Introduce Platform Firmware Runtime Update and Telemetry drivers

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

drivers/acpi/pfru/pfru_update.c new file +16 -0

+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *p;
+	int ret = 0, rev;
+
+	p = (void __user *)arg;
+
+	switch (cmd) {
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(unsigned int)))
+			return -EFAULT;
+		if (!pfru_valid_revid(rev))
+			return -EFAULT;
+		pfru_dev->rev_id = rev;
+		break;
+	case PFRU_IOC_STAGE:

Quoted 7 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Quoted 1 line

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

drivers/acpi/pfru/pfru_update.c line 297

Quoted 9 lines

drivers/acpi/pfru/pfru_update.c new file +9 -0

+static void dump_update_result(struct pfru_updated_result *result)
+{
+	pr_debug("Update result:\n");
+	pr_debug("Status:%d\n", result->status);
+	pr_debug("Extended Status:%d\n", result->ext_status);
+	pr_debug("Authentication Time Low:%lld\n", result->low_auth_time);
+	pr_debug("Authentication Time High:%lld\n", result->high_auth_time);
+	pr_debug("Execution Time Low:%lld\n", result->low_exec_time);
+	pr_debug("Execution Time High:%lld\n", result->high_exec_time);

Why not dev_dbg()? Same for all pr_* calls in this "driver".

Quoted 20 lines

drivers/acpi/pfru/pfru_update.c new file +20 -0

+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *p;
+	int ret = 0, rev;
+
+	p = (void __user *)arg;
+
+	switch (cmd) {
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(unsigned int)))
+			return -EFAULT;
+		if (!pfru_valid_revid(rev))
+			return -EFAULT;
+		pfru_dev->rev_id = rev;
+		break;
+	case PFRU_IOC_STAGE:
+		ret = start_acpi_update(START_STAGE);
+		break;
+	case PFRU_IOC_ACTIVATE:
+		ret = start_acpi_update(START_ACTIVATE);

drivers/acpi/pfru/pfru_update.c line 385

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+		break;
+	case PFRU_IOC_STAGE_ACTIVATE:
+		ret = start_acpi_update(START_STAGE_ACTIVATE);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;

Wrong value :(

Quoted 7 lines

drivers/acpi/pfru/pfru_update.c new file +7 -0

+		break;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT

drivers/acpi/pfru/pfru_update.c line 398

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+static long compat_pfru_ioctl(struct file *filep, unsigned int cmd,
+			      unsigned long arg)
+{
+	return pfru_ioctl(filep, cmd, arg);
+}
+#endif

Why is this compat ioctl needed at all?

drivers/acpi/pfru/pfru_update.c line 491

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+static struct miscdevice pfru_misc_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "pfru_update",
+	.nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

Hi Greg,

Quoted 8 lines · Greg Kroah-Hartman

Quoted 7 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Quoted 6 lines

Quoted 1 line

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

The patch [5/5] is a self testing tool to test the whole feature. I'll send a new version and Cc you too.

Quoted 13 lines

drivers/acpi/pfru/pfru_update.c line 297

Quoted 9 lines

drivers/acpi/pfru/pfru_update.c new file +9 -0

+static void dump_update_result(struct pfru_updated_result *result)
+{
+	pr_debug("Update result:\n");
+	pr_debug("Status:%d\n", result->status);
+	pr_debug("Extended Status:%d\n", result->ext_status);
+	pr_debug("Authentication Time Low:%lld\n", result->low_auth_time);
+	pr_debug("Authentication Time High:%lld\n", result->high_auth_time);
+	pr_debug("Execution Time Low:%lld\n", result->low_exec_time);
+	pr_debug("Execution Time High:%lld\n", result->high_exec_time);

Why not dev_dbg()? Same for all pr_* calls in this "driver".

Ok, I'll switch to dev_dbg() in next version.

Quoted 20 lines

Quoted 20 lines

drivers/acpi/pfru/pfru_update.c new file +20 -0

+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *p;
+	int ret = 0, rev;
+
+	p = (void __user *)arg;
+
+	switch (cmd) {
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(unsigned int)))
+			return -EFAULT;
+		if (!pfru_valid_revid(rev))
+			return -EFAULT;
+		pfru_dev->rev_id = rev;
+		break;
+	case PFRU_IOC_STAGE:
+		ret = start_acpi_update(START_STAGE);
+		break;
+	case PFRU_IOC_ACTIVATE:
+		ret = start_acpi_update(START_ACTIVATE);

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 385

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+		break;
+	case PFRU_IOC_STAGE_ACTIVATE:
+		ret = start_acpi_update(START_STAGE_ACTIVATE);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;

Wrong value :(

Previously I thought that ENOIOCTLCMD stands for 'invalid ioctl command'. After checking the lkml discussion, it seems that ENOIOCTLCMD should not be returned to user space. ENOTTY might be more suitible if I understand correctly.
http://lkml.iu.edu/hypermail/linux/kernel/0105.1/0734.html

Quoted 7 lines

Quoted 7 lines

drivers/acpi/pfru/pfru_update.c new file +7 -0

+		break;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT

Quoted 9 lines

drivers/acpi/pfru/pfru_update.c line 398

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+static long compat_pfru_ioctl(struct file *filep, unsigned int cmd,
+			      unsigned long arg)
+{
+	return pfru_ioctl(filep, cmd, arg);
+}
+#endif

Why is this compat ioctl needed at all?

We can not control if the user space tool would be compiled as 32bit.

But I realize that a compat_ptr() was missing. Will fix it in next version.

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 491

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+static struct miscdevice pfru_misc_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "pfru_update",
+	.nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

The pfru directory might be reused for pfru_telemetry device, whose driver is in 4/5 patch, I'll Cc you with the whole patch set in next version.

Quoted 16 lines · Chen Yu

Hi Greg,

Quoted 14 lines · Greg Kroah-Hartman

Quoted 8 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

Quoted 2 lines

The patch [5/5] is a self testing tool to test the whole feature. I'll send a new version and Cc you too.

That tests it, but does not answer the question of who will actually use this. What userspace tool needs this new api?

Quoted 42 lines

Quoted 13 lines

drivers/acpi/pfru/pfru_update.c line 297

Quoted 9 lines

drivers/acpi/pfru/pfru_update.c new file +9 -0

+static void dump_update_result(struct pfru_updated_result *result)
+{
+	pr_debug("Update result:\n");
+	pr_debug("Status:%d\n", result->status);
+	pr_debug("Extended Status:%d\n", result->ext_status);
+	pr_debug("Authentication Time Low:%lld\n", result->low_auth_time);
+	pr_debug("Authentication Time High:%lld\n", result->high_auth_time);
+	pr_debug("Execution Time Low:%lld\n", result->low_exec_time);
+	pr_debug("Execution Time High:%lld\n", result->high_exec_time);

Why not dev_dbg()? Same for all pr_* calls in this "driver".

Ok, I'll switch to dev_dbg() in next version.

Quoted 20 lines

Quoted 20 lines

drivers/acpi/pfru/pfru_update.c new file +20 -0

+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *p;
+	int ret = 0, rev;
+
+	p = (void __user *)arg;
+
+	switch (cmd) {
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(unsigned int)))
+			return -EFAULT;
+		if (!pfru_valid_revid(rev))
+			return -EFAULT;
+		pfru_dev->rev_id = rev;
+		break;
+	case PFRU_IOC_STAGE:
+		ret = start_acpi_update(START_STAGE);
+		break;
+	case PFRU_IOC_ACTIVATE:
+		ret = start_acpi_update(START_ACTIVATE);

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 385

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+		break;
+	case PFRU_IOC_STAGE_ACTIVATE:
+		ret = start_acpi_update(START_STAGE_ACTIVATE);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;

Wrong value :(

Quoted 5 lines

Previously I thought that ENOIOCTLCMD stands for 'invalid ioctl command'. After checking the lkml discussion, it seems that ENOIOCTLCMD should not be returned to user space. ENOTTY might be more suitible if I understand correctly.
http://lkml.iu.edu/hypermail/linux/kernel/0105.1/0734.html

Yes, ENOTTY is correct.

