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Date:   Wed, 27 Oct 2021 09:22:41 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Chen Yu <yu.c.chen@intel.com>
Cc:     linux-acpi@vger.kernel.org,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Ard Biesheuvel <ardb@kernel.org>, Len Brown <lenb@kernel.org>,
        Ashok Raj <ashok.raj@intel.com>,
        Andy Shevchenko <andriy.shevchenko@intel.com>,
        Mike Rapoport <rppt@kernel.org>,
        Aubrey Li <aubrey.li@intel.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 2/4] drivers/acpi: Introduce Platform Firmware Runtime
 Update device driver
Message-ID: <YXj+QaMcCeV71XbI@kroah.com>
References: <cover.1635317102.git.yu.c.chen@intel.com>
 <a318e4edc13e5a3ff95b901871b8929746535715.1635317102.git.yu.c.chen@intel.com>
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On Wed, Oct 27, 2021 at 03:07:51PM +0800, Chen Yu wrote:
> Introduce the pfru_update driver which can be used for Platform Firmware
> Runtime code injection and driver update [1]. The user is expected to
> provide the update firmware in the form of capsule file, and pass it to
> the driver via ioctl. Then the driver would hand this capsule file to the
> Platform Firmware Runtime Update via the ACPI device _DSM method. At last
> the low level Management Mode would do the firmware update.
> 
> The corresponding userspace tool and man page will be introduced at
> tools/power/acpi/pfru.
> 
> Link: https://uefi.org/sites/default/files/resources/Intel_MM_OS_Interface_Spec_Rev100.pdf # [1]
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> v7: Use ida_alloc() to allocate a ID, and release the ID when
>     device is removed. (Greg Kroah-Hartman)
>     Check the _DSM method at early stage, before allocate or parse
>     anything in acpi_pfru_probe(). (Greg Kroah-Hartman)
>     Set the parent of the misc device. (Greg Kroah-Hartman)
>     Use module_platform_driver() instead of platform_driver_register()
>     in module_init(). Separate pfru driver and pfru_telemetry driver
>     to two files. (Greg Kroah-Hartman) 
> v6: Use Link: tag to add the specification download address.
>     (Andy Shevchenko)
>     Remove linux/uuid.h and use raw buffers to contain uuid.
>     (Andy Shevchenko)
>     Drop comma for each terminator entry in the enum structure.
>     (Andy Shevchenko)
>     Remove redundant 'else' in get_image_type().
>     (Andy Shevchenko)
>     Directly return results from the switch cases in adjust_efi_size()
>     and pfru_ioctl().(Andy Shevchenko)
>     Keep comment style consistent by removing the period for
>     one line comment.
>     (Andy Shevchenko)
>     Remove devm_kfree() if .probe() failed. 
>     (Andy Shevchenko)
> v5: Remove Documentation/ABI/pfru, and move the content to kernel doc
>     in include/uapi/linux/pfru.h (Greg Kroah-Hartman)
>     Shrink the range of ioctl numbers declared in
>     Documentation/userspace-api/ioctl/ioctl-number.rst
>     from 16 to 8. (Greg Kroah-Hartman)
>     Change global variable struct pfru_device *pfru_dev to
>     per ACPI device. (Greg Kroah-Hartman)
>     Unregister the misc device in acpi_pfru_remove().
>     (Greg Kroah-Hartman)
>     Convert the kzalloc() to devm_kzalloc() in the driver so
>     as to avoid freeing the memory. (Greg Kroah-Hartman)
>     Fix the compile error by declaring the pfru_log_ioctl() as
>     static. (kernel test robot LKP)
>     Change to global variable misc_device to per ACPI device.
>     (Greg Kroah-Hartman)
> v4: Replace all pr_err() with dev_dbg() (Greg Kroah-Hartman,
>     Rafael J. Wysocki)
>     Returns ENOTTY rather than ENOIOCTLCMD if invalid ioctl command
>     is provided. (Greg Kroah-Hartman)
