diff mbox series

[v2,1/2] docs: Convert qemu-cpu-models.texi to rST

Message ID 20200219114607.1855-2-kchamart@redhat.com (mailing list archive)
State New, archived
Headers show
Series This small series does two things: | expand

Commit Message

Kashyap Chamarthy Feb. 19, 2020, 11:46 a.m. UTC 
This doc was originally written by Daniel P. Berrangé
<berrange@redhat.com>, introduced via commit[1]: 2544e9e4aa (docs: add
guidance on configuring CPU models for x86, 2018-06-27).

This is a 1-1 conversion of Texinfo to rST, besides a couple of minor
non-content tweaks that are too trivial to spell out.  Further
modifications will be done via a separate patch.

(Thanks to Stephen Finucane on IRC for the suggestion to use rST
"definition lists" instead of bullets in some places.)

[1] https://git.qemu.org/?p=qemu.git;a=commit;h=2544e9e4aa

Signed-off-by: Kashyap Chamarthy <kchamart@redhat.com>
---
 docs/qemu-cpu-models.texi       | 677 --------------------------------
 docs/system/index.rst           |   1 +
 docs/system/qemu-cpu-models.rst | 496 +++++++++++++++++++++++
 3 files changed, 497 insertions(+), 677 deletions(-)
 delete mode 100644 docs/qemu-cpu-models.texi
 create mode 100644 docs/system/qemu-cpu-models.rst

Comments

Peter Maydell Feb. 19, 2020, 1:16 p.m. UTC | #1 
On Wed, 19 Feb 2020 at 11:46, Kashyap Chamarthy <kchamart@redhat.com> wrote:
>
> This doc was originally written by Daniel P. Berrangé
> <berrange@redhat.com>, introduced via commit[1]: 2544e9e4aa (docs: add
> guidance on configuring CPU models for x86, 2018-06-27).
>
> This is a 1-1 conversion of Texinfo to rST, besides a couple of minor
> non-content tweaks that are too trivial to spell out.  Further
> modifications will be done via a separate patch.
>
> (Thanks to Stephen Finucane on IRC for the suggestion to use rST
> "definition lists" instead of bullets in some places.)
>
> [1] https://git.qemu.org/?p=qemu.git;a=commit;h=2544e9e4aa
>
> Signed-off-by: Kashyap Chamarthy <kchamart@redhat.com>
> ---
>  docs/qemu-cpu-models.texi       | 677 --------------------------------
>  docs/system/index.rst           |   1 +
>  docs/system/qemu-cpu-models.rst | 496 +++++++++++++++++++++++
>  3 files changed, 497 insertions(+), 677 deletions(-)
>  delete mode 100644 docs/qemu-cpu-models.texi
>  create mode 100644 docs/system/qemu-cpu-models.rst

Hi; I haven't looked in detail at the actual conversion
parts, but from the diffstat you're missing some parts:

1) qemu-doc.texi has an "@include docs/qemu-cpu-models.texi"
that needs to be removed. That then means that the
"CPU models" section in qemu-doc.texi is empty, so we
can just delete it (the @node and @section directives,
and the reference to it in the earlier @menu)
(I'm surprised this didn't cause 'make' to fail with
an error trying to build the texi docs.)

2) The bit of Makefile which lists the dependencies of
qemu-doc.html needs to be updated to remove
docs/qemu-cpu-models.texi.

3) we create a qemu-cpu-models.7 manpage, so the parts
of Makefile that currently handle creating it from the
texi need to be changed to do it from the rST instead.
You can look at how we handle qemu-block-drivers.7
for an example. Don't forget that you'll need to add
a line to docs/system/conf.py to get Sphinx to build
the manpage, as well as the makefile changes.
You can check how the manpage renders with
'man -l /path/to/builddir/docs/interop/qemu-cpu-models.7'

4) The qemu-cpu-models.texi uses a substitution
"@set qemu_system_x86 qemu-system-x86-64" so that
downstream RedHat can easily update the examples text
to refer to whatever they rename the binary to. The
equivalent of this in rST you can see in qemu-block-drivers.rst:
at the top of the file we have

