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, 18 insertions, 3 deletions

diff --git a/qapi/tpm.json b/qapi/tpm.json
index e8b2d8dcb7..7093f268fb 100644
--- a/qapi/tpm.json
+++ b/qapi/tpm.json
@@ -39,10 +39,12 @@
 # An enumeration of TPM types
 #
 # @passthrough: TPM passthrough type
+# @emulator: Software Emulator TPM type
+#            Since: 2.11
 #
 # Since: 1.5
 ##
-{ 'enum': 'TpmType', 'data': [ 'passthrough' ] }
+{ 'enum': 'TpmType', 'data': [ 'passthrough', 'emulator' ] }
 
 ##
 # @query-tpm-types:
@@ -56,7 +58,7 @@
 # Example:
 #
 # -> { "execute": "query-tpm-types" }
-# <- { "return": [ "passthrough" ] }
+# <- { "return": [ "passthrough", "emulator" ] }
 #
 ##
 { 'command': 'query-tpm-types', 'returns': ['TpmType'] }
@@ -77,16 +79,29 @@
                                              '*cancel-path' : 'str'} }
 
 ##
+# @TPMEmulatorOptions:
+#
+# Information about the TPM emulator type
+#
+# @chardev: Name of a unix socket chardev
+#
+# Since: 2.11
+##
+{ 'struct': 'TPMEmulatorOptions', 'data': { 'chardev' : 'str' } }
+
+##
 # @TpmTypeOptions:
 #
 # A union referencing different TPM backend types' configuration options
 #
 # @type: 'passthrough' The configuration options for the TPM passthrough type
+#        'emulator' The configuration options for TPM emulator backend type
 #
 # Since: 1.5
 ##
 { 'union': 'TpmTypeOptions',
-   'data': { 'passthrough' : 'TPMPassthroughOptions' } }
+   'data': { 'passthrough' : 'TPMPassthroughOptions',
+             'emulator': 'TPMEmulatorOptions' } }
 
 ##
 # @TPMInfo: