The following Oops can be encountered if a device removal or system shutdown
is initiated while an EEH recovery is in process:

[c000000ff2f479c0] c008000015256f18 cxlflash_pci_slot_reset+0xa0/0x100
                                      [cxlflash]
[c000000ff2f47a30] c00800000dae22e0 cxl_pci_slot_reset+0x168/0x290 [cxl]
[c000000ff2f47ae0] c00000000003ef1c eeh_report_reset+0xec/0x170
[c000000ff2f47b20] c00000000003d0b8 eeh_pe_dev_traverse+0x98/0x170
[c000000ff2f47bb0] c00000000003f80c eeh_handle_normal_event+0x56c/0x580
[c000000ff2f47c60] c00000000003fba4 eeh_handle_event+0x2a4/0x338
[c000000ff2f47d10] c0000000000400b8 eeh_event_handler+0x1f8/0x200
[c000000ff2f47dc0] c00000000013da48 kthread+0x1a8/0x1b0
[c000000ff2f47e30] c00000000000b528 ret_from_kernel_thread+0x5c/0xb4

The remove handler frees AFU memory while the EEH recovery is in progress,
leading to a race condition. This can result in a crash if the recovery thread
tries to access this memory.

To resolve this issue, the cxlflash remove handler will evaluate the device
state and yield to any active reset or probing threads.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This commit enables the OCXL operations for the OCXL devices.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Similar to user contexts, master contexts also require that the per-context
LISN registers be programmed for certain AFUs. The mapped trigger page is
obtained from underlying transport and registered with AFU for each master
context.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When an adapter is initialized, transport specific configuration and MMIO
mapping details need to be saved. For CXL, this data is managed by the
underlying kernel module. To maintain a separation between the cxlflash core
and underlying transports, introduce a new structure to store data specific to
the OCXL AFU.

Initially only the pointers to underlying PCI and generic devices are added to
this new structure - it will be expanded further in future commits. Services
to create and destroy this hardware AFU are added and integrated in the probe
and exit paths of the driver.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The SISLite specification originally defined the context control register with
a single field of bits to represent the LISN and also stipulated that the
register reset value be 0. The cxlflash driver took advantage of this when
programming the LISN for the master contexts via an unconditional write - no
other bits were preserved.

When unmap support was added, SISLite was updated to define bit 0 of the
context control register as a way for the AFU to notify the context owner that
unmap operations were supported. Thus the assumptions under which the register
is setup changed and the existing unconditional write is clobbering the unmap
state for master contexts. This is presently not an issue due to the order in
which the context control register is programmed in relation to the unmap bit
being queried but should be addressed to avoid a future regression in the
event this code is moved elsewhere.

To remedy this issue, preserve the bits when programming the LISN field in the
context control register. Since the LISN will now be programmed using a read
value, assert that the initial state of the LISN field is as described in
SISLite (0).
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The number of interrupts requested for user contexts are stored in the context
specific structures and utilized to manage the interrupts. For the master
contexts, this number is only used once and therefore not saved.

To prepare for future commits where the number of interrupts will be required
in more than one place, preserve the value in the master context structure.

[mkp: typo in comment]
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

As staging to support future accelerator transports, add a shim layer
such that the underlying services the cxlflash driver requires can be
conditional upon the accelerator infrastructure.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Adapter context creation can return either NULL or an error pointer.
Updating the check condition to reflect this.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The CXL-specific work structure used to request the number of interrupts
currently resides as a nested member of both the context information and
hardware queue structures. It is used to cache values (specifically the
number of interrupts) required by the CXL layer when starting a context.

To facilitate staging that will ultimately allow the cxlflash core to
become agnostic of the underlying accelerator transport, remove these
embedded work structures.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Convert cxl-specific pointers to generic cookies to facilitate future
enhancements.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

In the event of a command failure, cxlflash returns the failure to the upper
layers to process. After processing the error, when the command is queued
again, the private command structure will not be zeroed and the ioasc could be
stale. Per the SISLite specification, the AFU only sets the ioasc in the
presence of a failure. Thus, even though the original command succeeds the
second time, the command is considered a failure due to stale ioasc. This
cycle repeats indefinitely and can cause a hang or IO failure.

To fix the issue, clear the ioasc before queuing any command.

[mkp: added Cc: stable per request]

Fixes: 479ad8e9 ("scsi: cxlflash: Remove zeroing of private command data")
Cc: <stable@vger.kernel.org>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Currently, all adapters that cxlflash supports must have WWPN VPD
keywords to complete configuration. This was required as cards with
external FC ports needed to be programmed with WWPNs.

Newer supported cards do not have an external FC interface and therefore
do not require WWPN. To support backwards compatibility, these devices
have included 'dummy' WWPN VPD with WWPN values of zero. This however
places a dependency that all future cards have WWPN VPD, which may not
always be the case.

