Message-ID: <20201001003101.GC121420@archbook>
Date:   Wed, 30 Sep 2020 17:31:01 -0700
From:   Moritz Fischer <mdf@...nel.org>
To:     Russ Weight <russell.h.weight@...el.com>
Cc:     Moritz Fischer <mdf@...nel.org>, lee.jones@...aro.org,
        linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
        trix@...hat.com, lgoncalv@...hat.com, yilun.xu@...el.com,
        hao.wu@...el.com, matthew.gerlach@...el.com
Subject: Re: [PATCH v1 01/12] fpga: fpga security manager class driver

Hi Russ,

On Wed, Sep 30, 2020 at 01:54:50PM -0700, Russ Weight wrote:
> 
> 
> On 9/16/20 1:16 PM, Moritz Fischer wrote:
> > Hi Russ,
> >
> > On Fri, Sep 04, 2020 at 04:52:54PM -0700, Russ Weight wrote:
> >> Create the Intel 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@...el.com>
> >> Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> >> ---
> >>  .../ABI/testing/sysfs-class-ifpga-sec-mgr     |  75 ++++
> >>  MAINTAINERS                                   |   8 +
> >>  drivers/fpga/Kconfig                          |   9 +
> >>  drivers/fpga/Makefile                         |   3 +
> >>  drivers/fpga/ifpga-sec-mgr.c                  | 339 ++++++++++++++++++
> >>  include/linux/fpga/ifpga-sec-mgr.h            | 145 ++++++++
> >>  6 files changed, 579 insertions(+)
> >>  create mode 100644 Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> >>  create mode 100644 drivers/fpga/ifpga-sec-mgr.c
> >>  create mode 100644 include/linux/fpga/ifpga-sec-mgr.h
> >>
> >> diff --git a/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> >> new file mode 100644
> >> index 000000000000..86f8992559bf
> >> --- /dev/null
> >> +++ b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> >> @@ -0,0 +1,75 @@
> >> +What: 		/sys/class/ifpga_sec_mgr/ifpga_secX/name
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
Looking at the timing, those'll probably become 5.11

> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +Description:	Name of low level fpga security manager driver.
> >> +
> >> +What: 		/sys/class/ifpga_sec_mgr/ifpga_secX/security/sr_root_entry_hash
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/pr_root_entry_hash
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/bmc_root_entry_hash
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/sr_canceled_csks
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/pr_canceled_csks
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/bmc_canceled_csks
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +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/ifpga_sec_mgr/ifpga_secX/security/user_flash_count
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +Description:	Read only. Returns number of times the user image for the
> >> +		static region has been flashed.
> >> +		Format: "%d".
> >> +
> >> +What: 		/sys/class/ifpga_sec_mgr/ifpga_secX/security/bmc_flash_count
> >> +Date:		Sep 2020
> >> +KernelVersion:  5.10
> >> +Contact:	Russ Weight <russell.h.weight@...el.com>
> >> +Description:	Read only. Returns number of times the BMC image has been
> >> +		flashed.
> >> +		Format: "%d".
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index deaafb617361..4a2ebe6b120d 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -6830,6 +6830,14 @@ F:	Documentation/fpga/
> >>  F:	drivers/fpga/
> >>  F:	include/linux/fpga/
> >>  
> >> +INTEL FPGA SECURITY MANAGER DRIVERS
> >> +M:	Russ Weight <russell.h.weight@...el.com>
> >> +L:	linux-fpga@...r.kernel.org
> >> +S:	Maintained
> >> +F:	Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> >> +F:	drivers/fpga/ifpga-sec-mgr.c
> >> +F:	include/linux/fpga/ifpga-sec-mgr.h
> > Actually, ignore my previous comment, feel free to leave this in.
> OK. I'll also add the intel-m10-bmc-secure.c file to the maintained files (in
> the appropriate patch), as it is the first use of the security manager class
> driver.

