TPM: workaround to enforce PCR updates across suspends

Add a workaround for TPM's which fail to flush last written
PCR values in a TPM_SaveState, in preparation for suspend.

Signed-off-by: David Safford <safford@watson.ibm.com>
Acked-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d80930d58dae..e0df679c3902 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -99,6 +99,7 @@ parameter is applicable:
         SWSUSP  Software suspend (hibernation) is enabled.
         SUSPEND System suspend states are enabled.
         FTRACE  Function tracing enabled.
+        TPM     TPM drivers are enabled.
         TS      Appropriate touchscreen support is enabled.
         UMS     USB Mass Storage support is enabled.
         USB     USB support is enabled.
@@ -2619,6 +2620,15 @@ and is between 256 and 4096 characters. It is defined in the file
 
         tp720=          [HW,PS2]
 
+        tpm_suspend_pcr=[HW,TPM]
+                        Format: integer pcr id
+                        Specify that at suspend time, the tpm driver
+                        should extend the specified pcr with zeros,
+                        as a workaround for some chips which fail to
+                        flush the last written pcr on TPM_SaveState.
+                        This will guarantee that all the other pcrs
+                        are saved.
+
         trace_buf_size=nn[KMG]
                         [FTRACE] will set tracing buffer size.