diff mbox

[v2,5/9] tmp backend: Add new api to read backend TpmInfo

Message ID 1491575431-32170-6-git-send-email-amarnath.valluri@intel.com
State New
Headers show

Commit Message

Valluri, Amarnath April 7, 2017, 2:30 p.m. UTC
TPM configuration options are backend implementation details and shall not be
part of base TPMBackend object, and these shall not be accessed directly outside
of the class, hence added a new interface method, get_tpm_options() to
TPMDriverOps., which shall be implemented by the derived classes to return
configured tpm options.

A new tpm backend api - tpm_backend_query_tpm() which uses _get_tpm_options() to
prepare TpmInfo.

Made TPMPassthroughOptions type inherited from newly defined TPMOptions base type.
The TPMOptions base type is intentionally left empty and supposed to be
inherited by all backend implementations to define their tpm configuration
options.

Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
---
 backends/tpm.c               | 24 +++++++++++++++++--
 hmp.c                        | 10 ++++----
 hw/tpm/tpm_passthrough.c     | 57 +++++++++++++++++++++++++++++++++++---------
 include/sysemu/tpm_backend.h | 25 +++++++++++++++++--
 qapi-schema.json             | 41 +++++++++++++++----------------
 tpm.c                        | 32 +------------------------
 6 files changed, 118 insertions(+), 71 deletions(-)

