Manual: cpu-models.conf

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cpu-models.conf - Custom CPU model configuration file




The /etc/pve/virtual-guest/cpu-models.conf file stores custom CPU models, which can be used by VMs to get access to advanced CPU features (for example custom CPU flags).

File Format

CPU models each have their own section in the file, beginning with the header:

cpu-model: <name>

Note that <name> does not include the custom- prefix, which is required in VM configs to denote custom CPU models.

For example, if the <name> is foobar, the CPU for a VM would need to be configured as custom-foobar.

Each section can specify several options. They are indented by either one TAB character or multiple spaces. Every option and its value is separated by one space, for example:

reported-model qemu64

See below for all available options.

Blank lines and those starting with a # are ignored.


flags: <+FLAG[;-FLAG...]>

List of additional CPU flags separated by ;. Use +FLAG to enable, -FLAG to disable a flag. Custom CPU models can specify any flag supported by QEMU/KVM, VM-specific flags must be from the following set for security reasons: pcid, spec-ctrl, ibpb, ssbd, virt-ssbd, amd-ssbd, amd-no-ssb, pdpe1gb, md-clear, hv-tlbflush, hv-evmcs, aes

hidden: <boolean> (default = 0)

Do not identify as a KVM virtual machine.

hv-vendor-id: <vendor-id>

The Hyper-V vendor ID. Some drivers or programs inside Windows guests need a specific ID.

phys-bits: <8-64|host>

The physical memory address bits that are reported to the guest OS. Should be smaller or equal to the host’s. Set to host to use value from host CPU, but note that doing so will break live migration to CPUs with other values.

reported-model: <486 | Broadwell | Broadwell-IBRS | Broadwell-noTSX | Broadwell-noTSX-IBRS | Cascadelake-Server | Cascadelake-Server-noTSX | Cascadelake-Server-v2 | Cascadelake-Server-v4 | Cascadelake-Server-v5 | Conroe | Cooperlake | Cooperlake-v2 | EPYC | EPYC-Genoa | EPYC-IBPB | EPYC-Milan | EPYC-Milan-v2 | EPYC-Rome | EPYC-Rome-v2 | EPYC-Rome-v3 | EPYC-Rome-v4 | EPYC-v3 | EPYC-v4 | GraniteRapids | Haswell | Haswell-IBRS | Haswell-noTSX | Haswell-noTSX-IBRS | Icelake-Client | Icelake-Client-noTSX | Icelake-Server | Icelake-Server-noTSX | Icelake-Server-v3 | Icelake-Server-v4 | Icelake-Server-v5 | Icelake-Server-v6 | IvyBridge | IvyBridge-IBRS | KnightsMill | Nehalem | Nehalem-IBRS | Opteron_G1 | Opteron_G2 | Opteron_G3 | Opteron_G4 | Opteron_G5 | Penryn | SandyBridge | SandyBridge-IBRS | SapphireRapids | SapphireRapids-v2 | Skylake-Client | Skylake-Client-IBRS | Skylake-Client-noTSX-IBRS | Skylake-Client-v4 | Skylake-Server | Skylake-Server-IBRS | Skylake-Server-noTSX-IBRS | Skylake-Server-v4 | Skylake-Server-v5 | Westmere | Westmere-IBRS | athlon | core2duo | coreduo | host | kvm32 | kvm64 | max | pentium | pentium2 | pentium3 | phenom | qemu32 | qemu64> (default = kvm64)

CPU model and vendor to report to the guest. Must be a QEMU/KVM supported model. Only valid for custom CPU model definitions, default models will always report themselves to the guest OS.

Example File

cpu-model: avx
    flags +avx;+avx2
    phys-bits host
    hidden 0
    hv-vendor-id proxmox
    reported-model kvm64

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