>     Remove compat ioctl. (Greg Kroah-Hartman)
>     Rename /dev/pfru/pfru_update to /dev/acpi_pfru (Greg Kroah-Hartman)
>     Simplify the check for element of the package in query_capability()
>     (Rafael J. Wysocki)
>     Remove the loop in query_capability(), query_buffer() and query
>     the package elemenet directly. (Rafael J. Wysocki)
>     Check the the number of elements in case the number of package
>     elements is too small. (Rafael J. Wysocki)
>     Doing the assignment as initialization in get_image_type().
>     Meanwhile, returns the type or a negative error code in
>     get_image_type(). (Rafael J. Wysocki)
>     Put the comments inside the function. (Rafael J. Wysocki)
>     Returns the size or a negative error code in adjust_efi_size()
>     (Rafael J. Wysocki)
>     Fix the return value from EFAULT to EINVAL if pfru_valid_revid()
>     does not pass. (Rafael J. Wysocki)
>     Change the write() to be the code injection/update, the read() to
>     be telemetry retrieval and all of the rest to be ioctl()s under
>     one special device file.(Rafael J. Wysocki)
>     Putting empty code lines after an if () statement that is not
>     followed by a block. (Rafael J. Wysocki)
>     Remove "goto" tags to make the code more readable. (Rafael J. Wysocki)
> v3: Use __u32 instead of int and __64 instead of unsigned long
>     in include/uapi/linux/pfru.h (Greg Kroah-Hartman)
>     Rename the structure in uapi to start with a prefix pfru so as
>     to avoid confusing in the global namespace. (Greg Kroah-Hartman)
> v2: Add sanity check for duplicated instance of ACPI device.
>     Update the driver to work with allocated pfru_device objects.
>     (Mike Rapoport)
>     For each switch case pair, get rid of the magic case numbers
>     and add a default clause with the error handling.
>     (Mike Rapoport)
>     Move the obj->type checks outside the switch to reduce redundancy.
>     (Mike Rapoport)
>     Parse the code_inj_id and drv_update_id at driver initialization time
>     to reduce the re-parsing at runtime.(Mike Rapoport)
>     Explain in detail how the size needs to be adjusted when doing
>     version check.(Mike Rapoport)
>     Rename parse_update_result() to dump_update_result()(Mike Rapoport)
>     Remove redundant return.(Mike Rapoport)
>     Do not expose struct capsulate_buf_info to uapi, since it is
>     not needed in userspace.(Mike Rapoport)
> ---
>  .../userspace-api/ioctl/ioctl-number.rst      |   1 +
>  drivers/acpi/Kconfig                          |   1 +
>  drivers/acpi/Makefile                         |   1 +
>  drivers/acpi/pfru/Kconfig                     |  13 +
>  drivers/acpi/pfru/Makefile                    |   2 +
>  drivers/acpi/pfru/pfru_update.c               | 572 ++++++++++++++++++
>  include/uapi/linux/pfru.h                     | 186 ++++++
>  7 files changed, 776 insertions(+)
>  create mode 100644 drivers/acpi/pfru/Kconfig
>  create mode 100644 drivers/acpi/pfru/Makefile
>  create mode 100644 drivers/acpi/pfru/pfru_update.c
>  create mode 100644 include/uapi/linux/pfru.h
> 
> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> index 2e8134059c87..6f7c86b6deb7 100644
> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> @@ -365,6 +365,7 @@ Code  Seq#    Include File                                           Comments
>                                                                       <mailto:aherrman@de.ibm.com>
>  0xE5  00-3F  linux/fuse.h
>  0xEC  00-01  drivers/platform/chrome/cros_ec_dev.h                   ChromeOS EC driver
> +0xEE  00-08  uapi/linux/pfru.h                                       Platform Firmware Runtime Update and Telemetry