Quoted 16 lines

Quoted 16 lines

drivers/acpi/pfru/pfru_update.c line 398

Quoted 13 lines

drivers/acpi/pfru/pfru_update.c new file +13 -0

+		break;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static long compat_pfru_ioctl(struct file *filep, unsigned int cmd,
+			      unsigned long arg)
+{
+	return pfru_ioctl(filep, cmd, arg);
+}
+#endif

Why is this compat ioctl needed at all?

Quoted 1 line

We can not control if the user space tool would be compiled as 32bit.

Then create your ioctl so that a compat ioctl is not needed at all. There is no need to ever use this for new ioctl commands these days.

Quoted 9 lines

But I realize that a compat_ptr() was missing. Will fix it in next version.

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 491

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+static struct miscdevice pfru_misc_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "pfru_update",
+	.nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

Quoted 2 lines

The pfru directory might be reused for pfru_telemetry device, whose driver is in 4/5 patch, I'll Cc you with the whole patch set in next version.

"might be" is not a valid reason. Why does this simple driver deserve a whole /dev/ subdirectory?

Quoted 17 lines · Greg Kroah-Hartman

Quoted 16 lines · Chen Yu

Hi Greg,

Quoted 14 lines · Greg Kroah-Hartman

Quoted 8 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

Quoted 6 lines

Quoted 2 lines

The patch [5/5] is a self testing tool to test the whole feature. I'll send a new version and Cc you too.

That tests it, but does not answer the question of who will actually use this. What userspace tool needs this new api?

One end user is the cloud user.

Currently there is no dedicated userspace tool developed to use this feature AFAIK.

It was expected that the end users
could refer to the self test tool to customize their tools. I'm not sure if this is the proper way to propose the feature, may I have your suggestion on this, should I create a separate git repository for this tool, or put it in tools/selftestings as it is now?

Quoted 11 lines

Quoted 10 lines

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 491

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+static struct miscdevice pfru_misc_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "pfru_update",
+	.nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

The pfru directory might be reused for pfru_telemetry device, whose driver is in 4/5 patch, I'll Cc you with the whole patch set in next version.

Quoted 3 lines

"might be" is not a valid reason. Why does this simple driver deserve a whole /dev/ subdirectory?

There are pfru_update and pfru_telemetry in the patch, and there is plan to add a pfru_prm device in the future, which stands for "Platform Runtime Mechanism". I'll move them to /dev/ in next version.

Add the Platform Firmware Runtime Update/Telemetry documentation.

Signed-off-by Chen Yu <[email protected]>

---
v3: No change since v2.
v2: Add a spot in index.rst so it becomes part of the docs build
(Jonathan Corbet).
Sticking to the 80-column limit(Jonathan Corbet). Underline lengths should match the title text(Jonathan Corbet). Use literal blocks for the code samples(Jonathan Corbet).

---
 Documentation/x86/index.rst |   1 +
 Documentation/x86/pfru.rst  | 100 ++++++++++++++++++++++++++++++++++++

 2 files changed, 101 insertions(+)
 create mode 100644 Documentation/x86/pfru.rst

Documentation/x86/index.rst +1 -0

index 383048396336..3791fabf964c 100644
@@ -37,3 +37,4 @@ x86-specific Documentation
    sgx
    features
    elf_auxvec
+   pfru

Documentation/x86/pfru.rst new file +0 -0

new file mode 100644
index 000000000000..29fe0e518e6d

Documentation/x86/pfru.rst new file +50 -0

+
+The user space tool manipulates on /dev/pfru/update for code injection and
+driver update. PFRU stands for Platform Firmware Runtime Update, and the
+/dev/pfru directory might be reserved for future usage::
+
+ 1. mmap the capsule file.
+    fd_capsule = open("capsule.cap", O_RDONLY);
+    fstat(fd_capsule, &stat);
+    addr = mmap(0, stat.st_size, PROT_READ, fd_capsule);
+
+ 2. Get the capability information(version control, etc) from BIOS via
+    read() and do sanity check in user space.
+    fd_update = open("/dev/pfru/update", O_RDWR);
+    read(fd_update, &cap, sizeof(cap));
+    sanity_check(&cap);
+
+ 3. Write the capsule file to runtime update communication buffer.
+    kernel might return error if capsule file size is longer than
+    communication buffer.
+    write(fd_update, addr, stat.st_size);
+
+ 4. Stage the code injection.
+    ioctl(fd_update, PFRU_IOC_STATGE);
+
+ 5. Activate the code injection.
+    ioctl(fd_update, PFRU_IOC_ACTIVATE);
+
+ 6. Stage and activate the code injection.
+    ioctl(fd_update, PFRU_IOC_STAGE_ACTIVATE);
+
+    PFRU_IOC_STATGE: Stage a capsule image from communication buffer
+    and perform authentication.
+    [PFRU_IOC_ACTIVATE] Activate a previous staged capsule image.
+    [PFRU_IOC_STAGE_ACTIVATE] Perform both stage and activation actions.
+
+
+PFRU Telemetry interfaces
+=========================
+
+The user space tool manipulates on /dev/pfru/telemetry for PFRU telemetry log::
+
+ 1. Open telemetry device
+    fd_log = open("/dev/pfru/telemetry", O_RDWR);
+
+ 2. Get log level, log type, revision_id via one ioctl invoke
+    ioctl(fd_log, PFRU_IOC_GET_LOG_INFO, &info);
+
+ 3. Set log level, log type, revision_id
+    ioctl(fd_log, PFRU_IOC_SET_LOG_INFO, &info);
+

Documentation/x86/pfru.rst new file +3 -1

+sure that there is no more data appended while the user is reading the buffer.
+Besides, only after the runtime update has been run at least once, the telemetry
+log would have valid data, otherwise errno code of EBUSY would be returned.
--

Platform Firmware Runtime Update image starts with UEFI headers, and the headers are defined in UEFI specification, but some of them have not been defined in the kernel yet.

For example, the header layout of a capsule file looks like this:

EFI_CAPSULE_HEADER
EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER
EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER
EFI_FIRMWARE_IMAGE_AUTHENTICATION

These structures would be used by the Platform Firmware Runtime Update driver to parse the format of capsule file to verify if the corresponding version number is valid. The EFI_CAPSULE_HEADER has been defined in the kernel, however the rest are not, thus introduce corresponding UEFI structures accordingly.

The reason why efi_manage_capsule_header_t and efi_manage_capsule_image_header_t are packedi might be that:
According to the uefi spec,
[Figure 23-6 Firmware Management and Firmware Image Management headers] EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER is located at the lowest offset within the body of the capsule. And this structure is designed to be unaligned to save space, because in this way the adjacent drivers and binary payload elements could start on byte boundary with no padding. And the EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER is at the head of each payload, so packing this structure also makes room for more data.

