[libvirt] [PATCH 1/2] xenFormatNet: correct `type=netfront' to 'type=vif' to match libxl

[Jim Fehlig]

On 05/13/2016 06:59 AM, Joao Martins wrote:
>
> On 05/12/2016 09:55 PM, Jim Fehlig wrote:
>> Joao Martins wrote:
>>> On 05/12/2016 12:54 AM, Jim Fehlig wrote:
>>>> On 04/21/2016 05:10 AM, Chunyan Liu wrote:
>>>>> According to current xl.cfg docs and xl codes, it uses type=vif
>>>>> instead of type=netfront.
>>>>>
>>>>> Currently after domxml-to-native, libvirt xml model=netfront will be
>>>>> converted to xl type=netfront. This has no problem before, xen codes
>>>>> for a long time just check type=ioemu, if not, set type to _VIF.
>>>>>
>>>>> Since libxl uses parse_nic_config to avoid duplicate codes, it
>>>>> compares 'type=vif' and 'type=ioemu' for valid parameters, others
>>>>> are considered as invalid, thus we have problem with type=netfront
>>>>> in xl config file.
>>>>>  #xl create sles12gm-hvm.orig
>>>>>  Parsing config from sles12gm-hvm.orig
>>>>>  Invalid parameter `type'.
>>>>>
>>>>> Correct the convertion in libvirt, so that it matchs libxl codes
>>>>> and also xl.cfg.
>>>>>
>>>>> Signed-off-by: Chunyan Liu <cyliu at suse.com>
>>>>> ---
>>>>>  src/xenconfig/xen_common.c | 38 ++++++++++++++++++++++++--------------
>>>>>  src/xenconfig/xen_common.h |  7 ++++---
>>>>>  src/xenconfig/xen_xl.c     |  4 ++--
>>>>>  src/xenconfig/xen_xm.c     |  8 ++++----
>>>>>  4 files changed, 34 insertions(+), 23 deletions(-)
>>>>>
>>>>> diff --git a/src/xenconfig/xen_common.c b/src/xenconfig/xen_common.c
>>>>> index e1d9cf6..f54d6b6 100644
>>>>> --- a/src/xenconfig/xen_common.c
>>>>> +++ b/src/xenconfig/xen_common.c
>>>>> @@ -801,9 +801,8 @@ xenParseCharDev(virConfPtr conf, virDomainDefPtr def)
>>>>>      return -1;
>>>>>  }
>>>>>  
>>>>> -
>>>>>  static int
>>>>> -xenParseVif(virConfPtr conf, virDomainDefPtr def)
>>>>> +xenParseVif(virConfPtr conf, virDomainDefPtr def, const char *vif_typename)
>>>>>  {
>>>>>      char *script = NULL;
>>>>>      virDomainNetDefPtr net = NULL;
>>>>> @@ -942,7 +941,7 @@ xenParseVif(virConfPtr conf, virDomainDefPtr def)
>>>>>                  VIR_STRDUP(net->model, model) < 0)
>>>>>                  goto cleanup;
>>>>>  
>>>>> -            if (!model[0] && type[0] && STREQ(type, "netfront") &&
>>>>> +            if (!model[0] && type[0] && STREQ(type, vif_typename) &&
>>>>>                  VIR_STRDUP(net->model, "netfront") < 0)
>>>>>                  goto cleanup;
>>>>>  
>>>>> @@ -1042,11 +1041,17 @@ xenParseGeneralMeta(virConfPtr conf, virDomainDefPtr def, virCapsPtr caps)
>>>>>  
>>>>>  /*
>>>>>   * A convenience function for parsing all config common to both XM and XL
>>>>> + *
>>>>> + * vif_typename: type name for a paravirtualized network could
>>>>> + * be different for xm and xl. For xm, it uses type=netfront;
>>>>> + * for xl, it uses type=vif. So, for xm, should pass "netfront";
>>>>> + * for xl, should pass "vif".
>>>>>   */
>>>>>  int
>>>>>  xenParseConfigCommon(virConfPtr conf,
>>>>>                       virDomainDefPtr def,
>>>>> -                     virCapsPtr caps)
>>>>> +                     virCapsPtr caps,
>>>>> +                     const char *vif_typename)
>>>> One thing I didn't recall when suggesting this approach is that xenParseVif() is
>>>> called in xenParseConfigCommon(). I was thinking it was called from
>>>> xen_{xl,xm}.c and the extra parameter would only be added to the
>>>> xen{Format,Parse}Vif functions. I don't particularly like seeing the device
>>>> specific parameter added to the common functions, but wont object if others are
>>>> fine with it. Any other opinions on that? Joao?
>>> That's a good point - probably we can avoid it by using
>>> xen{Format,Parse}Vif (with the signature change Chunyan proposes) individually
>>> on xenParseXM and xenParseXL.
>> Nod.
>>
>>> And there wouldn't be any xenParseConfigCommon
>>> with device-specific parameters (as vif being one of the many devices that the
>>> routine is handling). The vif config is the same between xm and xl, with the
>>> small difference wrt to the validation on xen libxl side - so having in
>>> xen_common.c makes sense.
>> Nod again :-).
>>
>>>> And one reason I wont object is that the alternative (calling
>>>> xen{Format,Parse}Vif from xen_{xl,xm}.c) is a rather large change since all the
>>>> tests/{xl,xm}configdata/ files would need to be adjusted.
>>> Hm, perhaps I fail to see what the large change would be. We would keep the same
>>> interface (i.e. model=netfront as valid on libvirt-side and converting to
>>> type="vif" where applicable (libxl)) then the xml and .cfg won't change.
>>> Furthermore, we only use e1000 which is valid for both cases and Chunyan adds
>>> one test case to cover this series. So may be the adjustment you suggest above
>>> wouldn't be as cumbersome as to change all the tests/{xl,xm}configdata files?
>> On the Parse side we would be fine, but on the Format side 'vif =' would now be
>> emitted after xenFormatConfigCommon executed. So the xl.cfg output would change
>> from e.g.
>>
> Ah, totally missed that out: it looks a large change. I think XL vif won't
> diverge from XM anytime soon unless we start adding support for more qemu-ish
> features on xen libxl (e.g. vhostuser, or even block "target" field equivalent).

That's a good point. Instead of creating a bunch of turmoil now over 'netfront'
vs 'vif', we should wait until something more substantial drives the change.

> I am fine with the approach on the patch, but the way you suggested is indeed
> more correct.

Perhaps as a compromise, the new xen{Format,Parse}ConfigCommon parameter could
be of type 'enum xenConfigFlavor' or similar, with flavors XEN_CONFIG_FLAVOR_XL
and XEN_CONFIG_FLAVOR_XM. That would accommodate other trivial differences we
might find in the future.

Regards,
Jim