Works for me.
> >> +
> >>  FPU EMULATOR
> >>  M:	Bill Metzenthen <billm@...bpc.org.au>
> >>  S:	Maintained
> >> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> >> index 88f64fbf55e3..97c0a6cc2ba7 100644
> >> --- a/drivers/fpga/Kconfig
> >> +++ b/drivers/fpga/Kconfig
> >> @@ -235,4 +235,13 @@ config FPGA_MGR_ZYNQMP_FPGA
> >>  	  to configure the programmable logic(PL) through PS
> >>  	  on ZynqMP SoC.
> >>  
> >> +config IFPGA_SEC_MGR
> >> +	tristate "Intel Security Manager for FPGA"
> >> +        help
> >> +	  The Intel Security Manager class driver presents a common
> >> +	  user API for managing secure updates for Intel 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 c69bfc931519..ec9fbacdedd8 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-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
> >>  
> >> +# Intel FPGA Security Manager Framework
> >> +obj-$(CONFIG_IFPGA_SEC_MGR)		+= ifpga-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/ifpga-sec-mgr.c b/drivers/fpga/ifpga-sec-mgr.c
> >> new file mode 100644
> >> index 000000000000..97bf80277ed2
> >> --- /dev/null
> >> +++ b/drivers/fpga/ifpga-sec-mgr.c
> >> @@ -0,0 +1,339 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Intel Security Manager for FPGA
> >> + *
> >> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> >> + */
> >> +
> >> +#include <linux/fpga/ifpga-sec-mgr.h>
> >> +#include <linux/idr.h>
> >> +#include <linux/module.h>
> >> +#include <linux/slab.h>
> >> +#include <linux/vmalloc.h>
> >> +
> >> +static DEFINE_IDA(ifpga_sec_mgr_ida);
> >> +static struct class *ifpga_sec_mgr_class;
> >> +
> >> +static ssize_t show_canceled_csk(struct ifpga_sec_mgr *imgr,
> >> +				 sysfs_csk_hndlr_t get_csk,
> >> +				 sysfs_csk_nbits_t get_csk_nbits,
> >> +				 char *buf)
> >> +{
> >> +	unsigned long *csk_map = NULL;
> >> +	unsigned int nbits;
> >> +	int cnt, ret;
> >> +
> >> +	ret = get_csk_nbits(imgr);
> >> +	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(imgr, csk_map, nbits);
> >> +	if (ret)
> >> +		goto vfree_exit;
> >> +
> >> +	cnt = bitmap_print_to_pagebuf(1, buf, csk_map, nbits);
> >> +
> >> +vfree_exit:
> >> +	vfree(csk_map);
> >> +	return ret ? : cnt;
> >> +}
> >> +
> >> +static ssize_t show_root_entry_hash(struct ifpga_sec_mgr *imgr,
> >> +				    sysfs_reh_hndlr_t get_reh,
> >> +				    sysfs_reh_size_t get_reh_size,
> >> +				    char *buf)
> >> +{
> >> +	unsigned int size, i;
> >> +	int ret, cnt = 0;
> >> +	u8 *hash;
> >> +
> >> +	ret = get_reh_size(imgr);
> >> +	if (ret < 0)
> >> +		return ret;
> >> +	else if (!ret)
> >> +		return sprintf(buf, "hash not programmed\n");
> >> +
> >> +	size = (unsigned int)ret;
> >> +	hash = vmalloc(size);
> >> +	if (!hash)
> >> +		return -ENOMEM;
> >> +
> >> +	ret = get_reh(imgr, 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 to_sec_mgr(d) container_of(d, struct ifpga_sec_mgr, dev)
> >> +
> >> +#define DEVICE_ATTR_SEC_CSK(_name) \
> >> +static ssize_t _name##_canceled_csks_show(struct device *dev, \
> >> +					  struct device_attribute *attr, \
> >> +					  char *buf) \
> >> +{ \
> >> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev); \
> >> +	return show_canceled_csk(imgr, \
> >> +	       imgr->iops->_name##_canceled_csks, \
> >> +	       imgr->iops->_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 ifpga_sec_mgr *imgr = to_sec_mgr(dev); \
> >> +	return show_root_entry_hash(imgr, \
> >> +	       imgr->iops->_name##_root_entry_hash, \
> >> +	       imgr->iops->_name##_reh_size, buf); \
> >> +} \
> >> +static DEVICE_ATTR_RO(_name##_root_entry_hash)
> >> +
> >> +#define DEVICE_ATTR_SEC_FLASH_CNT(_name) \
> >> +static ssize_t _name##_flash_count_show(struct device *dev, \
> >> +		    struct device_attribute *attr, char *buf) \
> >> +{ \
> >> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev); \
> >> +	int cnt = imgr->iops->_name##_flash_count(imgr); \
> >> +	return cnt < 0 ? cnt : sprintf(buf, "%d\n", cnt); \
> >> +} \
> >> +static DEVICE_ATTR_RO(_name##_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_FLASH_CNT(user);
> >> +DEVICE_ATTR_SEC_FLASH_CNT(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_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 && imgr->iops->_name)
> >> +
> >> +static umode_t sec_mgr_visible(struct kobject *kobj,
> >> +			       struct attribute *attr, int n)
> >> +{
> >> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(kobj_to_dev(kobj));
> >> +
> >> +	if (check_attr(attr, user_flash_count) ||
> >> +	    check_attr(attr, bmc_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 ifpga_sec_mgr *imgr = to_sec_mgr(dev);
> >> +
> >> +	return sprintf(buf, "%s\n", imgr->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 *ifpga_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)
> >> +{
> >> +	if (sysfs_handler) {
> >> +		if (!size_handler) {
> >> +			dev_err(dev, "%s registered without %s\n",
> >> +				sysfs_handler_name, size_handler_name);
> >> +			return false;
> >> +		}
> >> +	} else if (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, _iops, _name) \
> >> +	check_sysfs_handler(_dev, (_iops)->_name##_root_entry_hash, \
> >> +			    (_iops)->_name##_reh_size, \
> >> +			    __stringify(_name##_root_entry_hash), \
> >> +			    __stringify(_name##_reh_size))
> >> +
> >> +#define check_csk_handler(_dev, _iops, _name) \
> >> +	check_sysfs_handler(_dev, (_iops)->_name##_canceled_csks, \
> >> +			    (_iops)->_name##_canceled_csk_nbits, \
> >> +			    __stringify(_name##_canceled_csks), \
> >> +			    __stringify(_name##_canceled_csk_nbits))
> >> +
> >> +/**
> >> + * ifpga_sec_mgr_register - register an IFPGA security manager struct
> >> + *
> >> + * @dev:  create ifpga security manager device from pdev
> > Create or register? Consider splitting this into a create and a
> > register function.
> I had originally coded it with both a create() and a register() function, but I
> became convinced that there wasn't a use case for doing anything between the create()
> and register() in the success case, or for doing anything other than failing out when
> create() or register() fails - and that error handling would be simpler for the caller
> if these functions were combined.
> 
> If I do split these up, then I believe the caller would be responsible for doing
> "put_device(&imgr->dev)" if register() fails.