Signed-off-by Chen Yu <[email protected]>

---
 include/linux/efi.h | 50 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

include/linux/efi.h +50 -1

index 6b5d36babfcc..19ff834e1388 100644
@@ -148,6 +148,56 @@ typedef struct {
        u32 imagesize;
 } efi_capsule_header_t;
 
+#pragma pack(1)
+
+/* EFI_FIRMWARE_MANAGEMENT_CAPSULE_HEADER */
+typedef struct {
+       u32     ver;
+       u16     emb_drv_cnt;
+       u16     payload_cnt;
+       /*
+        * Variable array indicated by number of
+        * (emb_drv_cnt + payload_cnt)
+        */
+       u64     offset_list[];
+} efi_manage_capsule_header_t;
+
+/* EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER */
+typedef struct {
+       u32     ver;
+       guid_t  image_type_id;
+       u8      image_index;
+       u8      reserved_bytes[3];
+       u32     image_size;
+       u32     vendor_code_size;
+       /* ver = 2. */
+       u64     hw_ins;
+       /* ver = v3. */
+       u64     capsule_support;
+} efi_manage_capsule_image_header_t;
+
+#pragma pack()
+
+/* WIN_CERTIFICATE */
+typedef struct {
+       u32     len;
+       u16     rev;
+       u16     cert_type;
+} win_cert_t;
+
+/* WIN_CERTIFICATE_UEFI_GUID */
+typedef struct {
+       win_cert_t      hdr;
+       guid_t          cert_type;
+       u8              cert_data[];
+} win_cert_uefi_guid_t;
+
+/* EFI_FIRMWARE_IMAGE_AUTHENTICATIO */
+typedef struct {
+       u64                             mon_count;
+       win_cert_uefi_guid_t            auth_info;
+} efi_image_auth_t;
+
 /*
  * EFI capsule flags
  */
--

2.25.1

Quoted 18 lines · Chen Yu

Quoted 17 lines · Greg Kroah-Hartman

Quoted 16 lines · Chen Yu

Hi Greg,

Quoted 14 lines · Greg Kroah-Hartman

Quoted 8 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

Quoted 7 lines

Quoted 6 lines

Quoted 2 lines

The patch [5/5] is a self testing tool to test the whole feature. I'll send a new version and Cc you too.

That tests it, but does not answer the question of who will actually use this. What userspace tool needs this new api?

One end user is the cloud user.

What exactly do you mean by "cloud user"?

Quoted 2 lines

Currently there is no dedicated userspace tool developed to use this feature AFAIK.

Wonderful, then it is not needed to be added to the kernel :)

Quoted 5 lines

It was expected that the end users
could refer to the self test tool to customize their tools. I'm not sure if this is the proper way to propose the feature, may I have your suggestion on this, should I create a separate git repository for this tool, or put it in tools/selftestings as it is now?

No, do not add this to the kernel unless you have a real need and user for this.

Quoted 14 lines

Quoted 14 lines

Quoted 10 lines

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c line 491

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+static struct miscdevice pfru_misc_dev = {
+     .minor = MISC_DYNAMIC_MINOR,
+     .name = "pfru_update",
+     .nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

The pfru directory might be reused for pfru_telemetry device, whose driver is in 4/5 patch, I'll Cc you with the whole patch set in next version.

"might be" is not a valid reason. Why does this simple driver deserve a whole /dev/ subdirectory?

Quoted 3 lines

There are pfru_update and pfru_telemetry in the patch, and there is plan to add a pfru_prm device in the future, which stands for "Platform Runtime Mechanism". I'll move them to /dev/ in next version.

That is a very generic name for a very platform specific and arch specific interface. As this is an ACPI interface, why not use that name prefix?

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

---
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                     |  15 +
 drivers/acpi/pfru/Makefile                    |   2 +
 drivers/acpi/pfru/pfru_update.c               | 567 ++++++++++++++++++
 include/uapi/linux/pfru.h                     | 101 ++++
 7 files changed, 688 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

Documentation/userspace-api/ioctl/ioctl-number.rst +1 -0

index 2e8134059c87..6e5a82fff408 100644
@@ -365,6 +365,7 @@ Code  Seq#    Include File                                           Comments
                                                                      <mailto:[email protected]>
 0xE5  00-3F  linux/fuse.h
 0xEC  00-01  drivers/platform/chrome/cros_ec_dev.h                   ChromeOS EC driver
+0xEE  00-1F  uapi/linux/pfru.h                                       Platform Firmware Runtime Update and Telemetry
 0xF3  00-3F  drivers/usb/misc/sisusbvga/sisusb.h                     sisfb (in development)
                                                                      <mailto:[email protected]>
 0xF6  all                                                            LTTng Linux Trace Toolkit Next Generation

drivers/acpi/Kconfig +1 -0

index 1da360c51d66..1d8d2e2cefac 100644
@@ -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

drivers/acpi/Makefile +1 -0

index 3018714e87d9..9c2c5ddff6ec 100644
@@ -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

drivers/acpi/pfru/Kconfig new file +15 -0

new file mode 100644
index 000000000000..3f31b7d95f3b
@@ -0,0 +1,15 @@
+# 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.
+
+         For more information, see:
+         <file:Documentation/x86/pfru_update.rst>
+
+         To compile this driver as a module, choose M here:
+         the module will be called pfru_update.

drivers/acpi/pfru/Makefile new file +2 -0

new file mode 100644
index 000000000000..098cbe80cf3d
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_ACPI_PFRU) += pfru_update.o

drivers/acpi/pfru/pfru_update.c new file +70 -0

new file mode 100644
index 000000000000..cd2039a195c9
@@ -0,0 +1,567 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI Platform Firmware Runtime Update Device Driver
+ *
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Chen Yu <[email protected]>
+ */
+#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/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,
+};
+
+enum buf_index {
+       BUF_STATUS_IDX,
+       BUF_EXT_STATUS_IDX,
+       BUF_ADDR_LOW_IDX,
+       BUF_ADDR_HI_IDX,
+       BUF_SIZE_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,
+};
+
+struct pfru_device {
+       guid_t uuid, code_uuid, drv_uuid;
+       int rev_id;
+       struct device *dev;
+};
+
+/*
+ * There would be only one instance of pfru_device.
+ */
+static struct pfru_device *pfru_dev;
+
+static bool valid_cap_type(int idx, union acpi_object *obj)
+{
+       acpi_object_type type = obj->type;
+
+       if (idx == CAP_STATUS_IDX || idx == CAP_UPDATE_IDX ||

drivers/acpi/pfru/pfru_update.c new file +5 -0

+
+static int query_capability(struct pfru_update_cap_info *cap)
+{
+       union acpi_object *out_obj;
+       acpi_handle handle;

drivers/acpi/pfru/pfru_update.c new file +26 -0

+               case CAP_UPDATE_IDX:
+                       cap->update_cap = obj->integer.value;
+                       break;
+               case CAP_CODE_TYPE_IDX:
+                       memcpy(&cap->code_type, obj->buffer.pointer,
+                              obj->buffer.length);
+                       break;
+               case CAP_FW_VER_IDX:
+                       cap->fw_version = obj->integer.value;
+                       break;
+               case CAP_CODE_RT_VER_IDX:
+                       cap->code_rt_version = obj->integer.value;
+                       break;
+               case CAP_DRV_TYPE_IDX:
+                       memcpy(&cap->drv_type, obj->buffer.pointer,
+                              obj->buffer.length);
+                       break;
+               case CAP_DRV_RT_VER_IDX:
+                       cap->drv_rt_version = obj->integer.value;
+                       break;
+               case CAP_DRV_SVN_IDX:
+                       cap->drv_svn = obj->integer.value;
+                       break;
+               case CAP_PLAT_ID_IDX:
+                       memcpy(&cap->platform_id, obj->buffer.pointer,
+                              obj->buffer.length);

drivers/acpi/pfru/pfru_update.c new file +15 -0

+                       goto free_acpi_buffer;
+               }
+       }
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+
+       return ret;
+}
+
+static int query_buffer(struct pfru_com_buf_info *info)
+{
+       union acpi_object *out_obj;
+       acpi_handle handle;

drivers/acpi/pfru/pfru_update.c new file +31 -0

+               union acpi_object *obj = &out_obj->package.elements[i];
+
+               if (obj->type != ACPI_TYPE_INTEGER)
+                       goto free_acpi_buffer;
+
+               switch (i) {
+               case BUF_STATUS_IDX:
+                       info->status = obj->integer.value;
+                       break;
+               case BUF_EXT_STATUS_IDX:
+                       info->ext_status = obj->integer.value;
+                       break;
+               case BUF_ADDR_LOW_IDX:
+                       info->addr_lo = obj->integer.value;
+                       break;
+               case BUF_ADDR_HI_IDX:
+                       info->addr_hi = obj->integer.value;
+                       break;
+               case BUF_SIZE_IDX:
+                       info->buf_size = obj->integer.value;
+                       break;
+               default:
+                       pr_err("Incorrect format of Communication Buffer.\n");
+                       goto free_acpi_buffer;
+               }
+       }
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+

