Add a TPM Passthrough backend driver implementation

This patch is based of off version 9 of Stefan Berger's patch series
  "QEMU Trusted Platform Module (TPM) integration"
and adds a new backend driver for it.

This patch adds a passthrough backend driver for passing commands sent to the
emulated TPM device directly to a TPM device opened on the host machine.
Thus it is possible to use a hardware TPM device in a system running on QEMU,
providing the ability to access a TPM in a special state (e.g. after a Trusted
Boot).

This functionality is being used in the acTvSM Trusted Virtualization Platform
which is available on [1].

Usage example:
  qemu-system-x86_64 -tpmdev passthrough,id=tpm0,path=/dev/tpm0 \
                     -device tpm-tis,tpmdev=tpm0 \
                     -cdrom test.iso -boot d

Some notes about the host TPM:
The TPM needs to be enabled and activated. If that's not the case one
has to go through the BIOS/UEFI and enable and activate that TPM for TPM
commands to work as expected.
It may be necessary to boot the kernel using tpm_tis.force=1 in the boot
command line or 'modprobe tpm_tis force=1' in case of using it as a module.

Regards,
Andreas Niederl, Stefan Berger

[1] http://trustedjava.sourceforge.net/

Signed-off-by: Andreas Niederl <andreas.niederl@iaik.tugraz.at>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Reviewed-by: Joel Schopp <jschopp@linux.vnet.ibm.com>
Message-id: 1361987275-26289-6-git-send-email-stefanb@linux.vnet.ibm.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/tpm/tpm_backend.c b/tpm/tpm_backend.c
new file mode 100644
index 0000000000..4144ef7d76
--- /dev/null
+++ b/tpm/tpm_backend.c
@@ -0,0 +1,58 @@
+/*
+ *  common TPM backend driver functions
+ *
+ *  Copyright (c) 2012-2013 IBM Corporation
+ *  Authors:
+ *    Stefan Berger <stefanb@us.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include "tpm/tpm.h"
+#include "qemu/thread.h"
+#include "tpm_backend.h"
+
+void tpm_backend_thread_deliver_request(TPMBackendThread *tbt)
+{
+   g_thread_pool_push(tbt->pool, (gpointer)TPM_BACKEND_CMD_PROCESS_CMD, NULL);
+}
+
+void tpm_backend_thread_create(TPMBackendThread *tbt,
+                               GFunc func, gpointer user_data)
+{
+    if (!tbt->pool) {
+        tbt->pool = g_thread_pool_new(func, user_data, 1, TRUE, NULL);
+        g_thread_pool_push(tbt->pool, (gpointer)TPM_BACKEND_CMD_INIT, NULL);
+    }
+}
+
+void tpm_backend_thread_end(TPMBackendThread *tbt)
+{
+    if (tbt->pool) {
+        g_thread_pool_push(tbt->pool, (gpointer)TPM_BACKEND_CMD_END, NULL);
+        g_thread_pool_free(tbt->pool, FALSE, TRUE);
+        tbt->pool = NULL;
+    }
+}
+
+void tpm_backend_thread_tpm_reset(TPMBackendThread *tbt,
+                                  GFunc func, gpointer user_data)
+{
+    if (!tbt->pool) {
+        tpm_backend_thread_create(tbt, func, user_data);
+    } else {
+        g_thread_pool_push(tbt->pool, (gpointer)TPM_BACKEND_CMD_TPM_RESET,
+                           NULL);
+    }
+}