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qemu: add cpu models documentation

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add doc for differents cpu models including
new x86-64-vX models

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
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Alexandre Derumier 2023-06-19 10:38:34 +02:00 committed by Fiona Ebner
parent c4d19b8984
commit 41379e9a77
1 changed files with 138 additions and 7 deletions
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@ -353,6 +353,9 @@ CPU Type
QEMU can emulate a number different of *CPU types* from 486 to the latest Xeon
processors. Each new processor generation adds new features, like hardware
assisted 3d rendering, random number generation, memory protection, etc ...
Also, a current generation can be upgraded through microcode update with bugs
or security fixes.
Usually you should select for your VM a processor type which closely matches the
CPU of the host system, as it means that the host CPU features (also called _CPU
flags_ ) will be available in your VMs. If you want an exact match, you can set
@ -360,17 +363,145 @@ the CPU type to *host* in which case the VM will have exactly the same CPU flags
as your host system.
This has a downside though. If you want to do a live migration of VMs between
different hosts, your VM might end up on a new system with a different CPU type.
different hosts, your VM might end up on a new system with a different CPU type
or a different microcode.
If the CPU flags passed to the guest are missing, the qemu process will stop. To
remedy this QEMU has also its own CPU type *kvm64*, that {pve} uses by defaults.
kvm64 is a Pentium 4 look a like CPU type, which has a reduced CPU flags set,
but is guaranteed to work everywhere.
remedy this QEMU has also its own virtual CPU types, that {pve} uses by defaults.
In short, if you care about live migration and moving VMs between nodes, leave
the kvm64 default. If you don’t care about live migration or have a homogeneous
cluster where all nodes have the same CPU, set the CPU type to host, as in
Default is x86-64-v2-AES, compatible with Intel >= Westmere and Amd >= Opteron_G4
In short:
If you don’t care about live migration or have a homogeneous cluster where
all nodes have the same CPU and same microcode version, set the CPU type to host, as in
theory this will give your guests maximum performance.
if you care about live migration and security, and you have only Intel CPU or only AMD CPU,
choose the lowest generation cpu model of your cluster.
if you care about live migration without security, or have mixed intel/amd cluster,
choose the lowest compatible virtual qemu type.
NOTE: Intel <> AMD migrations have no guarantee to work
Intel CPU Types since 2007
^^^^^^^^^^^^^^^^^^^^^^^^^^
https://en.wikipedia.org/wiki/List_of_Intel_Xeon_processors[Intel Processors]
* 'Nahelem' : https://fr.wikipedia.org/wiki/Nehalem[1th generation of the Intel Core Processor]
+
* 'Nahelem-IBRS (v2)' : add spectre (+spec-ctrl)
+
* 'Westmere' : https://en.wikipedia.org/wiki/Westmere_(microarchitecture)[1th generation of the Intel Core Processor (Xeon E7-)]
+
* 'Westmere-IBRS (v2)' : add spectre (+spec-ctrl)
+
* 'SandyBridge' : https://fr.wikipedia.org/wiki/Sandy_Bridge[2th generation of the Intel Core Processor]
+
* 'SandyBridge-IBRS (v2)' : add spectre v1 protection (+spec-ctrl)
+
* 'IvyBridge' : https://en.wikipedia.org/wiki/Ivy_Bridge_(microarchitecture)[3th generation of the Intel Core Processor]
+
* 'IvyBridge-IBRS (v2)': add spectre v1 protection (+spec-ctrl)
+
* 'Haswell' : https://fr.wikipedia.org/wiki/Haswell_(microarchitecture)[4th generation of the Intel Core Processor]
+
* 'Haswell-noTSX (v2)' : disable TSX (-hle,-rtm)
+
* 'Haswell-IBRS (v3)' : readd TSX, add spectre (+hle,+rtm, +spec-ctrl)
+