drivers/acpi/pfru/pfru_update.c new file +9 -0

+ */
+static int adjust_efi_size(efi_manage_capsule_image_header_t *img_hdr,
+                          int *size)
+{
+       int tmp_size = *size;
+
+       tmp_size += sizeof(efi_manage_capsule_image_header_t);
+       switch (img_hdr->ver) {
+       case 1:

drivers/acpi/pfru/pfru_update.c new file +39 -0

+ */
+static bool valid_version(const void *data, struct pfru_update_cap_info *cap)
+{
+       struct pfru_payload_hdr *payload_hdr;
+       efi_capsule_header_t *cap_hdr;
+       efi_manage_capsule_header_t *m_hdr;
+       efi_manage_capsule_image_header_t *m_img_hdr;
+       efi_image_auth_t *auth;
+       int type, size, ret;
+
+       cap_hdr = (efi_capsule_header_t *)data;
+       size = cap_hdr->headersize;
+       m_hdr = (efi_manage_capsule_header_t *)(data + size);
+       /*
+        * Current data structure size plus variable array indicated
+        * by number of (emb_drv_cnt + payload_cnt)
+        */
+       size += sizeof(efi_manage_capsule_header_t) +
+                     (m_hdr->emb_drv_cnt + m_hdr->payload_cnt) * sizeof(u64);
+       m_img_hdr = (efi_manage_capsule_image_header_t *)(data + size);
+
+       ret = get_image_type(m_img_hdr, &type);
+       if (ret)
+               return false;
+
+       ret = adjust_efi_size(m_img_hdr, &size);
+       if (ret)
+               return false;
+
+       auth = (efi_image_auth_t *)(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;
+}

drivers/acpi/pfru/pfru_update.c new file +15 -0

+}
+
+static int start_acpi_update(int action)
+{
+       union acpi_object *out_obj, in_obj, in_buf;
+       struct pfru_updated_result update_result;
+       acpi_handle handle;
+       int i, 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;

drivers/acpi/pfru/pfru_update.c new file +40 -0

+               union acpi_object *obj = &out_obj->package.elements[i];
+
+               if (obj->type != ACPI_TYPE_INTEGER)
+                       goto free_acpi_buffer;
+               switch (i) {
+               case UPDATE_STATUS_IDX:
+                       update_result.status = obj->integer.value;
+                       break;
+               case UPDATE_EXT_STATUS_IDX:
+                       update_result.ext_status = obj->integer.value;
+                       break;
+               case UPDATE_AUTH_TIME_LOW_IDX:
+                       update_result.low_auth_time = obj->integer.value;
+                       break;
+               case UPDATE_AUTH_TIME_HI_IDX:
+                       update_result.high_auth_time = obj->integer.value;
+                       break;
+               case UPDATE_EXEC_TIME_LOW_IDX:
+                       update_result.low_exec_time = obj->integer.value;
+                       break;
+               case UPDATE_EXEC_TIME_HI_IDX:
+                       update_result.high_exec_time = obj->integer.value;
+                       break;
+               default:
+                       pr_err("Incorrect format of Runtime Update result.\n");
+                       goto free_acpi_buffer;
+               }
+       }
+       dump_update_result(&update_result);
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+
+       return ret;
+}
+
+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+       void __user *p;

drivers/acpi/pfru/pfru_update.c new file +49 -0

+               pfru_dev->rev_id = rev;
+               break;
+       case PFRU_IOC_STAGE:
+               ret = start_acpi_update(START_STAGE);
+               break;
+       case PFRU_IOC_ACTIVATE:
+               ret = start_acpi_update(START_ACTIVATE);
+               break;
+       case PFRU_IOC_STAGE_ACTIVATE:
+               ret = start_acpi_update(START_STAGE_ACTIVATE);
+               break;
+       default:
+               ret = -ENOIOCTLCMD;
+               break;
+       }
+
+       return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static long compat_pfru_ioctl(struct file *filep, unsigned int cmd,
+                             unsigned long arg)
+{
+       return pfru_ioctl(filep, cmd, arg);
+}
+#endif
+
+static int pfru_open(struct inode *inode, struct file *file)
+{
+       return capable(CAP_SYS_RAWIO) ? stream_open(inode, file) : -EPERM;
+}
+
+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;
+       phys_addr_t phy_addr;
+       struct iov_iter iter;
+       struct iovec iov;
+       char *buf_ptr;
+       int ret;
+
+       ret = query_buffer(&info);
+       if (ret)
+               return ret;
+
+       if (len > info.buf_size)
+               return -EINVAL;

drivers/acpi/pfru/pfru_update.c new file +20 -0

+
+       if (cap.status != DSM_SUCCEED) {
+               ret = -EBUSY;
+               goto unmap;
+       }
+       if (!valid_version(buf_ptr, &cap)) {
+               ret = -EINVAL;
+               goto unmap;
+       }
+       ret = 0;
+unmap:
+       memunmap(buf_ptr);
+
+       return ret ?: len;
+}
+
+static ssize_t pfru_read(struct file *filp, char __user *ubuf,
+                        size_t size, loff_t *off)
+{
+       struct pfru_update_cap_info cap;

drivers/acpi/pfru/pfru_update.c new file +96 -0

+
+       return size;
+}
+
+static const struct file_operations acpi_pfru_fops = {
+       .owner          = THIS_MODULE,
+       .write          = pfru_write,
+       .read           = pfru_read,
+       .open           = pfru_open,
+       .unlocked_ioctl = pfru_ioctl,
+#ifdef CONFIG_COMPAT
+       .compat_ioctl   = compat_pfru_ioctl,
+#endif
+       .llseek         = noop_llseek,
+};
+
+static struct miscdevice pfru_misc_dev = {
+       .minor = MISC_DYNAMIC_MINOR,
+       .name = "pfru_update",
+       .nodename = "pfru/update",
+       .fops = &acpi_pfru_fops,
+};
+
+static int acpi_pfru_remove(struct platform_device *pdev)
+{
+       misc_deregister(&pfru_misc_dev);
+       kfree(pfru_dev);
+       pfru_dev = NULL;
+
+       return 0;
+}
+
+static int acpi_pfru_probe(struct platform_device *pdev)
+{
+       acpi_handle handle;
+       int ret;
+
+       if (pfru_dev) {
+               pr_err("Duplicated PFRU INTC1080 detected, skip...\n");
+               return 0;
+       }
+
+       pfru_dev = kzalloc(sizeof(*pfru_dev), GFP_KERNEL);
+       if (!pfru_dev)
+               return -ENOMEM;
+
+       ret = guid_parse(PFRU_UUID, &pfru_dev->uuid);
+       if (ret)
+               goto out;
+       ret = guid_parse(PFRU_CODE_INJ_UUID, &pfru_dev->code_uuid);
+       if (ret)
+               goto out;
+       ret = guid_parse(PFRU_DRV_UPDATE_UUID, &pfru_dev->drv_uuid);
+       if (ret)
+               goto out;
+
+       /* default rev id is 1 */
+       pfru_dev->rev_id = 1;
+       pfru_dev->dev = &pdev->dev;
+       handle = ACPI_HANDLE(pfru_dev->dev);
+       if (!acpi_has_method(handle, "_DSM")) {
+               pr_err("Missing _DSM\n");
+               ret = -ENODEV;
+               goto out;
+       }
+
+       ret = misc_register(&pfru_misc_dev);
+       if (ret)
+               goto out;
+
+       return 0;
+out:
+       kfree(pfru_dev);
+       pfru_dev = NULL;
+
+       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);
+
+MODULE_DESCRIPTION("Platform Firmware Runtime Update device driver");
+MODULE_LICENSE("GPL v2");

