On Thu, Feb 13, 2025 at 01:19:53PM -0500, Laine Stump wrote:
> 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
The presence of this element is not validated anywhere though, so if
you leave it out the network interface will just silently be
non-functional. I don't think that makes for a good user experience.
How does passt know where the backing file is located in the first
place? It's not passed on its command line, and I didn't spot any
logic to hand the information over. This part clearly works, I just
don't understand how :)
> +++ b/src/conf/domain_validate.c
> @@ -2163,7 +2163,8 @@ virDomainNetDefValidate(const virDomainNetDef *net)
> return -1;
> }
>
> - if (net->type != VIR_DOMAIN_NET_TYPE_USER) {
> + if (net->type != VIR_DOMAIN_NET_TYPE_USER &&
> + net->type != VIR_DOMAIN_NET_TYPE_VHOSTUSER) {
> if (net->backend.type == VIR_DOMAIN_NET_BACKEND_PASST) {
> virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> _("The 'passt' backend can only be used with interface type='user'"));
This error message needs to be updated.
> +++ b/tests/qemuxmlconfdata/net-vhostuser-passt.x86_64-latest.args
> @@ -0,0 +1,42 @@
> +LC_ALL=C \
> +PATH=/bin \
> +HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1 \
> +USER=test \
> +LOGNAME=test \
> +XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.local/share \
> +XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.cache \
> +XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
> +/usr/bin/qemu-system-x86_64 \
> +-name guest=QEMUGuest1,debug-threads=on \
> +-S \
> +-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/master-key.aes"}' \
> +-machine pc,usb=off,dump-guest-core=off,memory-backend=pc.ram,acpi=off \
> +-accel tcg \
> +-cpu qemu64 \
> +-m size=219136k \
> +-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":224395264}' \
> +-overcommit mem-lock=off \
> +-smp 1,sockets=1,cores=1,threads=1 \
> +-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
> +-display none \
> +-no-user-config \
> +-nodefaults \
> +-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
> +-mon chardev=charmonitor,id=monitor,mode=control \
> +-rtc base=utc \
> +-no-shutdown \
> +-boot strict=on \
> +-blockdev '{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest1","node-name":"libvirt-1-storage","read-only":false}' \
> +-device '{"driver":"ide-hd","bus":"ide.0","unit":0,"drive":"libvirt-1-storage","id":"ide0-0-0","bootindex":1}' \
> +-chardev socket,id=charnet0,path=/var/run/libvirt/qemu/passt/-1-QEMUGuest1-net0.socket \
> +-netdev '{"type":"vhost-user","chardev":"charnet0","id":"hostnet0"}' \
> +-device '{"driver":"virtio-net-pci","netdev":"hostnet0","id":"net0","mac":"00:11:22:33:44:55","bus":"pci.0","addr":"0x2"}' \
> +-chardev socket,id=charnet1,path=/var/run/libvirt/qemu/passt/-1-QEMUGuest1-net1.socket \
> +-netdev '{"type":"vhost-user","chardev":"charnet1","id":"hostnet1"}' \
> +-device '{"driver":"virtio-net-pci","netdev":"hostnet1","id":"net1","mac":"00:11:22:33:44:11","bus":"pci.0","addr":"0x3"}' \
> +-chardev socket,id=charnet2,path=/var/run/libvirt/qemu/passt/-1-QEMUGuest1-net2.socket \
> +-netdev '{"type":"vhost-user","chardev":"charnet2","id":"hostnet2"}' \
> +-device '{"driver":"virtio-net-pci","netdev":"hostnet2","id":"net2","mac":"00:11:22:33:44:11","bus":"pci.0","addr":"0x4"}' \
> +-audiodev '{"id":"audio1","driver":"none"}' \
> +-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
> +-msg timestamp=on
It's a real shame that we don't have a way to include the command
line for external programs (swtpm, passt) in the corresponding test
case...
--
Andrea Bolognani / Red Hat / Virtualization