* 'Harwell-noTSX-IBRS (v4)' : disable TSX (-hle,-rtm)
+
* 'Broadwell': https://en.wikipedia.org/wiki/Broadwell_(microarchitecture)[5th generation of the Intel Core Processor]
+
* 'Skylake': https://en.wikipedia.org/wiki/Skylake_(microarchitecture)[1st generation Xeon Scalable server processors]
+
* 'Skylake-IBRS (v2)' : add +spec-ctrl,-clflushopt
+
* 'Skylake-noTSX-IBRS (v3)' : disable TSX (-hle, -rtm)
+
* 'Skylake-v4': add EPT switching (+vmx-eptp-switching)
+
* 'Cascadelake': https://en.wikipedia.org/wiki/Cascade_Lake_(microprocessor)[2nd generation Xeon scalable processor]
+
* 'Cascadelake-v2' : add arch_capabilities msr (+arch-capabilities,+rdctl-no,+ibrs-all,+skip-l1dfl-vmentry,+mds-no)
+
* 'Cascadelake-v3' : disable TSX (-hle, -rtm)
+
* 'Cascadelake-v4' : add EPT switching (+vmx-eptp-switching)
+
* 'Cascadelake-v5' : add XSAVES (+xsaves,+vmx-xsaves)
+
* 'CooperLake' : https://en.wikipedia.org/wiki/Cooper_Lake_(microprocessor)[3rd generation Xeon scalable processors for 4 & 8 sockets servers]
+
* 'CooperLake-v2' : add XSAVES (+xsaves,+vmx-xsaves)
+
* 'IceLake': https://en.wikipedia.org/wiki/Ice_Lake_(microprocessor)[3rd generation Xeon Scalable server processors]
+
* 'Icelake-v2' : disable TSX(-hle,-rtm)
+
* 'Icelake-v3' : add arch_capabilities msr (+arch-capabilities, +rdctl-no, +ibrs-all, +skip-l1dfl-vmentry,+mds-no,+pschange-mc-no,+taa-no)
+
* 'Icelake-v4' : add missing flags (+sha-ni,+avx512ifma,+rdpid,+fsrm,+vmx-rdseed-exit,+vmx-pml,+vmx-eptp-switching)
+
* 'Icelake-v5' : add XSAVES (+xsaves,+vmx-xsaves)
+
* 'Icelake-v6' : add "5-level EPT" (+vmx-page-walk-5)
+
* 'Sapphire Rapids' : https://en.wikipedia.org/wiki/Sapphire_Rapids[4th generation Xeon Scalable server processors]
AMD CPU Types since 2007
^^^^^^^^^^^^^^^^^^^^^^^^
https://en.wikipedia.org/wiki/List_of_AMD_processors[AMD Processors]
* 'Opteron_G3' : https://en.wikipedia.org/wiki/AMD_10h[K10]
+
* 'Opteron_G4' : https://en.wikipedia.org/wiki/Bulldozer_(microarchitecture)[Bulldozer]
+
* 'Opteron_G5' : https://en.wikipedia.org/wiki/Piledriver_(microarchitecture)[Piledriver]
+
* 'EPYC' : https://en.wikipedia.org/wiki/Zen_(first_generation)[1st Generation of Zen Processors]
+
* 'EPYC-IBPB (v2)' : add spectre v1 protection (+ibpb)
+
* 'EPYC-v3' : add missing flags (+perfctr-core,+clzero,+xsaveerptr,+xsaves)
+
* 'EPYC-Rome' : https://en.wikipedia.org/wiki/Zen_2[2nd Generation of Zen Processors]
+
* 'EPYC-Rome-v2' : add spectre v2,v4 protection (+ibrs,+amd-ssbd)
+
* 'EPYC-Milan' : https://en.wikipedia.org/wiki/Zen_3[3th Generation of Zen Processors]
+
* 'EPYC-Milan-v2' : add missing flags (+vaes,+vpclmulqdq,+stibp-always-on,+amd-psfd,+no-nested-data-bp,+lfence-always-serializing,+null-sel-clr-base
Qemu CPU Types
^^^^^^^^^^^^^^
Qemu also provide virtual cpu types, compatible with both intel/amd.
NOTE: To keep best compatibility, no security flag for spectre/meltdown/... exist in qemu virtual types, so you need to do it manually
Historically, Proxmox had the kvm64 cpu model, with only pentium4 cpu flags enabled, so performance was not great for some workload.
In the summer of 2020, AMD, Intel, Red Hat, and SUSE collaborated to define three x86-64 microarchitecture levels on top of the x86-64 baseline,
with modern flags enabled. https://gitlab.com/x86-psABIs/x86-64-ABI[x86-64-ABI specs]
Some newer distro like Centos9 are now built with x86-64-v2 flags as minimum requirement !
* 'kvm64 (v1)' : Compatible >=pentium4 , >= phenom
+
* 'x86-64-v2' : Compatible >= Nehalem, >= Opteron_G3. add cx16,lahf-lm,popcnt,pni,sse4.1,sse4.2,ssse3
+
* 'x86-64-v2-AES' : Compatible >= Westmere, >= Opteron_G4 : add aes
+
* 'x86-64-v3' : Compatible >= Broadwell, >= Epyc : add +avx,+avx2,+bmi1,+bmi2,+f16c,+fma,+movbe,xsave
+
* 'x86-64-v4' : Compatible >= Skylake , >= EPYC-Genoa(V4) : add +avx512f, +avx512bw, +avx512cd,+avx512dq,+avx512vl
Custom CPU Types
^^^^^^^^^^^^^^^^