include/uapi/linux/pfru.h new file +101 -1

new file mode 100644
index 000000000000..ca0b7433f79f
@@ -0,0 +1,101 @@
+/* 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/ioctl.h>
+#include <linux/uuid.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 PFRU_IOC_SET_REV _IOW(PFRU_MAGIC, 0x01, unsigned int)
+#define PFRU_IOC_STAGE _IOW(PFRU_MAGIC, 0x02, unsigned int)
+#define PFRU_IOC_ACTIVATE _IOW(PFRU_MAGIC, 0x03, unsigned int)
+#define PFRU_IOC_STAGE_ACTIVATE _IOW(PFRU_MAGIC, 0x04, unsigned int)
+
+static inline int pfru_valid_revid(int id)
+{
+       return (id == REVID_1) || (id == REVID_2);
+}
+
+/* Capsule file payload header */
+struct pfru_payload_hdr {
+       __u32   sig;
+       __u32   hdr_version;
+       __u32   hdr_size;
+       __u32   hw_ver;
+       __u32   rt_ver;
+       uuid_t  platform_id;
+};
+
+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,
+};
+
+struct pfru_update_cap_info {
+       enum pfru_dsm_status status;
+       __u32 update_cap;
+
+       uuid_t code_type;
+       __u32 fw_version;
+       __u32 code_rt_version;
+
+       uuid_t drv_type;
+       __u32 drv_rt_version;
+       __u32 drv_svn;
+
+       uuid_t platform_id;
+       uuid_t oem_id;
+
+       char oem_info[];
+};
+
+struct pfru_com_buf_info {
+       enum pfru_dsm_status status;
+       enum pfru_dsm_status ext_status;
+       __u64 addr_lo;
+       __u64 addr_hi;
+       __u32 buf_size;
+};
+
+struct pfru_updated_result {
+       enum pfru_dsm_status status;
+       enum pfru_dsm_status ext_status;
+       __u64 low_auth_time;
+       __u64 high_auth_time;
+       __u64 low_exec_time;
+       __u64 high_exec_time;
+};
+
+#endif /* __PFRU_H__ */
--

Platform Firmware Runtime Update(PFRU) Telemetry Service is part of RoT (Root of Trust), which allows PFRU handler and other PFRU drivers to produce telemetry data to upper layer OS consumer at runtime.

The linux provides interfaces for the user to query the parameters of telemetry data, and the user could read out the telemetry data accordingly.

Typical log looks like:

[SmmRuntimeUpdateHandler.ProcessSmmRuntimeUpdate] ProcessSmmRuntimeUpdate = START, Action = 2 [SmmRuntimeUpdateHandler.ProcessSmmRuntimeUpdate]
FwVersion = 0, CodeInjectionVersion = 1 [ShadowSmmRuntimeUpdateImage]
Image = 0x74D9B000, ImageSize = 0x1172 [ProcessSmmRuntimeUpdate]
ShadowSmmRuntimeUpdateImage.Status = Success [ValidateSmmRuntimeUpdateImage]
CapsuleHeader.CapsuleGuid = 6DCBD5ED-E82D-4C44-BDA1-7194199AD92A [ValidateSmmRuntimeUpdateImage]
FmpCapHeader.Version = 1
[ValidateSmmRuntimeUpdateImage] FmpCapImageHeader.UpdateImageTypeId = B2F84B79-7B6E-4E45-885F-3FB9BB185402 [ValidateSmmRuntimeUpdateImage] SmmRuntimeUpdateVerifyImageWithDenylist.Status = Success [ValidateSmmRuntimeUpdateImage] SmmRuntimeUpdateVerifyImageWithAllowlist.Status = Success [SmmCodeInjectionVerifyPayloadHeader]
PayloadHeader.Signature = 0x31494353 [SmmCodeInjectionVerifyPayloadHeader]
PayloadHeader.PlatformId = 63462139-A8B1-AA4E-9024-F2BB53EA4723 [SmmCodeInjectionVerifyPayloadHeader] PayloadHeader.SupportedSmmFirmwareVersion = 0, PayloadHeader.SmmCodeInjectionRuntimeVersion = 1 [ProcessSmmRuntimeUpdate]
ValidateSmmRuntimeUpdateImage.Status = Success
CPU CSR[0B102D28] Before = 7FBF830E
CPU CSR[0B102D28] After = 7FBF8310
[ProcessSmmRuntimeUpdate] ProcessSmmCodeInjection.Status = Success [SmmRuntimeUpdateHandler.ProcessSmmRuntimeUpdate] ProcessSmmRuntimeUpdate = End, Status = Success

Signed-off-by Chen Yu <[email protected]>

---
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: Do similar clean up as pfru_update driver:
Add sanity check for duplicated instance of ACPI device. Update the driver to work with allocated telem_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)

---
 drivers/acpi/pfru/Kconfig          |  14 +
 drivers/acpi/pfru/Makefile         |   1 +
 drivers/acpi/pfru/pfru_telemetry.c | 412 +++++++++++++++++++++++++++++
 include/uapi/linux/pfru.h          |  43 +++
 4 files changed, 470 insertions(+)
 create mode 100644 drivers/acpi/pfru/pfru_telemetry.c

drivers/acpi/pfru/Kconfig +0 -0

index 3f31b7d95f3b..e2934058884e 100644

drivers/acpi/pfru/Kconfig +12 -0

+       tristate "ACPI Platform Firmware Runtime Update Telemetry Service"
+       depends on ACPI_PFRU
+       help
+         PFRU(Platform Firmware Runtime Update) Telemetry Service is part of
+         RoT(Root of Trust), which allows Platform Firmware Runtime Update handler
+         and other PFRU drivers to produce telemetry data to upper layer OS consumer
+         at runtime.
+
+         For more information, see:
+         <file:Documentation/x86/pfru_update.rst>
+
+         If unsure, please say N.

drivers/acpi/pfru/Makefile +0 -0

index 098cbe80cf3d..30060ba320ea 100644

drivers/acpi/pfru/pfru_telemetry.c new file +62 -0

new file mode 100644
index 000000000000..96dc9e69edc0
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI Platform Firmware Runtime Update
+ * Telemetry Service Device Driver
+ *
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Chen Yu <[email protected]>
+ */
+#include <linux/acpi.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/minmax.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/platform_device.h>
+#include <linux/uuid.h>
+#include <linux/uaccess.h>
+#include <uapi/linux/pfru.h>
+
+enum update_index {
+       LOG_STATUS_IDX,
+       LOG_EXT_STATUS_IDX,
+       LOG_MAX_SZ_IDX,
+       LOG_CHUNK1_LO_IDX,
+       LOG_CHUNK1_HI_IDX,
+       LOG_CHUNK1_SZ_IDX,
+       LOG_CHUNK2_LO_IDX,
+       LOG_CHUNK2_HI_IDX,
+       LOG_CHUNK2_SZ_IDX,
+       LOG_ROLLOVER_CNT_IDX,
+       LOG_RESET_CNT_IDX,
+};
+
+struct pfru_telem_device {
+       struct device *dev;
+       guid_t uuid;
+       struct pfru_telem_info info;
+};
+
+/*
+ * There would be only one instance of pfru_telem_device.
+ */
+static struct pfru_telem_device *telem_dev;
+
+static int get_pfru_data_info(struct pfru_telem_data_info *data_info,
+                             int log_type)
+{
+       union acpi_object *out_obj, in_obj, in_buf;
+       acpi_handle handle;
+       int i, ret = -EINVAL;
+
+       handle = ACPI_HANDLE(telem_dev->dev);
+
+       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 = log_type;