Comments

Stefan Berger April 25, 2017, 6:51 p.m. UTC | #1
On 04/07/2017 10:30 AM, Amarnath Valluri wrote:
> TPM configuration options are backend implementation details and shall not be
> part of base TPMBackend object, and these shall not be accessed directly outside
> of the class, hence added a new interface method, get_tpm_options() to
> TPMDriverOps., which shall be implemented by the derived classes to return
> configured tpm options.
>
> A new tpm backend api - tpm_backend_query_tpm() which uses _get_tpm_options() to
> prepare TpmInfo.
>
> Made TPMPassthroughOptions type inherited from newly defined TPMOptions base type.
> The TPMOptions base type is intentionally left empty and supposed to be
> inherited by all backend implementations to define their tpm configuration
> options.
>
> Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
> ---
>   backends/tpm.c               | 24 +++++++++++++++++--
>   hmp.c                        | 10 ++++----
>   hw/tpm/tpm_passthrough.c     | 57 +++++++++++++++++++++++++++++++++++---------
>   include/sysemu/tpm_backend.h | 25 +++++++++++++++++--
>   qapi-schema.json             | 41 +++++++++++++++----------------
>   tpm.c                        | 32 +------------------------
>   6 files changed, 118 insertions(+), 71 deletions(-)
>
> diff --git a/backends/tpm.c b/backends/tpm.c
> index c2be17b..c96f462 100644
> --- a/backends/tpm.c
> +++ b/backends/tpm.c
> @@ -156,6 +156,28 @@ TPMVersion tpm_backend_get_tpm_version(TPMBackend *s)
>       return k->ops->get_tpm_version(s);
>   }
>
> +TPMOptions *tpm_backend_get_tpm_options(TPMBackend *s)
> +{
> +    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
> +
> +    assert(k->ops->get_tpm_options);
> +
> +    return k->ops->get_tpm_options(s);
> +}
> +
> +TPMInfo *tpm_backend_query_tpm(TPMBackend *s)
> +{
> +    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
> +    TPMInfo *info = g_new0(TPMInfo, 1);
> +
> +    info->type = k->ops->type;
> +    info->id = g_strdup(s->id);
> +    info->model = s->fe_model;
> +    info->options = tpm_backend_get_tpm_options(s);
> +
> +    return info;
> +}
> +
>   static bool tpm_backend_prop_get_opened(Object *obj, Error **errp)
>   {
>       TPMBackend *s = TPM_BACKEND(obj);
> @@ -210,8 +232,6 @@ static void tpm_backend_instance_finalize(Object *obj)
>       TPMBackend *s = TPM_BACKEND(obj);
>
>       g_free(s->id);
> -    g_free(s->path);
> -    g_free(s->cancel_path);
>       tpm_backend_thread_end(s);
>   }
>
> diff --git a/hmp.c b/hmp.c
> index edb8970..9caf7c8 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -955,18 +955,18 @@ void hmp_info_tpm(Monitor *mon, const QDict *qdict)
>                          c, TpmModel_lookup[ti->model]);
>
>           monitor_printf(mon, "  \\ %s: type=%s",
> -                       ti->id, TpmTypeOptionsKind_lookup[ti->options->type]);
> +                       ti->id, TpmType_lookup[ti->type]);
>
> -        switch (ti->options->type) {
> -        case TPM_TYPE_OPTIONS_KIND_PASSTHROUGH:
> -            tpo = ti->options->u.passthrough.data;
> +        switch (ti->type) {
> +        case TPM_TYPE_PASSTHROUGH:
> +            tpo = (TPMPassthroughOptions *)ti->options;
>               monitor_printf(mon, "%s%s%s%s",
>                              tpo->has_path ? ",path=" : "",
>                              tpo->has_path ? tpo->path : "",
>                              tpo->has_cancel_path ? ",cancel-path=" : "",
>                              tpo->has_cancel_path ? tpo->cancel_path : "");
>               break;
> -        case TPM_TYPE_OPTIONS_KIND__MAX:
> +        default:
>               break;
>           }
>           monitor_printf(mon, "\n");
> diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
> index 0f543bd..71bdf25 100644
> --- a/hw/tpm/tpm_passthrough.c
> +++ b/hw/tpm/tpm_passthrough.c
> @@ -49,6 +49,7 @@
>   struct TPMPassthruState {
>       TPMBackend parent;
>
> +    TPMPassthroughOptions *ops;
>       char *tpm_dev;
>       int tpm_fd;
>       bool tpm_executing;
> @@ -313,15 +314,14 @@ static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
>    * in Documentation/ABI/stable/sysfs-class-tpm.
>    * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
>    */
> -static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
> +static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
>   {
> -    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
>       int fd = -1;
>       char *dev;
>       char path[PATH_MAX];
>
> -    if (tb->cancel_path) {
> -        fd = qemu_open(tb->cancel_path, O_WRONLY);
> +    if (tpm_pt->ops->cancel_path) {
> +        fd = qemu_open(tpm_pt->ops->cancel_path, O_WRONLY);
>           if (fd < 0) {
>               error_report("Could not open TPM cancel path : %s",
>                            strerror(errno));
> @@ -336,7 +336,7 @@ static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
>                        dev) < sizeof(path)) {
>               fd = qemu_open(path, O_WRONLY);
>               if (fd >= 0) {
> -                tb->cancel_path = g_strdup(path);
> +                tpm_pt->ops->cancel_path = g_strdup(path);
>               } else {
>                   error_report("tpm_passthrough: Could not open TPM cancel "
>                                "path %s : %s", path, strerror(errno));
> @@ -356,17 +356,24 @@ static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
>       const char *value;
>