.. |qemu_system| replace:: qemu-system-x86_64

and then an example block using it is like:

.. parsed-literal::

  |qemu_system| linux.img -hdb fat:/my_directory

(you have to use a parsed-literal block and not the
usual :: so that the expansion is done.)

thanks
-- PMM
Kashyap Chamarthy Feb. 19, 2020, 3:22 p.m. UTC | #2 
On Wed, Feb 19, 2020 at 01:16:11PM +0000, Peter Maydell wrote:
> On Wed, 19 Feb 2020 at 11:46, Kashyap Chamarthy <kchamart@redhat.com> wrote:

[...]

> >  docs/qemu-cpu-models.texi       | 677 --------------------------------
> >  docs/system/index.rst           |   1 +
> >  docs/system/qemu-cpu-models.rst | 496 +++++++++++++++++++++++
> >  3 files changed, 497 insertions(+), 677 deletions(-)
> >  delete mode 100644 docs/qemu-cpu-models.texi
> >  create mode 100644 docs/system/qemu-cpu-models.rst
> 
> Hi; I haven't looked in detail at the actual conversion
> parts, but from the diffstat you're missing some parts:

Hi, Peter.

Thanks for the helpfully detailed response.  I realized some of the
missing bits due to the Patchew failure and as I look closer into your
patch for qemu-block-drivers.rst.

> 1) qemu-doc.texi has an "@include docs/qemu-cpu-models.texi"
> that needs to be removed. That then means that the
> "CPU models" section in qemu-doc.texi is empty, so we
> can just delete it (the @node and @section directives,
> and the reference to it in the earlier @menu)
> (I'm surprised this didn't cause 'make' to fail with
> an error trying to build the texi docs.)
> 
> 2) The bit of Makefile which lists the dependencies of
> qemu-doc.html needs to be updated to remove
> docs/qemu-cpu-models.texi.
> 
> 3) we create a qemu-cpu-models.7 manpage, so the parts
> of Makefile that currently handle creating it from the
> texi need to be changed to do it from the rST instead.
> You can look at how we handle qemu-block-drivers.7
> for an example. Don't forget that you'll need to add
> a line to docs/system/conf.py to get Sphinx to build
> the manpage, as well as the makefile changes.
> You can check how the manpage renders with
> 'man -l /path/to/builddir/docs/interop/qemu-cpu-models.7'
> 
> 4) The qemu-cpu-models.texi uses a substitution
> "@set qemu_system_x86 qemu-system-x86-64" so that
> downstream RedHat can easily update the examples text
> to refer to whatever they rename the binary to. The
> equivalent of this in rST you can see in qemu-block-drivers.rst:
> at the top of the file we have
> 
> .. |qemu_system| replace:: qemu-system-x86_64
> 
> and then an example block using it is like:
> 
> .. parsed-literal::
> 
>   |qemu_system| linux.img -hdb fat:/my_directory
> 
> (you have to use a parsed-literal block and not the
> usual :: so that the expansion is done.)

Ah, noted.  I used the regular :: out of habit from elsewhere, and
didn't even look at the details of qemu-block-drivers.rst.

I'm addressing them as we speak; v2 upcoming.

Thanks, again.
Kashyap Chamarthy Feb. 19, 2020, 4:40 p.m. UTC | #3 
On Wed, Feb 19, 2020 at 01:16:11PM +0000, Peter Maydell wrote:

[...]

> 3) we create a qemu-cpu-models.7 manpage, so the parts
> of Makefile that currently handle creating it from the
> texi need to be changed to do it from the rST instead.
> You can look at how we handle qemu-block-drivers.7
> for an example. Don't forget that you'll need to add
> a line to docs/system/conf.py to get Sphinx to build
> the manpage, as well as the makefile changes.
> You can check how the manpage renders with
> 'man -l /path/to/builddir/docs/interop/qemu-cpu-models.7'

Peter, how are you able to generate those *.7 `nroff` man pages?  When I
do 'make sphinxbuild' from my build dir ($HOME/buld/qemu), I only see:

    $> make sphinxdocs
    [...]
    make: Nothing to be done for 'sphinxdocs'.
    
