Re: [Qemu-devel] [PATCH v7 8/8] tpm: Added support for TPM emulator

["Valluri, Amarnath" <amarnath.valluri@intel.com>]

Hi Marc,

Thanks for your time reviewing this patchset. Please find my inline
comments.

On Sun, 2017-09-24 at 20:52 +0200, Marc-André Lureau wrote:
> Hi
> 
> Thanks for the nice update, removing the exec() code, using chardev
> and a private socketpair. Some comments below:
> 
> On Fri, Sep 22, 2017 at 2:33 PM, Amarnath Valluri
> <amarnath.valluri@intel.com> wrote:
> > 
> > This change introduces a new TPM backend driver that can
> > communicate with
> > swtpm(software TPM emulator) using unix domain socket interface.
> > QEMU talks to
> > TPM emulator using 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
> > data socket
> > been 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-Spec
> > ification
> > 
> > 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>
> > ---
> >  configure             |  15 +-
> >  hmp.c                 |   5 +
> >  hw/tpm/Makefile.objs  |   1 +
> >  hw/tpm/tpm_emulator.c | 649
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  hw/tpm/tpm_ioctl.h    | 246 +++++++++++++++++++
> >  qapi/tpm.json         |  21 +-
> >  qemu-options.hx       |  22 +-
> >  7 files changed, 950 insertions(+), 9 deletions(-)
> >  create mode 100644 hw/tpm/tpm_emulator.c
> >  create mode 100644 hw/tpm/tpm_ioctl.h
> > 
> > diff --git a/configure b/configure
> > index cb0f7ed..ce2df2d 100755
> > --- a/configure
> > +++ b/configure
> > @@ -3461,10 +3461,15 @@ fi
> >  ##########################################
> >  # TPM passthrough is only on x86 Linux
> > 
> > -if test "$targetos" = Linux && test "$cpu" = i386 -o "$cpu" =
> > x86_64; then
> > -  tpm_passthrough=$tpm
> > +if test "$targetos" = Linux; then
> > +  tpm_emulator=$tpm
> > +  if test "$cpu" = i386 -o "$cpu" = x86_64; then
> > +    tpm_passthrough=$tpm
> > +  else
> > +    tpm_passthrough=no
> > +  fi
> >  else
> > -  tpm_passthrough=no
> > +  tpm_emulator=no
> >  fi
> > 
> >  ##########################################
> > @@ -5359,6 +5364,7 @@ echo "gcov enabled      $gcov"
> >  echo "TPM support       $tpm"
> >  echo "libssh2 support   $libssh2"
> >  echo "TPM passthrough   $tpm_passthrough"
> > +echo "TPM emulator      $tpm_emulator"
> >  echo "QOM debugging     $qom_cast_debug"
> >  echo "Live block migration $live_block_migration"
> >  echo "lzo support       $lzo"
> > @@ -5943,6 +5949,9 @@ if test "$tpm" = "yes"; then
> >    if test "$tpm_passthrough" = "yes"; then
> >      echo "CONFIG_TPM_PASSTHROUGH=y" >> $config_host_mak
> >    fi
> > +  if test "$tpm_emulator" = "yes"; then
> > +    echo "CONFIG_TPM_EMULATOR=y" >> $config_host_mak
> It shouldn't require Linux, but posix (and I assume a port to other
> systems isn't impossible). same for build-sys / help / comments.
I agree, Can you suggest, what is the Qemu way of limiting this to
'posix'.
> 
> > 
> > +  fi
> >  fi
> > 
> >  echo "TRACE_BACKENDS=$trace_backends" >> $config_host_mak
> > diff --git a/hmp.c b/hmp.c
> > index cf62b2e..7e69eca 100644
> > --- a/hmp.c
> > +++ b/hmp.c
> > @@ -995,6 +995,7 @@ void hmp_info_tpm(Monitor *mon, const QDict
> > *qdict)
> >      Error *err = NULL;
> >      unsigned int c = 0;
> >      TPMPassthroughOptions *tpo;
> > +    TPMEmulatorOptions *teo;
> > 
> >      info_list = qmp_query_tpm(&err);
> >      if (err) {
> > @@ -1024,6 +1025,10 @@ void hmp_info_tpm(Monitor *mon, const QDict
> > *qdict)
> >                             tpo->has_cancel_path ? ",cancel-path="
> > : "",
> >                             tpo->has_cancel_path ? tpo->cancel_path 
> > : "");
> >              break;
> > +        case TPM_TYPE_EMULATOR:
> > +            teo = ti->options->u.emulator.data;
> > +            monitor_printf(mon, ",chardev=%s", teo->chardev);
> > +            break;
> >          case TPM_TYPE__MAX:
> >              break;
> >          }
> > diff --git a/hw/tpm/Makefile.objs b/hw/tpm/Makefile.objs
> > index 64cecc3..41f0b7a 100644
> > --- a/hw/tpm/Makefile.objs
> > +++ b/hw/tpm/Makefile.objs
> > @@ -1,2 +1,3 @@
> >  common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
> >  common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o
> > tpm_util.o
> > +common-obj-$(CONFIG_TPM_EMULATOR) += tpm_emulator.o tpm_util.o
> > diff --git a/hw/tpm/tpm_emulator.c b/hw/tpm/tpm_emulator.c
> > new file mode 100644
> > index 0000000..c02bbe2
> > --- /dev/null
> > +++ b/hw/tpm/tpm_emulator.c
> > @@ -0,0 +1,649 @@
> > +/*
> > + *  emulator TPM driver
> > + *
> > + *  Copyright (c) 2017 Intel Corporation
> > + *  Author: Amarnath Valluri <amarnath.valluri@intel.com>
> > + *
> > + *  Copyright (c) 2010 - 2013 IBM Corporation
> > + *  Authors:
> > + *    Stefan Berger <stefanb@us.ibm.com>
> > + *
> > + *  Copyright (C) 2011 IAIK, Graz University of Technology
> > + *    Author: Andreas Niederl
> > + *
> > + * 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.or
> > g/licenses/>