>  0xF3  00-3F  drivers/usb/misc/sisusbvga/sisusb.h                     sisfb (in development)
>                                                                       <mailto:thomas@winischhofer.net>
>  0xF6  all                                                            LTTng Linux Trace Toolkit Next Generation
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 1da360c51d66..1d8d2e2cefac 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -482,6 +482,7 @@ source "drivers/acpi/nfit/Kconfig"
>  source "drivers/acpi/numa/Kconfig"
>  source "drivers/acpi/apei/Kconfig"
>  source "drivers/acpi/dptf/Kconfig"
> +source "drivers/acpi/pfru/Kconfig"
>  
>  config ACPI_WATCHDOG
>  	bool
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 3018714e87d9..9c2c5ddff6ec 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -102,6 +102,7 @@ obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
>  obj-$(CONFIG_ACPI_SPCR_TABLE)	+= spcr.o
>  obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
>  obj-$(CONFIG_ACPI_PPTT) 	+= pptt.o
> +obj-$(CONFIG_ACPI_PFRU)		+= pfru/
>  
>  # processor has its own "processor." module_param namespace
>  processor-y			:= processor_driver.o
> diff --git a/drivers/acpi/pfru/Kconfig b/drivers/acpi/pfru/Kconfig
> new file mode 100644
> index 000000000000..5b31675b173a
> --- /dev/null
> +++ b/drivers/acpi/pfru/Kconfig
> @@ -0,0 +1,13 @@
> +# SPDX-License-Identifier: GPL-2.0
> +config ACPI_PFRU
> +	tristate "ACPI Platform Firmware Runtime Update (PFRU)"
> +	depends on 64BIT
> +	help
> +	  In order to reduce the system reboot times and update the platform firmware
> +	  in time, Platform Firmware Runtime Update is leveraged to patch the system
> +	  without reboot. This driver supports Platform Firmware Runtime Update,
> +	  which is composed of two parts: code injection and driver update. It also
> +	  allows telemetry data to be retrieved from the platform firmware.
> +
> +	  To compile this driver as a module, choose M here:
> +	  the module will be called pfru_update.
> diff --git a/drivers/acpi/pfru/Makefile b/drivers/acpi/pfru/Makefile
> new file mode 100644
> index 000000000000..098cbe80cf3d
> --- /dev/null
> +++ b/drivers/acpi/pfru/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_ACPI_PFRU) += pfru_update.o
> diff --git a/drivers/acpi/pfru/pfru_update.c b/drivers/acpi/pfru/pfru_update.c
> new file mode 100644
> index 000000000000..a9953eb6c2d5
> --- /dev/null
> +++ b/drivers/acpi/pfru/pfru_update.c
> @@ -0,0 +1,572 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ACPI Platform Firmware Runtime Update Device Driver
> + *
> + * Copyright (C) 2021 Intel Corporation
> + * Author: Chen Yu <yu.c.chen@intel.com>
> + */
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/efi.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/idr.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/string.h>
> +#include <linux/uaccess.h>
> +#include <linux/uio.h>
> +#include <linux/uuid.h>
> +#include <uapi/linux/pfru.h>
> +
> +enum cap_index {
> +	CAP_STATUS_IDX,
> +	CAP_UPDATE_IDX,
> +	CAP_CODE_TYPE_IDX,
> +	CAP_FW_VER_IDX,
> +	CAP_CODE_RT_VER_IDX,
> +	CAP_DRV_TYPE_IDX,
> +	CAP_DRV_RT_VER_IDX,
> +	CAP_DRV_SVN_IDX,
> +	CAP_PLAT_ID_IDX,
> +	CAP_OEM_ID_IDX,
> +	CAP_OEM_INFO_IDX,
> +	CAP_NR_IDX
> +};
> +
> +enum buf_index {
> +	BUF_STATUS_IDX,
> +	BUF_EXT_STATUS_IDX,
> +	BUF_ADDR_LOW_IDX,
> +	BUF_ADDR_HI_IDX,
> +	BUF_SIZE_IDX,
> +	BUF_NR_IDX
> +};
> +
> +enum update_index {
> +	UPDATE_STATUS_IDX,
> +	UPDATE_EXT_STATUS_IDX,
> +	UPDATE_AUTH_TIME_LOW_IDX,
> +	UPDATE_AUTH_TIME_HI_IDX,
> +	UPDATE_EXEC_TIME_LOW_IDX,
> +	UPDATE_EXEC_TIME_HI_IDX,
> +	UPDATE_NR_IDX
> +};
> +
> +struct pfru_device {
> +	guid_t uuid, code_uuid, drv_uuid;
> +	int rev_id, index;

