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

David Riley
2026-05-06T14:31:15Z

Thanks for the patch. This seems to be a nice addition.

I’ve tested the series and found a regression in the VM creation
wizard. When creating a Windows guest with the 'Add additional drive
for VirtIO drivers' checkbox enabled and an ISO Image is added,
the creation fails with:

'Parameter verification failed. (400) ide0:
explicit media=cdrom is required for iso images'

Looking at the request payload, the 'media=cdrom' property is missing
for the VirtIO ISO:

Before: ide0: "sani:iso/virtio-win-0.1.271.iso,media=cdrom"
Now: ide0: "sani:iso/virtio-win-0.1.271.iso"

I also noticed that the wizard now defaults to the IDE bus for disks
instead of SCSI, when the Guest OS Type Microsoft Windows is selected.

On 4/30/26 5:59 PM, Arthur Bied-Charreton wrote:
> 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.
>
> Dependencies:
> pve-manager requires bumped pve-docs
> pve-manager requires bumped qemu-server
>
> Changes since v1:
> - Reorder patches according to dependency directions
>
> qemu-server:
> - Rebase
> - Add preparatory commit renaming $default_filename to
> $cpu_models_filename
> - Squash helpers into commits with their first users
> - Drop unrelated formatting change
> - Move cluster-wide cpu-flags to pve-manager, related changes in
> pve-manager changelog, keep vm-specific cpu-flags endpoint
> - Return all flags from cpu-flags endpoint, not only the ones with at
> least one node supporting them - allow filtering for that in the UI
> - Return only VM-specific cpu-flags by default in node-specific endpoint
> - Add acceleration type filter to cpu-flags endpoint, defaulting to kvm
> - Document why no flags are currently returned for aarch64
> - Only add nested-virt to flags for hosts that support one of svm/vmx
> - Rename extract_flags to query_available_cpu_flags
> - Remove web references from doc comments
> - Refactor query_available_cpu_flags to a more imperative style
> - Move custom CPU models CRUD endpoints to pve-manager, related changes
> in pve-manager changelog
> - Introduce QemuServer::CPUFlags module grouping flags-related helpers
> - Add flag_is_aliased helper to identify flags covered by nested-virt
>
> pve-manager:
> - Rebase
> - Drop unneeded dirty state fix from original series
> - Update unknown flags behavior to
> 1. Show unknown flags at the top of the list in the UI
> 2. Add a description to unknown flags signaling that the flag is not
> recognized in the cluster/for the currently selected acceleration type
> - Rename allowCustom CPU model selector config field to showCustomModels
> - Change "Reported Model" to "Base Model" in the UI
> - Link directly to "CPU Type" section in onlineHelp refs
> - Improve message in remove confirm dialog for custom CPU models
> - Move "Custom CPU Models" further down in Datacenter menu, and group it
> with "{Directory,Resource} Mappings" under "Guest Resources/Hardware"
> - Default VM-specific CPU flags selection to KVM during creation, and
> pre-select/lock it based on the VM's configured acceleration when
> editing
> - Remove hardcoded list of VM-specific flags in frontend
> - Change 'Set' to 'Value' in VMCpuFlagSelector
> - Use "" instead of `` for user-facing strings
> - Add search bar for long lists of CPU flags
> - Return all flags from the backend, not only the ones with at least one
> node supporting them - allow filtering for that in the UI
> - Show svm/vmx in cpu-flags list regardless of overlap with nested-virt