> > + *
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu/error-report.h"
> > +#include "qemu/sockets.h"
> > +#include "io/channel-socket.h"
> > +#include "sysemu/tpm_backend.h"
> > +#include "tpm_int.h"
> > +#include "hw/hw.h"
> > +#include "hw/i386/pc.h"
> > +#include "tpm_util.h"
> > +#include "tpm_ioctl.h"
> > +#include "migration/blocker.h"
> > +#include "qapi/error.h"
> > +#include "chardev/char-fe.h"
> > +
> > +#include <fcntl.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <stdio.h>
> > +
> > +#define DEBUG_TPM 0
> > +
> > +#define DPRINT(fmt, ...) do { \
> > +    if (DEBUG_TPM) { \
> > +        fprintf(stderr, fmt, ## __VA_ARGS__); \
> > +    } \
> > +} while (0);
> > +
> > +#define DPRINTF(fmt, ...) DPRINT("tpm-emulator: "fmt"\n",
> > __VA_ARGS__)
> I would define a single DPRINTF() (& drop DPRINT usage below)
Ok, will do
> 
> 
> > 
> > +
> > +#define TYPE_TPM_EMULATOR "tpm-emulator"
> > +#define TPM_EMULATOR(obj) \
> > +    OBJECT_CHECK(TPMEmulator, (obj), TYPE_TPM_EMULATOR)
> > +
> > +#define TPM_EMULATOR_IMPLEMENTS_ALL_CAPS(S, cap) (((S)->caps &
> > (cap)) == (cap))
> > +
> > +static const TPMDriverOps tpm_emulator_driver;
> > +
> > +/* data structures */
> > +typedef struct TPMEmulator {
> > +    TPMBackend parent;
> > +
> > +    TPMEmulatorOptions *options;
> Contrary to my comment on previous patch, I realize it is convenient
> to have a qapi pointer here, so you can use the free visitor later.
> 
> > 
> > +    CharBackend ctrl_dev;
> ctrl_chr perhaps? or just chr or be (the most common name in other
> devices).
> 
> > 
> > +    QIOChannel *data_ioc;
> > +    bool op_executing;
> > +    bool op_canceled;
> I think those 2 fields can be dropped, see below.
> 
> > 
> > +    bool had_startup_error;
> I think some little refactoring could remove the whole
> had_startup_error() backend & callback before or after the series.
> tpm_backend_startup_tpm() already returns an error code.  device or
> common backend code could handle & remember that.
Yes, i agree, we can avoid had_startup_error() from DriverOps, i will
do this.
> 
> > 
> > +    TPMVersion tpm_version;
> This is probably worth to consider in common code instead, but let's
> not worry about it.
> 
> > 
> > +    ptm_cap caps; /* capabilities of the TPM */
> > +    uint8_t cur_locty_number; /* last set locality */
> > +    QemuMutex state_lock;
> > +    Error *migration_blocker;
> > +} TPMEmulator;
> > +
> > +
> > +static int tpm_emulator_ctrlcmd(CharBackend *dev, unsigned long
> > cmd, void *msg,
> > +                                size_t msg_len_in, size_t
> > msg_len_out)
> > +{
> > +    uint32_t cmd_no = cpu_to_be32(cmd);
> > +    ssize_t n = sizeof(uint32_t) + msg_len_in;
> > +    uint8_t *buf = NULL;
> > +
> > +    buf = (uint8_t *)malloc(n);
> could be g_alloca() instead. Alternatively, why not call 2 write()
> instead?
> 
> none of the casts in this function are necessary, please remove them.
Ok, will change to aclloca()
> 
> > 
> > +    memcpy(buf, &cmd_no, sizeof(cmd_no));
> > +    memcpy(buf + sizeof(cmd_no), msg, msg_len_in);
> > +
> > +    n += qemu_chr_fe_write_all(dev, (const uint8_t *)buf, n);
> weird
> 
> > 
> > +    free(buf);
> > +
> > +    if (n > 0) {
> with the n += above, you'll get interesting behaviour :)
Ya, it was typo :)
> 
> You probably want to check if any write above failed, and return
> early
> for the error case.
> 
> Please improve the error handling in this function
> 
> > 
> > +        if (msg_len_out > 0) {
> > +            n = qemu_chr_fe_read_all(dev, (uint8_t *)msg,
> > msg_len_out);
> > +            /* simulate ioctl return value */
> > +            if (n > 0) {
> > +                n = 0;
> > +            }
> > +        } else {
> > +            n = 0;
> > +        }
> > +    }
> > +    return n;
> > +}
> > +
> > +static int tpm_emulator_unix_tx_bufs(TPMEmulator *tpm_pt,
> tpm_pt was tpm_passthrough I suppose.
> 
> Please rename tpm_pt tpm_emu (or I would suggest "self", but this
> isn't common name in qemu code - it's actually common in a close
> c-object world., and it is quite convenient...)
My interpretation about _pt was 'pointer' ;-) i will consider your
suggetion.
> 
> > 
> > +                                     const uint8_t *in, uint32_t
> > in_len,
> > +                                     uint8_t *out, uint32_t
> > out_len,
> > +                                     bool *selftest_done)
> > +{
> > +    ssize_t ret;
> > +    bool is_selftest = false;
> > +    const struct tpm_resp_hdr *hdr = NULL;
> > +    Error *err = NULL;
> > +
> > +    tpm_pt->op_canceled = false;
> > +    tpm_pt->op_executing = true;
> > +    if (selftest_done) {
> > +        *selftest_done = false;
> > +        is_selftest = tpm_util_is_selftest(in, in_len);
> > +    }
> > +
> > +    ret = qio_channel_write(tpm_pt->data_ioc, (char *)in, in_len,
> > &err);
> hmm, too bad qio_channel_write() doesn't take a void *
> 
> why not write_all()?