shouldn't rev_id be a u32 as you are copying this to/from userspace?

> +	struct device *dev;

What device is this, the parent?  Child?  Sibling?  need a hint...

> +	struct miscdevice miscdev;
> +};
> +
> +static DEFINE_IDA(pfru_ida);
> +
> +static inline struct pfru_device *to_pfru_dev(struct file *file)
> +{
> +	return container_of(file->private_data, struct pfru_device, miscdev);
> +}
> +
> +static int query_capability(struct pfru_update_cap_info *cap,
> +			    struct pfru_device *pfru_dev)
> +{
> +	union acpi_object *out_obj;
> +	acpi_handle handle;
> +	int ret = -EINVAL;
> +
> +	handle = ACPI_HANDLE(pfru_dev->dev);
> +	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_dev->uuid,
> +					  pfru_dev->rev_id,
> +					  FUNC_QUERY_UPDATE_CAP,
> +					  NULL, ACPI_TYPE_PACKAGE);
> +	if (!out_obj)
> +		return ret;
> +
> +	if (out_obj->package.count < CAP_NR_IDX)
> +		goto free_acpi_buffer;
> +
> +	if (out_obj->package.elements[CAP_STATUS_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->status = out_obj->package.elements[CAP_STATUS_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_UPDATE_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->update_cap = out_obj->package.elements[CAP_UPDATE_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_CODE_TYPE_IDX].type != ACPI_TYPE_BUFFER)
> +		goto free_acpi_buffer;
> +
> +	memcpy(&cap->code_type,
> +	       out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.pointer,
> +	       out_obj->package.elements[CAP_CODE_TYPE_IDX].buffer.length);
> +
> +	if (out_obj->package.elements[CAP_FW_VER_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->fw_version =
> +		out_obj->package.elements[CAP_FW_VER_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_CODE_RT_VER_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->code_rt_version =
> +		out_obj->package.elements[CAP_CODE_RT_VER_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_DRV_TYPE_IDX].type != ACPI_TYPE_BUFFER)
> +		goto free_acpi_buffer;
> +
> +	memcpy(&cap->drv_type,
> +	       out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.pointer,
> +	       out_obj->package.elements[CAP_DRV_TYPE_IDX].buffer.length);
> +
> +	if (out_obj->package.elements[CAP_DRV_RT_VER_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->drv_rt_version =
> +		out_obj->package.elements[CAP_DRV_RT_VER_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_DRV_SVN_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	cap->drv_svn =
> +		out_obj->package.elements[CAP_DRV_SVN_IDX].integer.value;
> +
> +	if (out_obj->package.elements[CAP_PLAT_ID_IDX].type != ACPI_TYPE_BUFFER)
> +		goto free_acpi_buffer;
> +
> +	memcpy(&cap->platform_id,
> +	       out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.pointer,
> +	       out_obj->package.elements[CAP_PLAT_ID_IDX].buffer.length);
> +
> +	if (out_obj->package.elements[CAP_OEM_ID_IDX].type != ACPI_TYPE_BUFFER)
> +		goto free_acpi_buffer;
> +
> +	memcpy(&cap->oem_id,
> +	       out_obj->package.elements[CAP_OEM_ID_IDX].buffer.pointer,
> +	       out_obj->package.elements[CAP_OEM_ID_IDX].buffer.length);
> +	ret = 0;
> +free_acpi_buffer:
> +	ACPI_FREE(out_obj);
> +
> +	return ret;
> +}
> +
> +static int query_buffer(struct pfru_com_buf_info *info,
> +			struct pfru_device *pfru_dev)
> +{
> +	union acpi_object *out_obj;
> +	acpi_handle handle;
> +	int ret = -EINVAL;
> +
> +	handle = ACPI_HANDLE(pfru_dev->dev);
> +	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_dev->uuid,
> +					  pfru_dev->rev_id, FUNC_QUERY_BUF,
> +					  NULL, ACPI_TYPE_PACKAGE);
> +	if (!out_obj)
> +		return ret;
> +
> +	if (out_obj->package.count < BUF_NR_IDX)
> +		goto free_acpi_buffer;
> +
> +	if (out_obj->package.elements[BUF_STATUS_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	info->status = out_obj->package.elements[BUF_STATUS_IDX].integer.value;
> +
> +	if (out_obj->package.elements[BUF_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	info->ext_status =
> +		out_obj->package.elements[BUF_EXT_STATUS_IDX].integer.value;
> +
> +	if (out_obj->package.elements[BUF_ADDR_LOW_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	info->addr_lo =
> +		out_obj->package.elements[BUF_ADDR_LOW_IDX].integer.value;
> +
> +	if (out_obj->package.elements[BUF_ADDR_HI_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	info->addr_hi =
> +		out_obj->package.elements[BUF_ADDR_HI_IDX].integer.value;
> +
> +	if (out_obj->package.elements[BUF_SIZE_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	info->buf_size = out_obj->package.elements[BUF_SIZE_IDX].integer.value;
> +
> +	ret = 0;
> +free_acpi_buffer:
> +	ACPI_FREE(out_obj);
> +
> +	return ret;
> +}
> +
> +static int get_image_type(struct efi_manage_capsule_image_header *img_hdr,
> +			  struct pfru_device *pfru_dev)
> +{
> +	guid_t *image_type_id = &img_hdr->image_type_id;
> +
> +	/* check whether this is a code injection or driver update */
> +	if (guid_equal(image_type_id, &pfru_dev->code_uuid))
> +		return CODE_INJECT_TYPE;
> +
> +	if (guid_equal(image_type_id, &pfru_dev->drv_uuid))