>       value = qemu_opt_get(opts, "cancel-path");
> -    tb->cancel_path = g_strdup(value);
> +    if (value) {
> +        tpm_pt->ops->cancel_path = g_strdup(value);
> +        tpm_pt->ops->has_cancel_path = true;
> +    } else {
> +        tpm_pt->ops->has_cancel_path = false;
> +    }
>
>       value = qemu_opt_get(opts, "path");
>       if (!value) {
>           value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
> +        tpm_pt->ops->has_path = false;
> +    } else {
> +        tpm_pt->ops->has_path = true;
>       }
>
> +    tpm_pt->ops->path = g_strdup(value);
>       tpm_pt->tpm_dev = g_strdup(value);
>
> -    tb->path = g_strdup(tpm_pt->tpm_dev);
> -
>       tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
>       if (tpm_pt->tpm_fd < 0) {
>           error_report("Cannot access TPM device using '%s': %s",
> @@ -387,8 +394,8 @@ static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
>       tpm_pt->tpm_fd = -1;
>
>    err_free_parameters:
> -    g_free(tb->path);
> -    tb->path = NULL;
> +    g_free(tpm_pt->ops->path);
> +    tpm_pt->ops->path = NULL;
>
>       g_free(tpm_pt->tpm_dev);
>       tpm_pt->tpm_dev = NULL;
> @@ -408,7 +415,7 @@ static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
>           goto err_exit;
>       }
>
> -    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
> +    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
>       if (tpm_pt->cancel_fd < 0) {
>           goto err_exit;
>       }
> @@ -430,6 +437,30 @@ static void tpm_passthrough_destroy(TPMBackend *tb)
>       qemu_close(tpm_pt->tpm_fd);
>       qemu_close(tpm_pt->cancel_fd);
>       g_free(tpm_pt->tpm_dev);
> +
> +    qapi_free_TPMPassthroughOptions(tpm_pt->ops);
> +}
> +
> +static TPMOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
> +{
> +    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
> +    TPMPassthroughOptions *ops = g_new0(TPMPassthroughOptions, 1);
> +
> +    if (!ops) {
> +        return NULL;
> +    }
> +
> +    if (tpm_pt->ops->has_path) {
> +        ops->has_path = true;
> +        ops->path = g_strdup(tpm_pt->ops->path);
> +    }
> +
> +    if (tpm_pt->ops->has_cancel_path) {
> +        ops->has_cancel_path = true;
> +        ops->cancel_path = g_strdup(tpm_pt->ops->cancel_path);
> +    }
> +
> +    return (TPMOptions *)ops;
>   }
>
>   static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
> @@ -460,12 +491,14 @@ static const TPMDriverOps tpm_passthrough_driver = {
>       .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
>       .reset_tpm_established_flag = tpm_passthrough_reset_tpm_established_flag,
>       .get_tpm_version          = tpm_passthrough_get_tpm_version,
> +    .get_tpm_options          = tpm_passthrough_get_tpm_options,
>   };
>
>   static void tpm_passthrough_inst_init(Object *obj)
>   {
>       TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
>
> +    tpm_pt->ops = g_new0(TPMPassthroughOptions, 1);
>       tpm_pt->tpm_fd = -1;
>       tpm_pt->cancel_fd = -1;
>   }
> @@ -478,6 +511,8 @@ static void tpm_passthrough_inst_finalize(Object *obj)
>
>       qemu_close(tpm_pt->tpm_fd);
>       qemu_close(tpm_pt->cancel_fd);
> +
> +    qapi_free_TPMPassthroughOptions(tpm_pt->ops);
>   }
>
>   static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
> diff --git a/include/sysemu/tpm_backend.h b/include/sysemu/tpm_backend.h
> index a538a7f..7f4d621 100644
> --- a/include/sysemu/tpm_backend.h
> +++ b/include/sysemu/tpm_backend.h
> @@ -48,10 +48,9 @@ struct TPMBackend {
>       GThreadPool *thread_pool;
>       TPMRecvDataCB *recv_data_callback;
>
> +    /* <public> */
>       char *id;
>       enum TpmModel fe_model;
> -    char *path;
> -    char *cancel_path;
>
>       QLIST_ENTRY(TPMBackend) list;
>   };
> @@ -98,6 +97,8 @@ struct TPMDriverOps {
>       int (*reset_tpm_established_flag)(TPMBackend *t, uint8_t locty);
>
>       TPMVersion (*get_tpm_version)(TPMBackend *t);
> +
> +    TPMOptions *(*get_tpm_options)(TPMBackend *t);
>   };
>
>
> @@ -230,6 +231,26 @@ void tpm_backend_open(TPMBackend *s, Error **errp);
>    */
>   TPMVersion tpm_backend_get_tpm_version(TPMBackend *s);
>
> +/**
> + * tpm_backend_get_tpm_options:
> + * @s: the backend
> + *
> + * Get the backend configuration options
> + *
> + * Returns newly allocated TPMOptions
> + */
> +TPMOptions *tpm_backend_get_tpm_options(TPMBackend *s);
> +
> +/**
> + * tpm_backend_query_tpm:
> + * @s: the backend
> + *
> + * Query backend tpm info
> + *
> + * Returns newly allocated TPMInfo
> + */
> +TPMInfo *tpm_backend_query_tpm(TPMBackend *s);
> +
>   TPMBackend *qemu_find_tpm(const char *id);
>
>   const TPMDriverOps *tpm_get_backend_driver(const char *type);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index b921994..3f1ca20 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -5140,6 +5140,16 @@
>   { 'command': 'query-tpm-types', 'returns': ['TpmType'] }
>
>   ##
> +# @TPMOptions:
> +#
> +# Base type for TPM options
> +#
> +# Since: 2.10
> +##
> +{ 'struct': 'TPMOptions',
> +  'data': { } }
> +
> +##
>   # @TPMPassthroughOptions:
>   #
>   # Information about the TPM passthrough type
> @@ -5151,20 +5161,9 @@
>   #
>   # Since: 1.5
>   ##
> -{ 'struct': 'TPMPassthroughOptions', 'data': { '*path' : 'str',
> -                                             '*cancel-path' : 'str'} }
> +{ 'struct': 'TPMPassthroughOptions', 'base': 'TPMOptions',
> +  'data': { '*path' : 'str', '*cancel-path' : 'str'} }