Agreed
> 
> > 
> > +    if (ret != in_len || err) {
> > +        if (!tpm_pt->op_canceled || errno != ECANCELED) {
> I don't think ECANCELED make sense for emulator code.
> 
> > 
> > +            error_report("tpm-emulator: error while transmitting
> > data "
> > +                         "to TPM: %s", err ? error_get_pretty(err)
> > : "");
> > +            error_free(err);
> > +        }
> > +        goto err_exit;
> > +    }
> > +
> > +    tpm_pt->op_executing = false;
> > +
> > +    ret = qio_channel_read(tpm_pt->data_ioc, (char *)out, out_len,
> > &err);
> > +    if (ret < 0 || err) {
> read_all() ?
The issue with read_all() is it does not return the no of bytes it
read, so i would like to stict to _read()
> 
> > 
> > +        if (!tpm_pt->op_canceled || errno != ECANCELED) {
> > +            error_report("tpm-emulator: error while reading data
> > from "
> > +                         "TPM: %s", err ? error_get_pretty(err) :
> > "");
> > +            error_free(err);
> > +        }
> > +    } else if (ret >= sizeof(*hdr)) {
> > +        hdr = (struct tpm_resp_hdr *)out;
> > +    }
> > +
> > +    if (!hdr || be32_to_cpu(hdr->len) != ret) {
> > +        error_report("tpm-emulator: received invalid response "
> > +                     "packet from TPM with length :%ld", ret);
> > +        ret = -1;
> > +        goto err_exit;
> > +    }
> > +
> > +    if (is_selftest) {
> > +        *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
> > +    }
> > +
> > +    return 0;
> > +
> > +err_exit:
> > +    if (ret < 0) {
> > +        tpm_util_write_fatal_error_response(out, out_len);
> > +    }
> > +
> > +    tpm_pt->op_executing = false;
> > +
> > +    return ret;
> > +}
> > +
> > +static int tpm_emulator_set_locality(TPMEmulator *tpm_pt, uint8_t
> > locty_number)
> > +{
> > +    ptm_loc loc;
> > +
> > +    DPRINTF("%s : locality: 0x%x", __func__, locty_number);
> > +
> > +    if (tpm_pt->cur_locty_number != locty_number) {
> return early instead if ==, to avoid code indent etc
Ok
> 
> > 
> > +        DPRINTF("setting locality : 0x%x", locty_number);
> > +        loc.u.req.loc = locty_number;
> This number isn't set in be like the rest of the protocol?
I doubt if i get ur point :(, can you please elaborate.
> 
> > 
> > +        if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev,
> > CMD_SET_LOCALITY, &loc,
> > +                             sizeof(loc), sizeof(loc)) < 0) {
> > +            error_report("tpm-emulator: could not set locality :
> > %s",
> > +                         strerror(errno));
> > +            return -1;
> > +        }
> > +        loc.u.resp.tpm_result =
> > be32_to_cpu(loc.u.resp.tpm_result);
> > +        if (loc.u.resp.tpm_result != 0) {
> > +            error_report("tpm-emulator: TPM result for set
> > locality : 0x%x",
> > +                         loc.u.resp.tpm_result);
> > +            return -1;
> > +        }
> > +        tpm_pt->cur_locty_number = locty_number;
> > +    }
> > +    return 0;
> > +}
> > +
> > +static void tpm_emulator_handle_request(TPMBackend *tb,
> > TPMBackendCmd cmd)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    TPMLocality *locty = NULL;
> > +    bool selftest_done = false;
> > +
> > +    DPRINTF("processing command type %d", cmd);
> > +
> > +    switch (cmd) {
> > +    case TPM_BACKEND_CMD_PROCESS_CMD:
> > +        qemu_mutex_lock(&tpm_pt->state_lock);
> > +        locty = tb->tpm_state->locty_data;
> > +        if (tpm_emulator_set_locality(tpm_pt,
> > +                                      tb->tpm_state->locty_number) 
> > < 0) {
> > +            tpm_util_write_fatal_error_response(locty-
> > >r_buffer.buffer,
> > +                                           locty->r_buffer.size);
> return / goto here instead of else.
We should not retrun from here, we have to propagte the error response
to device, and unlock the state.
> 
> > 
> > +        } else {
> > +            tpm_emulator_unix_tx_bufs(tpm_pt, locty-
> > >w_buffer.buffer,
> > +                                              locty->w_offset,
> > +                                              locty-
> > >r_buffer.buffer,
> > +                                              locty-
> > >r_buffer.size,
> > +                                              &selftest_done);
> no error handling?
The error case is supposed to handle by device, where we are filling
into out buffer, using tpm_util_write_fatal_error_response().