> +		return DRIVER_UPDATE_TYPE;
> +
> +	return -EINVAL;
> +}
> +
> +static int adjust_efi_size(struct efi_manage_capsule_image_header *img_hdr,
> +			   int size)
> +{
> +	/*
> +	 * The (u64 hw_ins) was introduced in UEFI spec version 2,
> +	 * and (u64 capsule_support) was introduced in version 3.
> +	 * The size needs to be adjusted accordingly. That is to
> +	 * say, version 1 should subtract the size of hw_ins+capsule_support,
> +	 * and version 2 should sbstract the size of capsule_support.
> +	 */
> +	size += sizeof(struct efi_manage_capsule_image_header);
> +	switch (img_hdr->ver) {
> +	case 1:
> +		return size - 2 * sizeof(u64);
> +	case 2:
> +		return size - sizeof(u64);
> +	default:
> +		/* only support version 1 and 2 */
> +		return -EINVAL;
> +	}
> +}
> +
> +static bool valid_version(const void *data, struct pfru_update_cap_info *cap,
> +			  struct pfru_device *pfru_dev)
> +{
> +	struct pfru_payload_hdr *payload_hdr;
> +	efi_capsule_header_t *cap_hdr;
> +	struct efi_manage_capsule_header *m_hdr;
> +	struct efi_manage_capsule_image_header *m_img_hdr;
> +	struct efi_image_auth *auth;
> +	int type, size;
> +
> +	/*
> +	 * Sanity check if the capsule image has a newer version
> +	 * than current one.
> +	 */
> +	cap_hdr = (efi_capsule_header_t *)data;
> +	size = cap_hdr->headersize;
> +	m_hdr = (struct efi_manage_capsule_header *)(data + size);
> +	/*
> +	 * Current data structure size plus variable array indicated
> +	 * by number of (emb_drv_cnt + payload_cnt)
> +	 */
> +	size += sizeof(struct efi_manage_capsule_header) +
> +		      (m_hdr->emb_drv_cnt + m_hdr->payload_cnt) * sizeof(u64);
> +	m_img_hdr = (struct efi_manage_capsule_image_header *)(data + size);
> +
> +	type = get_image_type(m_img_hdr, pfru_dev);
> +	if (type < 0)
> +		return false;
> +
> +	size = adjust_efi_size(m_img_hdr, size);
> +	if (size < 0)
> +		return false;
> +
> +	auth = (struct efi_image_auth *)(data + size);
> +	size += sizeof(u64) + auth->auth_info.hdr.len;
> +	payload_hdr = (struct pfru_payload_hdr *)(data + size);
> +
> +	/* finally compare the version */
> +	if (type == CODE_INJECT_TYPE)
> +		return payload_hdr->rt_ver >= cap->code_rt_version;
> +	else
> +		return payload_hdr->rt_ver >= cap->drv_rt_version;
> +}
> +
> +static void dump_update_result(struct pfru_updated_result *result,
> +			       struct pfru_device *pfru_dev)
> +{
> +	dev_dbg(pfru_dev->dev, "Update result:\n");
> +	dev_dbg(pfru_dev->dev, "Status:%d\n", result->status);
> +	dev_dbg(pfru_dev->dev, "Extended Status:%d\n", result->ext_status);
> +	dev_dbg(pfru_dev->dev, "Authentication Time Low:%lld\n",
> +		result->low_auth_time);
> +	dev_dbg(pfru_dev->dev, "Authentication Time High:%lld\n",
> +		result->high_auth_time);
> +	dev_dbg(pfru_dev->dev, "Execution Time Low:%lld\n",
> +		result->low_exec_time);
> +	dev_dbg(pfru_dev->dev, "Execution Time High:%lld\n",
> +		result->high_exec_time);
> +}
> +
> +static int start_acpi_update(int action, struct pfru_device *pfru_dev)
> +{
> +	union acpi_object *out_obj, in_obj, in_buf;
> +	struct pfru_updated_result update_result;
> +	acpi_handle handle;
> +	int ret = -EINVAL;
> +
> +	memset(&in_obj, 0, sizeof(in_obj));
> +	memset(&in_buf, 0, sizeof(in_buf));
> +	in_obj.type = ACPI_TYPE_PACKAGE;
> +	in_obj.package.count = 1;
> +	in_obj.package.elements = &in_buf;
> +	in_buf.type = ACPI_TYPE_INTEGER;
> +	in_buf.integer.value = action;
> +
> +	handle = ACPI_HANDLE(pfru_dev->dev);
> +	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_dev->uuid,
> +					  pfru_dev->rev_id, FUNC_START,
> +					  &in_obj, ACPI_TYPE_PACKAGE);
> +	if (!out_obj)
> +		return ret;
> +
> +	if (out_obj->package.count < UPDATE_NR_IDX)
> +		goto free_acpi_buffer;
> +
> +	if (out_obj->package.elements[UPDATE_STATUS_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.status =
> +		out_obj->package.elements[UPDATE_STATUS_IDX].integer.value;
> +
> +	if (out_obj->package.elements[UPDATE_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.ext_status =
> +		out_obj->package.elements[UPDATE_EXT_STATUS_IDX].integer.value;
> +
> +	if (out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.low_auth_time =
> +		out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].integer.value;
> +
> +	if (out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.high_auth_time =
> +		out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].integer.value;
> +
> +	if (out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.low_exec_time =
> +		out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].integer.value;
> +
> +	if (out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].type != ACPI_TYPE_INTEGER)
> +		goto free_acpi_buffer;
> +
> +	update_result.high_exec_time =
> +		out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].integer.value;
> +
> +	dump_update_result(&update_result, pfru_dev);
> +	ret = 0;
> +
> +free_acpi_buffer:
> +	ACPI_FREE(out_obj);
> +
> +	return ret;
> +}
> +
> +static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> +{
> +	struct pfru_update_cap_info cap;