Allow for cards to not have WWPN, designating which cards are expected
to have it in order to configure properly.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The AFU termination sequence has been refactored over time such that the
main tear down routine, term_afu(), can no longer can be invoked with a
NULL AFU pointer. Remove the unnecessary existence check from
term_afu().
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The copy_from/to_user() functions return the number of bytes remaining
to be copied but we had intended to return -EFAULT here.

Fixes: bc88ac47 ("scsi: cxlflash: Support AFU debug")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The device and host reset handler contain debug prints to help identify
the entities being reset. Today these reset handlers are based on a SCSI
EH design that uses a SCSI command reference as a means of identifying
the target entity. As such, the debug trace includes the SCSI command
pointer and associated CDB. This is not necessary as the SCSI command is
simply the messenger in these scenarios.

Refactor the debug prints in the host and reset handlers to only present
information that is applicable given the function scope.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The current send_tmf() implementation is based on the caller providing a
SCSI command reference. In reality all that is needed is a SCSI device
reference as the routine uses a private command.

Refactor send_tmf() to pass the private adapter configuration reference
and a SCSI device reference. As a nice side effect, this will ease the
burden of converting caller routines to be based solely off of a SCSI
device reference.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The device_unregister() service used when cleaning up the character
device is already responsible for the internal state associated with the
device upon successful creation. As the cxlflash driver does not obtain
a second reference to the character device, the explicit call to
put_device() is not required and can lead to an inconsistent sysfs among
other issues as the reference is no longer valid after the first
put_device() is performed.

Remove the unnecessary put_device() to remedy this issue.

Fixes: a834a36b ("scsi: cxlflash: Create character device to provide host management interface")
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Currently, the SCSI command presented to the device reset handler is used
to send TMFs to the AFU for a device reset. This behavior is incorrect as
the command presented is an actual command and not a special notification.
As such, it should only be used for reference and not be acted upon.

Additionally, the existing TMF transmission routine does not account for
actual errors from the hardware, only reflecting failure when a timeout
occurs. This can lead to a condition where the device reset handler is
presented with a false 'success'.

Update send_tmf() to dynamically allocate a private command for sending
the TMF command and properly reflect failure when the completed command
indicates an error or was aborted. Detect TMF commands during response
processing and avoid scsi_done() for these types of commands. Lastly,
update comments in the TMF processing paths to describe the new behavior.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The SCSI core now zeroes the per-command private data area prior to
calling into the LLD. Replace the clearing operation that takes place
when the private command data reference is obtained with a routine that
performs common initializations. The zeroing that takes place in the
device reset path remains intact as the private command data associated
with the specified SCSI command is not guaranteed to be cleared.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The cxlflash driver supports performing a write-same16 to scrub virtual
luns when they are released by a user. To date, AFUs for adapters that
are supported by cxlflash do not have the capability to unmap as part of
the WS operation. This can lead to fragmented flash devices which results
in performance degradation.

Future AFUs can optionally support unmap write-same commands and reflects
this support via the context control register. This provides userspace
applications with direct visibility such that they need not depend on a
host API.

Detect unmap support during cxlflash initialization by reading the context
control register associated with the primary hardware queue. Update the
existing write_same16() routine to set the unmap bit in the CDB when unmap
is supported by the host.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Adopt the SISLite AFU debug capability to allow future CXL Flash
adapters the ability to better debug AFU issues. Update the SISLite
header with the changes necessary to support AFU debug operations
and create a host ioctl interface for user debug software. Also
update the cxlflash documentation to describe this new host ioctl.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Adopt the SISLite AFU LUN provisioning capability to allow future CXL
Flash adapters the ability to better manage storage. Update the SISLite
header with the changes necessary to support LUN provision operations
and create a host ioctl interface for user LUN management software. Also
update the cxlflash documentation to describe this new host ioctl.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

As staging for supporting various host management functions, add a host
ioctl infrastructure to filter ioctl commands and perform operations that
are common for all host ioctls. Also update the cxlflash documentation to
create a new section for documenting host ioctls.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

To date the only supported internal AFU command is AFU sync. The logic
to send an internal AFU command is embedded in the specific AFU sync
handler and would need to be duplicated for new internal AFU commands.

In order to support new internal AFU commands, separate code that is
common for AFU internal commands into a generic transmission routine
and support passing back command status through an IOASA structure.
The first user of this new routine is the existing AFU sync command.
As a cleanup, use a descriptive name for the AFU sync command instead
of a magic number.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The cxlflash driver currently lacks host management interface. Future
devices supported by cxlflash will provide a variety of host-wide
management functions. Examples include LUN provisioning, hardware debug
support, and firmware download.