> 
> > 
> > +        }
> > +
> > +        tb->recv_data_callback(tb->tpm_state, tb->tpm_state-
> > >locty_number,
> > +                               selftest_done);
> > +        qemu_mutex_unlock(&tpm_pt->state_lock);
> > +
> > +        break;
> > +    case TPM_BACKEND_CMD_INIT:
> > +    case TPM_BACKEND_CMD_END:
> > +    case TPM_BACKEND_CMD_TPM_RESET:
> > +        /* nothing to do */
> > +        break;
> > +    }
> > +}
> > +
> > +/*
> > + * Gracefully shut down the external unixio TPM
> > + */
> > +static void tpm_emulator_shutdown(TPMEmulator *tpm_pt)
> > +{
> > +    ptm_res res;
> > +
> > +    if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev, CMD_SHUTDOWN,
> > &res, 0,
> > +                         sizeof(res)) < 0) {
> > +        error_report("tpm-emulator: Could not cleanly shutdown the
> > TPM: %s",
> > +                     strerror(errno));
> > +    } else if (res != 0) {
> > +        error_report("tpm-emulator: TPM result for sutdown: 0x%x",
> > +                     be32_to_cpu(res));
> > +    }
> > +}
> > +
> > +static int tpm_emulator_probe_caps(TPMEmulator *tpm_pt)
> > +{
> > +    DPRINTF("%s", __func__);
> > +    if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev,
> > CMD_GET_CAPABILITY,
> > +                         &tpm_pt->caps, 0, sizeof(tpm_pt->caps)) <
> > 0) {
> > +        error_report("tpm-emulator: probing failed : %s",
> > strerror(errno));
> > +        return -1;
> > +    }
> > +
> > +    tpm_pt->caps = be64_to_cpu(tpm_pt->caps);
> > +
> > +    DPRINTF("capbilities : 0x%lx", tpm_pt->caps);
> > +
> > +    return 0;
> > +}
> > +
> > +static int tpm_emulator_check_caps(TPMEmulator *tpm_pt)
> > +{
> > +    ptm_cap caps = 0;
> > +    const char *tpm = NULL;
> > +
> > +    /* check for min. required capabilities */
> > +    switch (tpm_pt->tpm_version) {
> > +    case TPM_VERSION_1_2:
> > +        caps = PTM_CAP_INIT | PTM_CAP_SHUTDOWN |
> > PTM_CAP_GET_TPMESTABLISHED |
> > +               PTM_CAP_SET_LOCALITY;
> > +        tpm = "1.2";
> > +        break;
> > +    case TPM_VERSION_2_0:
> > +        caps = PTM_CAP_INIT | PTM_CAP_SHUTDOWN |
> > PTM_CAP_GET_TPMESTABLISHED |
> > +               PTM_CAP_SET_LOCALITY |
> > PTM_CAP_RESET_TPMESTABLISHED;
> > +        tpm = "2";
> > +        break;
> > +    case TPM_VERSION_UNSPEC:
> > +        error_report("tpm-emulator: TPM version has not been
> > set");
> > +        return -1;
> > +    }
> > +
> > +    if (!TPM_EMULATOR_IMPLEMENTS_ALL_CAPS(tpm_pt, caps)) {
> > +        error_report("tpm-emulator: TPM does not implement minimum
> > set of "
> > +                     "required capabilities for TPM %s (0x%x)",
> > tpm, (int)caps);
> > +        return -1;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > +static int tpm_emulator_startup_tpm(TPMBackend *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    ptm_init init;
> > +    ptm_res res;
> > +
> > +    DPRINTF("%s", __func__);
> > +    if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev, CMD_INIT, &init,
> > sizeof(init),
> > +                         sizeof(init)) < 0) {
> > +        error_report("tpm-emulator: could not send INIT: %s",
> > +                     strerror(errno));
> > +        goto err_exit;
> > +    }
> > +
> > +    res = be32_to_cpu(init.u.resp.tpm_result);
> > +    if (res) {
> > +        error_report("tpm-emulator: TPM result for CMD_INIT:
> > 0x%x", res);
> > +        goto err_exit;
> > +    }
> > +    return 0;
> > +
> > +err_exit:
> > +    tpm_pt->had_startup_error = true;
> > +    return -1;
> > +}
> > +
> > +static bool tpm_emulator_get_tpm_established_flag(TPMBackend *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    ptm_est est;
> > +
> > +    DPRINTF("%s", __func__);
> > +    if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev,
> > CMD_GET_TPMESTABLISHED, &est, 0,
> > +                         sizeof(est)) < 0) {
> > +        error_report("tpm-emulator: Could not get the TPM
> > established flag: %s",
> > +                     strerror(errno));
> > +        return false;
> > +    }
> > +    DPRINTF("established flag: %0x", est.u.resp.bit);
> > +
> > +    return (est.u.resp.bit != 0);
> > +}
> > +
> > +static int tpm_emulator_reset_tpm_established_flag(TPMBackend *tb,
> > +                                                   uint8_t locty)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    ptm_reset_est reset_est;
> > +    ptm_res res;
> > +
> > +    /* only a TPM 2.0 will support this */
> > +    if (tpm_pt->tpm_version == TPM_VERSION_2_0) {
> > +        reset_est.u.req.loc = tpm_pt->cur_locty_number;
> > +
> > +        if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev,
> > CMD_RESET_TPMESTABLISHED,
> > +                                 &reset_est, sizeof(reset_est),
> > +                                 sizeof(reset_est)) < 0) {
> > +            error_report("tpm-emulator: Could not reset the
> > establishment bit: "
> > +                          "%s", strerror(errno));
> > +            return -1;
> > +        }
> > +
> > +        res = be32_to_cpu(reset_est.u.resp.tpm_result);
> > +        if (res) {
> > +            error_report("tpm-emulator: TPM result for rest
> > establixhed flag: "
> > +                         "0x%x", res);
> > +            return -1;
> > +        }
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > +static bool tpm_emulator_had_startup_error(TPMBackend *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +
> > +    return tpm_pt->had_startup_error;
> > +}
> > +
> > +static void tpm_emulator_cancel_cmd(TPMBackend *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    ptm_res res;
> > +
> > +    /*
> > +     * As of Linux 3.7 the tpm_tis driver does not properly cancel
> > +     * commands on all TPM manufacturers' TPMs.
> > +     * Only cancel if we're busy so we don't cancel someone else's
> > +     * command, e.g., a command executed on the host.
> > +     */
> > +    if (tpm_pt->op_executing) {
> The field is set in the worker thread. This is racy. Fortunately this
> is not relevant for emulator, I think you can simply drop that check
> and the variable. Stefan should confirm though.