You have a variable-length structure on the stack.  What ever could go
wrong with that?

{sigh}

How was this tested???

> +	struct pfru_device *pfru_dev;
> +	void __user *p;
> +	int ret, rev;
> +
> +	pfru_dev = to_pfru_dev(file);
> +	p = (void __user *)arg;
> +
> +	switch (cmd) {
> +	case PFRU_IOC_QUERY_CAP:
> +		ret = query_capability(&cap, pfru_dev);
> +		if (ret)
> +			return ret;
> +
> +		if (copy_to_user(p, &cap, sizeof(cap)))

But "sizeof" is not the real size of this structure, it's a variable
length structure, right?

Again, how was this tested?

> +			return -EFAULT;
> +
> +		return 0;
> +	case PFRU_IOC_SET_REV:
> +		if (copy_from_user(&rev, p, sizeof(unsigned int)))

But this isn't an unsigned int, it's an "int" here.

So again, make this explicit, probably u32, right?

> +			return -EFAULT;
> +
> +		if (!pfru_valid_revid(rev))
> +			return -EINVAL;
> +
> +		pfru_dev->rev_id = rev;

Why can't this just be a sysfs file?

Heck, why can't all of these be sysfs files, why do you need a char
device at all?  Who is going to use this thing?


> +
> +		return 0;
> +	case PFRU_IOC_STAGE:
> +		return start_acpi_update(START_STAGE, pfru_dev);
> +	case PFRU_IOC_ACTIVATE:
> +		return start_acpi_update(START_ACTIVATE, pfru_dev);
> +	case PFRU_IOC_STAGE_ACTIVATE:
> +		return start_acpi_update(START_STAGE_ACTIVATE, pfru_dev);
> +	default:
> +		return -ENOTTY;
> +	}
> +}
> +
> +static ssize_t pfru_write(struct file *file, const char __user *buf,
> +			  size_t len, loff_t *ppos)
> +{
> +	struct pfru_update_cap_info cap;
> +	struct pfru_com_buf_info info;
> +	struct pfru_device *pfru_dev;
> +	phys_addr_t phy_addr;
> +	struct iov_iter iter;
> +	struct iovec iov;
> +	char *buf_ptr;
> +	int ret;
> +
> +	pfru_dev = to_pfru_dev(file);
> +
> +	ret = query_buffer(&info, pfru_dev);
> +	if (ret)
> +		return ret;
> +
> +	if (len > info.buf_size)
> +		return -EINVAL;
> +
> +	iov.iov_base = (void __user *)buf;
> +	iov.iov_len = len;
> +	iov_iter_init(&iter, WRITE, &iov, 1, len);
> +
> +	/* map the communication buffer */
> +	phy_addr = (phys_addr_t)(info.addr_lo | (info.addr_hi << 32));
> +	buf_ptr = memremap(phy_addr, info.buf_size, MEMREMAP_WB);
> +	if (IS_ERR(buf_ptr))
> +		return PTR_ERR(buf_ptr);
> +
> +	if (!copy_from_iter_full(buf_ptr, len, &iter)) {
> +		ret = -EINVAL;
> +		goto unmap;
> +	}
> +
> +	/* check if the capsule header has a valid version number */
> +	ret = query_capability(&cap, pfru_dev);
> +	if (ret)
> +		goto unmap;
> +
> +	if (cap.status != DSM_SUCCEED)
> +		ret = -EBUSY;
> +	else if (!valid_version(buf_ptr, &cap, pfru_dev))
> +		ret = -EINVAL;
> +unmap:
> +	memunmap(buf_ptr);
> +
> +	return ret ?: len;
> +}
> +
> +static const struct file_operations acpi_pfru_fops = {
> +	.owner		= THIS_MODULE,
> +	.write		= pfru_write,
> +	.unlocked_ioctl = pfru_ioctl,
> +	.llseek		= noop_llseek,
> +};
> +
> +static int acpi_pfru_remove(struct platform_device *pdev)
> +{
> +	struct pfru_device *pfru_dev = platform_get_drvdata(pdev);
> +
> +	misc_deregister(&pfru_dev->miscdev);
> +	ida_free(&pfru_ida, pfru_dev->index);
> +
> +	return 0;
> +}
> +
> +static int acpi_pfru_probe(struct platform_device *pdev)
> +{
> +	struct pfru_device *pfru_dev;
> +	acpi_handle handle;
> +	int ret;
> +
> +	handle = ACPI_HANDLE(&pdev->dev);
> +	if (!acpi_has_method(handle, "_DSM")) {
> +		dev_dbg(&pdev->dev, "Missing _DSM\n");
> +		return -ENODEV;
> +	}
> +
> +	pfru_dev = devm_kzalloc(&pdev->dev, sizeof(*pfru_dev), GFP_KERNEL);
> +	if (!pfru_dev)
> +		return -ENOMEM;
> +
> +	ret = guid_parse(PFRU_UUID, &pfru_dev->uuid);
> +	if (ret)
> +		return ret;
> +
> +	ret = guid_parse(PFRU_CODE_INJ_UUID, &pfru_dev->code_uuid);
> +	if (ret)
> +		return ret;
> +
> +	ret = guid_parse(PFRU_DRV_UPDATE_UUID, &pfru_dev->drv_uuid);
> +	if (ret)
> +		return ret;
> +
> +	ret = ida_alloc(&pfru_ida, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +
> +	pfru_dev->index = ret;
> +	/* default rev id is 1 */
> +	pfru_dev->rev_id = 1;
> +	pfru_dev->dev = &pdev->dev;
> +
> +	pfru_dev->miscdev.minor = MISC_DYNAMIC_MINOR;
> +	pfru_dev->miscdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
> +						"pfru%d", pfru_dev->index);
> +	if (!pfru_dev->miscdev.name) {
> +		ret = -ENOMEM;
> +		goto failed;
> +	}
> +
> +	pfru_dev->miscdev.nodename = devm_kasprintf(&pdev->dev, GFP_KERNEL,
> +						    "acpi_pfru%d", pfru_dev->index);
> +	if (!pfru_dev->miscdev.nodename) {
> +		ret = -ENOMEM;
> +		goto failed;
> +	}
> +
> +	pfru_dev->miscdev.fops = &acpi_pfru_fops;
> +	pfru_dev->miscdev.parent = &pdev->dev;
> +
> +	ret = misc_register(&pfru_dev->miscdev);
> +	if (ret)
> +		goto failed;
> +
> +	platform_set_drvdata(pdev, pfru_dev);
> +
> +	return 0;
> +failed:
> +	ida_free(&pfru_ida, pfru_dev->index);
> +
> +	return ret;
> +}
> +
> +static const struct acpi_device_id acpi_pfru_ids[] = {
> +	{"INTC1080", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(acpi, acpi_pfru_ids);
> +
> +static struct platform_driver acpi_pfru_driver = {
> +	.driver = {
> +		.name = "pfru_update",
> +		.acpi_match_table = acpi_pfru_ids,
> +	},
> +	.probe = acpi_pfru_probe,
> +	.remove = acpi_pfru_remove,
> +};
> +module_platform_driver(acpi_pfru_driver);