    $> ls -ls docs/system/ | awk '{print $10}';
    
    genindex.html
    index.html
    objects.inv
    qemu-block-drivers.html
    qemu-cpu-models.html
    search.html
    searchindex.js
    _static

No *.7 `nroff` files in docs/system/ nor in docs/interop/.  

FWIW, I do have the below bit in docs/system/conf.py:

  ...
  man_pages = [
      ('qemu-block-drivers', 'qemu-block-drivers',
       u'QEMU block drivers reference',
       ['Fabrice Bellard and the QEMU Project developers'], 7),
      ('qemu-cpu-models', 'qemu-cpu-models',
       u'QEMU CPU Models',
       ['Fabrice Bellard and the QEMU Project developers'], 7)
  ]
  ...


[...]
Peter Maydell Feb. 19, 2020, 5:57 p.m. UTC | #4 
On Wed, 19 Feb 2020 at 16:40, Kashyap Chamarthy <kchamart@redhat.com> wrote:
> Peter, how are you able to generate those *.7 `nroff` man pages?  When I
> do 'make sphinxbuild' from my build dir ($HOME/buld/qemu), I only see:

Just run 'make'. As with the existing texinfo manpages, there
is no specific makefile target for "build the manpages and
nothing else".

thanks
-- PMM
Kashyap Chamarthy Feb. 20, 2020, 10:23 a.m. UTC | #5 
On Wed, Feb 19, 2020 at 05:57:16PM +0000, Peter Maydell wrote:
> On Wed, 19 Feb 2020 at 16:40, Kashyap Chamarthy <kchamart@redhat.com> wrote:
> > Peter, how are you able to generate those *.7 `nroff` man pages?  When I
> > do 'make sphinxbuild' from my build dir ($HOME/buld/qemu), I only see:
> 
> Just run 'make'. 

I did that, but I was missing the "--enable-docs" with my `configure`
invocation (which I didn't post in full on the list, but only on IRC
yesterday).  Thanks, Markus, for spotting that.

    $> cd ~/build/qemu
    $> ~/src/qemu//configure --target-list=x86_64-softmmu \
        --enable-debug --enable-docs
    $> make -j8

That did the trick:

    # From the build dir
    $> find -name \*.7
    ./docs/interop/qemu-ga-ref.7
    ./docs/interop/qemu-qmp-ref.7
    ./docs/system/qemu-block-drivers.7
    ./docs/system/qemu-cpu-models.7

> As with the existing texinfo manpages, there
> is no specific makefile target for "build the manpages and
> nothing else".

Yeah, noticed that from the Makefile.

All sorted now, thanks!

> thanks
> -- PMM
>
Peter Maydell Feb. 20, 2020, 10:56 a.m. UTC | #6 
On Thu, 20 Feb 2020 at 10:23, Kashyap Chamarthy <kchamart@redhat.com> wrote:
>
> On Wed, Feb 19, 2020 at 05:57:16PM +0000, Peter Maydell wrote:
> > On Wed, 19 Feb 2020 at 16:40, Kashyap Chamarthy <kchamart@redhat.com> wrote:
> > > Peter, how are you able to generate those *.7 `nroff` man pages?  When I
> > > do 'make sphinxbuild' from my build dir ($HOME/buld/qemu), I only see:
> >
> > Just run 'make'.
>
> I did that, but I was missing the "--enable-docs" with my `configure`
> invocation (which I didn't post in full on the list, but only on IRC
> yesterday).  Thanks, Markus, for spotting that.

