Re: [PATCH v5 1/7] fpga: sec-mgr: intel fpga security manager class driver

[Russ Weight]

I see that I need to remove "intel" from the subject line on this patch.
I'll take care of that.

I still have an outstanding question about treating a class-driver as a
managed resource of the parent device. I'm reposting the question inline.

On 10/20/20 5:16 PM, Russ Weight wrote:
> Create the FPGA Security Manager class driver. The security
> manager provides interfaces to manage secure updates for the
> FPGA and BMC images that are stored in FLASH. The driver can
> also be used to update root entry hashes and to cancel code
> signing keys.
>
> This patch creates the class driver and provides sysfs
> interfaces for displaying root entry hashes, canceled code
> signing keys and flash counts.
>
> Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
> Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
> ---
> v5:
>   - Added the devm_fpga_sec_mgr_unregister() function, following recent
>     changes to the fpga_manager() implementation.
>   - Changed some *_show() functions to use sysfs_emit() instead of sprintf(
> v4:
>   - Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
>     and removed unnecessary references to "Intel".
>   - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
> v3:
>   - Modified sysfs handler check in check_sysfs_handler() to make
>     it more readable.
> v2:
>   - Bumped documentation dates and versions
>   - Added Documentation/fpga/ifpga-sec-mgr.rst 
>   - Removed references to bmc_flash_count & smbus_flash_count (not supported)
>   - Split ifpga_sec_mgr_register() into create() and register() functions
>   - Added devm_ifpga_sec_mgr_create()
>   - Removed typedefs for imgr ops
> ---
>  .../ABI/testing/sysfs-class-fpga-sec-mgr      |  67 +++
>  Documentation/fpga/fpga-sec-mgr.rst           |  50 ++
>  Documentation/fpga/index.rst                  |   1 +
>  MAINTAINERS                                   |   9 +
>  drivers/fpga/Kconfig                          |   9 +
>  drivers/fpga/Makefile                         |   3 +
>  drivers/fpga/fpga-sec-mgr.c                   | 487 ++++++++++++++++++
>  include/linux/fpga/fpga-sec-mgr.h             |  83 +++
>  8 files changed, 709 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
>  create mode 100644 Documentation/fpga/fpga-sec-mgr.rst
>  create mode 100644 drivers/fpga/fpga-sec-mgr.c
>  create mode 100644 include/linux/fpga/fpga-sec-mgr.h
>
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> new file mode 100644
> index 000000000000..843f0b58f171
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> @@ -0,0 +1,67 @@
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/name
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Name of low level fpga security manager driver.
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/sr_root_entry_hash
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns the root entry hash for the static
> +		region if one is programmed, else it returns the
> +		string: "hash not programmed".  This file is only
> +		visible if the underlying device supports it.
> +		Format: "0x%x".
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/pr_root_entry_hash
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns the root entry hash for the partial
> +		reconfiguration region if one is programmed, else it
> +		returns the string: "hash not programmed".  This file
> +		is only visible if the underlying device supports it.
> +		Format: "0x%x".
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/bmc_root_entry_hash
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns the root entry hash for the BMC image
> +		if one is programmed, else it returns the string:
> +		"hash not programmed".  This file is only visible if the
> +		underlying device supports it.
> +		Format: "0x%x".
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/sr_canceled_csks
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the static region. The standard bitmap
> +		list format is used (e.g. "1,2-6,9").
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/pr_canceled_csks
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the partial reconfiguration region. The
> +		standard bitmap list format is used (e.g. "1,2-6,9").
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/bmc_canceled_csks
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the BMC.  The standard bitmap list format
> +		is used (e.g. "1,2-6,9").
> +
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/security/user_flash_count
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +Description:	Read only. Returns number of times the user image for the
> +		static region has been flashed.
> +		Format: "%u".
