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Re: [PATCH v7 0/3] Add support for TPM devices over I2C bus

From: Stefan Berger
Subject: Re: [PATCH v7 0/3] Add support for TPM devices over I2C bus
Date: Mon, 27 Mar 2023 07:11:23 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 


On 3/26/23 21:05, Joel Stanley wrote:

Hi Ninad,

On Sun, 26 Mar 2023 at 22:44, Ninad Palsule <ninad@linux.ibm.com> wrote:


Hello,

I have incorporated review comments from Stefan. Please review.

This drop adds support for the TPM devices attached to the I2C bus. It
only supports the TPM2 protocol. You need to run it with the external
TPM emulator like swtpm. I have tested it with swtpm.


Nice work. I tested these stop cedric's aspeed-8.0 qemu tree, using
the rainier machine and the openbmc dev-6.1 kernel.

We get this message when booting from a kernel:

[    0.582699] tpm_tis_i2c 12-002e: 2.0 TPM (device-id 0x1, rev-id 1)
[    0.586361] tpm tpm0: A TPM error (256) occurred attempting the self test
[    0.586623] tpm tpm0: starting up the TPM manually

Do we understand why the error appears?


The firmware did not initialize the TPM 2.





# grep -r . /sys/class/tpm/tpm0/pcr-sha256/ | sort -n -k 7 -t /
/sys/class/tpm/tpm0/pcr-sha256/0:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/1:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/2:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/3:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/4:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/5:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/6:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/7:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/8:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/9:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/10:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/11:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/12:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/13:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/14:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/15:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/16:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/17:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/18:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/19:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/20:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/21:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/22:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/23:0000000000000000000000000000000000000000000000000000000000000000

If I boot through the openbmc u-boot for the p10bmc machine, which
measures things into the PCRs:

[    0.556713] tpm_tis_i2c 12-002e: 2.0 TPM (device-id 0x1, rev-id 1)


In this case the firmware started up the TPM 2. Also the PCRs have been touched 
by the firmware in this case.



/ # grep -r . /sys/class/tpm/tpm0/pcr-sha256/ | sort -n -k 7 -t /
/sys/class/tpm/tpm0/pcr-sha256/0:AFA13691EFC7BC6E189E92347F20676FB4523302CB957DA9A65C3430C45E8BCC
/sys/class/tpm/tpm0/pcr-sha256/1:37F0F710A5502FAE6DB7433B36001FEE1CBF15BA2A7D6923207FF56888584714
/sys/class/tpm/tpm0/pcr-sha256/2:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/3:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/4:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/5:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/6:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/7:E21B703EE69C77476BCCB43EC0336A9A1B2914B378944F7B00A10214CA8FEA93
/sys/class/tpm/tpm0/pcr-sha256/8:AE67485BD01E8D6FE0208C46C473940173F66E9C6F43C75ABB404375787E9705
/sys/class/tpm/tpm0/pcr-sha256/9:DB99D92EADBB446894CB0C062AEB673F60DDAFBC62BC2A9CA561A13B31E5357C
/sys/class/tpm/tpm0/pcr-sha256/10:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/11:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/12:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/13:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/14:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/15:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/16:0000000000000000000000000000000000000000000000000000000000000000
/sys/class/tpm/tpm0/pcr-sha256/17:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/18:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/19:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/20:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/21:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/22:FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/sys/class/tpm/tpm0/pcr-sha256/23:0000000000000000000000000000000000000000000000000000000000000000

However on a clean boot into the TPM, the u-boot tpm commands fail:

ast# tpm info
tpm@2e v2.0: VendorID 0x1014, DeviceID 0x0001, RevisionID 0x01 [closed]
ast# tpINTERRUPT>


Is this normal output? Is it an indication of some sort of IRQ?


ast# tpm init
ast# tpm info
tpm@2e v2.0: VendorID 0x1014, DeviceID 0x0001, RevisionID 0x01 [open]
ast# tpm pcr_read 0 0x81000000
Error: 256
ast# md.l 0x81000000 16
81000000: 00000000 00000000 00000000 00000000    ................
81000010: 00000000 00000000 00000000 00000000    ................
81000020: 00000000 00000000 00000000 00000000    ................
81000030: 00000000 00000000 00000000 00000000    ................
81000040: 00000000 00000000 00000000 00000000    ................
81000050: 00000000 00000000                      ........

This doesn't need to block merging into qemu, as the model works fine
for pcr measurement and accessing under Linux. However it would be
good to work though these issues in case there's a modelling
discrepancy.



It reads the didvid and rid registers just fine and per the touched PCRs it 
knows how to talk to the TPM 2 to extend the PCRs.
So this is strange. What is the 0x81000000 parameter in this command? Is it 
some memory location?


   Stefan







I have refered to the work done by zhdaniel@meta.com but at the core
level out implementation is different.
https://github.com/theopolis/qemu/commit/2e2e57cde9e419c36af8071bb85392ad1ed70966

Based-on: $MESSAGE_ID


Ninad Palsule (3):
   docs: Add support for TPM devices over I2C bus
   tpm: Extend common APIs to support TPM TIS I2C
   tpm: Add support for TPM device over I2C bus

  docs/specs/tpm.rst      |  32 +++
  hw/arm/Kconfig          |   1 +
  hw/tpm/Kconfig          |   7 +
  hw/tpm/meson.build      |   1 +
  hw/tpm/tpm_tis.h        |   3 +
  hw/tpm/tpm_tis_common.c |  36 ++-
  hw/tpm/tpm_tis_i2c.c    | 540 ++++++++++++++++++++++++++++++++++++++++
  hw/tpm/trace-events     |   6 +
  include/hw/acpi/tpm.h   |  31 +++
  include/sysemu/tpm.h    |   3 +
  10 files changed, 652 insertions(+), 8 deletions(-)
  create mode 100644 hw/tpm/tpm_tis_i2c.c

--
2.37.2
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