Yeah, if you don't have the necessary tools then we'll
silently not build the docs (per configure's usual default
of "probe and enable only if possible").

thanks
-- PMM
diff mbox series

Patch

diff --git a/docs/qemu-cpu-models.texi b/docs/qemu-cpu-models.texi
deleted file mode 100644
index f88a1def0d..0000000000
--- a/docs/qemu-cpu-models.texi
+++ /dev/null
@@ -1,677 +0,0 @@ 
-@c man begin SYNOPSIS
-QEMU / KVM CPU model configuration
-@c man end
-
-@set qemu_system_x86 qemu-system-x86_64
-
-@c man begin DESCRIPTION
-
-@menu
-* recommendations_cpu_models_x86::  Recommendations for KVM CPU model configuration on x86 hosts
-* recommendations_cpu_models_MIPS:: Supported CPU model configurations on MIPS hosts
-* cpu_model_syntax_apps::           Syntax for configuring CPU models
-@end menu
-
-QEMU / KVM virtualization supports two ways to configure CPU models
-
-@table @option
-
-@item 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.
-
-@item 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.
-
-@node recommendations_cpu_models_x86
-@subsection 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.
-
-@menu
-* preferred_cpu_models_intel_x86::       Preferred CPU models for Intel x86 hosts
-* important_cpu_features_intel_x86::     Important CPU features for Intel x86 hosts
-* preferred_cpu_models_amd_x86::         Preferred CPU models for AMD x86 hosts
-* important_cpu_features_amd_x86::       Important CPU features for AMD x86 hosts
-* default_cpu_models_x86::               Default x86 CPU models
-* other_non_recommended_cpu_models_x86:: Other non-recommended x86 CPUs
-@end menu
-
-@node preferred_cpu_models_intel_x86
-@subsubsection 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.
-
-@table @option
-@item @code{Skylake-Server}
-@item @code{Skylake-Server-IBRS}
-
-Intel Xeon Processor (Skylake, 2016)
-
-
-@item @code{Skylake-Client}
-@item @code{Skylake-Client-IBRS}
-
-Intel Core Processor (Skylake, 2015)
-
-
-@item @code{Broadwell}
-@item @code{Broadwell-IBRS}
-@item @code{Broadwell-noTSX}
-@item @code{Broadwell-noTSX-IBRS}
-
-Intel Core Processor (Broadwell, 2014)
-
-
-@item @code{Haswell}
-@item @code{Haswell-IBRS}
-@item @code{Haswell-noTSX}
-@item @code{Haswell-noTSX-IBRS}
-
-Intel Core Processor (Haswell, 2013)
-
-
-@item @code{IvyBridge}
-@item @code{IvyBridge-IBRS}
-
-Intel Xeon E3-12xx v2 (Ivy Bridge, 2012)
-
-
-@item @code{SandyBridge}
-@item @code{SandyBridge-IBRS}
-
-Intel Xeon E312xx (Sandy Bridge, 2011)
-
-
-@item @code{Westmere}
-@item @code{Westmere-IBRS}
-
-Westmere E56xx/L56xx/X56xx (Nehalem-C, 2010)
-
-
-@item @code{Nehalem}
-@item @code{Nehalem-IBRS}
-
-Intel Core i7 9xx (Nehalem Class Core i7, 2008)
-
-
-@item @code{Penryn}
-
-Intel Core 2 Duo P9xxx (Penryn Class Core 2, 2007)
-
-
-@item @code{Conroe}
-
-Intel Celeron_4x0 (Conroe/Merom Class Core 2, 2006)
-
-@end table
-
-@node important_cpu_features_intel_x86
-@subsubsection 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".
-
-
-@table @option
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-@item @code{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.
-@end table
-
-