> diff --git a/Documentation/fpga/fpga-sec-mgr.rst b/Documentation/fpga/fpga-sec-mgr.rst
> new file mode 100644
> index 000000000000..4a1d6519b1d3
> --- /dev/null
> +++ b/Documentation/fpga/fpga-sec-mgr.rst
> @@ -0,0 +1,50 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +========================================
> +FPGA Security Manager Class Driver
> +========================================
> +
> +The FPGA Security Manager class driver provides a common
> +API for user-space tools to manage updates for secure FPGA
> +devices. Device drivers that instantiate the Security
> +Manager class driver will interact with a HW secure update
> +engine in order to transfer new FPGA and BMC images to FLASH so
> +that they will be automatically loaded when the FPGA card reboots.
> +
> +A significant difference between the FPGA Manager and the FPGA
> +Security Manager is that the FPGA Manager does a live update (Partial
> +Reconfiguration) to a device, whereas the FPGA Security Manager
> +updates the FLASH images for the Static Region and the BMC so that
> +they will be loaded the next time the FPGA card boots. Security is
> +enforced by hardware and firmware. The security manager interacts
> +with the firmware to initiate an update, pass in the necessary data,
> +and collect status on the update.
> +
> +In addition to managing secure updates of the FPGA and BMC images,
> +the FPGA Security Manager update process may also used to
> +program root entry hashes and cancellation keys for the FPGA static
> +region, the FPGA partial reconfiguration region, and the BMC.
> +
> +Secure updates make use of the request_firmware framework, which
> +requires that image files are accessible under /lib/firmware. A request
> +for a secure update returns immediately, while the update itself
> +proceeds in the context of a kernel worker thread. Sysfs files provide
> +a means for monitoring the progress of a secure update and for
> +retrieving error information in the event of a failure.
> +
> +Sysfs Attributes
> +================
> +
> +The API consists of two groups of sysfs attributes as described below.
> +
> +1. Files in the *security* sub-directory can be used to read security
> +   information including: Root Entry Hashes (REH), Cancelled Code
> +   Signing Keys (CSK), and the flash update count for FPGA images.
> +
> +2. Files in the *update* sub-directory can be used to instantiate and
> +   monitor a secure update.
> +
> +
> +See `<../ABI/testing/sysfs-class-fpga-sec-mgr>`__ for a full
> +description of the sysfs attributes for the FPGA Security
> +Manager.
> diff --git a/Documentation/fpga/index.rst b/Documentation/fpga/index.rst
> index f80f95667ca2..0b2f427042af 100644
> --- a/Documentation/fpga/index.rst
> +++ b/Documentation/fpga/index.rst
> @@ -8,6 +8,7 @@ fpga
>      :maxdepth: 1
>  
>      dfl
> +    fpga-sec-mgr
>  
>  .. only::  subproject and html
>  
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4538378de6f5..7997fff716a8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6901,6 +6901,15 @@ F:	Documentation/fpga/
>  F:	drivers/fpga/
>  F:	include/linux/fpga/
>  
> +FPGA SECURITY MANAGER DRIVERS
> +M:	Russ Weight <russell.h.weight@xxxxxxxxx>
> +L:	linux-fpga@xxxxxxxxxxxxxxx
> +S:	Maintained
> +F:	Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> +F:	Documentation/fpga/fpga-sec-mgr.rst
> +F:	drivers/fpga/fpga-sec-mgr.c
> +F:	include/linux/fpga/fpga-sec-mgr.h
> +
>  FPU EMULATOR
>  M:	Bill Metzenthen <billm@xxxxxxxxxxxxx>
>  S:	Maintained
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index 7cd5a29fc437..6810b23b178d 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -215,4 +215,13 @@ config FPGA_MGR_ZYNQMP_FPGA
>  	  to configure the programmable logic(PL) through PS
>  	  on ZynqMP SoC.
