Provided by: qemu-system-common_9.0.2+ds-4ubuntu8_amd64 bug

NAME

       qemu-cpu-models - QEMU CPU Models

SYNOPSIS

       QEMU CPU Modelling Infrastructure manual

DESCRIPTION

   Recommendations for KVM CPU model configuration on x86 hosts
       The  information  that  follows provides recommendations for configuring CPU models on x86
       hosts. The goals are to maximise performance, while protecting guest  OS  against  various
       CPU   hardware   flaws,   and  optionally  enabling  live  migration  between  hosts  with
       heterogeneous CPU models.

   Two ways to configure CPU models with QEMU / KVM
       1. Host passthrough

          This passes the host CPU model features, model, stepping, exactly to  the  guest.  Note
          that  KVM  may filter out some host CPU model features if they cannot be supported with
          virtualization. Live migration is unsafe when this mode  is  used  as  libvirt  /  QEMU
          cannot  guarantee  a  stable  CPU  is  exposed  to  the guest across hosts. This is the
          recommended CPU to use, provided live migration is not required.

       2. Named model

          QEMU comes with a number of predefined  named  CPU  models,  that  typically  refer  to
          specific  generations of hardware released by Intel and AMD.  These allow the guest VMs
          to have a degree of isolation from the host CPU, allowing greater flexibility  in  live
          migrating between hosts with differing hardware.  @end table

       In  both  cases,  it  is  possible to optionally add or remove individual CPU features, to
       alter what is presented to the guest by default.

       Libvirt supports a third way to configure CPU models known as "Host model".  This uses the
       QEMU  "Named  model"  feature,  automatically picking a CPU model that is similar the host
       CPU, and then adding extra features to approximate the host model as closely as  possible.
       This  does  not guarantee the CPU family, stepping, etc will precisely match the host CPU,
       as they would with "Host passthrough", but gives much of the benefit of passthrough, while
       making live migration safe.

   ABI compatibility levels for CPU models
       The  x86_64  architecture  has a number of ABI compatibility levels defined. Traditionally
       most operating systems and toolchains would only target the original baseline ABI.  It  is
       expected  that in future OS and toolchains are likely to target newer ABIs. The table that
       follows illustrates which ABI compatibility levels  can  be  satisfied  by  the  QEMU  CPU
       models.  Note  that  the  table  only  lists  the  long term stable CPU model versions (eg
       Haswell-v4).  In addition to what is listed, there are also many CPU model  aliases  which
       resolve to a different CPU model version, depending on the machine type is in use.

   x86-64 ABI compatibility levels
                           ┌──────────────────────┬──────────┬────┬────┬────┐
                           │Model                 │ baseline │ v2 │ v3 │ v4 │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │486-v1                │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Broadwell-v1          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Broadwell-v2          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Broadwell-v3          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Broadwell-v4          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cascadelake-Server-v1 │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cascadelake-Server-v2 │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cascadelake-Server-v3 │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cascadelake-Server-v4 │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cascadelake-Server-v5 │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Conroe-v1             │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cooperlake-v1         │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Cooperlake-v2         │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Denverton-v1          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Denverton-v2          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Denverton-v3          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Dhyana-v1             │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Dhyana-v2             │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Genoa-v1         │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Milan-v1         │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Milan-v2         │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Rome-v1          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Rome-v2          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Rome-v3          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-Rome-v4          │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-v1               │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-v2               │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-v3               │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │EPYC-v4               │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │GraniteRapids-v1      │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Haswell-v1            │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Haswell-v2            │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Haswell-v3            │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Haswell-v4            │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v1     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v2     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v3     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v4     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v5     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Icelake-Server-v6     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │IvyBridge-v1          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │IvyBridge-v2          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │KnightsMill-v1        │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Nehalem-v1            │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Nehalem-v2            │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Opteron_G1-v1         │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Opteron_G2-v1         │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Opteron_G3-v1         │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Opteron_G4-v1         │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Opteron_G5-v1         │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Penryn-v1             │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │SandyBridge-v1        │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │SandyBridge-v2        │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │SapphireRapids-v1     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │SapphireRapids-v2     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Client-v1     │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Client-v2     │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Client-v3     │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Client-v4     │ ✅       │ ✅ │ ✅ │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Server-v1     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Server-v2     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Server-v3     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Server-v4     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Skylake-Server-v5     │ ✅       │ ✅ │ ✅ │ ✅ │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Snowridge-v1          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Snowridge-v2          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Snowridge-v3          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Snowridge-v4          │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Westmere-v1           │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │Westmere-v2           │ ✅       │ ✅ │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │athlon-v1             │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │core2duo-v1           │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │coreduo-v1            │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │kvm32-v1              │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │kvm64-v1              │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │n270-v1               │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │pentium-v1            │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │pentium2-v1           │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │pentium3-v1           │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │phenom-v1             │ ✅       │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │qemu32-v1             │          │    │    │    │
                           ├──────────────────────┼──────────┼────┼────┼────┤
                           │qemu64-v1             │ ✅       │    │    │    │
                           └──────────────────────┴──────────┴────┴────┴────┘
   Preferred CPU models for Intel x86 hosts
       The following CPU  models  are  preferred  for  use  on  Intel  hosts.   Administrators  /
       applications  are recommended to use the CPU model that matches the generation of the host
       CPUs in use. In a deployment with a mixture of host CPU models between machines,  if  live
       migration  compatibility  is  required, use the newest CPU model that is compatible across
       all desired hosts.

