[libvirt] [REPOSTv2 PATCH v3 4/6] qemu: Add VM Generation ID to qemu command line

[Michal Privoznik]

On 05/25/2018 12:58 PM, John Ferlan wrote:
> 
> 
> On 05/25/2018 04:24 AM, Michal Privoznik wrote:
>> On 05/17/2018 02:42 PM, John Ferlan wrote:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1149445
>>>
>>> If the domain requests usage of the genid functionality,
>>> then add the QEMU '-device vmgenid' to the command line
>>> providing either the supplied or generated GUID value.
>>>
>>> Add tests for both a generated and supplied GUID value.
>>>
>>> Signed-off-by: John Ferlan <jferlan at redhat.com>
>>> ---
>>>  src/qemu/qemu_command.c                            | 24 +++++++++++++++++
>>>  .../qemuxml2argvdata/genid-auto.x86_64-latest.args | 30 ++++++++++++++++++++++
>>>  tests/qemuxml2argvdata/genid.x86_64-latest.args    | 30 ++++++++++++++++++++++
>>>  tests/qemuxml2argvtest.c                           |  4 +++
>>>  4 files changed, 88 insertions(+)
>>>  create mode 100644 tests/qemuxml2argvdata/genid-auto.x86_64-latest.args
>>>  create mode 100644 tests/qemuxml2argvdata/genid.x86_64-latest.args
>>>
>>> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>>> index c4237339bf..78bd685008 100644
>>> --- a/src/qemu/qemu_command.c
>>> +++ b/src/qemu/qemu_command.c
>>> @@ -6002,6 +6002,27 @@ qemuBuildSmbiosCommandLine(virCommandPtr cmd,
>>>  }
>>>  
>>>  
>>> +static int
>>> +qemuBuildVMGenIDCommandLine(virCommandPtr cmd,
>>> +                            const virDomainDef *def)
>>> +{
>>> +    virBuffer opts = VIR_BUFFER_INITIALIZER;
>>> +    char guid[VIR_UUID_STRING_BUFLEN];
>>> +
>>> +    if (!def->genidRequested)
>>> +        return 0;
>>> +
>>> +    virUUIDFormat(def->genid, guid);
>>> +    virBufferAsprintf(&opts, "vmgenid,guid=%s,id=vmgenid0", guid);
>>> +
>>> +    virCommandAddArg(cmd, "-device");
>>> +    virCommandAddArgBuffer(cmd, &opts);
>>> +
>>> +    virBufferFreeAndReset(&opts);
>>> +    return 0;
>>
>> As mentioned in previous patch this function must check for
>> DEVICE_VMGENID capability. Otherwise we might put -device vmgenid on
>> command line for qemu that doesn't support it.
>>
> 
> Which path would do that?  I believe I'm making "interesting" use of the
> DO_TEST_CAPS_LATEST actually.
> 
> There are two ways to call qemuBuildCommandLine - one via the PretendCmd
> logic and one via the Launch logic.
> 
> In the Launch logic prior to calling qemuBuildCommandLine, the
> capability is checked *and* the "need" for generating a new GUID is
> determined. It was a "design decision" to not check/change it earlier.
> Is there somewhere else you believe that code should go? IDC, I can move
> it, but understand the risk of doing so.
> 
> Now that we have DO_TEST_CAPS_LATEST there's no need to pass an explicit
> flag for the PretendCmd line logic, so we get it for free for the
> test/fake command line.

Well, qemuConnectDomainXMLToNative() for instance. So I suggest leaving
the capability check in qemuProcessGenID() and having it repeated here.

Michal