drivers/acpi/pfru/pfru_telemetry.c new file +31 -0

+               union acpi_object *obj = &out_obj->package.elements[i];
+
+               if (obj->type != ACPI_TYPE_INTEGER)
+                       goto free_acpi_buffer;
+
+               switch (i) {
+               case LOG_STATUS_IDX:
+                       data_info->status = obj->integer.value;
+                       break;
+               case LOG_EXT_STATUS_IDX:
+                       data_info->ext_status = obj->integer.value;
+                       break;
+               case LOG_MAX_SZ_IDX:
+                       data_info->max_data_size = obj->integer.value;
+                       break;
+               case LOG_CHUNK1_LO_IDX:
+                       data_info->chunk1_addr_lo = obj->integer.value;
+                       break;
+               case LOG_CHUNK1_HI_IDX:
+                       data_info->chunk1_addr_hi = obj->integer.value;
+                       break;
+               case LOG_CHUNK1_SZ_IDX:
+                       data_info->chunk1_size = obj->integer.value;
+                       break;
+               case LOG_CHUNK2_LO_IDX:
+                       data_info->chunk2_addr_lo = obj->integer.value;
+                       break;
+               case LOG_CHUNK2_HI_IDX:
+                       data_info->chunk2_addr_hi = obj->integer.value;
+                       break;
+               case LOG_CHUNK2_SZ_IDX:

drivers/acpi/pfru/pfru_telemetry.c new file +98 -0

+                       goto free_acpi_buffer;
+               }
+       }
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+
+       return ret;
+}
+
+static int set_pfru_log_level(int level)
+{
+       union acpi_object *out_obj, *obj, in_obj, in_buf;
+       enum pfru_dsm_status status;
+       acpi_handle handle;
+       int ret = -EINVAL;
+
+       handle = ACPI_HANDLE(telem_dev->dev);
+
+       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 = level;
+
+       out_obj = acpi_evaluate_dsm_typed(handle, &telem_dev->uuid,
+                                         telem_dev->info.log_revid, FUNC_SET_LEV,
+                                         &in_obj, ACPI_TYPE_PACKAGE);
+       if (!out_obj)
+               return -EINVAL;
+
+       obj = &out_obj->package.elements[0];
+       status = obj->integer.value;
+       if (status) {
+               pr_err("get MM telemetry level error status %d\n",
+                      status);
+               goto free_acpi_buffer;
+       }
+
+       obj = &out_obj->package.elements[1];
+       status = obj->integer.value;
+       if (status) {
+               pr_err("get MM telemetry level error extend status %d\n",
+                      status);
+               goto free_acpi_buffer;
+       }
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+
+       return ret;
+}
+
+static int get_pfru_log_level(int *level)
+{
+       union acpi_object *out_obj, *obj;
+       enum pfru_dsm_status status;
+       acpi_handle handle;
+       int ret = -EINVAL;
+
+       handle = ACPI_HANDLE(telem_dev->dev);
+       out_obj = acpi_evaluate_dsm_typed(handle, &telem_dev->uuid,
+                                         telem_dev->info.log_revid, FUNC_GET_LEV,
+                                         NULL, ACPI_TYPE_PACKAGE);
+       if (!out_obj)
+               return -EINVAL;
+
+       obj = &out_obj->package.elements[0];
+       if (obj->type != ACPI_TYPE_INTEGER)
+               goto free_acpi_buffer;
+       status = obj->integer.value;
+       if (status) {
+               pr_err("get MM telemetry level error status %d\n",
+                      status);
+               goto free_acpi_buffer;
+       }
+
+       obj = &out_obj->package.elements[1];
+       if (obj->type != ACPI_TYPE_INTEGER)
+               goto free_acpi_buffer;
+       status = obj->integer.value;
+       if (status) {
+               pr_err("get MM telemetry level error status %d\n",
+                      status);
+               goto free_acpi_buffer;
+       }
+
+       obj = &out_obj->package.elements[2];
+       if (obj->type != ACPI_TYPE_INTEGER)
+               goto free_acpi_buffer;
+       *level = obj->integer.value;
+
+       ret = 0;
+

drivers/acpi/pfru/pfru_telemetry.c new file +6 -0

+}
+
+static long pfru_telemetry_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+
+{
+       struct pfru_telem_data_info data_info;

drivers/acpi/pfru/pfru_telemetry.c new file +33 -0

+               break;
+       case PFRU_LOG_IOC_GET_INFO:
+               ret = get_pfru_log_level(&info.log_level);
+               if (ret)
+                       return ret;
+               info.log_type = telem_dev->info.log_type;
+               info.log_revid = telem_dev->info.log_revid;
+               if (copy_to_user(p, &info, sizeof(info)))
+                       ret = -EFAULT;
+               break;
+       case PFRU_LOG_IOC_GET_DATA_INFO:
+               ret = get_pfru_data_info(&data_info, telem_dev->info.log_type);
+               if (ret)
+                       return ret;
+               if (copy_to_user(p, &data_info, sizeof(struct pfru_telem_data_info)))
+                       ret = -EFAULT;
+               break;
+       default:
+               ret = -ENOIOCTLCMD;
+               break;
+       }
+       return ret;
+}
+
+static ssize_t pfru_telemetry_read(struct file *filp, char __user *ubuf,
+                                  size_t size, loff_t *off)
+{
+       struct pfru_telem_data_info info;
+       phys_addr_t base_addr;
+       int buf_size, ret;
+       char *buf_ptr;
+
+       if (*off < 0)

drivers/acpi/pfru/pfru_telemetry.c new file +9 -0

+       if (!base_addr) {
+               pr_err("Telemetry data not ready\n");
+               return -EBUSY;
+       }
+
+       buf_size = info.max_data_size;
+       if (*off >= buf_size)
+               return 0;
+

drivers/acpi/pfru/pfru_telemetry.c new file +13 -0

+out:
+       memunmap(buf_ptr);
+
+       return ret ? ret : size;
+}
+
+#ifdef CONFIG_COMPAT
+static long compat_pfru_telemetry_ioctl(struct file *filep, unsigned int cmd,
+                                       unsigned long arg)
+{
+       return pfru_telemetry_ioctl(filep, cmd, arg);
+}
+#endif

drivers/acpi/pfru/pfru_telemetry.c new file +74 -0

+
+static struct miscdevice pfru_telemetry_misc_dev = {
+       .minor = MISC_DYNAMIC_MINOR,
+       .name = "pfru_telemetry",
+       .nodename = "pfru/telemetry",
+       .fops = &acpi_pfru_telemetry_fops,
+};
+
+static int acpi_pfru_telemetry_remove(struct platform_device *pdev)
+{
+       misc_deregister(&pfru_telemetry_misc_dev);
+       kfree(telem_dev);
+       telem_dev = NULL;
+
+       return 0;
+}
+
+static int acpi_pfru_telemetry_probe(struct platform_device *pdev)
+{
+       acpi_handle handle;
+       int ret;
+
+       if (telem_dev) {
+               pr_err("Duplicated PFRU Telemetry INTC1081 detected, skip...\n");
+               return 0;
+       }
+
+       telem_dev = kzalloc(sizeof(*telem_dev), GFP_KERNEL);
+       if (!telem_dev)
+               return -ENOMEM;
+
+       ret = guid_parse(PFRU_TELEMETRY_UUID, &telem_dev->uuid);
+       if (ret)
+               goto out;
+
+       telem_dev->info.log_revid = 1;
+       telem_dev->dev = &pdev->dev;
+       handle = ACPI_HANDLE(telem_dev->dev);
+       if (!acpi_has_method(handle, "_DSM")) {
+               pr_err("Missing _DSM\n");
+               ret = -ENODEV;
+               goto out;
+       }
+
+       ret = misc_register(&pfru_telemetry_misc_dev);
+       if (ret)
+               goto out;
+
+       return 0;
+out:
+       kfree(telem_dev);
+       telem_dev = NULL;
+
+       return ret;
+}
+
+static const struct acpi_device_id acpi_pfru_telemetry_ids[] = {
+       {"INTC1081", 0},
+       {}
+};
+MODULE_DEVICE_TABLE(acpi, acpi_pfru_telemetry_ids);
+
+static struct platform_driver acpi_pfru_telemetry_driver = {
+       .driver = {
+               .name = "pfru_telemetry",
+               .acpi_match_table = acpi_pfru_telemetry_ids,
+       },
+       .probe = acpi_pfru_telemetry_probe,
+       .remove = acpi_pfru_telemetry_remove,
+};
+module_platform_driver(acpi_pfru_telemetry_driver);
+
+MODULE_DESCRIPTION("Platform Firmware Runtime Update Telemetry Service device driver");
+MODULE_LICENSE("GPL v2");

include/uapi/linux/pfru.h +43 -1

index ca0b7433f79f..b04852602133 100644
@@ -98,4 +98,47 @@ struct pfru_updated_result {
        __u64 high_exec_time;
 };
 
