diff mbox series

[v8,08/14] crypto: iaa - Add IAA Compression Accelerator Documentation

Message ID 20230731212939.1391453-9-tom.zanussi@linux.intel.com (mailing list archive)
State Superseded
Delegated to: Herbert Xu
Headers show
Series crypto: Add Intel Analytics Accelerator (IAA) crypto compression driver | expand

Commit Message

Zanussi, Tom July 31, 2023, 9:29 p.m. UTC
Because the IAA Compression Accelerator requires significant user
setup in order to be used properly, this adds documentation on the
iaa_crypto driver including setup, usage, and examples.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 .../driver-api/crypto/iaa/iaa-crypto.rst      | 645 ++++++++++++++++++
 Documentation/driver-api/crypto/iaa/index.rst |  20 +
 Documentation/driver-api/crypto/index.rst     |  20 +
 Documentation/driver-api/index.rst            |   1 +
 4 files changed, 686 insertions(+)
 create mode 100644 Documentation/driver-api/crypto/iaa/iaa-crypto.rst
 create mode 100644 Documentation/driver-api/crypto/iaa/index.rst
 create mode 100644 Documentation/driver-api/crypto/index.rst

Comments

Pavel Machek Aug. 21, 2023, 5:21 p.m. UTC | #1
Hi!

> Because the IAA Compression Accelerator requires significant user
> setup in order to be used properly, this adds documentation on the
> iaa_crypto driver including setup, usage, and examples.
> 
> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>


> +accel-config
> +------------
> +
> +Unlike typical drivers, the iaa_crypto driver does not enable the
> +device on driver load.  Due to complexity and configurability of the
> +accelerator devices, it was a design decision to have the user
> +configure the device and manually enable the desired devices and
> +workqueues.

Is the driver really so special? Is it widely used besides of zswap? Could some kind of 
simple default configuration good enough for zswap be provided?

> +The userspace tool to help doing that is called accel-config.  Using
> +accel-config to configure device or loading a previously saved config
> +is highly recommended.  The device can be controlled via sysfs
> +directly but comes with the warning that do this ONLY if you know
> +exactly what you are doing.  This document will not cover the sysfs
> +interface but assumes you will be using accel-config.

Not covering the interface here is okay, but we really should have description somewhere, 
and there should be pointer to it here.

> +++ b/Documentation/driver-api/crypto/iaa/index.rst
> @@ -0,0 +1,20 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=================================
> +IAA (Intel Analytics Accelerator)
> +=================================
> +
> +IAA provides hardware compression and decompression via the crypto
> +API.

Why is it called "analytics accelerator" when its main function is compression?

Best regards,
                                                                        Pavel
Zanussi, Tom Aug. 21, 2023, 6:44 p.m. UTC | #2
Hi Pavel,

On Mon, 2023-08-21 at 19:21 +0200, Pavel Machek wrote:
> Hi!
> 
> > Because the IAA Compression Accelerator requires significant user
> > setup in order to be used properly, this adds documentation on the
> > iaa_crypto driver including setup, usage, and examples.
> > 
> > Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
> 
> 
> > +accel-config
> > +------------
> > +
> > +Unlike typical drivers, the iaa_crypto driver does not enable the
> > +device on driver load.  Due to complexity and configurability of
> > the
> > +accelerator devices, it was a design decision to have the user
> > +configure the device and manually enable the desired devices and
> > +workqueues.
> 
> Is the driver really so special? Is it widely used besides of zswap?
> Could some kind of 
> simple default configuration good enough for zswap be provided?

You're right, currently its main use is for zswap (though the original
submission also supported zram).

This idea of a simple default configuration makes sense and has come up
before. I'll try to come up with a good way to accomplish that in the
next revision.

> 
> > +The userspace tool to help doing that is called accel-config. 
> > Using
> > +accel-config to configure device or loading a previously saved
> > config
> > +is highly recommended.  The device can be controlled via sysfs
> > +directly but comes with the warning that do this ONLY if you know
> > +exactly what you are doing.  This document will not cover the
> > sysfs
> > +interface but assumes you will be using accel-config.
> 
> Not covering the interface here is okay, but we really should have
> description somewhere, 
> and there should be pointer to it here.

