Enable the passing of a file descriptor via fd=<..> to access the host's
TPM device using the TPM passthrough driver.
Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com>
---
hmp.c | 7 +++++-
hw/tpm_passthrough.c | 53 ++++++++++++++++++++++++++++++++++++++-----------
qapi-schema.json | 4 ++-
qemu-config.c | 5 ++++
qemu-options.hx | 11 +++++++--
tpm.c | 4 +++
tpm.h | 1 +
7 files changed, 68 insertions(+), 17 deletions(-)
diff --git a/hmp.c b/hmp.c
index 9aedaff..3176c74 100644
--- a/hmp.c
+++ b/hmp.c
@@ -567,10 +567,15 @@ void hmp_info_tpm(Monitor *mon)
TPMInfo *ti = info->value;
monitor_printf(mon, " tpm%d: model=%s\n",
c, ti->model);
- monitor_printf(mon, " \\ %s: type=%s%s%s\n",
+ monitor_printf(mon, " \\ %s: type=%s%s%s",
ti->id, ti->type,
ti->has_path ? ",path=" : "",
ti->has_path ? ti->path : "");
+ if (ti->has_fd) {
+ monitor_printf(mon, ",fd=%" PRId64,
+ ti->fd);
+ }
+ monitor_printf(mon, "\n");
c++;
}
qapi_free_TPMInfoList(info_list);
diff --git a/hw/tpm_passthrough.c b/hw/tpm_passthrough.c
index 8914705..44cf272 100644
--- a/hw/tpm_passthrough.c
+++ b/hw/tpm_passthrough.c
@@ -305,26 +305,54 @@ static int tpm_passthrough_test_tpmdev(int fd)
static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
{
const char *value;
+ struct stat statbuf;
- value = qemu_opt_get(opts, "path");
- if (!value) {
- value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
- }
+ value = qemu_opt_get(opts, "fd");
+ if (value) {
+ if (qemu_opt_get(opts, "path")) {
+ error_report("fd= is invalid with path=");
+ goto err_exit;
+ }
+
+ tb->s.tpm_pt->tpm_fd = qemu_parse_fd(value);
+ if (tb->s.tpm_pt->tpm_fd < 0) {
+ error_report("Illegal file descriptor for TPM device.\n");
+ goto err_exit;
+ }
+
+ tb->tpm_fd = &tb->s.tpm_pt->tpm_fd;
+ } else {
+ value = qemu_opt_get(opts, "path");
+ if (!value) {
+ value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
+ }
- tb->s.tpm_pt->tpm_dev = g_strdup(value);
+ tb->s.tpm_pt->tpm_dev = g_strdup(value);
- tb->path = g_strdup(tb->s.tpm_pt->tpm_dev);
+ tb->path = g_strdup(value);
+
+ tb->s.tpm_pt->tpm_fd = open(tb->s.tpm_pt->tpm_dev, O_RDWR);
+ if (tb->s.tpm_pt->tpm_fd < 0) {
+ error_report("Cannot access TPM device using '%s'.\n",
+ tb->s.tpm_pt->tpm_dev);
+ goto err_free_parameters;
+ }
+ }
+
+ if (fstat(tb->s.tpm_pt->tpm_fd, &statbuf) != 0) {
+ error_report("Cannot determine file descriptor type for TPM "
+ "device: %s", strerror(errno));
+ goto err_close_tpmdev;
+ }
- tb->s.tpm_pt->tpm_fd = open(tb->s.tpm_pt->tpm_dev, O_RDWR);
- if (tb->s.tpm_pt->tpm_fd < 0) {
- error_report("Cannot access TPM device using '%s'.\n",
- tb->s.tpm_pt->tpm_dev);
+ /* only allow character devices for now */
+ if (!S_ISCHR(statbuf.st_mode)) {
+ error_report("TPM file descriptor is not a character device");
goto err_free_parameters;
}
if (tpm_passthrough_test_tpmdev(tb->s.tpm_pt->tpm_fd)) {
- error_report("'%s' is not a TPM device.\n",
- tb->s.tpm_pt->tpm_dev);
+ error_report("Device is not a TPM.\n");