       Cascadelake-Server, Cascadelake-Server-noTSX
              Intel Xeon Processor (Cascade Lake, 2019), with "stepping"  levels  6  or  7  only.
              (The Cascade Lake Xeon processor with stepping 5 is vulnerable to MDS variants.)

       Skylake-Server, Skylake-Server-IBRS, Skylake-Server-IBRS-noTSX
              Intel Xeon Processor (Skylake, 2016)

       Skylake-Client, Skylake-Client-IBRS, Skylake-Client-noTSX-IBRS}
              Intel Core Processor (Skylake, 2015)

       Broadwell, Broadwell-IBRS, Broadwell-noTSX, Broadwell-noTSX-IBRS
              Intel Core Processor (Broadwell, 2014)

       Haswell, Haswell-IBRS, Haswell-noTSX, Haswell-noTSX-IBRS
              Intel Core Processor (Haswell, 2013)

       IvyBridge, IvyBridge-IBR
              Intel Xeon E3-12xx v2 (Ivy Bridge, 2012)

       SandyBridge, SandyBridge-IBRS
              Intel Xeon E312xx (Sandy Bridge, 2011)

       Westmere, Westmere-IBRS
              Westmere E56xx/L56xx/X56xx (Nehalem-C, 2010)

       Nehalem, Nehalem-IBRS
              Intel Core i7 9xx (Nehalem Class Core i7, 2008)

       Penryn Intel Core 2 Duo P9xxx (Penryn Class Core 2, 2007)

       Conroe Intel Celeron_4x0 (Conroe/Merom Class Core 2, 2006)

   Important CPU features for Intel x86 hosts
       The  following  are  important  CPU  features that should be used on Intel x86 hosts, when
       available in the host CPU. Some of them require explicit configuration to enable, as  they
       are  not  included  by  default  in some, or all, of the named CPU models listed above. In
       general all of these features are included if using "Host passthrough" or "Host model".

       pcid   Recommended to mitigate the cost of the Meltdown (CVE-2017-5754) fix.

              Included by default in Haswell, Broadwell & Skylake Intel CPU models.

              Should be explicitly turned on for Westmere, SandyBridge, and IvyBridge  Intel  CPU
              models. Note that some desktop/mobile Westmere CPUs cannot support this feature.

       spec-ctrl
              Required to enable the Spectre v2 (CVE-2017-5715) fix.

              Included by default in Intel CPU models with -IBRS suffix.

              Must be explicitly turned on for Intel CPU models without -IBRS suffix.

              Requires  the  host CPU microcode to support this feature before it can be used for
              guest CPUs.

       stibp  Required to enable stronger Spectre v2  (CVE-2017-5715)  fixes  in  some  operating
              systems.

