tpm: Added support for TPM emulator

This change introduces a new TPM backend driver that can communicate with
swtpm(software TPM emulator) using unix domain socket interface. QEMU talks to
the TPM emulator using QEMU's socket-based chardev backend device.

Swtpm uses two Unix sockets for communications, one for plain TPM commands and
responses, and one for out-of-band control messages. QEMU passes the data
socket to be used over the control channel.

The swtpm and associated tools can be found here:
    https://github.com/stefanberger/swtpm

The swtpm's control channel protocol specification can be found here:
    https://github.com/stefanberger/swtpm/wiki/Control-Channel-Specification

Usage:
    # setup TPM state directory
    mkdir /tmp/mytpm
    chown -R tss:root /tmp/mytpm
    /usr/bin/swtpm_setup --tpm-state /tmp/mytpm --createek

    # Ask qemu to use TPM emulator with given tpm state directory
    qemu-system-x86_64 \
        [...] \
        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock \
        -tpmdev emulator,id=tpm0,chardev=chrtpm \
        -device tpm-tis,tpmdev=tpm0 \
        [...]

Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/hmp.c b/hmp.c
index 739d330..ec61329 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1000,6 +1000,7 @@ void hmp_info_tpm(Monitor *mon, const QDict *qdict)
     Error *err = NULL;
     unsigned int c = 0;
     TPMPassthroughOptions *tpo;
+    TPMEmulatorOptions *teo;
 
     info_list = qmp_query_tpm(&err);
     if (err) {
@@ -1029,6 +1030,10 @@ void hmp_info_tpm(Monitor *mon, const QDict *qdict)
                            tpo->has_cancel_path ? ",cancel-path=" : "",
                            tpo->has_cancel_path ? tpo->cancel_path : "");
             break;
+        case TPM_TYPE_OPTIONS_KIND_EMULATOR:
+            teo = ti->options->u.emulator.data;
+            monitor_printf(mon, ",chardev=%s", teo->chardev);
+            break;
         case TPM_TYPE_OPTIONS_KIND__MAX:
             break;
         }