+#define PFRU_TELEMETRY_UUID    "75191659-8178-4D9D-B88F-AC5E5E93E8BF"
+
+/* Telemetry structures. */
+struct pfru_telem_data_info {
+       enum pfru_dsm_status status;
+       enum pfru_dsm_status ext_status;
+       __u64 chunk1_addr_lo;
+       __u64 chunk1_addr_hi;
+       __u64 chunk2_addr_lo;
+       __u64 chunk2_addr_hi;
+       __u32 max_data_size;
+       __u32 chunk1_size;
+       __u32 chunk2_size;
+       __u32 rollover_cnt;
+       __u32 reset_cnt;
+};
+
+struct pfru_telem_info {
+       __u32 log_level;
+       __u32 log_type;
+       __u32 log_revid;
+};
+
+/* Two logs: history and execution log */
+#define LOG_EXEC_IDX   0
+#define LOG_HISTORY_IDX        1
+#define NR_LOG_TYPE    2
+
+#define LOG_ERR                0
+#define LOG_WARN       1
+#define LOG_INFO       2
+#define LOG_VERB       4
+
+#define FUNC_SET_LEV           1
+#define FUNC_GET_LEV           2
+#define FUNC_GET_DATA          3
+
+#define LOG_NAME_SIZE          10
+
+#define PFRU_LOG_IOC_SET_INFO _IOW(PFRU_MAGIC, 0x05, struct pfru_telem_info)
+#define PFRU_LOG_IOC_GET_INFO _IOR(PFRU_MAGIC, 0x06, struct pfru_telem_info)
+#define PFRU_LOG_IOC_GET_DATA_INFO _IOR(PFRU_MAGIC, 0x07, struct pfru_telem_data_info)
+
 #endif /* __PFRU_H__ */
--

Quoted 31 lines · Greg Kroah-Hartman

Quoted 18 lines · Chen Yu

Quoted 17 lines · Greg Kroah-Hartman

Quoted 16 lines · Chen Yu

Hi Greg,

Quoted 14 lines · Greg Kroah-Hartman

Quoted 8 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

Where is the userspace code that uses this ioctl and has tested it out to verify it works properly? A link to that in the changelog would be great to have.

Quoted 8 lines

Quoted 6 lines

Quoted 2 lines

The patch [5/5] is a self testing tool to test the whole feature. I'll send a new version and Cc you too.

That tests it, but does not answer the question of who will actually use this. What userspace tool needs this new api?

Currently there is no dedicated userspace tool developed to use this feature AFAIK.

Wonderful, then it is not needed to be added to the kernel :)

Quoted 8 lines

Quoted 5 lines

It was expected that the end users
could refer to the self test tool to customize their tools. I'm not sure if this is the proper way to propose the feature, may I have your suggestion on this, should I create a separate git repository for this tool, or put it in tools/selftestings as it is now?

No, do not add this to the kernel unless you have a real need and user for this.

Quoted 15 lines · Greg Kroah-Hartman

Quoted 13 lines · Chen Yu

Quoted 12 lines · Greg Kroah-Hartman

Quoted 11 lines · Chen Yu

Hi Greg,

Quoted 9 lines · Greg Kroah-Hartman

Quoted 8 lines · Chen Yu

Introduce the pfru_update driver which can be used for Platform Firmware Runtime code injection and driver update. 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.

Signed-off-by Chen Yu <[email protected]>

Quoted 14 lines

Quoted 14 lines

Quoted 14 lines

Quoted 10 lines

Quoted 8 lines

Review

Quoted 4 lines

(quoted diff) +4 -0

+static struct miscdevice pfru_misc_dev = {
+     .minor = MISC_DYNAMIC_MINOR,
+     .name = "pfru_update",
+     .nodename = "pfru/update",

Why is this in a subdirectory? What requires this? Why not just "pfru"?

The pfru directory might be reused for pfru_telemetry device, whose driver is in 4/5 patch, I'll Cc you with the whole patch set in next version.

"might be" is not a valid reason. Why does this simple driver deserve a whole /dev/ subdirectory?

Quoted 7 lines

Quoted 3 lines

There are pfru_update and pfru_telemetry in the patch, and there is plan to add a pfru_prm device in the future, which stands for "Platform Runtime Mechanism". I'll move them to /dev/ in next version.

That is a very generic name for a very platform specific and arch specific interface. As this is an ACPI interface, why not use that name prefix?

It is not supposed to be either arch-specific or platform-specific. The spec is hosted by the UEFI Forum and it is fairly generic IIUC. In principle, it could be used to update any kind of platform firmware possible to update without system restart.

That said, the I/F to the platform firmware is based on ACPI methods, so "acpi_" would be a reasonable prefix choice.

On Thu, Sep 16, 2021 at 5:56 PM Chen Yu <[email protected]> wrote:

Quoted 5 lines

drivers/acpi/pfru/pfru_update.c new file +5 -0

+static bool valid_cap_type(int idx, union acpi_object *obj)
+{
+       acpi_object_type type = obj->type;
+
+       if (idx == CAP_STATUS_IDX || idx == CAP_UPDATE_IDX ||

drivers/acpi/pfru/pfru_update.c line 80

Quoted 10 lines

drivers/acpi/pfru/pfru_update.c new file +10 -0

+           idx == CAP_FW_VER_IDX || idx == CAP_CODE_RT_VER_IDX ||
+           idx == CAP_DRV_RT_VER_IDX || idx == CAP_DRV_SVN_IDX)
+               return type == ACPI_TYPE_INTEGER;
+       else if (idx == CAP_CODE_TYPE_IDX || idx == CAP_DRV_TYPE_IDX ||
+                idx == CAP_PLAT_ID_IDX || idx == CAP_OEM_ID_IDX ||
+                idx == CAP_OEM_INFO_IDX)
+               return type == ACPI_TYPE_BUFFER;
+       else
+               return false;
+}

IMO, this is way overdesigned. It is not necessary to do all of these checks for every element of the package in query_capability().

It is not very useful to do a loop if there is a switch () on the control variable in every step.

drivers/acpi/pfru/pfru_update.c line 104

Quoted 9 lines

drivers/acpi/pfru/pfru_update.c new file +9 -0

+               union acpi_object *obj = &out_obj->package.elements[i];
+
+               if (!valid_cap_type(i, obj))
+                       goto free_acpi_buffer;
+
+               switch (i) {
+               case CAP_STATUS_IDX:
+                       cap->status = obj->integer.value;
+                       break;

The above can be written as

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;

and analogously for all of the other index values.

But check the number of elements upfront.