-@node preferred_cpu_models_amd_x86
-@subsubsection Preferred CPU models for AMD 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.
-
-@table @option
-
-@item @code{EPYC}
-@item @code{EPYC-IBPB}
-
-AMD EPYC Processor (2017)
-
-
-@item @code{Opteron_G5}
-
-AMD Opteron 63xx class CPU (2012)
-
-
-@item @code{Opteron_G4}
-
-AMD Opteron 62xx class CPU (2011)
-
-
-@item @code{Opteron_G3}
-
-AMD Opteron 23xx (Gen 3 Class Opteron, 2009)
-
-
-@item @code{Opteron_G2}
-
-AMD Opteron 22xx (Gen 2 Class Opteron, 2006)
-
-
-@item @code{Opteron_G1}
-
-AMD Opteron 240 (Gen 1 Class Opteron, 2004)
-@end table
-
-@node important_cpu_features_amd_x86
-@subsubsection 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".
-
-
-@table @option
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-
-
-@item @code{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.
-@end table
-
-
-@node default_cpu_models_x86
-@subsubsection 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.
-
-@table @option
-@item @code{qemu32}
-@item @code{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.
-@end table
-
-
-@node other_non_recommended_cpu_models_x86
-@subsubsection 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.
-
-@table @option
-
-@item @code{kvm32}
-@item @code{kvm64}
-
-Common KVM processor (32 & 64 bit variants)
-
-Legacy models just for historical compatibility with ancient QEMU versions.
-
-
-@item @code{486}
-@item @code{athlon}
-@item @code{phenom}
-@item @code{coreduo}
-@item @code{core2duo}
-@item @code{n270}
-@item @code{pentium}
-@item @code{pentium2}
-@item @code{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.
-@end table
-
-@node recommendations_cpu_models_MIPS
-@subsection Supported CPU model configurations on MIPS hosts
-
-QEMU supports variety of MIPS CPU models:
-
-@menu
-* cpu_models_MIPS32::               Supported CPU models for MIPS32 hosts
-* cpu_models_MIPS64::               Supported CPU models for MIPS64 hosts
-* cpu_models_nanoMIPS::             Supported CPU models for nanoMIPS hosts
-* preferred_cpu_models_MIPS::       Preferred CPU models for MIPS hosts
-@end menu
-
-@node cpu_models_MIPS32
-@subsubsection 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.
-
-@table @option
-@item @code{mips32r6-generic}
-
-MIPS32 Processor (Release 6, 2015)
-
-
-@item @code{P5600}
-
-MIPS32 Processor (P5600, 2014)
-
-
-@item @code{M14K}
-@item @code{M14Kc}
-
-MIPS32 Processor (M14K, 2009)
-
-
-@item @code{74Kf}
-
-MIPS32 Processor (74K, 2007)
-
-
-@item @code{34Kf}
-
-MIPS32 Processor (34K, 2006)
-
-
-@item @code{24Kc}
-@item @code{24KEc}
-@item @code{24Kf}
-
-MIPS32 Processor (24K, 2003)
-
-
-@item @code{4Kc}
-@item @code{4Km}
-@item @code{4KEcR1}
-@item @code{4KEmR1}
-@item @code{4KEc}
-@item @code{4KEm}
-
-MIPS32 Processor (4K, 1999)
-@end table
-
-@node cpu_models_MIPS64
-@subsubsection 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.
-
-@table @option
-@item @code{I6400}
-
-MIPS64 Processor (Release 6, 2014)
-
-
-@item @code{Loongson-2F}
-
-MIPS64 Processor (Loongson 2, 2008)
-
-
-@item @code{Loongson-2E}
-
-MIPS64 Processor (Loongson 2, 2006)
-
-