In order to provide a way to manage the device, a character device will
be created during probe of each adapter. This device will support a set of
ioctls defined in the SISLite specification from which administrators can
manage the adapter.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

To date, CXL flash devices do not support a single command abort operation.
Instead, the SISLite specification provides a context reset operation to
cleanup all pending commands for a given context.

When a context reset is successful, it is guaranteed that the AFU has
aborted all currently pending I/O. This sequence is less invasive than a
device or host reset and can be executed to support scsi command abort
requests. Add eh_abort_handler callback support to process command timeouts
and abort requests.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When the AFU is reset in an error path, pending scsi commands can be
silently dropped without completion or a formal abort. This puts the onus
on the cxlflash driver to notify mid-layer and indicating that the command
can be retried.

Once the card has been quiesced, the hardware send queue lock is acquired
to prevent any data movement while the pending commands are processed.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Currently, there is no book keeping of the pending scsi commands in the
cxlflash driver. This lack of tracking in-flight requests is too
restrictive and requires a heavy-hammer reset each time an adapter error is
encountered. Additionally, it does not allow for commands to be properly
retried.

In order to avoid this problem and to better handle error path command
cleanup, introduce a linked list for each hardware queue that tracks
pending commands.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

A context reset failure indicates the AFU is in a bad state. At present,
when such a situation occurs, no further action is taken. This leaves the
adapter in an unusable state with no recoverable actions.

To avoid this situation, context reset failures will be escalated to a host
reset operation. This will be done asynchronously to allow the acting
thread to return to the user with a failure.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Per the SISLite specification, context_reset() writes 0x1 to the LSB of the
reset register. When the AFU processes this reset request, it is expected
to clear the bit after reset is complete. The current implementation simply
checks that the entire value read back is not 1, instead of masking off the
LSB and evaluating it for a change to 0. Should the AFU manipulate other
bits during the reset (reading back a value of 0xF for example), successful
completion will be prematurely indicated given the existing logic.

Additionally, in the event that the context reset operation fails, there
does not currently exist a way to provide feedback to the initiator of the
reset. This poses a problem for the rare case that a context reset fails as
the caller will proceed on the assumption that all is well.

To remedy these issues, refactor the context reset routine to only mask off
the LSB when evaluating for success and return status to the caller. Also
update the context reset handler parameters to pass a hardware queue
reference instead of a single command to better reflect that the entire
queue associated with the context is impacted by the reset.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The cxlflash_afu_sync() routine returns a negative one to indicate any kind
of failure. This makes it impossible to establish why the error occurred.

Update the return codes to clearly indicate the failure cause to the
caller.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Currently there are separate spin locks for the two supported I/O queueing
models. This makes it difficult to serialize with paths outside the enqueue
path.

As a design simplification and to support serialization with enqueue
operations, move to only a single lock that is used for enqueueing
regardless of the queueing model.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

As an enhancement to distribute requests to multiple hardware queues, add the
infrastructure to hash a SCSI command into a particular hardware queue.
Support the following scenarios when deriving which queue to use: single
queue, tagging when SCSI-MQ enabled, and simple hash via CPU ID when SCSI-MQ
is disabled. Rather than altering the existing send API, the derived hardware
queue is stored in the AFU command where it can be used for sending a command
to the chosen hardware queue.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

As staging for supporting multiple hardware queues, add an attribute to show
and set the current number of hardware queues for the host. Support specifying
a hard limit or a CPU affinitized value. This will allow the number of
hardware queues to be tuned by a system administrator.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Introduce multiple hardware queues to improve legacy I/O path performance.
Each hardware queue is comprised of a master context and associated I/O
resources. The hardware queues are initially implemented as a static array
embedded in the AFU. This will be transitioned to a dynamic allocation in a
later series to improve the memory footprint of the driver.
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The method used to decode asynchronous interrupts involves unnecessary loops
to match up bits that are set with corresponding entries in the asynchronous
interrupt information table. This algorithm is wasteful and does not scale
well as new status bits are supported.

As an improvement, use the for_each_set_bit() service to iterate over the
asynchronous status bits and refactor the information table such that it can
be indexed by bit position.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Validation statements to enforce assumptions about specific defines are not
being evaluated by the compiler due to the fact that they reside in a routine
that is not used. To activate them, call the routine as part of module
initialization. As an additional, related cleanup, remove the now-defunct
CXLFLASH_NUM_CMDS.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Devices supported by the cxlflash driver are fully coherent and do not require
a bus address mapping. Avoid unnecessary path length by using the virtual
address and length already present in the scatter-gather entry.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

An EEH during probe can lead to a crash as the recovery thread races with the
probe thread. To avoid this issue, introduce new states to fence out EEH
recovery until probe has completed. Also ensure the reset wait queue is
flushed during device removal to avoid orphaned threads.
Signed-off-by: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>