>  
> +config FPGA_SEC_MGR
> +	tristate "FPGA Security Manager"
> +	help
> +	  The Security Manager class driver presents a common
> +	  user API for managing secure updates for FPGA
> +	  devices, including flash images for the FPGA static
> +	  region and for the BMC. Select this option to enable
> +	  updates for secure FPGA devices.
> +
>  endif # FPGA
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index d8e21dfc6778..0e357262faed 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -21,6 +21,9 @@ obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE)         += altera-pr-ip-core.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
>  
> +# FPGA Security Manager Framework
> +obj-$(CONFIG_FPGA_SEC_MGR)		+= fpga-sec-mgr.o
> +
>  # FPGA Bridge Drivers
>  obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
>  obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)	+= altera-hps2fpga.o altera-fpga2sdram.o
> diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
> new file mode 100644
> index 000000000000..95b5a7ccbe44
> --- /dev/null
> +++ b/drivers/fpga/fpga-sec-mgr.c
> @@ -0,0 +1,487 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * FPGA Security Manager
> + *
> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> + */
> +
> +#include <linux/fpga/fpga-sec-mgr.h>
> +#include <linux/idr.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +
> +static DEFINE_IDA(fpga_sec_mgr_ida);
> +static struct class *fpga_sec_mgr_class;
> +
> +struct fpga_sec_mgr_devres {
> +	struct fpga_sec_mgr *smgr;
> +};
> +
> +#define to_sec_mgr(d) container_of(d, struct fpga_sec_mgr, dev)
> +
> +static ssize_t
> +show_canceled_csk(struct fpga_sec_mgr *smgr,
> +		  int (*get_csk)(struct fpga_sec_mgr *smgr,
> +				 unsigned long *csk_map, unsigned int nbits),
> +		  int (*get_csk_nbits)(struct fpga_sec_mgr *smgr),
> +		  char *buf)
> +{
> +	unsigned long *csk_map = NULL;
> +	unsigned int nbits;
> +	int ret;
> +
> +	ret = get_csk_nbits(smgr);
> +	if (ret < 0)
> +		return ret;
> +
> +	nbits = (unsigned int)ret;
> +	csk_map = vmalloc(sizeof(unsigned long) * BITS_TO_LONGS(nbits));
> +	if (!csk_map)
> +		return -ENOMEM;
> +
> +	ret = get_csk(smgr, csk_map, nbits);
> +	if (ret)
> +		goto vfree_exit;
> +
> +	ret = bitmap_print_to_pagebuf(1, buf, csk_map, nbits);
> +
> +vfree_exit:
> +	vfree(csk_map);
> +	return ret;
> +}
> +
> +static ssize_t
> +show_root_entry_hash(struct fpga_sec_mgr *smgr,
> +		     int (*get_reh)(struct fpga_sec_mgr *smgr, u8 *hash,
> +				    unsigned int size),
> +		     int (*get_reh_size)(struct fpga_sec_mgr *smgr),
> +		     char *buf)
> +{
> +	int size, i, cnt, ret;
> +	u8 *hash;
> +
> +	ret = get_reh_size(smgr);
> +	if (ret < 0)
> +		return ret;
> +	else if (!ret)
> +		return sysfs_emit(buf, "hash not programmed\n");
> +
> +	size = ret;
> +	hash = vmalloc(size);
> +	if (!hash)
> +		return -ENOMEM;
> +
> +	ret = get_reh(smgr, hash, size);
> +	if (ret)
> +		goto vfree_exit;
> +
> +	cnt = sprintf(buf, "0x");
> +	for (i = 0; i < size; i++)
> +		cnt += sprintf(buf + cnt, "%02x", hash[i]);
> +	cnt += sprintf(buf + cnt, "\n");
> +
> +vfree_exit:
> +	vfree(hash);
> +	return ret ? : cnt;
> +}
> +
> +#define DEVICE_ATTR_SEC_CSK(_name) \
> +static ssize_t _name##_canceled_csks_show(struct device *dev, \
> +					  struct device_attribute *attr, \
> +					  char *buf) \
> +{ \
