File is empty when reading contents of /sys/class/misc/tpm0/devices/pcrs
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Ubuntu |
Invalid
|
Undecided
|
Unassigned |
Bug Description
This problem is observed randomly on a system that previously had the contents of the file present. It happens on a system running tboot, and qemu-kVM. As stated, during initial deployment and boot up, the file contains the PCR values (tpm) however, after some time, the file becomes empty. The only solution is to reboot the system.
I am using tboot 1.7, Ubuntu 12.04.2 LTS kernel 3.5.0-36-generic on a Romley platform x86_64 with qemu-1.0.0, libvirt 1.0.2.
Further investigation reveals (dmesg output), the error points to the tpm_tis timing out.
[ 18.012502] tpm_tis 00:0a: 1.2 TPM (device-id 0x0, rev-id 78)
[335872.663975] tpm_tis 00:0a: Operation Timed out
[335872.735917] tpm_tis 00:0a: tpm_transmit: tpm_recv: error -5
[598356.471981] tpm_tis 00:0a: tpm_transmit: tpm_send: error -5
[598412.438490] tpm_tis 00:0a: tpm_transmit: tpm_send: error -5
[598412.440376] tpm_tis 00:0a: tpm_transmit: tpm_send: error -5
[598412.442055] tpm_tis 00:0a: tpm_transmit: tpm_send: error -5
[2130096.482415] tpm_tis 00:0a: tpm_transmit: tpm_send: error -5
tpm_selftest shows that it is failing with an I/O error.
# tpm_selftest -l debugTspi_
Tspi_Context_
Tspi_Context_
Tspi_TPM_
Tspi_Context_
Tspi_Context_Close success
# tpm_takeownership -l debug -z -yTspi_
Tspi_Context_
Tspi_Context_
Tspi_GetPolicyO
Tspi_Policy_
Tspi_Context_
Tspi_GetPolicyO
Tspi_Policy_
Tspi_TPM_
Tspi_Context_
Tspi_Context_
Tspi_Context_Close success
On most occassions, this file contains the PCR values of the tpm.
tags: | added: precise |
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