You can look at the fpga_mgr/bridge/region for a working pattern. I
think devres and the release functions as a result take care of it.

> Do you think it is better, more standard to split these up? I can do that for the
> next patch submission if you would like to see it that way.

I think providing the devm_ managed APIs is nicer, and makes it easier
for the consumer of the API to do the right thing.
> 
> >
> > Also it might be nice to have a devm_ifpga_create_sec_mgr /
> > ifpga_register_sec_mgr set.
> 
> I also considered a devm_ function, as is done in the fpga manager. As I understand it,
> the purpose of the devm_ functions is to automatically clean up the memory resources
> so that it does not have to be done explicitly in error handling. Currently, there
> is a class dev_release() function ifpga_sec_mgr_dev_release() that frees the resources.
> It seemed to me that it was essentially performing the same function as the managed
> resource approach.

I'd prefer if we could keep the pattern the same within drivers/fpga,
that makes refactoring easier if we decide to do so.

I think the networking subsystem uses a similar pattern with alloc() and
register() split up.

The SPI subsystem uses a variation of it.

> Looking at the core device function, device_release(), I can see that it calls first
> the managed device functions, and later the class dev_release functions. So if I
> provide both methods, then both methods would be called in the devm_ case, right?
> So I would need to alter ifpga_sec_mgr_dev_release() to check/avoid a double free?

If you look at FPGA manager/bridge code the class release ones are empty.
> 
> Am I understanding this correctly? I'm not sure I understand why the devm_ version of
> a function might be preferred in this case, but I'm happy to code this up if you think
> it is needed.

You might want to have finer control over when you unregister vs free.
The current pattern provides that.