              Must be explicitly turned on for all Intel CPU models.

              Requires  the  host CPU microcode to support this feature before it can be used for
              guest CPUs.

       ssbd   Required to enable the CVE-2018-3639 fix.

              Not included by default in any Intel CPU model.

              Must be explicitly turned on for all Intel CPU models.

              Requires the host CPU microcode to support this feature before it can be  used  for
              guest CPUs.

       pdpe1gb
              Recommended to allow guest OS to use 1GB size pages.

              Not included by default in any Intel CPU model.

              Should be explicitly turned on for all Intel CPU models.

              Note that not all CPU hardware will support this feature.

       md-clear
              Required  to  confirm  the  MDS  (CVE-2018-12126,  CVE-2018-12127,  CVE-2018-12130,
              CVE-2019-11091) fixes.

              Not included by default in any Intel CPU model.

              Must be explicitly turned on for all Intel CPU models.

              Requires the host CPU microcode to support this feature before it can be  used  for
              guest CPUs.

       mds-no Recommended  to  inform  the guest OS that the host is not vulnerable to any of the
              MDS   variants   ([MFBDS]   CVE-2018-12130,   [MLPDS]    CVE-2018-12127,    [MSBDS]
              CVE-2018-12126).

              This is an MSR (Model-Specific Register) feature rather than a CPUID feature, so it
              will not appear in the Linux /proc/cpuinfo in the host or guest.  Instead, the host
              kernel uses it to populate the MDS vulnerability file in sysfs.

              So it should only be enabled for VMs if the host reports @code{Not affected} in the
              /sys/devices/system/cpu/vulnerabilities/mds file.

       taa-no Recommended  to  inform  that  the  guest  that  the  host  is  not  vulnerable  to
              CVE-2019-11135, TSX Asynchronous Abort (TAA).

              This  too  is  an MSR feature, so it does not show up in the Linux /proc/cpuinfo in
              the host or guest.

              It should only be enabled  for  VMs  if  the  host  reports  Not  affected  in  the
              /sys/devices/system/cpu/vulnerabilities/tsx_async_abort file.

       tsx-ctrl
              Recommended  to  inform  the guest that it can disable the Intel TSX (Transactional
              Synchronization Extensions) feature; or, if the processor is  vulnerable,  use  the
              Intel  VERW  instruction  (a  processor-level  instruction  that performs checks on
              memory access) as a mitigation for the TAA vulnerability.  (For details,  refer  to
              Intel's deep dive into MDS.)

              Expose  this  to the guest OS if and only if: (a) the host has TSX enabled; and (b)
              the guest has rtm CPU flag enabled.

              By disabling TSX, KVM-based  guests  can  avoid  paying  the  price  of  mitigating
              TSX-based attacks.

              Note  that  tsx-ctrl  too  is  an  MSR feature, so it does not show up in the Linux
              /proc/cpuinfo in the host or guest.

              To validate that Intel TSX is indeed disabled for the guest, there  are  two  ways:
              (a)  check  for  the  absence  of  rtm  in  the  guest's  /proc/cpuinfo; or (b) the
              /sys/devices/system/cpu/vulnerabilities/tsx_async_abort file in  the  guest  should
              report Mitigation: TSX disabled.

   Preferred CPU models for AMD x86 hosts
       The  following  CPU  models  are  preferred  for  use  on  AMD  hosts.   Administrators  /
       applications are recommended to use the CPU model that matches the generation of the  host
       CPUs  in  use. In a deployment with a mixture of host CPU models between machines, if live
       migration compatibility is required, use the newest CPU model that  is  compatible  across
       all desired hosts.

       EPYC, EPYC-IBPB
              AMD EPYC Processor (2017)

       Opteron_G5
              AMD Opteron 63xx class CPU (2012)

       Opteron_G4
              AMD Opteron 62xx class CPU (2011)

       Opteron_G3
              AMD Opteron 23xx (Gen 3 Class Opteron, 2009)

       Opteron_G2
              AMD Opteron 22xx (Gen 2 Class Opteron, 2006)

       Opteron_G1
              AMD Opteron 240 (Gen 1 Class Opteron, 2004)

   Important CPU features for AMD x86 hosts
       The  following  are  important  CPU  features  that  should be used on AMD x86 hosts, when
       available in the host CPU. Some of them require explicit configuration to enable, as  they
       are  not  included  by  default  in some, or all, of the named CPU models listed above. In
       general all of these features are included if using "Host passthrough" or "Host model".

       ibpb   Required to enable the Spectre v2 (CVE-2017-5715) fix.