OK, yeah, that also makes sense - I'll add something for that too.

> 
> > +++ b/Documentation/driver-api/crypto/iaa/index.rst
> > @@ -0,0 +1,20 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +=================================
> > +IAA (Intel Analytics Accelerator)
> > +=================================
> > +
> > +IAA provides hardware compression and decompression via the crypto
> > +API.
> 
> Why is it called "analytics accelerator" when its main function is
> compression?
> 

Well, the compression/decompression functions are only a part of what
the hardware provides, so I guess the designers used 'analytics
accelerator' as an umbrella term covering everything.

From the hardware documentation, the IAA hardware "provides very high
throughput compression and decompression combined with analytics
primitive functions. The analytic functions are commonly used for
filtering data during analytic query processing. It primarily targets
applications such as big-data and in-memory analytics databases, as
well as application-transparent usages such as memory page
compression."

Hope that helps explain the naming..

Tom


> Best regards,
>                                                                      
>    Pavel
diff mbox series

Patch

diff --git a/Documentation/driver-api/crypto/iaa/iaa-crypto.rst b/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
new file mode 100644
index 000000000000..aa7b5fa8dbfa
--- /dev/null
+++ b/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
@@ -0,0 +1,645 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+=========================================
+IAA Compression Accelerator Crypto Driver
+=========================================
+
+Tom Zanussi <tom.zanussi@linux.intel.com>
+
+The IAA crypto driver supports compression/decompression compatible
+with the DEFLATE compression standard described in RFC 1951, which is
+the compression/decompression algorithm exported by this module.
+
+The IAA hardware spec can be found here:
+
+  https://cdrdv2.intel.com/v1/dl/getContent/721858
+
+The iaa_crypto driver is designed to work as a layer underneath
+higher-level compression devices such as zswap.
+
+Users can select IAA compress/decompress acceleration by specifying
+one of the supported IAA compression algorithms in whatever facility
+allows compression algorithms to be selected.
+
+For example, a zswap device can select the IAA 'fixed' mode
+represented by selecting the 'deflate-iaa' crypto compression
+algorithm::
+
+  # echo deflate-iaa > /sys/module/zswap/parameters/compressor
+
+This will tell zswap to use the IAA 'fixed' compression mode for all
+compresses and decompresses.
+
+Currently, there is only one compression modes available, 'fixed'
+mode.
+
+The 'fixed' compression mode implements the compression scheme
+specified by RFC 1951 and is given the crypto algorithm name
+'deflate-iaa'.  (Because the IAA hardware has a 4k history-window
+limitation, only buffers <= 4k, or that have been compressed using a
+<= 4k history window, are technically compliant with the deflate spec,
+which allows for a window of up to 32k.  Because of this limitation,
+the IAA fixed mode deflate algorithm is given its own algorithm name
+rather than simply 'deflate').
+
+'fixed' mode can be chosen as the mode to be used for
+compression/decompression via the corresponding crypto algorithm
+name::
+
+  # echo deflate-iaa >  /sys/bus/dsa/drivers/crypto/compression_mode
+
+
+Config options and other setup
+==============================
+
+The IAA crypto driver is available via menuconfig using the following
+path::
+
+  Cryptographic API -> Hardware crypto devices -> Support for Intel(R) IAA Compression Accelerator