I think we had originally discussed making it a devm_register() API that
would do all the cleanup and unregister in one go, but I don't recall
why we didn't go that far. I'll try to remember :)

> >> + * @name: ifpga security manager name
> >> + * @iops: pointer to a structure of ifpga callback functions
> >> + * @priv: ifpga security manager private data
> >> + *
> >> + * Returns &struct ifpga_sec_mgr pointer on success, or ERR_PTR() on error.
> >> + */
> >> +struct ifpga_sec_mgr *
> >> +ifpga_sec_mgr_register(struct device *dev, const char *name,
> >> +		       const struct ifpga_sec_mgr_ops *iops, void *priv)
> >> +{
> >> +	struct ifpga_sec_mgr *imgr;
> >> +	int id, ret;
> >> +
> >> +	if (!check_reh_handler(dev, iops, bmc) ||
> >> +	    !check_reh_handler(dev, iops, sr) ||
> >> +	    !check_reh_handler(dev, iops, pr) ||
> >> +	    !check_csk_handler(dev, iops, bmc) ||
> >> +	    !check_csk_handler(dev, iops, sr) ||
> >> +	    !check_csk_handler(dev, iops, pr)) {
> >> +		return ERR_PTR(-EINVAL);
> >> +	}
> >> +
> >> +	if (!name || !strlen(name)) {
> >> +		dev_err(dev, "Attempt to register with no name!\n");
> >> +		return ERR_PTR(-EINVAL);
> >> +	}
> >> +
> >> +	imgr = kzalloc(sizeof(*imgr), GFP_KERNEL);
> >> +	if (!imgr)
> >> +		return ERR_PTR(-ENOMEM);
> >> +
> >> +	imgr->name = name;
> >> +	imgr->priv = priv;
> >> +	imgr->iops = iops;
> >> +	mutex_init(&imgr->lock);
> >> +
> >> +	id = ida_simple_get(&ifpga_sec_mgr_ida, 0, 0, GFP_KERNEL);
> >> +	if (id < 0) {
> >> +		ret = id;
> >> +		goto exit_free;
> >> +	}
> >> +
> >> +	imgr->dev.class = ifpga_sec_mgr_class;
> >> +	imgr->dev.parent = dev;
> >> +	imgr->dev.id = id;
> >> +
> >> +	ret = dev_set_name(&imgr->dev, "ifpga_sec%d", id);
> >> +	if (ret) {
> >> +		dev_err(dev, "Failed to set device name: ifpga_sec%d\n", id);
> >> +		ida_simple_remove(&ifpga_sec_mgr_ida, id);
> >> +		goto exit_free;
> >> +	}
> > Consider
> >    	ret = dev_set_name(&imgr->dev, "ifpga_sec%d", id);
> >    	if (ret) {
> > 		goto exit_device;
> >    	}
> > and above exit_free:
> > exit_device:
> >    		ida_simple_remove(&ifpga_sec_mgr_ida, id);
> Yes - I'll change it this way.
> >
> >> +
> >> +	ret = device_register(&imgr->dev);
> >> +	if (ret) {
> >> +		put_device(&imgr->dev);
> >> +		return ERR_PTR(ret);
> >> +	}
> >> +
> >> +	return imgr;
> >> +
> >> +exit_free:
> >> +	kfree(dev);
> >> +	return ERR_PTR(ret);
> >> +}
> >> +EXPORT_SYMBOL_GPL(ifpga_sec_mgr_register);
> >> +
> >> +/**
> >> + * ifpga_sec_mgr_unregister - unregister a IFPGA security manager
> > Nit: a or an IFPGA?
> Yes - I'll change it. Actually, I think I'll change IFPGA to Intel FPGA as well.
> >> + *
