Wrong number of cpu cores inside VM

[N3xus8]

With Proxmox(8.4.14) I have a VM with Rocky Linux 9 installed:
I've specified Processors 4(1 socket, 4 cores) [x86-64-v3] [numa=1]
BIOS: OVMF(UEFI)
Machine = q35 viommu=intel(with/without)

When I check inside the VM I only see 1 core:
I run the command lscpu and nproc

Why am I only seeing 1 core when I have specified 4 cores?

In a different VM setup again with Rocky Linux 9 but instead with Machine = default(i440 fx), I can see 4 cores inside the VM.

Tested a bunch of experiments:
I've tried numa=0
I've tried Processor to:
- host: doesn't work and super slow
- x86-64-v2-AES: doesn't work

 

[SteveITS]

If you changed that (hardware settings) you need to power off the VM for them to apply.

 

[leesteken]

Did you enable Hotplug CPU in VM Options? Does the operating system inside support CPU hotplug? Did you prepare the operating system inside the VM for CPU hotplug? Maybe just disable CPU hotplug in VM Options.
If host is much slower then you probably have Windows 11 with VBS and there a some threads about fixing that on this forum. I don't know the details as I don't run Windows.

 

[N3xus8]

Did you enable Hotplug CPU in VM Options? Does the operating system inside support CPU hotplug? Did you prepare the operating system inside the VM for CPU hotplug? Maybe just disable CPU hotplug in VM Options.
If host is much slower then you probably have Windows 11 with VBS and there a some threads about fixing that on this forum. I don't know the details as I don't run Windows.

Thank you for your answer:
I've enabled/disabled Hotplug on the host
When cpu hotplug is enabled in VM options, I've checked inside the VM CONFIG_HOTPLUG_CPU=y
But so far I'm still unsuccessful.
Note: that ACPI is off otherwise if set to on, the VM just freezes during boot.

 

[N3xus8]

If you changed that (hardware settings) you need to power off the VM for them to apply.

Thanks. I did