Quoted 26 lines

drivers/acpi/pfru/pfru_update.c new file +26 -0

+               case CAP_UPDATE_IDX:
+                       cap->update_cap = obj->integer.value;
+                       break;
+               case CAP_CODE_TYPE_IDX:
+                       memcpy(&cap->code_type, obj->buffer.pointer,
+                              obj->buffer.length);
+                       break;
+               case CAP_FW_VER_IDX:
+                       cap->fw_version = obj->integer.value;
+                       break;
+               case CAP_CODE_RT_VER_IDX:
+                       cap->code_rt_version = obj->integer.value;
+                       break;
+               case CAP_DRV_TYPE_IDX:
+                       memcpy(&cap->drv_type, obj->buffer.pointer,
+                              obj->buffer.length);
+                       break;
+               case CAP_DRV_RT_VER_IDX:
+                       cap->drv_rt_version = obj->integer.value;
+                       break;
+               case CAP_DRV_SVN_IDX:
+                       cap->drv_svn = obj->integer.value;
+                       break;
+               case CAP_PLAT_ID_IDX:
+                       memcpy(&cap->platform_id, obj->buffer.pointer,
+                              obj->buffer.length);

drivers/acpi/pfru/pfru_update.c line 140

Quoted 10 lines

drivers/acpi/pfru/pfru_update.c new file +10 -0

+                       break;
+               case CAP_OEM_ID_IDX:
+                       memcpy(&cap->oem_id, obj->buffer.pointer,
+                              obj->buffer.length);
+                       break;
+               case CAP_OEM_INFO_IDX:
+                       /*vendor specific data*/
+                       break;
+               default:
+                       pr_err("Incorrect format of Update Capability.\n");

Why pr_err() and not dev_dbg()?

Besides, it looks like you're going to fail if the package has more elements than expected, but is this really a big deal?

Moreover, what if the number of package elements is too small?

Quoted 19 lines

drivers/acpi/pfru/pfru_update.c new file +19 -0

+                       goto free_acpi_buffer;
+               }
+       }
+       ret = 0;
+
+free_acpi_buffer:
+       ACPI_FREE(out_obj);
+
+       return ret;
+}
+
+static int query_buffer(struct pfru_com_buf_info *info)
+{
+       union acpi_object *out_obj;
+       acpi_handle handle;
+       int i, ret = -EINVAL;
+
+       handle = ACPI_HANDLE(pfru_dev->dev);
+       out_obj = acpi_evaluate_dsm_typed(handle, &pfru_dev->uuid,

drivers/acpi/pfru/pfru_update.c line 165

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+                                         pfru_dev->rev_id, FUNC_QUERY_BUF,
+                                         NULL, ACPI_TYPE_PACKAGE);
+       if (!out_obj)
+               return -EINVAL;
+
+       for (i = 0; i < out_obj->package.count; i++) {

Again, what is the benefit from doing this loop?

drivers/acpi/pfru/pfru_update.c line 206

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c new file +8 -0

+
+static int get_image_type(efi_manage_capsule_image_header_t *img_hdr,
+                         int *type)
+{
+       guid_t *image_type_id;
+
+       /* check whether this is a code injection or driver update */
+       image_type_id = &img_hdr->image_type_id;

Anything wrong with doing this assignment as initialization?

drivers/acpi/pfru/pfru_update.c line 210

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+       if (guid_equal(image_type_id, &pfru_dev->code_uuid))
+               *type = CODE_INJECT_TYPE;
+       else if (guid_equal(image_type_id, &pfru_dev->drv_uuid))
+               *type = DRIVER_UPDATE_TYPE;

And what would be wrong with returning the type or a negative error code?

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+       else
+               return -EINVAL;
+
+       return 0;
+}
+

Quoted 6 lines

+/*
+ * 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.

Either turn this into a kerneldoc comment or put it inside the function.

Quoted 13 lines

+ */

drivers/acpi/pfru/pfru_update.c new file +12 -0

+static int adjust_efi_size(efi_manage_capsule_image_header_t *img_hdr,
+                          int *size)
+{
+       int tmp_size = *size;
+
+       tmp_size += sizeof(efi_manage_capsule_image_header_t);
+       switch (img_hdr->ver) {
+       case 1:
+               tmp_size -= 2 * sizeof(u64);
+               break;
+       case 2:
+               tmp_size -= sizeof(u64);

drivers/acpi/pfru/pfru_update.c line 241

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+               break;
+       default:
+               /* only support version 1 and 2 */
+               return -EINVAL;
+       }
+       *size = tmp_size;

Why not simply return the size or a negative error code?

drivers/acpi/pfru/pfru_update.c line 248

Quoted 7 lines

drivers/acpi/pfru/pfru_update.c new file +7 -0

+
+       return 0;
+}
+
+/*
+ * Sanity check if the capsule image has a newer version than current one.
+ * Return: true if it is valid, false otherwise.

Would it hurt if this was a proper kerneldoc comment?

Quoted 4 lines

drivers/acpi/pfru/pfru_update.c new file +4 -0

+
+static void dump_update_result(struct pfru_updated_result *result)
+{
+       pr_debug("Update result:\n");

drivers/acpi/pfru/pfru_update.c line 297

Quoted 6 lines

drivers/acpi/pfru/pfru_update.c new file +6 -0

+       pr_debug("Status:%d\n", result->status);
+       pr_debug("Extended Status:%d\n", result->ext_status);
+       pr_debug("Authentication Time Low:%lld\n", result->low_auth_time);
+       pr_debug("Authentication Time High:%lld\n", result->high_auth_time);
+       pr_debug("Execution Time Low:%lld\n", result->low_exec_time);
+       pr_debug("Execution Time High:%lld\n", result->high_exec_time);

All of these could be dev_dbg() I suppose?

Quoted 3 lines

drivers/acpi/pfru/pfru_update.c new file +3 -0

+}
+
+

Quoted 1 line

+ for (i = 0; i < out_obj->package.count; i++) {

Same comment regarding the benefit of doing a loop: why is it needed?

drivers/acpi/pfru/pfru_update.c line 372

Quoted 7 lines

drivers/acpi/pfru/pfru_update.c new file +7 -0

+
+       switch (cmd) {
+       case PFRU_IOC_SET_REV:
+               if (copy_from_user(&rev, p, sizeof(unsigned int)))
+                       return -EFAULT;
+               if (!pfru_valid_revid(rev))
+                       return -EFAULT;

Why is this the right error code to return here?

drivers/acpi/pfru/pfru_update.c line 431

Quoted 5 lines

drivers/acpi/pfru/pfru_update.c new file +5 -0

+       /* 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);

Empty line here, please.

drivers/acpi/pfru/pfru_update.c line 433

Quoted 2 lines

drivers/acpi/pfru/pfru_update.c new file +2 -0

+       if (!copy_from_iter_full(buf_ptr, len, &iter)) {
+               pr_err("error! could not read capsule file\n");

dev_dbg()?

drivers/acpi/pfru/pfru_update.c line 441

Quoted 8 lines

drivers/acpi/pfru/pfru_update.c new file +8 -0

+               ret = -EINVAL;
+               goto unmap;
+       }
+
+       /* Check if the capsule header has a valid version number. */
+       ret = query_capability(&cap);
+       if (ret)
+               goto unmap;

ret is guaranteed to be 0 here, so you can do

if (cap.status != DSM_SUCCEED)

        ret = -EBUSY;
else if (!valid_version(buf_ptr, &cap))
        ret = -EINVAL;

and the gotos and the "ret = 0" statement below won't be necessary.

Quoted 13 lines

drivers/acpi/pfru/pfru_update.c new file +13 -0

+static ssize_t pfru_read(struct file *filp, char __user *ubuf,
+                        size_t size, loff_t *off)
+{
+       struct pfru_update_cap_info cap;
+       int ret;
+
+       ret = query_capability(&cap);
+       if (ret)
+               return ret;
+
+       size = min_t(size_t, size, sizeof(cap));
+
+       if (copy_to_user(ubuf, &cap, size))

Quoted 1 line

+ return -EFAULT;

Well, if the read() is only needed for this, maybe consider implementing it as an ioctl() command and using read() for the telemetry retrieval? Then, you won't need the other special device file, the write() will be the code injection/update, the read() will be telemetry retrieval and all of the rest can be ioctl()s under one special device file.