-@item @code{mips64dspr2}
-
-MIPS64 Processor (Release 2, 2006)
-
-
-@item @code{MIPS64R2-generic}
-@item @code{5KEc}
-@item @code{5KEf}
-
-MIPS64 Processor (Release 2, 2002)
-
-
-@item @code{20Kc}
-
-MIPS64 Processor (20K, 2000)
-
-
-@item @code{5Kc}
-@item @code{5Kf}
-
-MIPS64 Processor (5K, 1999)
-
-
-@item @code{VR5432}
-
-MIPS64 Processor (VR, 1998)
-
-
-@item @code{R4000}
-
-MIPS64 Processor (MIPS III, 1991)
-@end table
-
-@node cpu_models_nanoMIPS
-@subsubsection 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.
-
-@table @option
-@item @code{I7200}
-
-MIPS I7200 (nanoMIPS, 2018)
-
-@end table
-
-@node preferred_cpu_models_MIPS
-@subsubsection Preferred CPU models for MIPS hosts
-
-The following CPU models are preferred for use on different MIPS hosts:
-
-@table @option
-@item @code{MIPS III}
-R4000
-
-@item @code{MIPS32R2}
-34Kf
-
-@item @code{MIPS64R6}
-I6400
-
-@item @code{nanoMIPS}
-I7200
-@end table
-
-@node cpu_model_syntax_apps
-@subsection Syntax for configuring CPU models
-
-The example below illustrate the approach to configuring the various
-CPU models / features in QEMU and libvirt
-
-@menu
-* cpu_model_syntax_qemu::    QEMU command line
-* cpu_model_syntax_libvirt:: Libvirt guest XML
-@end menu
-
-@node cpu_model_syntax_qemu
-@subsubsection QEMU command line
-
-@table @option
-
-@item Host passthrough
-
-@example
-   $ @value{qemu_system_x86} -cpu host
-@end example
-
-With feature customization:
-
-@example
-   $ @value{qemu_system_x86} -cpu host,-vmx,...
-@end example
-
-@item Named CPU models
-
-@example
-   $ @value{qemu_system_x86} -cpu Westmere
-@end example
-
-With feature customization:
-
-@example
-   $ @value{qemu_system_x86} -cpu Westmere,+pcid,...
-@end example
-
-@end table
-
-@node cpu_model_syntax_libvirt
-@subsubsection Libvirt guest XML
-
-@table @option
-
-@item Host passthrough
-
-@example
-   <cpu mode='host-passthrough'/>
-@end example
-
-With feature customization:
-
-@example
-   <cpu mode='host-passthrough'>
-       <feature name="vmx" policy="disable"/>
-       ...
-   </cpu>
-@end example
-
-@item Host model
-
-@example
-   <cpu mode='host-model'/>
-@end example
-
-With feature customization:
-
-@example
-   <cpu mode='host-model'>
-       <feature name="vmx" policy="disable"/>
-       ...
-   </cpu>
-@end example
-
-@item Named model
-
-@example
-   <cpu mode='custom'>
-       <model name="Westmere"/>
-   </cpu>
-@end example
-
-With feature customization:
-
-@example
-   <cpu mode='custom'>
-       <model name="Westmere"/>
-       <feature name="pcid" policy="require"/>
-       ...
-   </cpu>
-@end example
-
-@end table
-
-@c man end
-
-@ignore
-
-@setfilename qemu-cpu-models
-@settitle QEMU / KVM CPU model configuration
-
-@c man begin SEEALSO
-The HTML documentation of QEMU for more precise information and Linux
-user mode emulator invocation.
-@c man end
-
-@c man begin AUTHOR
-Daniel P. Berrange
-@c man end
-
-@end ignore
diff --git a/docs/system/index.rst b/docs/system/index.rst
index f66e6ea585..849dcd8cb8 100644
--- a/docs/system/index.rst
+++ b/docs/system/index.rst
@@ -15,3 +15,4 @@  Contents:
    :maxdepth: 2
 