> - Add endpoint for querying CPU flags cluster-wide
> (`/cluster/qemu/cpu-flags`)
> - Document missing supported flags for `aarch64`
> - Add CRUD endpoint for custom CPU models
> (`/cluster/qemu/custom-cpu-models`)
>
> pve-docs:
> - Add qm_cpu_type anchor to CPU Type section in qm.adoc
>
> Changes since v2:
> - Rebase all repos
> - Remove JS component names from commit subjects
>
> pve-manager:
> - Avoid losing flags that were set while "Show only flags supported by
> at least one node" was not checked when checking it again
> - Avoid overwriting the whole extraParams in setArch
>
> Changes since v3:
> - Fix custom CPU model create requests by cleaning empty optional
> values in the input panel value hook and dropping the unsupported
> delete param on create
>
> [0] https://lore.proxmox.com/pve-devel/20211028114150.3245864-1-s.reiter@proxmox.com/
>
>
> pve-docs:
>
> Arthur Bied-Charreton (1):
> qm: add anchor to "CPU Type" section
>
> qm.adoc | 1 +
> 1 file changed, 1 insertion(+)
>
>
> qemu-server:
>
> Arthur Bied-Charreton (7):
> cpu config: rename CPU models config path variable
> cpu flags: move cpu flags-related utilities to their own module
> cpu flags: add helper querying CPU flags with nodes supporting them
> cpu config: add helpers to lock and write config
> cpu: register standard option for CPU format
> cpu config: set 'type' field before writing
> cpu flags: improve flags list returned by endpoint
>
> src/PVE/API2/Qemu/CPUFlags.pm | 27 +++-
> src/PVE/QemuServer.pm | 24 +---
> src/PVE/QemuServer/CPUConfig.pm | 110 +++------------
> src/PVE/QemuServer/CPUFlags.pm | 230 ++++++++++++++++++++++++++++++++
> src/PVE/QemuServer/Makefile | 1 +
> 5 files changed, 280 insertions(+), 112 deletions(-)
> create mode 100644 src/PVE/QemuServer/CPUFlags.pm
>
>
> pve-manager:
>
> Arthur Bied-Charreton (9):
> api: add endpoint querying available CPU flags cluster-wide
> api: add CRUD handlers for custom CPU models
> ui: cpu model selector: allow filtering out custom models
> ui: add basic custom CPU model editor
> ui: cpu flags selector: add CPU flag editor for custom models
> ui: cpu flags selector: fix buffered rendering error
> ui: cpu flags selector: allow filtering out flags supported on 0 nodes
> ui: cpu flags selector: add search bar for large lists of flags
> RFC: ui: group custom CPU with resource mappings
>
> PVE/API2/Cluster.pm | 7 +
> PVE/API2/Cluster/Makefile | 4 +-
> PVE/API2/Cluster/Qemu.pm | 47 ++++
> PVE/API2/Cluster/Qemu/CPUFlags.pm | 68 +++++
> PVE/API2/Cluster/Qemu/CustomCPUModels.pm | 211 ++++++++++++++++
> PVE/API2/Cluster/Qemu/Makefile | 18 ++
> www/css/ext6-pve.css | 4 +
> www/manager6/Makefile | 3 +
> www/manager6/dc/CPUTypeEdit.js | 105 ++++++++
> www/manager6/dc/CPUTypeView.js | 149 +++++++++++
> www/manager6/dc/Config.js | 27 ++
> www/manager6/form/CPUModelSelector.js | 11 +
> www/manager6/form/PhysBitsSelector.js | 153 +++++++++++
> www/manager6/form/VMCPUFlagSelector.js | 308 ++++++++++++++++++++---
> www/manager6/qemu/ProcessorEdit.js | 6 +
> 15 files changed, 1090 insertions(+), 31 deletions(-)
> create mode 100644 PVE/API2/Cluster/Qemu.pm
> create mode 100644 PVE/API2/Cluster/Qemu/CPUFlags.pm
> create mode 100644 PVE/API2/Cluster/Qemu/CustomCPUModels.pm
> create mode 100644 PVE/API2/Cluster/Qemu/Makefile
> create mode 100644 www/manager6/dc/CPUTypeEdit.js
> create mode 100644 www/manager6/dc/CPUTypeView.js
> create mode 100644 www/manager6/form/PhysBitsSelector.js
>
>
> Summary over all repositories:
> 21 files changed, 1371 insertions(+), 143 deletions(-)
>