> 
> > 
> > +        if (TPM_EMULATOR_IMPLEMENTS_ALL_CAPS(tpm_pt,
> > PTM_CAP_CANCEL_TPM_CMD)) {
> > +            if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev,
> > CMD_CANCEL_TPM_CMD,
> > +                                     &res, 0, sizeof(res)) < 0) {
> > +                error_report("tpm-emulator: Could not cancel
> > command: %s",
> > +                             strerror(errno));
> > +            } else if (res != 0) {
> > +                error_report("tpm-emulator: Failed to cancel TPM:
> > 0x%x",
> > +                             be32_to_cpu(res));
> > +            } else {
> > +                tpm_pt->op_canceled = true;
> > +            }
> > +        }
> > +    }
> > +}
> > +
> > +static void tpm_emulator_reset(TPMBackend *tb)
> > +{
> > +    DPRINTF("%s", __func__);
> > +
> > +    tpm_emulator_cancel_cmd(tb);
> > +}
> > +
> > +static TPMVersion tpm_emulator_get_tpm_version(TPMBackend *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +
> > +    return tpm_pt->tpm_version;
> > +}
> > +
> > +static void tpm_emulator_block_migration(TPMEmulator *tpm_pt)
> > +{
> > +    Error *err = NULL;
> > +
> > +    error_setg(&tpm_pt->migration_blocker,
> > +               "Migration disabled: TPM emulator not yet
> > migratable");
> > +    migrate_add_blocker(tpm_pt->migration_blocker, &err);
> > +    if (err) {
> > +        error_free(err);
> probably better to report_err it instead
Ok
> 
> > 
> > +        error_free(tpm_pt->migration_blocker);
> > +        tpm_pt->migration_blocker = NULL;
> and return an error code.
Will do
> 
> > 
> > +    }
> > +}
> > +
> > +static int tpm_emulator_prepare_data_fd(TPMEmulator *tpm_pt)
> > +{
> > +    ptm_res res;
> > +    Error *err = NULL;
> > +    int fds[2] = { -1, -1 };
> > +
> > +    if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds) < 0) {
> > +        error_report("tpm-emulator: Failed to create socketpair");
> > +        return -1;
> > +    }
> > +
> > +    qemu_chr_fe_set_msgfds(&tpm_pt->ctrl_dev, fds + 1, 1);
> > +
> > +    if (tpm_emulator_ctrlcmd(&tpm_pt->ctrl_dev, CMD_SET_DATAFD,
> > &res, 0,
> > +                    sizeof(res)) || res != 0) {
> Yay! for making life easier and hiding a protocol detail.
> 
> > 
> > +        error_report("tpm-emulator: Failed to send CMD_SET_DATAFD:
> > %s",
> > +                     strerror(errno));
> > +        goto err_exit;
> > +    }
> > +
> > +    tpm_pt->data_ioc =
> > QIO_CHANNEL(qio_channel_socket_new_fd(fds[0], &err));
> > +    if (err) {
> > +        error_report("tpm-emulator: Failed to create io channel :
> > %s",
> > +                       error_get_pretty(err));
> error_prepend()?
Ok
> 
> > 
> > +        error_free(err);
> > +        goto err_exit;
> > +    }
> close fds[1] ?
I guess we are not supposed to close the other end of the
socketpair/pipe, as it is not forked process.
> 
> > 
> > +
> > +    return 0;
> > +
> > +err_exit:
> > +    closesocket(fds[0]);
> > +    closesocket(fds[1]);
> > +    return -1;
> > +}
> > +
> > +static int tpm_emulator_handle_device_opts(TPMEmulator *tpm_pt,
> > QemuOpts *opts)
> > +{
> > +    const char *value;
> > +
> > +    value = qemu_opt_get(opts, "chardev");
> > +    if (value) {
> > +        Error *err = NULL;
> > +        Chardev *dev = qemu_chr_find(value);
> > +
> > +        tpm_pt->options->chardev = g_strdup(value);
> > +
> > +        if (!dev || !qemu_chr_fe_init(&tpm_pt->ctrl_dev, dev,
> > &err)) {
> > +            error_report("tpm-emulator: No valid chardev found at
> > '%s': %s",
> > +                         value, err ? error_get_pretty(err) : "");
> > +            error_free(err);
> error_prepend
Ok
> 
> > 
> > +            goto err;
> > +        }
> > +    }
> > +
> > +    if (tpm_emulator_prepare_data_fd(tpm_pt) < 0) {
> > +        goto err;
> > +    }
> > +
> > +    /* FIXME: tpm_util_test_tpmdev() accepts only on socket fd, as
> > it also used
> > +     * by passthrough driver, which not yet using GIOChannel.
> > +     */
> > +    if (tpm_util_test_tpmdev(QIO_CHANNEL_SOCKET(tpm_pt->data_ioc)-
> > >fd,
> > +                             &tpm_pt->tpm_version)) {
> > +        error_report("'%s' is not emulating TPM device. Error:
> > %s",
> > +                      tpm_pt->options->chardev, strerror(errno));
> > +        goto err;
> > +    }
> > +
> > +    DPRINTF("TPM Version %s", tpm_pt->tpm_version ==
> > TPM_VERSION_1_2 ? "1.2" :
> > +             (tpm_pt->tpm_version == TPM_VERSION_2_0 ?  "2.0" :
> > "Unspecified"));
> > +
> > +    if (tpm_emulator_probe_caps(tpm_pt) ||
> > +        tpm_emulator_check_caps(tpm_pt)) {
> > +        goto err;
> > +    }
> > +
> > +    tpm_emulator_block_migration(tpm_pt);
> > +
> > +    return 0;
> > +
> > +err:
> > +    DPRINT("Startup error\n");
> > +    return -1;
> > +}
> > +
> > +static TPMBackend *tpm_emulator_create(QemuOpts *opts, const char
> > *id)
> > +{
> > +    TPMBackend *tb = TPM_BACKEND(object_new(TYPE_TPM_EMULATOR));
> > +
> > +    tb->id = g_strdup(id);
> > +
> > +    if (tpm_emulator_handle_device_opts(TPM_EMULATOR(tb), opts)) {
> > +        goto err_exit;
> > +    }
> > +
> > +    return tb;
> > +
> > +err_exit:
> > +    object_unref(OBJECT(tb));
> > +
> > +    return NULL;
> > +}
> > +
> > +static TpmTypeOptions *tpm_emulator_get_tpm_options(TPMBackend
> > *tb)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(tb);
> > +    TpmTypeOptions *options = NULL;
> > +    TPMEmulatorOptions *eoptions = NULL;
> > +
> > +    eoptions = g_new0(TPMEmulatorOptions, 1);
> > +    if (!eoptions) {
> > +        return NULL;
> > +    }
> > +    DPRINTF("%s", __func__);
> > +
> > +    eoptions->chardev = g_strdup(tpm_pt->options->chardev);
> > +    options = g_new0(TpmTypeOptions, 1);
> > +    if (!options) {
> > +        qapi_free_TPMEmulatorOptions(eoptions);
> > +        return NULL;
> > +    }
> > +
> > +    options->type = TPM_TYPE_EMULATOR;
> > +    options->u.emulator.data = eoptions;
> I think this is a job for QAPI_CLONE.
