,17 +94,19 @@ enum {
 	ATA_DFLAG_DMADIR	= (1 << 10), /* device requires DMADIR */
 	ATA_DFLAG_NCQ_SEND_RECV = (1 << 11), /* device supports NCQ SEND and RECV */
 	ATA_DFLAG_NCQ_PRIO	= (1 << 12), /* device supports NCQ priority */
-	ATA_DFLAG_CFG_MASK	= (1 << 13) - 1,
-
-	ATA_DFLAG_PIO		= (1 << 13), /* device limited to PIO mode */
-	ATA_DFLAG_NCQ_OFF	= (1 << 14), /* device limited to non-NCQ mode */
-	ATA_DFLAG_SLEEPING	= (1 << 15), /* device is sleeping */
-	ATA_DFLAG_DUBIOUS_XFER	= (1 << 16), /* data transfer not verified */
-	ATA_DFLAG_NO_UNLOAD	= (1 << 17), /* device doesn't support unload */
-	ATA_DFLAG_UNLOCK_HPA	= (1 << 18), /* unlock HPA */
-	ATA_DFLAG_INIT_MASK	= (1 << 19) - 1,
-
-	ATA_DFLAG_NCQ_PRIO_ENABLED = (1 << 19), /* Priority cmds sent to dev */
+	ATA_DFLAG_CDL		= (1 << 13), /* supports cmd duration limits */
+	ATA_DFLAG_CFG_MASK	= (1 << 14) - 1,
+
+	ATA_DFLAG_PIO		= (1 << 14), /* device limited to PIO mode */
+	ATA_DFLAG_NCQ_OFF	= (1 << 15), /* device limited to non-NCQ mode */
+	ATA_DFLAG_SLEEPING	= (1 << 16), /* device is sleeping */
+	ATA_DFLAG_DUBIOUS_XFER	= (1 << 17), /* data transfer not verified */
+	ATA_DFLAG_NO_UNLOAD	= (1 << 18), /* device doesn't support unload */
+	ATA_DFLAG_UNLOCK_HPA	= (1 << 19), /* unlock HPA */
+	ATA_DFLAG_INIT_MASK	= (1 << 20) - 1,
+
+	ATA_DFLAG_NCQ_PRIO_ENABLED = (1 << 20), /* Priority cmds sent to dev */
+	ATA_DFLAG_CDL_ENABLED	= (1 << 21), /* cmd duration limits is enabled */
 	ATA_DFLAG_DETACH	= (1 << 24),
 	ATA_DFLAG_DETACHED	= (1 << 25),
 	ATA_DFLAG_DA		= (1 << 26), /* device supports Device Attention */
@@ -115,7 +117,8 @@ enum {
 
 	ATA_DFLAG_FEATURES_MASK	= (ATA_DFLAG_TRUSTED | ATA_DFLAG_DA |	\
 				   ATA_DFLAG_DEVSLP | ATA_DFLAG_NCQ_SEND_RECV | \
-				   ATA_DFLAG_NCQ_PRIO | ATA_DFLAG_FUA),
+				   ATA_DFLAG_NCQ_PRIO | ATA_DFLAG_FUA | \
+				   ATA_DFLAG_CDL),
 
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */
@@ -206,10 +209,12 @@ enum {
 	ATA_QCFLAG_CLEAR_EXCL	= (1 << 5), /* clear excl_link on completion */
 	ATA_QCFLAG_QUIET	= (1 << 6), /* don't report device error */
 	ATA_QCFLAG_RETRY	= (1 << 7), /* retry after failure */
+	ATA_QCFLAG_HAS_CDL	= (1 << 8), /* qc has CDL a descriptor set */
 
 	ATA_QCFLAG_EH		= (1 << 16), /* cmd aborted and owned by EH */
 	ATA_QCFLAG_SENSE_VALID	= (1 << 17), /* sense data valid */
 	ATA_QCFLAG_EH_SCHEDULED = (1 << 18), /* EH scheduled (obsolete) */
+	ATA_QCFLAG_EH_SUCCESS_CMD = (1 << 19), /* EH should fetch sense for this successful cmd */
 
 	/* host set flags */
 	ATA_HOST_SIMPLEX	= (1 << 0),	/* Host is simplex, one DMA channel per host only */
@@ -308,8 +313,10 @@ enum {
 	ATA_EH_RESET		= ATA_EH_SOFTRESET | ATA_EH_HARDRESET,
 	ATA_EH_ENABLE_LINK	= (1 << 3),
 	ATA_EH_PARK		= (1 << 5), /* unload heads and stop I/O */
+	ATA_EH_GET_SUCCESS_SENSE = (1 << 6), /* Get sense data for successful cmd */
 
-	ATA_EH_PERDEV_MASK	= ATA_EH_REVALIDATE | ATA_EH_PARK,
+	ATA_EH_PERDEV_MASK	= ATA_EH_REVALIDATE | ATA_EH_PARK |
+				  ATA_EH_GET_SUCCESS_SENSE,
 	ATA_EH_ALL_ACTIONS	= ATA_EH_REVALIDATE | ATA_EH_RESET |
 				  ATA_EH_ENABLE_LINK,
 
@@ -709,6 +716,9 @@ struct ata_device {
 	/* Concurrent positioning ranges */
 	struct ata_cpr_log	*cpr_log;
 
+	/* Command Duration Limits log support */
+	u8			cdl[ATA_LOG_CDL_SIZE];
+
 	/* error history */
 	int			spdn_cnt;
 	/* ering is CLEAR_END, read comment above CLEAR_END */
@@ -860,6 +870,7 @@ struct ata_port {
 	struct ata_acpi_gtm	__acpi_init_gtm; /* use ata_acpi_init_gtm() */
 #endif
 	/* owned by EH */
+	u8			*ncq_sense_buf;
 	u8			sector_buf[ATA_SECT_SIZE] ____cacheline_aligned;
 };
 
@@ -1178,6 +1189,7 @@ extern int sata_link_hardreset(struct ata_link *link,
 			bool *online, int (*check_ready)(struct ata_link *));
 extern int sata_link_resume(struct ata_link *link, const unsigned long *params,
 			    unsigned long deadline);
+extern int ata_eh_read_sense_success_ncq_log(struct ata_link *link);
 extern void ata_eh_analyze_ncq_error(struct ata_link *link);
 #else
 static inline const unsigned long *
@@ -1215,6 +1227,10 @@ static inline int sata_link_resume(struct ata_link *link,
 {
 	return -EOPNOTSUPP;
 }
+static inline int ata_eh_read_sense_success_ncq_log(struct ata_link *link)
+{
+	return -EOPNOTSUPP;
+}
 static inline void ata_eh_analyze_ncq_error(struct ata_link *link) { }
 #endif
 extern int sata_link_debounce(struct ata_link *link,