[Qemu-devel] [PATCH 1/2] tpm_tis: Return TPM_VERSION_UNSPEC in case of BE failure

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

In case the backend has a failure, such as the tpm_emulator's CMD_INIT
failing, the TIS goes into failure mode and does not respond to reads
or writes to MMIO registers. In this case we need to prevent the ACPI
table from being added and the straight-forward way is to indicate that
there's no known TPM version being used.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
---
 hw/tpm/tpm_tis.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
index c0a0204..eca3374 100644
--- a/hw/tpm/tpm_tis.c
+++ b/hw/tpm/tpm_tis.c
@@ -970,6 +970,10 @@ static enum TPMVersion tpm_tis_get_tpm_version(TPMIf *ti)
 {
     TPMState *s = TPM(ti);
 
+    if (tpm_backend_had_startup_error(s->be_driver)) {
+        return TPM_VERSION_UNSPEC;
+    }
+
     return tpm_backend_get_tpm_version(s->be_driver);
 }
 
-- 
2.5.5