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(dev); \
> +	return show_canceled_csk(smgr, \
> +	       smgr->sops->_name##_canceled_csks, \
> +	       smgr->sops->_name##_canceled_csk_nbits, buf); \
> +} \
> +static DEVICE_ATTR_RO(_name##_canceled_csks)
> +
> +#define DEVICE_ATTR_SEC_ROOT_ENTRY_HASH(_name) \
> +static ssize_t _name##_root_entry_hash_show(struct device *dev, \
> +				     struct device_attribute *attr, \
> +				     char *buf) \
> +{ \
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(dev); \
> +	return show_root_entry_hash(smgr, \
> +	       smgr->sops->_name##_root_entry_hash, \
> +	       smgr->sops->_name##_reh_size, buf); \
> +} \
> +static DEVICE_ATTR_RO(_name##_root_entry_hash)
> +
> +static ssize_t user_flash_count_show(struct device *dev,
> +				     struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
> +	int cnt = smgr->sops->user_flash_count(smgr);
> +
> +	return cnt < 0 ? cnt : sysfs_emit(buf, "%u\n", cnt);
> +}
> +static DEVICE_ATTR_RO(user_flash_count);
> +
> +DEVICE_ATTR_SEC_ROOT_ENTRY_HASH(sr);
> +DEVICE_ATTR_SEC_ROOT_ENTRY_HASH(pr);
> +DEVICE_ATTR_SEC_ROOT_ENTRY_HASH(bmc);
> +DEVICE_ATTR_SEC_CSK(sr);
> +DEVICE_ATTR_SEC_CSK(pr);
> +DEVICE_ATTR_SEC_CSK(bmc);
> +
> +static struct attribute *sec_mgr_security_attrs[] = {
> +	&dev_attr_user_flash_count.attr,
> +	&dev_attr_bmc_root_entry_hash.attr,
> +	&dev_attr_sr_root_entry_hash.attr,
> +	&dev_attr_pr_root_entry_hash.attr,
> +	&dev_attr_sr_canceled_csks.attr,
> +	&dev_attr_pr_canceled_csks.attr,
> +	&dev_attr_bmc_canceled_csks.attr,
> +	NULL,
> +};
> +
> +#define check_attr(attribute, _name) \
> +	((attribute) == &dev_attr_##_name.attr && smgr->sops->_name)
> +
> +static umode_t sec_mgr_visible(struct kobject *kobj,
> +			       struct attribute *attr, int n)
> +{
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(kobj_to_dev(kobj));
> +
> +	/*
> +	 * Only display optional sysfs attributes if a
> +	 * corresponding handler is provided
> +	 */
> +	if (check_attr(attr, user_flash_count) ||
> +	    check_attr(attr, bmc_root_entry_hash) ||
> +	    check_attr(attr, sr_root_entry_hash) ||
> +	    check_attr(attr, pr_root_entry_hash) ||
> +	    check_attr(attr, sr_canceled_csks) ||
> +	    check_attr(attr, pr_canceled_csks) ||
> +	    check_attr(attr, bmc_canceled_csks))
> +		return attr->mode;
> +
> +	return 0;
> +}
> +
> +static struct attribute_group sec_mgr_security_attr_group = {
> +	.name = "security",
> +	.attrs = sec_mgr_security_attrs,
> +	.is_visible = sec_mgr_visible,
> +};
> +
> +static ssize_t name_show(struct device *dev,
> +			 struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
> +
> +	return sysfs_emit(buf, "%s\n", smgr->name);
> +}
> +static DEVICE_ATTR_RO(name);
> +
> +static struct attribute *sec_mgr_attrs[] = {
> +	&dev_attr_name.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group sec_mgr_attr_group = {
> +	.attrs = sec_mgr_attrs,
> +};
> +
> +static const struct attribute_group *fpga_sec_mgr_attr_groups[] = {
> +	&sec_mgr_attr_group,
> +	&sec_mgr_security_attr_group,
> +	NULL,
> +};
> +
> +static bool check_sysfs_handler(struct device *dev,
> +				void *sysfs_handler, void *size_handler,
> +				const char *sysfs_handler_name,
> +				const char *size_handler_name)
> +{
> +	/*
> +	 * sysfs_handler and size_handler must either both be
> +	 * defined or both be NULL.