> >> + * @mgr: fpga manager struct
> >> + *
> >> + * This function is intended for use in a IFPGA security manager
> > Nit: a or an?
> Same
> >> + * driver's remove() function.
> >> + */
> >> +void ifpga_sec_mgr_unregister(struct ifpga_sec_mgr *imgr)
> >> +{
> >> +	dev_info(&imgr->dev, "%s %s\n", __func__, imgr->name);
> >> +
> >> +	device_unregister(&imgr->dev);
> >> +}
> >> +EXPORT_SYMBOL_GPL(ifpga_sec_mgr_unregister);
> >> +
> >> +static void ifpga_sec_mgr_dev_release(struct device *dev)
> >> +{
> >> +	struct ifpga_sec_mgr *imgr = to_sec_mgr(dev);
> >> +
> >> +	mutex_destroy(&imgr->lock);
> >> +	ida_simple_remove(&ifpga_sec_mgr_ida, imgr->dev.id);
> >> +	kfree(imgr);
> >> +}
> >> +
> >> +static int __init ifpga_sec_mgr_class_init(void)
> >> +{
> >> +	pr_info("Intel FPGA Security Manager\n");
> >> +
> >> +	ifpga_sec_mgr_class = class_create(THIS_MODULE, "ifpga_sec_mgr");
> >> +	if (IS_ERR(ifpga_sec_mgr_class))
> >> +		return PTR_ERR(ifpga_sec_mgr_class);
> >> +
> >> +	ifpga_sec_mgr_class->dev_groups = ifpga_sec_mgr_attr_groups;
> >> +	ifpga_sec_mgr_class->dev_release = ifpga_sec_mgr_dev_release;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void __exit ifpga_sec_mgr_class_exit(void)
> >> +{
> >> +	class_destroy(ifpga_sec_mgr_class);
> >> +	ida_destroy(&ifpga_sec_mgr_ida);
> >> +}
> >> +
> >> +MODULE_DESCRIPTION("Intel FPGA Security Manager Driver");
> >> +MODULE_LICENSE("GPL v2");
> >> +
> >> +subsys_initcall(ifpga_sec_mgr_class_init);
> >> +module_exit(ifpga_sec_mgr_class_exit)
> >> diff --git a/include/linux/fpga/ifpga-sec-mgr.h b/include/linux/fpga/ifpga-sec-mgr.h
> >> new file mode 100644
> >> index 000000000000..e391b0c8f448
> >> --- /dev/null
> >> +++ b/include/linux/fpga/ifpga-sec-mgr.h
> >> @@ -0,0 +1,145 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +/*
> >> + * Header file for Intel FPGA Security Manager
> >> + *
> >> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> >> + */
> >> +#ifndef _LINUX_IFPGA_SEC_MGR_H
> >> +#define _LINUX_IFPGA_SEC_MGR_H
> >> +
> >> +#include <linux/device.h>
> >> +#include <linux/mutex.h>
> >> +#include <linux/types.h>
> >> +
> >> +struct ifpga_sec_mgr;
> >> +
> >> +/**
> >> + * typedef sysfs_reh_size_t - Function to return byte size of root entry hash
> >> + *
> >> + * @imgr:      pointer to security manager structure
> >> + *
> >> + * This datatype is used to define a function that returns the byte size of a
> >> + * root entry hash.
> >> + *
> >> + * Context: No locking requirements are imposed by the security manager.
> >> + * Return:  Byte count on success, negative errno on failure
> >> + */
> >> +typedef int (*sysfs_reh_size_t)(struct ifpga_sec_mgr *imgr);

