Re: [libvirt] [PATCH V1 1/6] Add QMP probing for TPM

On 03/14/2013 10:20 AM, Daniel P. Berrange wrote: >On Wed, Mar 13, 2013 at 12:03:49PM -0400, Stefan Berger wrote: >>Probe for QEMU's QMP TPM support by querying the lists of >>supported TPM models (query-tpm-models) and backend types >>(query-tpm-types). >> >>The setting of the capability flags following the strings >>returned from the commands above is only provided in the >>patch where domain_conf.c gets TPM support due to dependencies >>on functions only introduced there. >> >>Signed-off-by: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; >> >>--- >> src/libvirt_private.syms | 1 >> src/qemu/qemu_capabilities.c | 61 ++++++++++++++++++++++++++++ >> src/qemu/qemu_capabilities.h | 3 + >> src/qemu/qemu_monitor.c | 44 ++++++++++++++++++++ >> src/qemu/qemu_monitor.h | 6 ++ >> src/qemu/qemu_monitor_json.c | 91 +++++++++++++++++++++++++++++++++++++++++++ >> src/qemu/qemu_monitor_json.h | 8 +++ >> src/util/virutil.c | 14 ++++++ >> src/util/virutil.h | 3 + >> 9 files changed, 231 insertions(+) >> >>Index: libvirt/src/qemu/qemu_capabilities.c >>=================================================================== >>--- libvirt.orig/src/qemu/qemu_capabilities.c >>+++ libvirt/src/qemu/qemu_capabilities.c >>@@ -210,6 +210,8 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAS >> "rng-random", /* 130 */ >> "rng-egd", >>+ "tpm-passthrough", >>+ "tpm-tis", >> ); >> struct _virQEMUCaps { >>Index: libvirt/src/qemu/qemu_capabilities.h >>=================================================================== >>--- libvirt.orig/src/qemu/qemu_capabilities.h >>+++ libvirt/src/qemu/qemu_capabilities.h >>@@ -171,6 +171,8 @@ enum virQEMUCapsFlags { >> QEMU_CAPS_OBJECT_RNG_RANDOM = 130, /* the rng-random backend for >> virtio rng */ >> QEMU_CAPS_OBJECT_RNG_EGD = 131, /* EGD protocol daemon for rng */ >>+ QEMU_CAPS_DEVICE_TPM_PASSTHROUGH = 132, /* -tpmdev passthrough */ >>+ QEMU_CAPS_DEVICE_TPM_TIS = 133, /* -device tpm_tis */ >I'm wondering whether we really need to spend 2 capability bits on >this. Is it possible to build QEMU such that we have one, but not >the other ? If not then one capability would suffice I had it with a single capability bit QEMU_CAPS_DEVICE_TPM *and* was reading the strings about the supported models and backend types from QEMU via QMP and held them in qemuCaps. When building the command line I then compared the intended model and backend type to be used against the list held in qemuCaps. That went fine until I wrote the test. There we end up using a pseudo executable (/usr/bin/qemu or so) as well and the test failed because it wasn't probed for the models and types. So I ended up changing the code so that I can set those bits inside the tests rather than having to set the needed strings in the array. Presumably query-tpm-models and query-tpm-lists allows us to report an error from libvirt about non-availability of a model/backend type rather than having QEMU report an error which we reflect to the user. + +static int +qemuMonitorJSONGetStringArray(qemuMonitorPtr mon, const char *qmpCmd, + char ***array) +{ + int ret; + virJSONValuePtr cmd; + virJSONValuePtr reply = NULL; + virJSONValuePtr data; + char **list = NULL; + int n = 0; + size_t i; + + *array = NULL; + + if (!(cmd = qemuMonitorJSONMakeCommand(qmpCmd, NULL))) + return -1; + + ret = qemuMonitorJSONCommand(mon, cmd, &reply); + + if (ret == 0) + ret = qemuMonitorJSONCheckError(cmd, reply); + + if (ret < 0) + goto cleanup; + + ret = -1; + + if (!(data = virJSONValueObjectGet(reply, "return"))) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("%s reply was missing return data"), + qmpCmd); + goto cleanup; + } >I think everything above this point should be in the main monitor APIs, >and this method concern itself solely with converting the virJSONValuePtr >into a string array, not actually executing command. This makes the code >more portable for use in commands which need control over the command >execution to handle errors / pass arguments. Hm, this surprises me since this would put JSON specific code into the monitor APIs (qemu_monitor.c) while qemu_monitor.c typically only serves as a dispatcher for either text monitor or json monitor.