    qemu-block-drivers
+   qemu-cpu-models
diff --git a/docs/system/qemu-cpu-models.rst b/docs/system/qemu-cpu-models.rst
new file mode 100644
index 0000000000..2332fba1f9
--- /dev/null
+++ b/docs/system/qemu-cpu-models.rst
@@ -0,0 +1,496 @@ 
+QEMU / KVM CPU model configuration
+==================================
+
+QEMU / KVM virtualization supports two ways to configure CPU models:
+
+(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.
+
+
+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.
+
+
+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.
+
+* Intel Xeon Processor (Skylake, 2016)
+
+  * ``Skylake-Server``
+  * ``Skylake-Server-IBRS``
+
+* Intel Core Processor (Skylake, 2015)
+
+  * ``Skylake-Client``
+  * ``Skylake-Client-IBRS``
+
+* Intel Core Processor (Broadwell, 2014)
+
+  * ``Broadwell``
+  * ``Broadwell-IBRS``
+  * ``Broadwell-noTSX``
+  * ``Broadwell-noTSX-IBRS``
+
+* Intel Core Processor (Haswell, 2013)
+
+  * ``Haswell``
+  * ``Haswell-IBRS``
+  * ``Haswell-noTSX``
+  * ``Haswell-noTSX-IBRS``
+
+* Intel Xeon E3-12xx v2 (Ivy Bridge, 2012)
+
+  * ``IvyBridge``
+  * ``IvyBridge-IBR``
+
+* Intel Xeon E312xx (Sandy Bridge, 2011)
+
+  * ``SandyBridge``
+  * ``SandyBridge-IBRS``
+
+* Westmere E56xx/L56xx/X56xx (Nehalem-C, 2010)
+
+  * ``Westmere``
+  * ``Westmere-IBRS``
+
+* Intel Core i7 9xx (Nehalem Class Core i7, 2008)
+
+  * ``Nehalem``
+  * ``Nehalem-IBRS``
+
+* Intel Core 2 Duo P9xxx (Penryn Class Core 2, 2007)
+
+  * ``Penryn``
+
+* Intel Celeron_4x0 (Conroe/Merom Class Core 2, 2006)
+
+  * ``Conroe``
+
+
+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.
+
+
+Preferred CPU models for AMD 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.
+
+* AMD EPYC Processor (2017)
+
+  * ``EPYC``
+  * ``EPYC-IBPB``
+
+* ``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.
+
+* QEMU Virtual CPU version 2.5+ (32 & 64 bit variants)
+
+  * ``qemu32``
+  * ``qemu64``
+
+  ``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.
+
+* Common KVM processor (32 & 64 bit variants):
+
+  * ``kvm32``
+  * ``kvm64``
+
+  Legacy models just for historical compatibility with ancient QEMU
+  versions.
+
+* Various very old x86 CPU models, mostly predating the introduction of
+  hardware assisted virtualization, that should thus not be required for
+  running virtual machines.
+
+  * ``486``
+  * ``athlon``
+  * ``phenom``
+  * ``coreduo``
+  * ``core2duo``
+  * ``n270``
+  * ``pentium``
+  * ``pentium2``
+  * ``pentium3``
+
+
+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)
+
+* MIPS32 Processor (M14K, 2009)
+
+  * ``M14K``
+  * ``M14Kc``
+
+* ``74Kf`` -- MIPS32 Processor (74K, 2007)
+
+* ``34Kf`` -- MIPS32 Processor (34K, 2006)
+
+* MIPS32 Processor (24K, 2003)
+
+  * ``24Kc``
+  * ``24KEc``
+  * ``24Kf``
+
+* MIPS32 Processor (4K, 1999)
+
+  * ``4Kc``
+  * ``4Km``
+  * ``4KEcR1``
+  * ``4KEmR1``
+  * ``4KEc``
+  * ``4KEm``
+
+
+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-2F`` -- MIPS64 Processor (Loongson 2, 2008)
+
+* ``Loongson-2E`` -- MIPS64 Processor (Loongson 2, 2006)
+
+* ``mips64dspr2`` -- MIPS64 Processor (Release 2, 2006)
+
+* MIPS64 Processor (Release 2, 2002)
+
+  * ``MIPS64R2-generic``
+  * ``5KEc``
+  * ``5KEf``
+
+* ``20Kc`` -- MIPS64 Processor (20K, 2000
+
+* MIPS64 Processor (5K, 1999)
+
+  * ``5Kc``
+  * ``5Kf``
+
+* ``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
+
+Syntax for configuring CPU models
+---------------------------------
+
+The example below illustrate the approach to configuring the various
+CPU models / features in QEMU and libvirt
+
+QEMU command line
+~~~~~~~~~~~~~~~~~
+
+Host passthrough::
+
+    $ qemu_system_x86 -cpu host
+
+Host passthrough with feature customization::
+
+    $ qemu_system_x86 -cpu host,-vmx,...
+
+Named CPU models::
+
+    $ qemu_system_x86 -cpu Westmere
+
+Named CPU models with feature customization::
+
+    $ qemu_system_x86 -cpu Westmere,+pcid,...
+
+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>