+
+In the configuration file the option called CONFIG_CRYPTO_DEV_IAA_CRYPTO.
+
+The IAA crypto driver also supports statistics, which are available
+via menuconfig using the following path::
+
+  Cryptographic API -> Hardware crypto devices -> Support for Intel(R) IAA Compression -> Enable Intel(R) IAA Compression Accelerator Statistics
+
+In the configuration file the option called CONFIG_CRYPTO_DEV_IAA_CRYPTO_STATS.
+
+The following config options should also be enabled::
+
+  CONFIG_IRQ_REMAP=y
+  CONFIG_INTEL_IOMMU=y
+  CONFIG_INTEL_IOMMU_SVM=y
+  CONFIG_PCI_ATS=y
+  CONFIG_PCI_PRI=y
+  CONFIG_PCI_PASID=y
+  CONFIG_INTEL_IDXD=m
+  CONFIG_INTEL_IDXD_SVM=y
+
+IAA is one of the first Intel accelerator IPs that can work in
+conjunction with the Intel IOMMU.  There are multiple modes that exist
+for testing. Based on IOMMU configuration, there are 3 modes::
+
+  - Scalable
+  - Legacy
+  - No IOMMU
+
+
+Scalable mode
+-------------
+
+Scalable mode supports Shared Virtual Memory (SVM or SVA). It is
+entered when using the kernel boot commandline::
+
+  intel_iommu=on,sm_on
+
+with VT-d turned on in BIOS.
+
+With scalable mode, both shared and dedicated workqueues are available
+for use.
+
+For scalable mode, the following BIOS settings should be enabled::
+
+  Socket Configuration > IIO Configuration > Intel VT for Directed I/O (VT-d) > Intel VT for Directed I/O
+
+  Socket Configuration > IIO Configuration > PCIe ENQCMD > ENQCMDS
+
+
+Legacy mode
+-----------
+
+Legacy mode is entered when using the kernel boot commandline::
+
+  intel_iommu=off, intel_iommu=on
+
+or VT-d is not turned on in BIOS.
+
+If you have booted into Linux and not sure if VT-d is on, do a "dmesg
+| grep -i dmar". If you don't see a number of DMAR devices enumerated,
+most likely VT-d is not on.
+
+With legacy mode, only dedicated workqueues are available for use.
+
+
+No IOMMU mode
+-------------
+
+No IOMMU mode is entered when using the kernel boot commandline::
+
+  iommu=off.
+
+With no IOMMU mode, only dedicated workqueues are available for use.
+
+
+Usage
+=====
+
+accel-config
+------------
+
+Unlike typical drivers, the iaa_crypto driver does not enable the
+device on driver load.  Due to complexity and configurability of the
+accelerator devices, it was a design decision to have the user
+configure the device and manually enable the desired devices and
+workqueues.
+
+The userspace tool to help doing that is called accel-config.  Using
+accel-config to configure device or loading a previously saved config
+is highly recommended.  The device can be controlled via sysfs
+directly but comes with the warning that do this ONLY if you know
+exactly what you are doing.  This document will not cover the sysfs
+interface but assumes you will be using accel-config.
+
+The accel-config tool along with instructions for building it can be
+found here:
+
+  https://github.com/intel/idxd-config/#readme
+
+
+Typical usage
+-------------
+
+In order for the iaa_crypto module to actually do any
+compression/decompression work on behalf of a facility, one or more
+IAA workqueues need to be bound to the iaa_crypto driver.
+
+For instance, here's an example of configuring an IAA workqueue and
+binding it to the iaa_crypto driver (note that device names are
+specified as 'iax' rather than 'iaa' - this is because upstream still
+has the old 'iax' device naming in place) ::
+
+  # configure wq1.0
+
+  accel-config config-wq --group-id=0 --mode=dedicated --type=kernel --name="iaa_crypto" --device_name="crypto" iax1/wq1.0
+
+  # enable IAA device iax1
+
+  accel-config enable-device iax1
+
+  # enable wq1.0 on IAX device iax1