I don't think that you can change it like this anymore since this is 
part of the public interface.

> -##
> -# @TpmTypeOptions:
> -#
> -# A union referencing different TPM backend types' configuration options
> -#
> -# @type: 'passthrough' The configuration options for the TPM passthrough type
> -#
> -# Since: 1.5
> -##
> -{ 'union': 'TpmTypeOptions',
> -   'data': { 'passthrough' : 'TPMPassthroughOptions' } }
>
>   ##
>   # @TPMInfo:
> @@ -5173,6 +5172,8 @@
>   #
>   # @id: The Id of the TPM
>   #
> +# @type: The TPM backend type
> +#
>   # @model: The TPM frontend model
>   #
>   # @options: The TPM (backend) type configuration options
> @@ -5181,8 +5182,9 @@
>   ##
>   { 'struct': 'TPMInfo',
>     'data': {'id': 'str',
> +           'type': 'TpmType',
>              'model': 'TpmModel',
> -           'options': 'TpmTypeOptions' } }
> +           'options': 'TPMOptions' } }
>
>   ##
>   # @query-tpm:
> @@ -5199,13 +5201,12 @@
>   # <- { "return":
>   #      [
>   #        { "model": "tpm-tis",
> +#          "type": "passthrough",
>   #          "options":
> -#            { "type": "passthrough",
> -#              "data":
> -#                { "cancel-path": "/sys/class/misc/tpm0/device/cancel",
> -#                  "path": "/dev/tpm0"
> -#                }
> -#            },
> +#          {
> +#            "cancel-path": "/sys/class/misc/tpm0/device/cancel",
> +#            "path": "/dev/tpm0"
> +#          },
>   #          "id": "tpm0"
>   #        }
>   #      ]
> diff --git a/tpm.c b/tpm.c
> index 0ee021a..1b6b550 100644
> --- a/tpm.c
> +++ b/tpm.c
> @@ -249,36 +249,6 @@ static const TPMDriverOps *tpm_driver_find_by_type(enum TpmType type)
>       return NULL;
>   }
>
> -static TPMInfo *qmp_query_tpm_inst(TPMBackend *drv)
> -{
> -    TPMInfo *res = g_new0(TPMInfo, 1);
> -    TPMPassthroughOptions *tpo;
> -
> -    res->id = g_strdup(drv->id);
> -    res->model = drv->fe_model;
> -    res->options = g_new0(TpmTypeOptions, 1);
> -
> -    switch (tpm_backend_get_type(drv)) {
> -    case TPM_TYPE_PASSTHROUGH:
> -        res->options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
> -        tpo = g_new0(TPMPassthroughOptions, 1);
> -        res->options->u.passthrough.data = tpo;
> -        if (drv->path) {
> -            tpo->path = g_strdup(drv->path);
> -            tpo->has_path = true;
> -        }
> -        if (drv->cancel_path) {
> -            tpo->cancel_path = g_strdup(drv->cancel_path);
> -            tpo->has_cancel_path = true;
> -        }
> -        break;
> -    case TPM_TYPE__MAX:
> -        break;
> -    }
> -
> -    return res;
> -}
> -
>   /*
>    * Walk the list of active TPM backends and collect information about them
>    * following the schema description in qapi-schema.json.
> @@ -293,7 +263,7 @@ TPMInfoList *qmp_query_tpm(Error **errp)
>               continue;
>           }
>           info = g_new0(TPMInfoList, 1);
> -        info->value = qmp_query_tpm_inst(drv);
> +        info->value = tpm_backend_query_tpm(drv);
>
>           if (!cur_item) {
>               head = cur_item = info;
Eric Blake April 25, 2017, 6:59 p.m. UTC | #2
On 04/25/2017 01:51 PM, Stefan Berger wrote:

>> +++ b/qapi-schema.json
>> @@ -5140,6 +5140,16 @@
>>   { 'command': 'query-tpm-types', 'returns': ['TpmType'] }
>>
>>   ##
>> +# @TPMOptions:
>> +#
>> +# Base type for TPM options
>> +#
>> +# Since: 2.10
>> +##
>> +{ 'struct': 'TPMOptions',
>> +  'data': { } }
>> +
>> +##
>>   # @TPMPassthroughOptions:
>>   #
>>   # Information about the TPM passthrough type
>> @@ -5151,20 +5161,9 @@
>>   #
>>   # Since: 1.5
>>   ##
>> -{ 'struct': 'TPMPassthroughOptions', 'data': { '*path' : 'str',
>> -                                             '*cancel-path' : 'str'} }
>> +{ 'struct': 'TPMPassthroughOptions', 'base': 'TPMOptions',
>> +  'data': { '*path' : 'str', '*cancel-path' : 'str'} }
> 
> 
> I don't think that you can change it like this anymore since this is
> part of the public interface.

The change is backwards compatible; it doesn't break any existing QMP
usage.  It's weird to have an empty base class, though.
Valluri, Amarnath May 2, 2017, 7:17 a.m. UTC | #3
On 04/25/2017 09:59 PM, Eric Blake wrote:
> On 04/25/2017 01:51 PM, Stefan Berger wrote:
>
>>> +++ b/qapi-schema.json
>>> @@ -5140,6 +5140,16 @@
>>>    { 'command': 'query-tpm-types', 'returns': ['TpmType'] }
>>>
>>>    ##
>>> +# @TPMOptions:
>>> +#
>>> +# Base type for TPM options
>>> +#
>>> +# Since: 2.10
>>> +##
>>> +{ 'struct': 'TPMOptions',
>>> +  'data': { } }
>>> +
>>> +##
>>>    # @TPMPassthroughOptions:
>>>    #
>>>    # Information about the TPM passthrough type
>>> @@ -5151,20 +5161,9 @@
>>>    #
>>>    # Since: 1.5
>>>    ##
>>> -{ 'struct': 'TPMPassthroughOptions', 'data': { '*path' : 'str',
>>> -                                             '*cancel-path' : 'str'} }
>>> +{ 'struct': 'TPMPassthroughOptions', 'base': 'TPMOptions',
>>> +  'data': { '*path' : 'str', '*cancel-path' : 'str'} }
>>
>> I don't think that you can change it like this anymore since this is
>> part of the public interface.
> The change is backwards compatible; it doesn't break any existing QMP
> usage.  It's weird to have an empty base class, though.
This empty base class(TPMOptions) makes sense when its shared by more 
than one(Passthrough and Emulator) bakcends.

- Amarnath
diff mbox

Patch

diff --git a/backends/tpm.c b/backends/tpm.c
index c2be17b..c96f462 100644
--- a/backends/tpm.c
+++ b/backends/tpm.c
@@ -156,6 +156,28 @@  TPMVersion tpm_backend_get_tpm_version(TPMBackend *s)
     return k->ops->get_tpm_version(s);
 }
 
+TPMOptions *tpm_backend_get_tpm_options(TPMBackend *s)
+{
+    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
+
+    assert(k->ops->get_tpm_options);
+
+    return k->ops->get_tpm_options(s);
+}
+
+TPMInfo *tpm_backend_query_tpm(TPMBackend *s)
+{
+    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
+    TPMInfo *info = g_new0(TPMInfo, 1);
+
+    info->type = k->ops->type;
+    info->id = g_strdup(s->id);
+    info->model = s->fe_model;
+    info->options = tpm_backend_get_tpm_options(s);
+
+    return info;
+}
+
 static bool tpm_backend_prop_get_opened(Object *obj, Error **errp)
 {
     TPMBackend *s = TPM_BACKEND(obj);
@@ -210,8 +232,6 @@  static void tpm_backend_instance_finalize(Object *obj)
     TPMBackend *s = TPM_BACKEND(obj);
 