              Included by default in AMD CPU models with -IBPB suffix.

              Must be explicitly turned on for AMD CPU models without -IBPB suffix.

              Requires the host CPU microcode to support this feature before it can be  used  for
              guest CPUs.

       stibp  Required  to  enable  stronger  Spectre  v2 (CVE-2017-5715) fixes in some operating
              systems.

              Must be explicitly turned on for all AMD CPU models.

              Requires the host CPU microcode to support this feature before it can be  used  for
              guest CPUs.

       virt-ssbd
              Required to enable the CVE-2018-3639 fix

              Not included by default in any AMD CPU model.

              Must be explicitly turned on for all AMD CPU models.

              This  should  be provided to guests, even if amd-ssbd is also provided, for maximum
              guest compatibility.

              Note for some QEMU / libvirt versions, this must be force enabled when  when  using
              "Host  model", because this is a virtual feature that doesn't exist in the physical
              host CPUs.

       amd-ssbd
              Required to enable the CVE-2018-3639 fix

              Not included by default in any AMD CPU model.

              Must be explicitly turned on for all AMD CPU models.

              This provides higher performance than virt-ssbd so  should  be  exposed  to  guests
              whenever  available in the host. virt-ssbd should none the less also be exposed for
              maximum guest compatibility as some kernels only know about virt-ssbd.

       amd-no-ssb
              Recommended to indicate the host is not vulnerable CVE-2018-3639

              Not included by default in any AMD CPU model.

              Future hardware generations of CPU will not be  vulnerable  to  CVE-2018-3639,  and
              thus  the  guest  should  be  told  not  to  enable  its  mitigations,  by exposing
              amd-no-ssb. This is mutually exclusive with virt-ssbd and amd-ssbd.

       pdpe1gb
              Recommended to allow guest OS to use 1GB size pages

              Not included by default in any AMD CPU model.

              Should be explicitly turned on for all AMD CPU models.

              Note that not all CPU hardware will support this feature.

   Default x86 CPU models
       The default QEMU CPU models are designed such that they can  run  on  all  hosts.   If  an
       application  does  not  wish  to do perform any host compatibility checks before launching
       guests, the default is guaranteed to work.

       The default CPU models will, however,  leave  the  guest  OS  vulnerable  to  various  CPU
       hardware  flaws,  so  their  use  is strongly discouraged.  Applications should follow the
       earlier guidance to setup a better CPU configuration, with host passthrough recommended if
       live migration is not needed.

       qemu32, qemu64
              QEMU Virtual CPU version 2.5+ (32 & 64 bit variants)

       qemu64 is used for x86_64 guests and qemu32 is used for i686 guests, when no -cpu argument
       is given to QEMU, or no <cpu> is provided in libvirt XML.

   Other non-recommended x86 CPUs
       The following CPUs models are compatible with most AMD and  Intel  x86  hosts,  but  their
       usage  is  discouraged,  as  they  expose a very limited featureset, which prevents guests
       having optimal performance.

       kvm32, kvm64
              Common KVM processor (32 & 64 bit variants).

              Legacy models just for historical compatibility with ancient QEMU versions.

       486, athlon, phenom, coreduo, core2duo, n270, pentium, pentium2, pentium3
              Various very old x86 CPU models, mostly  predating  the  introduction  of  hardware
              assisted  virtualization,  that  should  thus  not  be required for running virtual
              machines.

   Syntax for configuring CPU models
       The examples below illustrate the  approach  to  configuring  the  various  CPU  models  /
       features in QEMU and libvirt.

   QEMU command line
       Host passthrough:

          qemu-system-x86_64 -cpu host

       Host passthrough with feature customization:

          qemu-system-x86_64 -cpu host,vmx=off,...