+
+  accel-config enable-wq iax1/wq1.0
+
+Whenever a new workqueue is bound to or unbound from the iaa_crypto
+driver, the available workqueues are 'rebalanced' such that work
+submitted from a particular CPU is given to the most appropriate
+workqueue available.  Current best practice is to configure and bind
+at least one workqueue for each IAA device, but as long as there is at
+least one workqueue configured and bound to any IAA device in the
+system, the iaa_crypto driver will work, albeit most likely not as
+efficiently.
+
+The IAA crypto algorigthms is operational and compression and
+decompression operations are fully enabled following the successful
+binding of the first IAA workqueue to the iaa_crypto driver.
+
+Similarly, the IAA crypto algorithm is not operational and compression
+and decompression operations are disabled following the unbinding of
+the last IAA worqueue to the iaa_crypto driver.
+
+As a result, the IAA crypto algorithms and thus the IAA hardware are
+only available when one or more workques are bound to the iaa_crypto
+driver.
+
+When there are no IAA workqueues bound to the driver, the IAA crypto
+algorithms can be unregistered by removing the module.
+
+
+Driver attributes
+-----------------
+
+There are a couple user-configurable driver attributes that can be
+used to configure various modes of operation.  They're listed below,
+along with their default values.  To set any of these attributes, echo
+the appropriate values to the attribute file located under
+/sys/bus/dsa/drivers/crypto/
+
+The attribute settings at the time the IAA algorithms are registered
+are captured in each algorithm's crypto_ctx and used for all compresses
+and decompresses when using that algorithm.
+
+The available attributes are:
+
+  - verify_compress
+
+    Toggle compression verification.  If set, each compress will be
+    internally decompressed and the contents verified, returning error
+    codes if unsuccessful.  This can be toggled with 0/1::
+
+      echo 0 > /sys/bus/dsa/drivers/crypto/verify_compress
+
+    The default setting is '1' - verify all compresses.
+
+  - sync_mode
+
+    Select mode to be used to wait for completion of each compresses
+    and decompress operation.
+
+    The crypto async interface support implemented by iaa_crypto
+    provides an implementation that satisfies the interface but does
+    so in a synchronous manner - it fills and submits the IDXD
+    descriptor and then loops around waiting for it to complete before
+    returning.  This isn't a problem at the moment, since all existing
+    callers (e.g. zswap) wrap any asynchronous callees in a
+    synchronous wrapper anyway.
+
+    The iaa_crypto driver does however provide true asynchronous
+    support for callers that can make use of it.  In this mode, it
+    fills and submits the IDXD descriptor, then returns immediately
+    with -EINPROGRESS.  The caller can then either poll for completion
+    itself, which requires specific code in the caller which currently
+    nothing in the upstream kernel implements, or go to sleep and wait
+    for an interrupt signaling completion.  This latter mode is
+    supported by current users in the kernel such as zswap via
+    synchronous wrappers.  Although it is supported this mode is
+    significantly slower than the synchronous mode that does the
+    polling in the iaa_crypto driver previously mentioned.
+
+    This mode can be enabled by writing 'async_irq' to the sync_mode
+    iaa_crypto driver attribute::
+
+      echo async_irq > /sys/bus/dsa/drivers/crypto/sync_mode
+
+    Async mode without interrupts (caller must poll) can be enabled by