> +	 */
> +	if (sysfs_handler && !size_handler) {
> +		dev_err(dev, "%s registered without %s\n",
> +			sysfs_handler_name, size_handler_name);
> +		return false;
> +	} else if (!sysfs_handler && size_handler) {
> +		dev_err(dev, "%s registered without %s\n",
> +			size_handler_name, sysfs_handler_name);
> +		return false;
> +	}
> +	return true;
> +}
> +
> +#define check_reh_handler(_dev, _sops, _name) \
> +	check_sysfs_handler(_dev, (_sops)->_name##_root_entry_hash, \
> +			    (_sops)->_name##_reh_size, \
> +			    __stringify(_name##_root_entry_hash), \
> +			    __stringify(_name##_reh_size))
> +
> +#define check_csk_handler(_dev, _sops, _name) \
> +	check_sysfs_handler(_dev, (_sops)->_name##_canceled_csks, \
> +			    (_sops)->_name##_canceled_csk_nbits, \
> +			    __stringify(_name##_canceled_csks), \
> +			    __stringify(_name##_canceled_csk_nbits))
> +
> +/**
> + * fpga_sec_mgr_create - create and initialize an FPGA
> + *			  security manager struct
> + *
> + * @dev:  fpga security manager device from pdev
> + * @name: fpga security manager name
> + * @sops: pointer to a structure of fpga callback functions
> + * @priv: fpga security manager private data
> + *
> + * The caller of this function is responsible for freeing the struct
> + * with ifpg_sec_mgr_free(). Using devm_fpga_sec_mgr_create() instead
> + * is recommended.
> + *
> + * Return: pointer to struct fpga_sec_mgr or NULL
> + */
> +struct fpga_sec_mgr *
> +fpga_sec_mgr_create(struct device *dev, const char *name,
> +		    const struct fpga_sec_mgr_ops *sops, void *priv)
> +{
> +	struct fpga_sec_mgr *smgr;
> +	int id, ret;
> +
> +	if (!check_reh_handler(dev, sops, bmc) ||
> +	    !check_reh_handler(dev, sops, sr) ||
> +	    !check_reh_handler(dev, sops, pr) ||
> +	    !check_csk_handler(dev, sops, bmc) ||
> +	    !check_csk_handler(dev, sops, sr) ||
> +	    !check_csk_handler(dev, sops, pr)) {
> +		return NULL;
> +	}
> +
> +	if (!name || !strlen(name)) {
> +		dev_err(dev, "Attempt to register with no name!\n");
> +		return NULL;
> +	}
> +
> +	smgr = kzalloc(sizeof(*smgr), GFP_KERNEL);
> +	if (!smgr)
> +		return NULL;
> +
> +	id = ida_simple_get(&fpga_sec_mgr_ida, 0, 0, GFP_KERNEL);
> +	if (id < 0)
> +		goto error_kfree;
> +
> +	mutex_init(&smgr->lock);
> +
> +	smgr->name = name;
> +	smgr->priv = priv;
> +	smgr->sops = sops;
> +
> +	device_initialize(&smgr->dev);
> +	smgr->dev.class = fpga_sec_mgr_class;
> +	smgr->dev.parent = dev;
> +	smgr->dev.id = id;
> +
> +	ret = dev_set_name(&smgr->dev, "fpga_sec%d", id);
> +	if (ret) {
> +		dev_err(dev, "Failed to set device name: fpga_sec%d\n", id);
> +		goto error_device;
> +	}
> +
> +	return smgr;
> +
> +error_device:
> +	ida_simple_remove(&fpga_sec_mgr_ida, id);
> +
> +error_kfree:
> +	kfree(smgr);
> +
> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_create);
> +
> +/**
> + * fpga_sec_mgr_free - free an FPGA security manager created
> + *			with fpga_sec_mgr_create()
> + *
> + * @smgr:	FPGA security manager structure
> + */
> +void fpga_sec_mgr_free(struct fpga_sec_mgr *smgr)
> +{
> +	ida_simple_remove(&fpga_sec_mgr_ida, smgr->dev.id);
> +	kfree(smgr);
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_free);