     g_free(s->id);
-    g_free(s->path);
-    g_free(s->cancel_path);
     tpm_backend_thread_end(s);
 }
 
diff --git a/hmp.c b/hmp.c
index edb8970..9caf7c8 100644
--- a/hmp.c
+++ b/hmp.c
@@ -955,18 +955,18 @@  void hmp_info_tpm(Monitor *mon, const QDict *qdict)
                        c, TpmModel_lookup[ti->model]);
 
         monitor_printf(mon, "  \\ %s: type=%s",
-                       ti->id, TpmTypeOptionsKind_lookup[ti->options->type]);
+                       ti->id, TpmType_lookup[ti->type]);
 
-        switch (ti->options->type) {
-        case TPM_TYPE_OPTIONS_KIND_PASSTHROUGH:
-            tpo = ti->options->u.passthrough.data;
+        switch (ti->type) {
+        case TPM_TYPE_PASSTHROUGH:
+            tpo = (TPMPassthroughOptions *)ti->options;
             monitor_printf(mon, "%s%s%s%s",
                            tpo->has_path ? ",path=" : "",
                            tpo->has_path ? tpo->path : "",
                            tpo->has_cancel_path ? ",cancel-path=" : "",
                            tpo->has_cancel_path ? tpo->cancel_path : "");
             break;
-        case TPM_TYPE_OPTIONS_KIND__MAX:
+        default:
             break;
         }
         monitor_printf(mon, "\n");
diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
index 0f543bd..71bdf25 100644
--- a/hw/tpm/tpm_passthrough.c
+++ b/hw/tpm/tpm_passthrough.c
@@ -49,6 +49,7 @@ 
 struct TPMPassthruState {
     TPMBackend parent;
 
+    TPMPassthroughOptions *ops;
     char *tpm_dev;
     int tpm_fd;
     bool tpm_executing;
@@ -313,15 +314,14 @@  static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
  * in Documentation/ABI/stable/sysfs-class-tpm.
  * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
  */
-static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
+static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
 {
-    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
     int fd = -1;
     char *dev;
     char path[PATH_MAX];
 
-    if (tb->cancel_path) {
-        fd = qemu_open(tb->cancel_path, O_WRONLY);
+    if (tpm_pt->ops->cancel_path) {
+        fd = qemu_open(tpm_pt->ops->cancel_path, O_WRONLY);
         if (fd < 0) {
             error_report("Could not open TPM cancel path : %s",
                          strerror(errno));
@@ -336,7 +336,7 @@  static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
                      dev) < sizeof(path)) {
             fd = qemu_open(path, O_WRONLY);
             if (fd >= 0) {
-                tb->cancel_path = g_strdup(path);
+                tpm_pt->ops->cancel_path = g_strdup(path);
             } else {
                 error_report("tpm_passthrough: Could not open TPM cancel "
                              "path %s : %s", path, strerror(errno));
@@ -356,17 +356,24 @@  static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
     const char *value;
 
     value = qemu_opt_get(opts, "cancel-path");
-    tb->cancel_path = g_strdup(value);
+    if (value) {
+        tpm_pt->ops->cancel_path = g_strdup(value);
+        tpm_pt->ops->has_cancel_path = true;
+    } else {
+        tpm_pt->ops->has_cancel_path = false;
+    }
 
     value = qemu_opt_get(opts, "path");
     if (!value) {
         value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
+        tpm_pt->ops->has_path = false;
+    } else {
+        tpm_pt->ops->has_path = true;
     }
 
+    tpm_pt->ops->path = g_strdup(value);
     tpm_pt->tpm_dev = g_strdup(value);
 
-    tb->path = g_strdup(tpm_pt->tpm_dev);
-
     tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
     if (tpm_pt->tpm_fd < 0) {
         error_report("Cannot access TPM device using '%s': %s",
@@ -387,8 +394,8 @@  static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
     tpm_pt->tpm_fd = -1;
 
  err_free_parameters:
-    g_free(tb->path);
-    tb->path = NULL;
+    g_free(tpm_pt->ops->path);
+    tpm_pt->ops->path = NULL;
 
     g_free(tpm_pt->tpm_dev);
     tpm_pt->tpm_dev = NULL;
@@ -408,7 +415,7 @@  static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)
         goto err_exit;
     }
 