+    writing 'async' to it::
+
+      echo async > /sys/bus/dsa/drivers/crypto/sync_mode
+
+    The mode that does the polling in the iaa_crypto driver can be
+    enabled by writing 'sync' to it::
+
+      echo sync > /sys/bus/dsa/drivers/crypto/sync_mode
+
+    The default mode is 'sync'.
+
+
+Statistics
+==========
+
+If the optional debugfs statistics support is enabled, the IAA crypto
+driver will generate statistics which can be accessed in debugfs at::
+
+  # ls -al /sys/kernel/debug/iaa-crypto/
+  total 0
+  drwxr-xr-x  2 root root 0 Mar  3 09:35 .
+  drwx------ 47 root root 0 Mar  3 09:35 ..
+  -rw-r--r--  1 root root 0 Mar  3 09:35 max_acomp_delay_ns
+  -rw-r--r--  1 root root 0 Mar  3 09:35 max_adecomp_delay_ns
+  -rw-r--r--  1 root root 0 Mar  3 09:35 max_comp_delay_ns
+  -rw-r--r--  1 root root 0 Mar  3 09:35 max_decomp_delay_ns
+  -rw-r--r--  1 root root 0 Mar  3 09:35 stats_reset
+  -rw-r--r--  1 root root 0 Mar  3 09:35 total_comp_bytes_out
+  -rw-r--r--  1 root root 0 Mar  3 09:35 total_comp_calls
+  -rw-r--r--  1 root root 0 Mar  3 09:35 total_decomp_bytes_in
+  -rw-r--r--  1 root root 0 Mar  3 09:35 total_decomp_calls
+  -rw-r--r--  1 root root 0 Mar  3 09:35 wq_stats
+
+Most of the above statisticss are self-explanatory.  The wq_stats file
+shows per-wq stats, a set for each iaa device and wq in addition to
+some global stats::
+
+  # cat wq_stats
+  global stats:
+    total_comp_calls: 100
+    total_decomp_calls: 100
+    total_comp_bytes_out: 22800
+    total_decomp_bytes_in: 22800
+    total_completion_einval_errors: 0
+    total_completion_timeout_errors: 0
+    total_completion_comp_buf_overflow_errors: 0
+
+  iaa device:
+    id: 1
+    n_wqs: 1
+    comp_calls: 0
+    comp_bytes: 0
+    decomp_calls: 0
+    decomp_bytes: 0
+    wqs:
+      name: iaa_crypto
+      comp_calls: 0
+      comp_bytes: 0
+      decomp_calls: 0
+      decomp_bytes: 0
+
+  iaa device:
+    id: 3
+    n_wqs: 1
+    comp_calls: 0
+    comp_bytes: 0
+    decomp_calls: 0
+    decomp_bytes: 0
+    wqs:
+      name: iaa_crypto
+      comp_calls: 0
+      comp_bytes: 0
+      decomp_calls: 0
+      decomp_bytes: 0
+
+  iaa device:
+    id: 5
+    n_wqs: 1
+    comp_calls: 100
+    comp_bytes: 22800
+    decomp_calls: 100
+    decomp_bytes: 22800
+    wqs:
+      name: iaa_crypto
+      comp_calls: 100
+      comp_bytes: 22800
+      decomp_calls: 100
+      decomp_bytes: 22800
+
+Writing 0 to 'stats_reset' resets all the stats, including the
+per-device and per-wq stats::
+
+  # echo 0 > stats_reset
+  # cat wq_stats
+    global stats:
+    total_comp_calls: 0
+    total_decomp_calls: 0
+    total_comp_bytes_out: 0
+    total_decomp_bytes_in: 0
+    total_completion_einval_errors: 0
+    total_completion_timeout_errors: 0
+    total_completion_comp_buf_overflow_errors: 0
+    ...
+
+
+Use cases
+=========
+
+Simple zswap test
+-----------------
+
+For this example, the kernel should be configured according to the
+dedicated mode options described above, and zswap should be enabled as
+well::
+
+  CONFIG_ZSWAP=y
+
+This is a simple test that uses iaa_compress as the compressor for a
+swap (zswap) device.  It sets up the zswap device and then uses the
+memory_memadvise program listed below to forcibly swap out and in a
+specified number of pages, demonstrating both compress and decompress.
+
+The zswap test expects the work queues for each IAA device on the
+system to be configured properly as a kernel workqueue with a
+workqueue driver_name of "crypto".
+
+The first step is to make sure the iaa_crypto module is loaded::
+
+  modprobe iaa_crypto
+
+Following that the IAA device(s) should be configured and enabled.