Are you cleaning up your ida structure when the module is unloaded?

> +
> +MODULE_DESCRIPTION("Platform Firmware Runtime Update device driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/uapi/linux/pfru.h b/include/uapi/linux/pfru.h
> new file mode 100644
> index 000000000000..d6f57a75afd2
> --- /dev/null
> +++ b/include/uapi/linux/pfru.h
> @@ -0,0 +1,186 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Platform Firmware Runtime Update header
> + *
> + * Copyright(c) 2021 Intel Corporation. All rights reserved.
> + */
> +#ifndef __PFRU_H__
> +#define __PFRU_H__
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +#define PFRU_UUID		"ECF9533B-4A3C-4E89-939E-C77112601C6D"
> +#define PFRU_CODE_INJ_UUID		"B2F84B79-7B6E-4E45-885F-3FB9BB185402"
> +#define PFRU_DRV_UPDATE_UUID		"4569DD8C-75F1-429A-A3D6-24DE8097A0DF"
> +
> +#define FUNC_STANDARD_QUERY	0
> +#define FUNC_QUERY_UPDATE_CAP	1
> +#define FUNC_QUERY_BUF		2
> +#define FUNC_START		3
> +
> +#define CODE_INJECT_TYPE	1
> +#define DRIVER_UPDATE_TYPE	2
> +
> +#define REVID_1		1
> +#define REVID_2		2
> +
> +#define PFRU_MAGIC 0xEE
> +
> +#define UUID_SIZE 16
> +
> +/**
> + * PFRU_IOC_SET_REV - _IOW(PFRU_MAGIC, 0x01, unsigned int)
> + *
> + * Return: 0 on success, -errno on failure
> + *
> + * Set the Revision ID for PFRU Runtime Update. It could be either 1 or 2.
> + */
> +#define PFRU_IOC_SET_REV _IOW(PFRU_MAGIC, 0x01, unsigned int)
> +/**

Please use blank lines between these, it's hard to read.