-    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);
+    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
     if (tpm_pt->cancel_fd < 0) {
         goto err_exit;
     }
@@ -430,6 +437,30 @@  static void tpm_passthrough_destroy(TPMBackend *tb)
     qemu_close(tpm_pt->tpm_fd);
     qemu_close(tpm_pt->cancel_fd);
     g_free(tpm_pt->tpm_dev);
+
+    qapi_free_TPMPassthroughOptions(tpm_pt->ops);
+}
+
+static TPMOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
+{
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
+    TPMPassthroughOptions *ops = g_new0(TPMPassthroughOptions, 1);
+
+    if (!ops) {
+        return NULL;
+    }
+
+    if (tpm_pt->ops->has_path) {
+        ops->has_path = true;
+        ops->path = g_strdup(tpm_pt->ops->path);
+    }
+
+    if (tpm_pt->ops->has_cancel_path) {
+        ops->has_cancel_path = true;
+        ops->cancel_path = g_strdup(tpm_pt->ops->cancel_path);
+    }
+
+    return (TPMOptions *)ops;
 }
 
 static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
@@ -460,12 +491,14 @@  static const TPMDriverOps tpm_passthrough_driver = {
     .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,
     .reset_tpm_established_flag = tpm_passthrough_reset_tpm_established_flag,
     .get_tpm_version          = tpm_passthrough_get_tpm_version,
+    .get_tpm_options          = tpm_passthrough_get_tpm_options,
 };
 
 static void tpm_passthrough_inst_init(Object *obj)
 {
     TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
 
+    tpm_pt->ops = g_new0(TPMPassthroughOptions, 1);
     tpm_pt->tpm_fd = -1;
     tpm_pt->cancel_fd = -1;
 }
@@ -478,6 +511,8 @@  static void tpm_passthrough_inst_finalize(Object *obj)
 
     qemu_close(tpm_pt->tpm_fd);
     qemu_close(tpm_pt->cancel_fd);
+
+    qapi_free_TPMPassthroughOptions(tpm_pt->ops);
 }
 
 static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
diff --git a/include/sysemu/tpm_backend.h b/include/sysemu/tpm_backend.h
index a538a7f..7f4d621 100644
--- a/include/sysemu/tpm_backend.h
+++ b/include/sysemu/tpm_backend.h
@@ -48,10 +48,9 @@  struct TPMBackend {
     GThreadPool *thread_pool;
     TPMRecvDataCB *recv_data_callback;
 
+    /* <public> */
     char *id;
     enum TpmModel fe_model;
-    char *path;
-    char *cancel_path;
 
     QLIST_ENTRY(TPMBackend) list;
 };
@@ -98,6 +97,8 @@  struct TPMDriverOps {
     int (*reset_tpm_established_flag)(TPMBackend *t, uint8_t locty);
 
     TPMVersion (*get_tpm_version)(TPMBackend *t);
+
+    TPMOptions *(*get_tpm_options)(TPMBackend *t);
 };
 
 
@@ -230,6 +231,26 @@  void tpm_backend_open(TPMBackend *s, Error **errp);
  */
 TPMVersion tpm_backend_get_tpm_version(TPMBackend *s);
 
+/**
+ * tpm_backend_get_tpm_options:
+ * @s: the backend
+ *
+ * Get the backend configuration options
+ *
+ * Returns newly allocated TPMOptions
+ */
+TPMOptions *tpm_backend_get_tpm_options(TPMBackend *s);
+
+/**
+ * tpm_backend_query_tpm:
+ * @s: the backend
+ *
+ * Query backend tpm info
+ *
+ * Returns newly allocated TPMInfo
+ */
+TPMInfo *tpm_backend_query_tpm(TPMBackend *s);
+
 TPMBackend *qemu_find_tpm(const char *id);
 
 const TPMDriverOps *tpm_get_backend_driver(const char *type);
diff --git a/qapi-schema.json b/qapi-schema.json
index b921994..3f1ca20 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -5140,6 +5140,16 @@ 
 { 'command': 'query-tpm-types', 'returns': ['TpmType'] }
 