> +
> +static void devm_fpga_sec_mgr_release(struct device *dev, void *res)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	fpga_sec_mgr_free(dr->smgr);
> +}
> +
> +/**
> + * devm_fpga_sec_mgr_create - create and initialize an FPGA
> + *			       security manager struct
> + *
> + * @dev:  fpga security manager device from pdev
> + * @name: fpga security manager name
> + * @sops: pointer to a structure of fpga callback functions
> + * @priv: fpga security manager private data
> + *
> + * This function is intended for use in a FPGA Security manager
> + * driver's probe function.  After the security manager driver creates
> + * the fpga_sec_mgr struct with devm_fpga_sec_mgr_create(), it should
> + * register it with devm_fpga_sec_mgr_register().
> + * The fpga_sec_mgr struct allocated with this function will be freed
> + * automatically on driver detach.
> + *
> + * Return: pointer to struct fpga_sec_mgr or NULL
> + */
> +struct fpga_sec_mgr *
> +devm_fpga_sec_mgr_create(struct device *dev, const char *name,
> +			 const struct fpga_sec_mgr_ops *sops, void *priv)
> +{
> +	struct fpga_sec_mgr_devres *dr;
> +
> +	dr = devres_alloc(devm_fpga_sec_mgr_release, sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return NULL;
> +
> +	dr->smgr = fpga_sec_mgr_create(dev, name, sops, priv);
> +	if (!dr->smgr) {
> +		devres_free(dr);
> +		return NULL;
> +	}
> +
> +	devres_add(dev, dr);
> +
> +	return dr->smgr;
> +}
> +EXPORT_SYMBOL_GPL(devm_fpga_sec_mgr_create);
> +
> +/**
> + * fpga_sec_mgr_register - register an FPGA security manager
> + *
> + * @smgr: fpga security manager struct
> + *
> + * Return: 0 on success, negative error code otherwise.
> + */
> +int fpga_sec_mgr_register(struct fpga_sec_mgr *smgr)
> +{
> +	int ret;
> +
> +	ret = device_add(&smgr->dev);
> +	if (ret)
> +		goto error_device;

The comment header for device_add() includes the following text:

 * NOTE: _Never_ directly free @dev after calling this function, even
 * if it returned an error! Always use put_device() to give up your
 * reference instead.
 *
 * Rule of thumb is: if device_add() succeeds, you should call
 * device_del() when you want to get rid of it. If device_add() has
 * *not* succeeded, use *only* put_device() to drop the reference
 * count.

This implementation of the security manager requires that the parent
driver treat the fpga_sec_mgr data structure as a a managed resource
of the parent device using the devm_ version of the create() function.

The device structure that is passed to device_add() is embedded in the
fpga_sec_mgr data structure.

Does this conflict with the core driver functions? Is it possible that
we are deleting a device structure that is still being tracked by the
core driver code?

- Russ

> +
> +	dev_info(&smgr->dev, "%s registered\n", smgr->name);
> +
> +	return 0;
> +
> +error_device:
> +	ida_simple_remove(&fpga_sec_mgr_ida, smgr->dev.id);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_register);
> +
> +/**
> + * fpga_sec_mgr_unregister - unregister an FPGA security manager
> + *
> + * @mgr: fpga manager struct
> + *
> + * This function is intended for use in an FPGA security manager
> + * driver's remove() function.