> + * PFRU_IOC_STAGE - _IOW(PFRU_MAGIC, 0x02, unsigned int)
> + *
> + * Return: 0 on success, -errno on failure

What -errno?

Same for all of these, be explicit please.

> + *
> + * Stage a capsule image from communication buffer and perform authentication.
> + */
> +#define PFRU_IOC_STAGE _IOW(PFRU_MAGIC, 0x02, unsigned int)
> +/**
> + * PFRU_IOC_ACTIVATE - _IOW(PFRU_MAGIC, 0x03, unsigned int)
> + *
> + * Return: 0 on success, -errno on failure
> + *
> + * Activate a previous staged capsule image.
> + */
> +#define PFRU_IOC_ACTIVATE _IOW(PFRU_MAGIC, 0x03, unsigned int)
> +/**
> + * PFRU_IOC_STAGE_ACTIVATE - _IOW(PFRU_MAGIC, 0x04, unsigned int)
> + *
> + * Return: 0 on success, -errno on failure
> + *
> + * Perform both stage and activation actions.
> + */
> +#define PFRU_IOC_STAGE_ACTIVATE _IOW(PFRU_MAGIC, 0x04, unsigned int)
> +/**
> + * PFRU_IOC_QUERY_CAP - _IOR(PFRU_MAGIC, 0x05,
> + *			     struct pfru_update_cap_info)
> + *
> + * Return: 0 on success, -errno on failure.
> + *
> + * Retrieve information about the PFRU Runtime Update capability.
> + * The information is a struct pfru_update_cap_info.
> + */
> +#define PFRU_IOC_QUERY_CAP _IOR(PFRU_MAGIC, 0x05, struct pfru_update_cap_info)
> +
> +static inline int pfru_valid_revid(int id)
> +{
> +	return id == REVID_1 || id == REVID_2;

Why is this in a uapi file?  You just poluted the global namespace of
all userspace programs with this function :(

> +}
> +
> +/**
> + * struct pfru_payload_hdr - Capsule file payload header.
> + *
> + * @sig: Signature of this capsule file.
> + * @hdr_version: Revision of this header structure.
> + * @hdr_size: Size of this header, including the OemHeader bytes.
> + * @hw_ver: The supported firmware version.
> + * @rt_ver: Version of the code injection image.
> + * @platform_id: A platform specific GUID to specify the platform what
> + *               this capsule image support.
> + */
> +struct pfru_payload_hdr {
> +	__u32 sig;
> +	__u32 hdr_version;
> +	__u32 hdr_size;
> +	__u32 hw_ver;
> +	__u32 rt_ver;
> +	__u8 platform_id[UUID_SIZE];
> +};
> +
> +enum pfru_start_action {
> +	START_STAGE,
> +	START_ACTIVATE,
> +	START_STAGE_ACTIVATE,
> +};
> +
> +enum pfru_dsm_status {
> +	DSM_SUCCEED,
> +	DSM_FUNC_NOT_SUPPORT,
> +	DSM_INVAL_INPUT,
> +	DSM_HARDWARE_ERR,
> +	DSM_RETRY_SUGGESTED,
> +	DSM_UNKNOWN,
> +	DSM_FUNC_SPEC_ERR,

Do you need to be explicit about the numbers here?  I never remember if
this is guaranteed by all C compilers or not...

> +};
> +
> +/**
> + * struct pfru_update_cap_info - Runtime update capability information.
> + *
> + * @status: Indicator of whether this query succeed.
> + * @update_cap: Bitmap to indicate whether the feature is supported.
> + * @code_type: A buffer containing an image type GUID.
> + * @fw_version: Platform firmware version.
> + * @code_rt_version: Code injection runtime version for anti-rollback.
> + * @drv_type: A buffer containing an image type GUID.
> + * @drv_rt_version: The version of the driver update runtime code.
> + * @drv_svn: The secure version number(SVN) of the driver update runtime code.
> + * @platform_id: A buffer containing a platform ID GUID.
> + * @oem_id: A buffer containing an OEM ID GUID.
> + * @oem_info: A buffer containing the vendor specific information.
> + */
> +struct pfru_update_cap_info {
> +	__u32 status;
> +	__u32 update_cap;
> +
> +	__u8 code_type[UUID_SIZE];

Don't we have a uuid structure that crosses the user/kernel boundry?

> +	__u32 fw_version;
> +	__u32 code_rt_version;
> +
> +	__u8 drv_type[UUID_SIZE];
> +	__u32 drv_rt_version;
> +	__u32 drv_svn;
> +
> +	__u8 platform_id[UUID_SIZE];
> +	__u8 oem_id[UUID_SIZE];
> +
> +	char oem_info[];

As mentioned above, this is variable length, right?  Where are you
copying this extra data and how big do you know it is going to be?

thanks,

greg k-h