> 
> > 
> > +
> > +    return options;
> > +}
> > +
> > +static const QemuOptDesc tpm_emulator_cmdline_opts[] = {
> > +    TPM_STANDARD_CMDLINE_OPTS,
> > +    {
> > +        .name = "chardev",
> > +        .type = QEMU_OPT_STRING,
> > +        .help = "Character device to use for out-of-band control
> > messages",
> > +    },
> > +    { /* end of list */ },
> > +};
> > +
> > +static const TPMDriverOps tpm_emulator_driver = {
> > +    .type                     = TPM_TYPE_EMULATOR,
> > +    .opts                     = tpm_emulator_cmdline_opts,
> > +    .desc                     = "TPM emulator backend driver",
> > +
> > +    .create                   = tpm_emulator_create,
> > +    .startup_tpm              = tpm_emulator_startup_tpm,
> > +    .reset                    = tpm_emulator_reset,
> > +    .had_startup_error        = tpm_emulator_had_startup_error,
> > +    .cancel_cmd               = tpm_emulator_cancel_cmd,
> > +    .get_tpm_established_flag =
> > tpm_emulator_get_tpm_established_flag,
> > +    .reset_tpm_established_flag =
> > tpm_emulator_reset_tpm_established_flag,
> > +    .get_tpm_version          = tpm_emulator_get_tpm_version,
> > +    .get_tpm_options          = tpm_emulator_get_tpm_options,
> > +};
> > +
> > +static void tpm_emulator_inst_init(Object *obj)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(obj);
> > +
> > +    DPRINTF("%s", __func__);
> > +    tpm_pt->options = g_new0(TPMEmulatorOptions, 1);
> > +    tpm_pt->op_executing = tpm_pt->op_canceled = false;
> > +    tpm_pt->had_startup_error = false;
> > +    tpm_pt->cur_locty_number = ~0;
> > +    qemu_mutex_init(&tpm_pt->state_lock);
> > +}
> > +
> > +static void tpm_emulator_inst_finalize(Object *obj)
> > +{
> > +    TPMEmulator *tpm_pt = TPM_EMULATOR(obj);
> > +
> > +    tpm_emulator_cancel_cmd(TPM_BACKEND(obj));
> > +    tpm_emulator_shutdown(tpm_pt);
> > +
> > +    if (tpm_pt->data_ioc) {
> > +        qio_channel_close(tpm_pt->data_ioc, NULL);
> > +    }
> > +
> > +    qemu_chr_fe_deinit(&tpm_pt->ctrl_dev, false);
> > +
> > +    if (tpm_pt->options) {
> > +        qapi_free_TPMEmulatorOptions(tpm_pt->options);
> > +    }
> > +
> > +    if (tpm_pt->migration_blocker) {
> > +        migrate_del_blocker(tpm_pt->migration_blocker);
> > +        error_free(tpm_pt->migration_blocker);
> > +    }
> > +}
> > +
> > +static void tpm_emulator_class_init(ObjectClass *klass, void
> > *data)
> > +{
> > +    TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
> > +    tbc->ops = &tpm_emulator_driver;
> > +    tbc->handle_request = tpm_emulator_handle_request;
> > +}
> > +
> > +static const TypeInfo tpm_emulator_info = {
> > +    .name = TYPE_TPM_EMULATOR,
> > +    .parent = TYPE_TPM_BACKEND,
> > +    .instance_size = sizeof(TPMEmulator),
> > +    .class_init = tpm_emulator_class_init,
> > +    .instance_init = tpm_emulator_inst_init,
> > +    .instance_finalize = tpm_emulator_inst_finalize,
> > +};
> > +
> > +static void tpm_emulator_register(void)
> > +{
> > +    type_register_static(&tpm_emulator_info);
> > +    tpm_register_driver(&tpm_emulator_driver);
> > +}
> > +
> > +type_init(tpm_emulator_register)
> > diff --git a/hw/tpm/tpm_ioctl.h b/hw/tpm/tpm_ioctl.h
> > new file mode 100644
> > index 0000000..33564b1
> > --- /dev/null
> > +++ b/hw/tpm/tpm_ioctl.h
> This file is copied from swtpm project. Could swtpm have it installed
> on system instead?
> 
> > 
> > @@ -0,0 +1,246 @@
> > +/*
> > + * tpm_ioctl.h
> > + *
> > + * (c) Copyright IBM Corporation 2014, 2015.
> > + *
> > + * This file is licensed under the terms of the 3-clause BSD
> > license
> > + */
> > +#ifndef _TPM_IOCTL_H_
> > +#define _TPM_IOCTL_H_
> > +
> > +#include <stdint.h>
> > +#include <sys/uio.h>
> > +#include <sys/types.h>
> > +#include <sys/ioctl.h>
> > +
> > +/*
> > + * Every response from a command involving a TPM command execution
> > must hold
> > + * the ptm_res as the first element.
