[openstack-dev] [nova][neutron] PCI pass-through SRIOV on Jan. 29th

Robert Kukura rkukura at redhat.com
Wed Jan 29 21:57:54 UTC 2014

On 01/29/2014 09:46 AM, Robert Li (baoli) wrote:

> Another issue that came up during the meeting is about whether or not
> vnic-type should be part of the top level binding or part of
> binding:profile. In other words, should it be defined as
> binding:vnic-type or binding:profile:vnic-type.   

I'd phrase that choice as "top-level attribute" vs. "key/value pair
within the binding:profile attribute". If we go with a new top-level
attribute, it may or may not end up being part of the portbindings

Although I've been advocating making vnic_type a key within
binding:profile (minimizing effort), it just occurred to me that
policy.json contains:

    "create_port:binding:profile": "rule:admin_only",
    "get_port:binding:profile": "rule:admin_only",
    "update_port:binding:profile": "rule:admin_only",

This means that only administrative users (including nova's integration
with neutron) can read or write the binding:profile attribute by default.

But my (limited) understanding of the PCI-passthru use cases is that
normal users need to specify vnic_type because this is what determines
the NIC type that their VMs see for the port. If that is correct, then I
think this tips the balance towards vnic_type being a new top-level
attribute to which normal users have read/write access. Comments?

If I'm mistaken on the above, please ignore the rest of this email...

If vnic_type is a new top-level attribute accessible to normal users,
then I'm not sure it belongs in the portbindings extension. First,
everything else in that extension is only visible to administrative
users. Second, from the normal user's point of view, vnic_type has to do
with the type of NIC they want within their VM, not with how the port is
bound outside their VM to some underlying network segment and networking
mechanism they aren't even aware of. So we need a new extension for
vnic_type, which has the advantage of not requiring any change to
existing plugins that don't support that extension.

If vnic_type is a new top-level attribute in a new API extension, it
deserves its own neutron BP covering defining the extension and
implementing it in ML2. This is probably an update of Irena's
Implementations for other plugins could follow via separate BPs as they
choose to implement the extension.

If anything else we've been planning to put in binding:profile needs
normal user access, it could be defined in this new extension instead.
For now, I'm assuming other input data for PCI-passthru (such as the
slot info from nova) is only accessible to administrators and will go in
binding:profile. I'll submit a separate BP for generically implementing
the binding:profile attribute in ML2, as we've discussed.

This leaves us with potentially 3 separate generic neutron/Ml2 BPs
providing the infrastructure for PCI-passthru:

1) Irena's
2) My BP to implement binding:profile in ML2
3) Definition/implementation of binding:vif_details based on Nachi's
binding:vif_security patch, for which I could submit a BP.


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