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

[Stefan Berger]

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>
---
 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