goto err_close_tpmdev;
}
@@ -341,6 +369,7 @@ static int tpm_passthrough_handle_device_opts(QemuOpts
*opts, TPMBackend *tb)
g_free(tb->s.tpm_pt->tpm_dev);
tb->s.tpm_pt->tpm_dev = NULL;
+ err_exit:
return 1;
}
diff --git a/qapi-schema.json b/qapi-schema.json
index 8799322..9d6f664 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1769,10 +1769,12 @@
#
# @path: #optional Path to the TPM backend device
#
+# @fd: #optional File descriptor for the TPM backend device
# Since: 1.1
##
{ 'type': 'TPMInfo',
- 'data': {'model': 'str', 'id': 'str', 'type': 'str', '*path': 'str' } }
+ 'data': {'model': 'str', 'id': 'str', 'type': 'str', '*path': 'str',
+ '*fd' : 'int' } }
##
# @query-tpm
diff --git a/qemu-config.c b/qemu-config.c
index edc8d5d..a5e2677 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -628,6 +628,11 @@ static QemuOptsList qemu_tpmdev_opts = {
.type = QEMU_OPT_STRING,
.help = "Persistent storage for TPM state",
},
+ {
+ .name = "fd",
+ .type = QEMU_OPT_STRING,
+ .help = "Filedescriptor for accessing the TPM",
+ },
{ /* end of list */ }
},
};
diff --git a/qemu-options.hx b/qemu-options.hx
index 0b9fa0b..cb9892b 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2017,8 +2017,9 @@ DEFHEADING()
DEFHEADING(TPM device options:)
DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
- "-tpmdev passthrough,id=id[,path=path]\n"
- " use path to provide path to a character device; default is
/dev/tpm0\n",
+ "-tpmdev passthrough,id=id[,path=path][,fd=h]\n"
+ " use path to provide path to a character device; default is
/dev/tpm0\n"
+ " use fd to provide a file descriptor to a character
device\n",
QEMU_ARCH_ALL)
STEXI
@@ -2040,7 +2041,7 @@ Use ? to print all available TPM backend types.
qemu -tpmdev ?
@end example
-@item -tpmdev passthrough, id=@var{id}, path=@var{path}
+@item -tpmdev passthrough, id=@var{id}, path=@var{path}, fd=@var{h}
(Linux-host only) Enable access to the host's TPM using the passthrough
driver.
@@ -2049,6 +2050,10 @@ driver.
a Linux host this would be @code{/dev/tpm0}.
@option{path} is optional and by default @code{/dev/tpm0} is used.
+@option{fd} specifies the file descriptor of the host's TPM device.
+@option{fd} and @option{path} are mutually exclusive.
+@option{fd} is optional.
+
Some notes about using the host's TPM with the passthrough driver:
The TPM device accessed by the passthrough driver must not be
diff --git a/tpm.c b/tpm.c
index 79530c9..64d3140 100644
--- a/tpm.c
+++ b/tpm.c
@@ -201,6 +201,10 @@ static TPMInfo *qmp_query_tpm_inst(TPMBackend *drv)
res->path = g_strdup(drv->path);
res->has_path = true;
}
+ if (drv->tpm_fd != NULL && *drv->tpm_fd >= 0) {
+ res->fd = *drv->tpm_fd;
+ res->has_fd = true;
+ }
res->type = g_strdup(drv->ops->id);
return res;
diff --git a/tpm.h b/tpm.h
index bacaff3..00f7600 100644
--- a/tpm.h
+++ b/tpm.h
@@ -24,6 +24,7 @@ typedef struct TPMBackend {
char *id;
const char *fe_model;
char *path;
+ int *tpm_fd;
const TPMDriverOps *ops;
union {
