Re: [PATCH] docs: Update TPM documentation for usage of a TPM 2

[Marc-André Lureau]

On Tue, Sep 27, 2022 at 4:21 PM Stefan Berger <stefanb@linux.ibm.com> wrote:
>
> Update the TPM documentation for usage of a TPM 2 rather than a TPM 1.2.
> Adjust the command lines and expected outputs inside the VM accordingly.
> Update the command line to start a TPM 2 with swtpm.
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


> ---
>  docs/specs/tpm.rst | 44 ++++++++++++++++++++++++--------------------
>  1 file changed, 24 insertions(+), 20 deletions(-)
>
> diff --git a/docs/specs/tpm.rst b/docs/specs/tpm.rst
> index 3be190343a..535912a92b 100644
> --- a/docs/specs/tpm.rst
> +++ b/docs/specs/tpm.rst
> @@ -250,24 +250,25 @@ hardware TPM ``/dev/tpm0``:
>
>  The following commands should result in similar output inside the VM
>  with a Linux kernel that either has the TPM TIS driver built-in or
> -available as a module:
> +available as a module (assuming a TPM 2 is passed through):
>
>  .. code-block:: console
>
>    # dmesg | grep -i tpm
> -  [    0.711310] tpm_tis 00:06: 1.2 TPM (device=id 0x1, rev-id 1)
> -
> -  # dmesg | grep TCPA
> -  [    0.000000] ACPI: TCPA 0x0000000003FFD191C 000032 (v02 BOCHS  \
> -      BXPCTCPA 0000001 BXPC 00000001)
> +  [    0.012560] ACPI: TPM2 0x000000000BFFD1900 00004C (v04 BOCHS  \
> +      BXPC     0000001 BXPC 00000001)
>
>    # ls -l /dev/tpm*
> -  crw-------. 1 root root 10, 224 Jul 11 10:11 /dev/tpm0
> +  crw-rw----. 1 tss root  10,   224 Sep  6 12:36 /dev/tpm0
> +  crw-rw----. 1 tss rss  253, 65536 Sep  6 12:36 /dev/tpmrm0
>
> -  # find /sys/devices/ | grep pcrs$ | xargs cat
> -  PCR-00: 35 4E 3B CE 23 9F 38 59 ...
> +  Starting with Linux 5.12 there are PCR entries for TPM 2 in sysfs:
> +  # find /sys/devices/ -type f | grep pcr-sha
> +  ...
> +  /sys/devices/LNXSYSTEM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/1
> +  ...
> +  /sys/devices/LNXSYSTEM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/9
>    ...
> -  PCR-23: 00 00 00 00 00 00 00 00 ...
>
>  The QEMU TPM emulator device
>  ----------------------------
> @@ -304,6 +305,7 @@ a socket interface. They do not need to be run as root.
>    mkdir /tmp/mytpm1
>    swtpm socket --tpmstate dir=/tmp/mytpm1 \
>      --ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock \
> +    --tpm2 \
>      --log level=20
>
>  Command line to start QEMU with the TPM emulator device communicating
> @@ -365,19 +367,20 @@ available as a module:
>  .. code-block:: console
>
>    # dmesg | grep -i tpm
> -  [    0.711310] tpm_tis 00:06: 1.2 TPM (device=id 0x1, rev-id 1)
> -
> -  # dmesg | grep TCPA
> -  [    0.000000] ACPI: TCPA 0x0000000003FFD191C 000032 (v02 BOCHS  \
> -      BXPCTCPA 0000001 BXPC 00000001)
> +  [    0.012560] ACPI: TPM2 0x000000000BFFD1900 00004C (v04 BOCHS  \
> +      BXPC     0000001 BXPC 00000001)
>
>    # ls -l /dev/tpm*
> -  crw-------. 1 root root 10, 224 Jul 11 10:11 /dev/tpm0
> +  crw-rw----. 1 tss root  10,   224 Sep  6 12:36 /dev/tpm0
> +  crw-rw----. 1 tss rss  253, 65536 Sep  6 12:36 /dev/tpmrm0
>
> -  # find /sys/devices/ | grep pcrs$ | xargs cat
> -  PCR-00: 35 4E 3B CE 23 9F 38 59 ...
> +  Starting with Linux 5.12 there are PCR entries for TPM 2 in sysfs:
> +  # find /sys/devices/ -type f | grep pcr-sha
> +  ...
> +  /sys/devices/LNXSYSTEM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/1
> +  ...
> +  /sys/devices/LNXSYSTEM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/9
>    ...
> -  PCR-23: 00 00 00 00 00 00 00 00 ...
>
>  Migration with the TPM emulator
>  ===============================
> @@ -398,7 +401,8 @@ In a 1st terminal start an instance of a swtpm using the 
> following command:
>    mkdir /tmp/mytpm1
>    swtpm socket --tpmstate dir=/tmp/mytpm1 \
>      --ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock \
> -    --log level=20 --tpm2
> +    --tpm2 \
> +    --log level=20
>
>  In a 2nd terminal start the VM:
>
> --
> 2.37.2
>