> -----Original Message----- > From: Michal Privoznik <mprivozn@xxxxxxxxxx> > Sent: Wednesday, March 31, 2021 5:49 PM > To: Moshe Levi <moshele@xxxxxxxxxx>; Daniel P. Berrangé > <berrange@xxxxxxxxxx> > Cc: Waleed Musa <waleedm@xxxxxxxxxx>; libvir-list@xxxxxxxxxx; Adrian > Chiris <adrianc@xxxxxxxxxx> > Subject: Re: [Libvirt] Attach qemu commands to an running xml domain > > External email: Use caution opening links or attachments > > > On 3/31/21 4:01 PM, Moshe Levi wrote: > > > > > >> -----Original Message----- > >> From: Daniel P. Berrangé <berrange@xxxxxxxxxx> > >> Sent: Wednesday, March 31, 2021 3:23 PM > >> To: Michal Privoznik <mprivozn@xxxxxxxxxx> > >> Cc: Waleed Musa <waleedm@xxxxxxxxxx>; libvir-list@xxxxxxxxxx; > Moshe > >> Levi <moshele@xxxxxxxxxx>; Adrian Chiris <adrianc@xxxxxxxxxx> > >> Subject: Re: [Libvirt] Attach qemu commands to an running xml domain > > >> > >> I've always thought if we wanted to support use of resources from > >> other namespaces, then that would involve use of a namespace="$PID" > >> attribute to identify the namespace. > >> > >> <source type='unix' namespace="523532" > >> path='/var/lib/vhost_sockets/sock7f9a971a-cf3' mode='server'/> > >> > >> IOW, libvirt could enter the namespace, and then talk to the OVS > >> db.sock at its normal location. > >> > >> It would be bit strange having namespace refer to a different NS for > >> the OVS, but using the path=/var/lib/..... from the current > >> namespace, but as long as we define the semantics clearly its not the end > of the world. > > Just to better explain the use case here so we have user space vdpa > solution which requires the following qemu flags to work: > > 1. page-per-vq=on > > 2. host_mtu > > > > I understand the adding page-per-vq is feature requested to I am putting > that aside. > > Correct. > > > > > Regarding the host_mtu we want to use the libvirt xml to set mtu like in [1] > so we can set mtu in hot plug. > > Basically we just want that the libvirt xml mtu will just set the qemu > host_mtu. > > Th problem is the this using mtu in libvirt xml will query ovs (it assume that > if ovs installed on the host it needs to set it mtu). > > In our case we have OVS running on the host for switching and OVS in > > container to connect the VF netdevice with vhostuser to qemu to just > > forward traffic from VF to virtio using vdpa) 1. One option is to > > allow to disable the set of mtu in ovs so it will just add the qemu > > host_mtu flag (we can set the mtu on ovs by openstack) > > Don't you need to set the MTU also on the TAP device? Or will it be inherited > from the OVS bridge? In our case it MTU of the VF nerdevice and we set it by OVS. > > > 2. Second option is to change how we query ovs to add --db flag so we > > can change the query to be on the ovs in the container > > > > Both option are fine with me. > > > Michal