> + */
> +void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr)
> +{
> +	dev_info(&smgr->dev, "%s %s\n", __func__, smgr->name);
> +
> +	device_unregister(&smgr->dev);
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_unregister);
> +
> +static int fpga_sec_mgr_devres_match(struct device *dev, void *res,
> +				     void *match_data)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	return match_data == dr->smgr;
> +}
> +
> +static void devm_fpga_sec_mgr_unregister(struct device *dev, void *res)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	fpga_sec_mgr_unregister(dr->smgr);
> +}
> +
> +/**
> + * devm_fpga_sec_mgr_register - resource managed variant of
> + *				fpga_sec_mgr_register()
> + *
> + * @dev: managing device for this FPGA security manager
> + * @smgr: fpga security manager struct
> + *
> + * This is the devres variant of fpga_sec_mgr_register() for which the
> + * unregister function will be called automatically when the managing
> + * device is detached.
> + */
> +int devm_fpga_sec_mgr_register(struct device *dev, struct fpga_sec_mgr *smgr)
> +{
> +	struct fpga_sec_mgr_devres *dr;
> +	int ret;
> +
> +	/*
> +	 * Make sure that the struct fpga_sec_mgr * that is passed in is
> +	 * managed itself.
> +	 */
> +	if (WARN_ON(!devres_find(dev, devm_fpga_sec_mgr_release,
> +				 fpga_sec_mgr_devres_match, smgr)))
> +		return -EINVAL;
> +
> +	dr = devres_alloc(devm_fpga_sec_mgr_unregister, sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return -ENOMEM;
> +
> +	ret = fpga_sec_mgr_register(smgr);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	dr->smgr = smgr;
> +	devres_add(dev, dr);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_fpga_sec_mgr_register);
> +
> +static void fpga_sec_mgr_dev_release(struct device *dev)
> +{
> +}
> +
> +static int __init fpga_sec_mgr_class_init(void)
> +{
> +	pr_info("FPGA Security Manager\n");
> +
> +	fpga_sec_mgr_class = class_create(THIS_MODULE, "fpga_sec_mgr");
> +	if (IS_ERR(fpga_sec_mgr_class))
> +		return PTR_ERR(fpga_sec_mgr_class);
> +
> +	fpga_sec_mgr_class->dev_groups = fpga_sec_mgr_attr_groups;
> +	fpga_sec_mgr_class->dev_release = fpga_sec_mgr_dev_release;
> +
> +	return 0;
> +}
> +
> +static void __exit fpga_sec_mgr_class_exit(void)
> +{
> +	class_destroy(fpga_sec_mgr_class);
> +	ida_destroy(&fpga_sec_mgr_ida);
> +}
> +
> +MODULE_DESCRIPTION("FPGA Security Manager Driver");
> +MODULE_LICENSE("GPL v2");
> +
> +subsys_initcall(fpga_sec_mgr_class_init);
> +module_exit(fpga_sec_mgr_class_exit)
> diff --git a/include/linux/fpga/fpga-sec-mgr.h b/include/linux/fpga/fpga-sec-mgr.h
> new file mode 100644
> index 000000000000..dd596c6c3748
> --- /dev/null
> +++ b/include/linux/fpga/fpga-sec-mgr.h
> @@ -0,0 +1,83 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Header file for FPGA Security Manager
> + *
> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> + */
> +#ifndef _LINUX_FPGA_SEC_MGR_H
> +#define _LINUX_FPGA_SEC_MGR_H
> +
> +#include <linux/device.h>
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +struct fpga_sec_mgr;
> +
> +/**
> + * struct fpga_sec_mgr_ops - device specific operations