       Named CPU models:

          qemu-system-x86_64 -cpu Westmere

       Named CPU models with feature customization:

          qemu-system-x86_64 -cpu Westmere,pcid=on,...

   Libvirt guest XML
       Host passthrough:

          <cpu mode='host-passthrough'/>

       Host passthrough with feature customization:

          <cpu mode='host-passthrough'>
              <feature name="vmx" policy="disable"/>
              ...
          </cpu>

       Host model:

          <cpu mode='host-model'/>

       Host model with feature customization:

          <cpu mode='host-model'>
              <feature name="vmx" policy="disable"/>
              ...
          </cpu>

       Named model:

          <cpu mode='custom'>
              <model name="Westmere"/>
          </cpu>

       Named model with feature customization:

          <cpu mode='custom'>
              <model name="Westmere"/>
              <feature name="pcid" policy="require"/>
              ...
          </cpu>

   Supported CPU model configurations on MIPS hosts
       QEMU supports variety of MIPS CPU models:

   Supported CPU models for MIPS32 hosts
       The  following  CPU  models  are  supported  for  use  on  MIPS32 hosts.  Administrators /
       applications are recommended to use the CPU model that matches the generation of the  host
       CPUs  in  use. In a deployment with a mixture of host CPU models between machines, if live
       migration compatibility is required, use the newest CPU model that  is  compatible  across
       all desired hosts.

       mips32r6-generic
              MIPS32 Processor (Release 6, 2015)

       P5600  MIPS32 Processor (P5600, 2014)

       M14K, M14Kc
              MIPS32 Processor (M14K, 2009)

       74Kf   MIPS32 Processor (74K, 2007)

       34Kf   MIPS32 Processor (34K, 2006)

       24Kc, 24KEc, 24Kf
              MIPS32 Processor (24K, 2003)

       4Kc, 4Km, 4KEcR1, 4KEmR1, 4KEc, 4KEm
              MIPS32 Processor (4K, 1999)

   Supported CPU models for MIPS64 hosts
       The  following  CPU  models  are  supported  for  use  on  MIPS64 hosts.  Administrators /
       applications are recommended to use the CPU model that matches the generation of the  host
       CPUs  in  use. In a deployment with a mixture of host CPU models between machines, if live
       migration compatibility is required, use the newest CPU model that  is  compatible  across
       all desired hosts.

       I6400  MIPS64 Processor (Release 6, 2014)

       Loongson-2E
              MIPS64 Processor (Loongson 2, 2006)

       Loongson-2F
              MIPS64 Processor (Loongson 2, 2008)

       Loongson-3A1000
              MIPS64 Processor (Loongson 3, 2010)

       Loongson-3A4000
              MIPS64 Processor (Loongson 3, 2018)

       mips64dspr2
              MIPS64 Processor (Release 2, 2006)

       MIPS64R2-generic, 5KEc, 5KEf
              MIPS64 Processor (Release 2, 2002)

       20Kc   MIPS64 Processor (20K, 2000

       5Kc, 5Kf
              MIPS64 Processor (5K, 1999)

       VR5432 MIPS64 Processor (VR, 1998)

       R4000  MIPS64 Processor (MIPS III, 1991)

   Supported CPU models for nanoMIPS hosts
       The  following  CPU  models  are  supported  for  use on nanoMIPS hosts.  Administrators /
       applications are recommended to use the CPU model that matches the generation of the  host
       CPUs  in  use. In a deployment with a mixture of host CPU models between machines, if live
       migration compatibility is required, use the newest CPU model that  is  compatible  across
       all desired hosts.

       I7200  MIPS I7200 (nanoMIPS, 2018)

   Preferred CPU models for MIPS hosts
       The following CPU models are preferred for use on different MIPS hosts:

       MIPS III
              R4000

       MIPS32R2
              34Kf

       MIPS64R6
              I6400

       nanoMIPS
              I7200

SEE ALSO

       The  HTML  documentation of QEMU for more precise information and Linux user mode emulator
       invocation.

AUTHOR

       The QEMU Project developers

COPYRIGHT

       2024, The QEMU Project Developers