> > + * ptm_res corresponds to the error code of a command executed by
> > the TPM.
> > + */
> > +
> > +typedef uint32_t ptm_res;
> > +
> > +/* PTM_GET_TPMESTABLISHED: get the establishment bit */
> > +struct ptm_est {
> > +    union {
> > +        struct {
> > +            ptm_res tpm_result;
> > +            unsigned char bit; /* TPM established bit */
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/* PTM_RESET_TPMESTABLISHED: reset establishment bit */
> > +struct ptm_reset_est {
> > +    union {
> > +        struct {
> > +            uint8_t loc; /* locality to use */
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/* PTM_INIT */
> > +struct ptm_init {
> > +    union {
> > +        struct {
> > +            uint32_t init_flags; /* see definitions below */
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/* above init_flags */
> > +#define PTM_INIT_FLAG_DELETE_VOLATILE (1 << 0)
> > +    /* delete volatile state file after reading it */
> > +
> > +/* PTM_SET_LOCALITY */
> > +struct ptm_loc {
> > +    union {
> > +        struct {
> > +            uint8_t loc; /* locality to set */
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/* PTM_HASH_DATA: hash given data */
> > +struct ptm_hdata {
> > +    union {
> > +        struct {
> > +            uint32_t length;
> > +            uint8_t data[4096];
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/*
> > + * size of the TPM state blob to transfer; x86_64 can handle 8k,
> > + * ppc64le only ~7k; keep the response below a 4k page size
> > + */
> > +#define PTM_STATE_BLOB_SIZE (3 * 1024)
> > +
> > +/*
> > + * The following is the data structure to get state blobs from the
> > TPM.
> > + * If the size of the state blob exceeds the PTM_STATE_BLOB_SIZE,
> > multiple reads
> > + * with this ioctl and with adjusted offset are necessary. All
> > bytes
> > + * must be transferred and the transfer is done once the last byte
> > has been
> > + * returned.
> > + * It is possible to use the read() interface for reading the
> > data; however, the
> > + * first bytes of the state blob will be part of the response to
> > the ioctl(); a
> > + * subsequent read() is only necessary if the total length
> > (totlength) exceeds
> > + * the number of received bytes. seek() is not supported.
> > + */
> > +struct ptm_getstate {
> > +    union {
> > +        struct {
> > +            uint32_t state_flags; /* may be:
> > PTM_STATE_FLAG_DECRYPTED */
> > +            uint32_t type;        /* which blob to pull */
> > +            uint32_t offset;      /* offset from where to read */
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +            uint32_t state_flags; /* may be:
> > PTM_STATE_FLAG_ENCRYPTED */
> > +            uint32_t totlength;   /* total length that will be
> > transferred */
> > +            uint32_t length;      /* number of bytes in following
> > buffer */
> > +            uint8_t  data[PTM_STATE_BLOB_SIZE];
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/* TPM state blob types */
> > +#define PTM_BLOB_TYPE_PERMANENT  1
> > +#define PTM_BLOB_TYPE_VOLATILE   2
> > +#define PTM_BLOB_TYPE_SAVESTATE  3
> > +
> > +/* state_flags above : */
> > +#define PTM_STATE_FLAG_DECRYPTED     1 /* on input:  get decrypted
> > state */
> > +#define PTM_STATE_FLAG_ENCRYPTED     2 /* on output: state is
> > encrypted */
> > +
> > +/*
> > + * The following is the data structure to set state blobs in the
> > TPM.
> > + * If the size of the state blob exceeds the PTM_STATE_BLOB_SIZE,
> > multiple
> > + * 'writes' using this ioctl are necessary. The last packet is
> > indicated
> > + * by the length being smaller than the PTM_STATE_BLOB_SIZE.
> > + * The very first packet may have a length indicator of '0'
> > enabling
> > + * a write() with all the bytes from a buffer. If the write()
> > interface
> > + * is used, a final ioctl with a non-full buffer must be made to
> > indicate
> > + * that all data were transferred (a write with 0 bytes would not
> > work).
> > + */
> > +struct ptm_setstate {
> > +    union {
> > +        struct {
> > +            uint32_t state_flags; /* may be
> > PTM_STATE_FLAG_ENCRYPTED */
> > +            uint32_t type;        /* which blob to set */
> > +            uint32_t length;      /* length of the data;
> > +                                     use 0 on the first packet to
> > +                                     transfer using write() */
> > +            uint8_t data[PTM_STATE_BLOB_SIZE];
> > +        } req; /* request */
> > +        struct {
> > +            ptm_res tpm_result;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +/*
> > + * PTM_GET_CONFIG: Data structure to get runtime configuration
> > information
> > + * such as which keys are applied.