 ##
+# @TPMOptions:
+#
+# Base type for TPM options
+#
+# Since: 2.10
+##
+{ 'struct': 'TPMOptions',
+  'data': { } }
+
+##
 # @TPMPassthroughOptions:
 #
 # Information about the TPM passthrough type
@@ -5151,20 +5161,9 @@ 
 #
 # Since: 1.5
 ##
-{ 'struct': 'TPMPassthroughOptions', 'data': { '*path' : 'str',
-                                             '*cancel-path' : 'str'} }
+{ 'struct': 'TPMPassthroughOptions', 'base': 'TPMOptions',
+  'data': { '*path' : 'str', '*cancel-path' : 'str'} }
 
-##
-# @TpmTypeOptions:
-#
-# A union referencing different TPM backend types' configuration options
-#
-# @type: 'passthrough' The configuration options for the TPM passthrough type
-#
-# Since: 1.5
-##
-{ 'union': 'TpmTypeOptions',
-   'data': { 'passthrough' : 'TPMPassthroughOptions' } }
 
 ##
 # @TPMInfo:
@@ -5173,6 +5172,8 @@ 
 #
 # @id: The Id of the TPM
 #
+# @type: The TPM backend type
+#
 # @model: The TPM frontend model
 #
 # @options: The TPM (backend) type configuration options
@@ -5181,8 +5182,9 @@ 
 ##
 { 'struct': 'TPMInfo',
   'data': {'id': 'str',
+           'type': 'TpmType',
            'model': 'TpmModel',
-           'options': 'TpmTypeOptions' } }
+           'options': 'TPMOptions' } }
 
 ##
 # @query-tpm:
@@ -5199,13 +5201,12 @@ 
 # <- { "return":
 #      [
 #        { "model": "tpm-tis",
+#          "type": "passthrough",
 #          "options":
-#            { "type": "passthrough",
-#              "data":
-#                { "cancel-path": "/sys/class/misc/tpm0/device/cancel",
-#                  "path": "/dev/tpm0"
-#                }
-#            },
+#          {
+#            "cancel-path": "/sys/class/misc/tpm0/device/cancel",
+#            "path": "/dev/tpm0"
+#          },
 #          "id": "tpm0"
 #        }
 #      ]
diff --git a/tpm.c b/tpm.c
index 0ee021a..1b6b550 100644
--- a/tpm.c
+++ b/tpm.c
@@ -249,36 +249,6 @@  static const TPMDriverOps *tpm_driver_find_by_type(enum TpmType type)
     return NULL;
 }
 
-static TPMInfo *qmp_query_tpm_inst(TPMBackend *drv)
-{
-    TPMInfo *res = g_new0(TPMInfo, 1);
-    TPMPassthroughOptions *tpo;
-
-    res->id = g_strdup(drv->id);
-    res->model = drv->fe_model;
-    res->options = g_new0(TpmTypeOptions, 1);
-
-    switch (tpm_backend_get_type(drv)) {
-    case TPM_TYPE_PASSTHROUGH:
-        res->options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
-        tpo = g_new0(TPMPassthroughOptions, 1);
-        res->options->u.passthrough.data = tpo;
-        if (drv->path) {
-            tpo->path = g_strdup(drv->path);
-            tpo->has_path = true;
-        }
-        if (drv->cancel_path) {
-            tpo->cancel_path = g_strdup(drv->cancel_path);
-            tpo->has_cancel_path = true;
-        }
-        break;
-    case TPM_TYPE__MAX:
-        break;
-    }
-
-    return res;
-}
-
 /*
  * Walk the list of active TPM backends and collect information about them
  * following the schema description in qapi-schema.json.
@@ -293,7 +263,7 @@  TPMInfoList *qmp_query_tpm(Error **errp)
             continue;
         }
         info = g_new0(TPMInfoList, 1);
-        info->value = qmp_query_tpm_inst(drv);
+        info->value = tpm_backend_query_tpm(drv);
 
         if (!cur_item) {
             head = cur_item = info;