+
+The zswap test expects the work queues for each IAA device on the
+system to be configured properly as a kernel workqueue with a
+workqueue driver_name of "crypto".
+
+The below script automatically does that::
+
+  #!/bin/bash
+
+  echo "IAA devices:"
+  lspci -d:0cfe
+  echo "# IAA devices:"
+  lspci -d:0cfe | wc -l
+
+  #
+  # count iaa instances
+  #
+  iaa_dev_id="0cfe"
+  num_iaa=$(lspci -d:${iaa_dev_id} | wc -l)
+  echo "Found ${num_iaa} IAA instances"
+
+  #
+  # disable iaa wqs and devices
+  #
+  echo "Disable IAA"
+
+  for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
+      echo disable wq iax${i}/wq${i}.0
+      accel-config disable-wq iax${i}/wq${i}.0
+      echo disable iaa iax${i}
+      accel-config disable-device iax${i}
+  done
+
+  echo "End Disable IAA"
+
+  #
+  # configure iaa wqs and devices
+  #
+  echo "Configure IAA"
+  for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
+      accel-config config-wq --group-id=0 --mode=dedicated --size=128 --priority=10 --type=kernel --name="iaa_crypto" --driver_name="crypto" iax${i}/wq${i}
+  done
+
+  echo "End Configure IAA"
+
+  #
+  # enable iaa wqs and devices
+  #
+  echo "Enable IAA"
+
+  for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
+      echo enable iaa iaa${i}
+      accel-config enable-device iaa${i}
+      echo enable wq iaa${i}/wq${i}.0
+      accel-config enable-wq iaa${i}/wq${i}.0
+  done
+
+  echo "End Enable IAA"
+
+When the workqueues are bound to the iaa_crypto driver, you should
+see something similar to the following in dmesg output if you've
+enabled debug output (echo -n 'module iaa_crypto +p' >
+/sys/kernel/debug/dynamic_debug/control)::
+
+  [   60.752344] idxd 0000:f6:02.0: add_iaa_wq: added wq 000000004068d14d to iaa 00000000c9585ba2, n_wq 1
+  [   60.752346] iaa_crypto: rebalance_wq_table: nr_nodes=2, nr_cpus 160, nr_iaa 8, cpus_per_iaa 20
+  [   60.752347] iaa_crypto: rebalance_wq_table: iaa=0
+  [   60.752349] idxd 0000:6a:02.0: request_iaa_wq: getting wq from iaa_device 0000000042d7bc52 (0)
+  [   60.752350] idxd 0000:6a:02.0: request_iaa_wq: returning unused wq 00000000c8bb4452 (0) from iaa device 0000000042d7bc52 (0)
+  [   60.752352] iaa_crypto: rebalance_wq_table: assigned wq for cpu=0, node=0 = wq 00000000c8bb4452
+  [   60.752354] iaa_crypto: rebalance_wq_table: iaa=0
+  [   60.752355] idxd 0000:6a:02.0: request_iaa_wq: getting wq from iaa_device 0000000042d7bc52 (0)
+  [   60.752356] idxd 0000:6a:02.0: request_iaa_wq: returning unused wq 00000000c8bb4452 (0) from iaa device 0000000042d7bc52 (0)
+  [   60.752358] iaa_crypto: rebalance_wq_table: assigned wq for cpu=1, node=0 = wq 00000000c8bb4452
+  [   60.752359] iaa_crypto: rebalance_wq_table: iaa=0
+  [   60.752360] idxd 0000:6a:02.0: request_iaa_wq: getting wq from iaa_device 0000000042d7bc52 (0)
+  [   60.752361] idxd 0000:6a:02.0: request_iaa_wq: returning unused wq 00000000c8bb4452 (0) from iaa device 0000000042d7bc52 (0)
+  [   60.752362] iaa_crypto: rebalance_wq_table: assigned wq for cpu=2, node=0 = wq 00000000c8bb4452
+  [   60.752364] iaa_crypto: rebalance_wq_table: iaa=0
+  .
+  .
+  .
+
+Once the workqueues and devices have been enabled, the IAA crypto
+algorithms are enabled and available.  When the IAA crypto algorithms
+have been successfully enabled, you should see the following dmesg
+output::
+
+  [   64.893759] iaa_crypto: iaa_crypto_enable: iaa_crypto now ENABLED
+
+Now run the following zswap-specific setup commands to have zswap use
+the 'fixed' compression mode::
+
+  echo 0 > /sys/module/zswap/parameters/enabled
+  echo 50 > /sys/module/zswap/parameters/max_pool_percent
+  echo deflate-iaa > /sys/module/zswap/parameters/compressor
