This can/should also be done for a traditional vhost-user interface
(ie not backend type='passt') but that will be a separate change.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
<interface type='vhostuser'><backend type='passt'/> needs to run the
passt command just as is done for interface type='user', but then add
vhostuser bits to the qemu commandline/monitor command.
There are some changes to the parsing/validation along with changes to
the vhostuser codepath do do the extra stuff for passt. I tried
keeping them separated into different patches, but then the unit test
failed in a strange way deep down in the bowels of the commandline
generation, so this patch both 1) makes the final changes to
parsing/formatting and 2) adds passt stuff at appropriate places for
vhostuser (as well as making a couple of things *not* happen when the
passt backend is chosen). The result is that you can now have:
<interface type='vhostuser'>
<backend type='passt'/>
...
</interface>
Then as long as you also have the following as a subelement of
<domain>:
<memoryBacking>
<access mode='shared'/>
</memoryBacking>
your passt interfaces will benefit from the greatly improved
efficiency of a vhost-user data path, and all without requiring
special privileges or capabilities *anywhere* (i.e. it works for
unprivileged libvirt (qemu:///session) as well as privileged libvirt).
Resolves: https://issues.redhat.com/browse/RHEL-69455
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
