Re: [PATCH docs/manager/qemu-server v4 00/17] Add API and UI for custom CPU models

[Arthur Bied-Charreton <a.bied-charreton@proxmox.com>]

On Mon, May 11, 2026 at 04:08:32PM +0200, Fiona Ebner wrote:
> Am 30.04.26 um 5:59 PM schrieb Arthur Bied-Charreton:
> > This picks up and extends an old series [0] by Stefan Reiter.
> > 
> > This series adds a full CRUD API and a UI editor for custom CPU models
> > which allows users to manage them in the Datacenter interface rather
> > than editing /etc/pve/virtual-guest/cpu-models.conf manually.
> > 
> > It also improves on the existing VM CPU flags selector by providing a
> > list of nodes supporting each flag to help gauge cluster compatibility.
> > 
> > qemu-server gets a new CPUFlags module grouping cpu-flags-related
> > helpers. A new helper (query_available_cpu_flags) is introduced, which
> > derives the set of flags accepted by QEMU as -cpu arguments and
> > annotates each with the cluster nodes that report supporting it. The
> > existing node-level endpoint is extended with an accel parameter to
> > filter flags by acceleration type. Its default behavior is preserved
> > modulo the added 'supported-on' field per flag in the return value.
> > 
> > pve-manager gets two new cluster-level endpoints:
> > 
> > 1. /cluster/qemu/cpu-flags queries flags available across the cluster
> >    and reports which node supports each of them. It differs from the
> >    node-level endpoint in qemu-server in that it returns *all* flags,
> >    as opposed to the VM-specific ones.
> > 
> > 2. /cluster/qemu/custom-cpu-models provides full CRUD for custom CPU
> >    model definitions.
> > 
> > The UI gets a "Custom CPU models" view in the Datacenter panel (at the
> > bottom under "Guest Resources/Hardware") with an editor for model
> > properties. The flags can now be filtered by acceleration type when
> > creating a new VM or custom CPU model, and it is pre-selected based on
> > the VM's KVM config key when editing a pre-existing VM's CPU. The CPU
> > flags selector is also improved with the option to filter out flags
> > that are not supported anywhere in the cluster.
> 
> Very good work! I know I made a lot of comments and suggestions, but
> there are relatively few that I would consider blockers. The feature is
> shaping up nicely and most changes should be rather straight-forward.
> Except maybe the 'kvm' qm.conf checkbox might be a bit more work. If
> it's too much, we can also consider doing that later on.
> 
Thanks a lot for the thorough testing and review!

I already adressed your qemu-server and pve-manager backend comments,
will get to the UI parts now and should have a v5 ready in the next few
days!
> > Dependencies:
> >  pve-manager requires bumped pve-docs
> 
> Just for completeness/as a reminder: it build-depends on
> pve-doc-generator and depends on pve-docs.
> 
> >  pve-manager requires bumped qemu-server
> 
> build+normal depends here.
Thanks for the feedback, I overlooked that distinction