> > + */
> > +struct ptm_getconfig {
> > +    union {
> > +        struct {
> > +            ptm_res tpm_result;
> > +            uint32_t flags;
> > +        } resp; /* response */
> > +    } u;
> > +};
> > +
> > +#define PTM_CONFIG_FLAG_FILE_KEY        0x1
> > +#define PTM_CONFIG_FLAG_MIGRATION_KEY   0x2
> > +
> > +
> > +typedef uint64_t ptm_cap;
> > +typedef struct ptm_est ptm_est;
> > +typedef struct ptm_reset_est ptm_reset_est;
> > +typedef struct ptm_loc ptm_loc;
> > +typedef struct ptm_hdata ptm_hdata;
> > +typedef struct ptm_init ptm_init;
> > +typedef struct ptm_getstate ptm_getstate;
> > +typedef struct ptm_setstate ptm_setstate;
> > +typedef struct ptm_getconfig ptm_getconfig;
> > +
> > +/* capability flags returned by PTM_GET_CAPABILITY */
> > +#define PTM_CAP_INIT               (1)
> > +#define PTM_CAP_SHUTDOWN           (1 << 1)
> > +#define PTM_CAP_GET_TPMESTABLISHED (1 << 2)
> > +#define PTM_CAP_SET_LOCALITY       (1 << 3)
> > +#define PTM_CAP_HASHING            (1 << 4)
> > +#define PTM_CAP_CANCEL_TPM_CMD     (1 << 5)
> > +#define PTM_CAP_STORE_VOLATILE     (1 << 6)
> > +#define PTM_CAP_RESET_TPMESTABLISHED (1 << 7)
> > +#define PTM_CAP_GET_STATEBLOB      (1 << 8)
> > +#define PTM_CAP_SET_STATEBLOB      (1 << 9)
> > +#define PTM_CAP_STOP               (1 << 10)
> > +#define PTM_CAP_GET_CONFIG         (1 << 11)
> > +#define PTM_CAP_SET_DATAFD         (1 << 12)
> > +
> > +enum {
> > +    PTM_GET_CAPABILITY     = _IOR('P', 0, ptm_cap),
> > +    PTM_INIT               = _IOWR('P', 1, ptm_init),
> > +    PTM_SHUTDOWN           = _IOR('P', 2, ptm_res),
> > +    PTM_GET_TPMESTABLISHED = _IOR('P', 3, ptm_est),
> > +    PTM_SET_LOCALITY       = _IOWR('P', 4, ptm_loc),
> > +    PTM_HASH_START         = _IOR('P', 5, ptm_res),
> > +    PTM_HASH_DATA          = _IOWR('P', 6, ptm_hdata),
> > +    PTM_HASH_END           = _IOR('P', 7, ptm_res),
> > +    PTM_CANCEL_TPM_CMD     = _IOR('P', 8, ptm_res),
> > +    PTM_STORE_VOLATILE     = _IOR('P', 9, ptm_res),
> > +    PTM_RESET_TPMESTABLISHED = _IOWR('P', 10, ptm_reset_est),
> > +    PTM_GET_STATEBLOB      = _IOWR('P', 11, ptm_getstate),
> > +    PTM_SET_STATEBLOB      = _IOWR('P', 12, ptm_setstate),
> > +    PTM_STOP               = _IOR('P', 13, ptm_res),
> > +    PTM_GET_CONFIG         = _IOR('P', 14, ptm_getconfig),
> > +    PTM_SET_DATAFD         = _IOR('P', 15, ptm_res),
> > +};
> > +
> > +/*
> > + * Commands used by the non-CUSE TPMs
> > + *
> > + * All messages container big-endian data.
> > + *
> > + * The return messages only contain the 'resp' part of the unions
> > + * in the data structures above. Besides that the limits in the
> > + * buffers above (ptm_hdata:u.req.data and
> > ptm_get_state:u.resp.data
> > + * and ptm_set_state:u.req.data) are 0xffffffff.
> > + */
> > +enum {
> > +    CMD_GET_CAPABILITY = 1,
> > +    CMD_INIT,
> > +    CMD_SHUTDOWN,
> > +    CMD_GET_TPMESTABLISHED,
> > +    CMD_SET_LOCALITY,
> > +    CMD_HASH_START,
> > +    CMD_HASH_DATA,
> > +    CMD_HASH_END,
> > +    CMD_CANCEL_TPM_CMD,
> > +    CMD_STORE_VOLATILE,
> > +    CMD_RESET_TPMESTABLISHED,
> > +    CMD_GET_STATEBLOB,
> > +    CMD_SET_STATEBLOB,
> > +    CMD_STOP,
> > +    CMD_GET_CONFIG,
> > +    CMD_SET_DATAFD
> > +};
> > +
> > +#endif /* _TPM_IOCTL_H */
> > diff --git a/qapi/tpm.json b/qapi/tpm.json
> > index e8b2d8d..7093f26 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:
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 77859a2..1e93e53 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -3121,7 +3121,9 @@ DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
> >      "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
> >      "                use path to provide path to a character
> > device; default is /dev/tpm0\n"
> >      "                use cancel-path to provide path to TPM's
> > cancel sysfs entry; if\n"
> > -    "                not provided it will be searched for in
> > /sys/class/misc/tpm?/device\n",
> > +    "                not provided it will be searched for in
> > /sys/class/misc/tpm?/device\n"
> > +    "-tpmdev emulator,id=id,chardev=dev\n"
> > +    "                configure the TPM device using chardev
> > backend\n",
> >      QEMU_ARCH_ALL)
> >  STEXI
> > 
> > @@ -3130,8 +3132,8 @@ The general form of a TPM device option is:
> > 
> >  @item -tpmdev @var{backend} ,id=@var{id} [,@var{options}]
> >  @findex -tpmdev
> > -Backend type must be:
> > -@option{passthrough}.
> > +Backend type must be either one of the following:
> > +@option{passthrough}, @option{emulator}.
> > 
> >  The specific backend type will determine the applicable options.
> >  The @code{-tpmdev} option creates the TPM backend and requires a
> > @@ -3181,6 +3183,20 @@ To create a passthrough TPM use the
> > following two options:
> >  Note that the @code{-tpmdev} id is @code{tpm0} and is referenced
> > by
> >  @code{tpmdev=tpm0} in the device option.
> > 
> > +@item -tpmdev emulator, id=@var{id}, chardev=@var{dev}
> > +
> > +(Linux-host only) Enable access to a TPM emulator using Unix
> > domain socket based
> > +chardev backend.
> > +
> > +@option{chardev} specifies the unique ID of a character device
> > backend that provides connection to the software TPM server.
> > +
> > +To create a TPM emulator backend device with chardev socket
> > backend:
> > +@example
> > +
> > +-chardev socket,id=chrtpm,path=/tmp/swtpm-ctrl -tpmdev
> > emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
> > +
> > +@end example
> > +
> >  @end table
> > 
> >  ETEXI
> > --
> > 2.7.4
> > 
> 
> 
- Amarnath