As I had mentioned can we keep those as function pointers?
> >> +
> >> +/**
> >> + * typedef sysfs_reh_hndlr_t - Function pointer to sysfs file handler
> >> + *			       for root entry hashes
> >> + * @imgr:      pointer to security manager structure
> >> + * @hash:      pointer to an array of bytes in which to store the hash
> >> + * @size:      byte size of root entry hash
> >> + *
> >> + * This datatype is used to define a sysfs file handler function to
> >> + * return root entry hash data to be displayed via sysfs.
> >> + *
> >> + * Context: No locking requirements are imposed by the security manager.
> >> + * Return:  0 on success, negative errno on failure
> >> + */
> >> +typedef int (*sysfs_reh_hndlr_t)(struct ifpga_sec_mgr *imgr, u8 *hash,
> >> +				 unsigned int size);
> >> +
> >> +/**
> >> + * typedef sysfs_cnt_hndlr_t - Function pointer to sysfs file handler
> >> + *			       for flash counts
> >> + * @imgr: pointer to security manager structure
> >> + *
> >> + * This datatype is used to define a sysfs file handler function to
> >> + * return a flash count to be displayed via sysfs.
> >> + *
> >> + * Context: No locking requirements are imposed by the security manager
> >> + * Return: flash count or negative errno
> >> + */
> >> +typedef int (*sysfs_cnt_hndlr_t)(struct ifpga_sec_mgr *imgr);
> >> +
> >> +/**
> >> + * typedef sysfs_csk_nbits_t - Function to return the number of bits in
> >> + *				      a Code Signing Key cancellation vector
> >> + *
> >> + * @imgr:      pointer to security manager structure
> >> + *
> >> + * This datatype is used to define a function that returns the number of bits
> >> + * in a Code Signing Key cancellation vector.
> >> + *
> >> + * Context: No locking requirements are imposed by the security manager.
> >> + * Return:  Number of bits on success, negative errno on failure
> >> + */
> >> +typedef int (*sysfs_csk_nbits_t)(struct ifpga_sec_mgr *imgr);
> >> +
> >> +/**
> >> + * typedef sysfs_csk_hndlr_t - Function pointer to sysfs file handler
> >> + *			       bit vector of canceled keys
> >> + *
> >> + * @imgr:    pointer to security manager structure
> >> + * @csk_map: pointer to a bitmap to contain cancellation key vector
> >> + * @nbits:   number of bits in CSK vector
> >> + *
> >> + * This datatype is used to define a sysfs file handler function to
> >> + * return a bitmap of canceled keys to be displayed via sysfs.
> >> + *
> >> + * Context: No locking requirements are imposed by the security manager.
> >> + * Return:  0 on success, negative errno on failure
> >> + */
> >> +typedef int (*sysfs_csk_hndlr_t)(struct ifpga_sec_mgr *imgr,
> >> +				 unsigned long *csk_map, unsigned int nbits);
> >> +
> >> +/**
> >> + * struct ifpga_sec_mgr_ops - device specific operations
> >> + * @user_flash_count:	    Optional: Return sysfs string output for FPGA
> >> + *			    image flash count
> >> + * @bmc_flash_count:	    Optional: Return sysfs string output for BMC
> >> + *			    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 ifpga_sec_mgr_ops {
> >> +	sysfs_cnt_hndlr_t user_flash_count;
> >> +	sysfs_cnt_hndlr_t bmc_flash_count;
> >> +	sysfs_cnt_hndlr_t smbus_flash_count;
> >> +	sysfs_reh_hndlr_t sr_root_entry_hash;
> >> +	sysfs_reh_hndlr_t pr_root_entry_hash;
> >> +	sysfs_reh_hndlr_t bmc_root_entry_hash;
> >> +	sysfs_csk_hndlr_t sr_canceled_csks;
> >> +	sysfs_csk_hndlr_t pr_canceled_csks;
> >> +	sysfs_csk_hndlr_t bmc_canceled_csks;
> >> +	sysfs_reh_size_t bmc_reh_size;
> >> +	sysfs_reh_size_t sr_reh_size;
> >> +	sysfs_reh_size_t pr_reh_size;
> >> +	sysfs_csk_nbits_t bmc_canceled_csk_nbits;
> >> +	sysfs_csk_nbits_t sr_canceled_csk_nbits;
> >> +	sysfs_csk_nbits_t pr_canceled_csk_nbits;
> >> +};
> > I agree with Tom's feedback, please don't use typedefs here.
> I'll remove them.
> 
> Thanks for the comments! I've been reworking the patches. I'll split up the class
> driver and the Max10 BMC security engine into two patch sets for the next submission.

Great. Send a new version, and then we can see where it's at :-)
> 
> - Russ
> >> +
> >> +struct ifpga_sec_mgr {
> >> +	const char *name;
> >> +	struct device dev;
> >> +	const struct ifpga_sec_mgr_ops *iops;
> >> +	struct mutex lock;		/* protect data structure contents */
> >> +	void *priv;
> >> +};
> >> +
> >> +struct ifpga_sec_mgr *
> >> +ifpga_sec_mgr_register(struct device *dev, const char *name,
> >> +		       const struct ifpga_sec_mgr_ops *iops, void *priv);
> >> +void ifpga_sec_mgr_unregister(struct ifpga_sec_mgr *imgr);
> >> +
> >> +#endif
> >> -- 
> >> 2.17.1
> >>
> > Thanks,
> > Moritz
> 

Thanks,
Moritz

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