+  echo zsmalloc > /sys/module/zswap/parameters/zpool
+  echo 1 > /sys/module/zswap/parameters/enabled
+  echo 0 > /sys/module/zswap/parameters/same_filled_pages_enabled
+
+  echo 100 > /proc/sys/vm/swappiness
+  echo never > /sys/kernel/mm/transparent_hugepage/enabled
+  echo 1 > /proc/sys/vm/overcommit_memory
+
+Finally, you can now run the zswap workload you want to measure. For
+example, using the code below, the following command will swap in and
+out 100 pages::
+
+  ./memory_madvise 100
+
+  Allocating 100 pages to swap in/out
+  Swapping out 100 pages
+  Swapping in 100 pages
+  Swapped out and in 100 pages
+
+You should see something like the following in the dmesg output if
+you've enabled debug output (echo -n 'module iaa_crypto +p' >
+/sys/kernel/debug/dynamic_debug/control)::
+
+  [  404.202972] idxd 0000:e7:02.0: iaa_comp_acompress: dma_map_sg, src_addr 223925c000, nr_sgs 1, req->src 00000000ee7cb5e6, req->slen 4096, sg_dma_len(sg) 4096
+  [  404.202973] idxd 0000:e7:02.0: iaa_comp_acompress: dma_map_sg, dst_addr 21dadf8000, nr_sgs 1, req->dst 000000008d6acea8, req->dlen 4096, sg_dma_len(sg) 8192
+  [  404.202975] idxd 0000:e7:02.0: iaa_compress: desc->src1_addr 223925c000, desc->src1_size 4096, desc->dst_addr 21dadf8000, desc->max_dst_size 4096, desc->src2_addr 2203543000, desc->src2_size 1568
+  [  404.202981] idxd 0000:e7:02.0: iaa_compress_verify: (verify) desc->src1_addr 21dadf8000, desc->src1_size 228, desc->dst_addr 223925c000, desc->max_dst_size 4096, desc->src2_addr 0, desc->src2_size 0
+  [  409.203227] idxd 0000:e7:02.0: iaa_comp_adecompress: dma_map_sg, src_addr 21ddd8b100, nr_sgs 1, req->src 0000000084adab64, req->slen 228, sg_dma_len(sg) 228
+  [  409.203235] idxd 0000:e7:02.0: iaa_comp_adecompress: dma_map_sg, dst_addr 21ee3dc000, nr_sgs 1, req->dst 000000004e2990d0, req->dlen 4096, sg_dma_len(sg) 4096
+  [  409.203239] idxd 0000:e7:02.0: iaa_decompress: desc->src1_addr 21ddd8b100, desc->src1_size 228, desc->dst_addr 21ee3dc000, desc->max_dst_size 4096, desc->src2_addr 0, desc->src2_size 0
+  [  409.203254] idxd 0000:e7:02.0: iaa_comp_adecompress: dma_map_sg, src_addr 21ddd8b100, nr_sgs 1, req->src 0000000084adab64, req->slen 228, sg_dma_len(sg) 228
+  [  409.203256] idxd 0000:e7:02.0: iaa_comp_adecompress: dma_map_sg, dst_addr 21f1551000, nr_sgs 1, req->dst 000000004e2990d0, req->dlen 4096, sg_dma_len(sg) 4096
+  [  409.203257] idxd 0000:e7:02.0: iaa_decompress: desc->src1_addr 21ddd8b100, desc->src1_size 228, desc->dst_addr 21f1551000, desc->max_dst_size 4096, desc->src2_addr 0, desc->src2_size 0
+
+In order to unregister the IAA crypto algorithms, and register new
+ones using different parameters, any users of the current algorithm
+should be stopped and the IAA workqueues and devices disabled.
+
+In the case of zswap, remove the IAA crypto algorithm as the
+compressor and turn off swap (to remove all references to
+iaa_crypto)::
+
+  echo lzo > /sys/module/zswap/parameters/compressor
+  swapoff -a
+
+  echo 0 > /sys/module/zswap/parameters/accept_threshold_percent
+  echo 0 > /sys/module/zswap/parameters/max_pool_percent
+  echo 0 > /sys/module/zswap/parameters/enabled
+
+Once zswap is disabled and no longer using iaa_crypto, the IAA wqs and
+devices can be disabled.
+
+The below script automatically does that::
+
+  #!/bin/bash
+
+  echo "IAA devices:"
+  lspci -d:0cfe
+  echo "# IAA devices:"
+  lspci -d:0cfe | wc -l
+
+  #
+  # count iaa instances
+  #
+  iaa_dev_id="0cfe"
+  num_iaa=$(lspci -d:${iaa_dev_id} | wc -l)
+  echo "Found ${num_iaa} IAA instances"
+
+  #
+  # disable iaa wqs and devices
+  #
+  echo "Disable IAA"
+