> + * @user_flash_count:	    Optional: Return sysfs string output for FPGA
> + *			    image flash count
> + * @sr_root_entry_hash:	    Optional: Return sysfs string output for static
> + *			    region root entry hash
> + * @pr_root_entry_hash:	    Optional: Return sysfs string output for partial
> + *			    reconfiguration root entry hash
> + * @bmc_root_entry_hash:    Optional: Return sysfs string output for BMC
> + *			    root entry hash
> + * @sr_canceled_csks:	    Optional: Return sysfs string output for static
> + *			    region canceled keys
> + * @pr_canceled_csks:	    Optional: Return sysfs string output for partial
> + *			    reconfiguration canceled keys
> + * @bmc_canceled_csks:	    Optional: Return sysfs string output for bmc
> + *			    canceled keys
> + * @bmc_canceled_csk_nbits: Optional: Return BMC canceled csk vector bit count
> + * @sr_canceled_csk_nbits:  Optional: Return SR canceled csk vector bit count
> + * @pr_canceled_csk_nbits:  Optional: Return PR canceled csk vector bit count
> + * @bmc_reh_size:	    Optional: Return byte size for BMC root entry hash
> + * @sr_reh_size:	    Optional: Return byte size for SR root entry hash
> + * @pr_reh_size:	    Optional: Return byte size for PR root entry hash
> + */
> +struct fpga_sec_mgr_ops {
> +	int (*user_flash_count)(struct fpga_sec_mgr *smgr);
> +	int (*bmc_root_entry_hash)(struct fpga_sec_mgr *smgr, u8 *hash,
> +				   unsigned int size);
> +	int (*sr_root_entry_hash)(struct fpga_sec_mgr *smgr, u8 *hash,
> +				  unsigned int size);
> +	int (*pr_root_entry_hash)(struct fpga_sec_mgr *smgr, u8 *hash,
> +				  unsigned int size);
> +	int (*bmc_canceled_csks)(struct fpga_sec_mgr *smgr,
> +				 unsigned long *csk_map, unsigned int nbits);
> +	int (*sr_canceled_csks)(struct fpga_sec_mgr *smgr,
> +				unsigned long *csk_map, unsigned int nbits);
> +	int (*pr_canceled_csks)(struct fpga_sec_mgr *smgr,
> +				unsigned long *csk_map, unsigned int nbits);
> +	int (*bmc_reh_size)(struct fpga_sec_mgr *smgr);
> +	int (*sr_reh_size)(struct fpga_sec_mgr *smgr);
> +	int (*pr_reh_size)(struct fpga_sec_mgr *smgr);
> +	int (*bmc_canceled_csk_nbits)(struct fpga_sec_mgr *smgr);
> +	int (*sr_canceled_csk_nbits)(struct fpga_sec_mgr *smgr);
> +	int (*pr_canceled_csk_nbits)(struct fpga_sec_mgr *smgr);
> +};
> +
> +struct fpga_sec_mgr {
> +	const char *name;
> +	struct device dev;
> +	const struct fpga_sec_mgr_ops *sops;
> +	struct mutex lock;		/* protect data structure contents */
> +	void *priv;
> +};
> +
> +struct fpga_sec_mgr *
> +fpga_sec_mgr_create(struct device *dev, const char *name,
> +		    const struct fpga_sec_mgr_ops *sops, void *priv);
> +
> +struct fpga_sec_mgr *
> +devm_fpga_sec_mgr_create(struct device *dev, const char *name,
> +			 const struct fpga_sec_mgr_ops *sops, void *priv);
> +
> +int fpga_sec_mgr_register(struct fpga_sec_mgr *smgr);
> +int devm_fpga_sec_mgr_register(struct device *dev,
> +			       struct fpga_sec_mgr *smgr);
> +void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr);
> +void fpga_sec_mgr_free(struct fpga_sec_mgr *smgr);
> +
> +#endif