Re: [PATCH qemu-server] cpu config: expose CPU 'level' property required for certain host/guest configurations

[David Riley <d.riley@proxmox.com>]

Thanks for sending in this patch.

I was able to apply the series without issues. I tested the new
`level=30` option by adding it to my <vmid>.conf for a Windows Server
Guest.

Checked the output from `qm showcmd <vmid>` and was able to verify
that the option was set correctly and the default Hyper-V
Enlightenments were also still present as expected.

Tested-by: David Riley <d.riley@proxmox.com>
Reviewed-by: David Riley <d.riley@proxmox.com>

On 5/18/26 2:40 PM, Fiona Ebner wrote:
> As reported in the community forum in 2024 [0] already, with somewhat
> recent Intel CPUs, Windows guests with Hyper-V enabled will fail to
> boot with certain CPU types like 'host' or 'max'. A workaround is
> using 'level=30' in the '-cpu' QEMU commandline. The 'level' property
> is currently not exposed, so users were forced to use custom 'args',
> which means they lose other CPU configuration made by Proxmox VE.
> Expose the 'level' setting, so it can be done without custom args.
>
> While the problem is not new, it will become more common, since
> virtualization-based security is being adapted more broadly.
>
> [0]: https://forum.proxmox.com/threads/131950/post-642093
>
> Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
> ---
>   src/PVE/QemuServer/CPUConfig.pm     | 18 ++++++++++++++++++
>   src/test/cfg2cmd/cpu-level.conf     |  6 ++++++
>   src/test/cfg2cmd/cpu-level.conf.cmd | 26 ++++++++++++++++++++++++++
>   3 files changed, 50 insertions(+)
>   create mode 100644 src/test/cfg2cmd/cpu-level.conf
>   create mode 100644 src/test/cfg2cmd/cpu-level.conf.cmd
>
>
> [snip]