+  for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
+      echo disable wq iax${i}/wq${i}.0
+      accel-config disable-wq iax${i}/wq${i}.0
+      echo disable iaa iax${i}
+      accel-config disable-device iax${i}
+  done
+
+  echo "End Disable IAA"
+
+Finally, at this point the iaa_crypto module can be removed, which
+will unregister the current IAA crypto algorithms::
+
+  rmmod iaa_crypto
+
+
+memory_madvise.c (gcc -o memory_memadvise memory_madvise.c)::
+
+  #include <stdio.h>
+  #include <stdlib.h>
+  #include <string.h>
+  #include <unistd.h>
+  #include <sys/mman.h>
+  #include <linux/mman.h>
+
+  #ifndef MADV_PAGEOUT
+  #define MADV_PAGEOUT    21      /* force pages out immediately */
+  #endif
+
+  #define PG_SZ           4096
+
+  int main(int argc, char **argv)
+  {
+        int i, nr_pages = 1;
+        int64_t *dump_ptr;
+        char *addr, *a;
+        int loop = 1;
+
+        if (argc > 1)
+                nr_pages = atoi(argv[1]);
+
+        printf("Allocating %d pages to swap in/out\n", nr_pages);
+
+        /* allocate pages */
+        addr = mmap(NULL, nr_pages * PG_SZ, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+        *addr = 1;
+
+        /* initialize data in page to all '*' chars */
+        memset(addr, '*', nr_pages * PG_SZ);
+
+         printf("Swapping out %d pages\n", nr_pages);
+
+        /* Tell kernel to swap it out */
+        madvise(addr, nr_pages * PG_SZ, MADV_PAGEOUT);
+
+        while (loop > 0) {
+                /* Wait for swap out to finish */
+                sleep(5);
+
+                a = addr;
+
+                printf("Swapping in %d pages\n", nr_pages);
+
+                /* Access the page ... this will swap it back in again */
+                for (i = 0; i < nr_pages; i++) {
+                        if (a[0] != '*') {
+                                printf("Bad data from decompress!!!!!\n");
+
+                                dump_ptr = (int64_t *)a;
+                                 for (int j = 0; j < 100; j++) {
+                                        printf("  page %d data: %#llx\n", i, *dump_ptr);
+                                        dump_ptr++;
+                                }
+                        }
+
+                        a += PG_SZ;
+                }
+
+                loop --;
+        }
+
+       printf("Swapped out and in %d pages\n", nr_pages);
diff --git a/Documentation/driver-api/crypto/iaa/index.rst b/Documentation/driver-api/crypto/iaa/index.rst
new file mode 100644
index 000000000000..aa6837e27264
--- /dev/null
+++ b/Documentation/driver-api/crypto/iaa/index.rst
@@ -0,0 +1,20 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================
+IAA (Intel Analytics Accelerator)
+=================================
+
+IAA provides hardware compression and decompression via the crypto
+API.
+
+.. toctree::
+   :maxdepth: 1
+
+   iaa-crypto
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/driver-api/crypto/index.rst b/Documentation/driver-api/crypto/index.rst
new file mode 100644
index 000000000000..fb9709b98bea
--- /dev/null
+++ b/Documentation/driver-api/crypto/index.rst
@@ -0,0 +1,20 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+Crypto Drivers
+==============
+
+Documentation for crypto drivers that may need more involved setup and
+configuration.
+
+.. toctree::
+   :maxdepth: 1
+
+   iaa/index
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst
index 1e16a40da3ba..f0f8f521f65b 100644
--- a/Documentation/driver-api/index.rst
+++ b/Documentation/driver-api/index.rst
@@ -114,6 +114,7 @@  available subsections can be seen below.
    zorro
    hte/index
    wmi
+   crypto/index
 
 .. only::  subproject and html