[PATCH v6 0/4] introduce support for acpi-bridge-hotplug feature

Ani Sinha ani at anisinha.ca
Thu Oct 7 23:45:10 UTC 2021 

Also just for the statistics , it's been almost 2 months now since the
effort on the two patches started.

On Fri, Oct 8, 2021 at 4:46 AM Ani Sinha <ani at anisinha.ca> wrote:

> Other than laine doesn't anyone have any feedback on this patch set?
> Timely reviews help contributions. It's difficult to sit on a patch set and
> keep rebasing for ever.
>
> On Tue, Oct 5, 2021 at 11:21 AM Ani Sinha <ani at anisinha.ca> wrote:
>
>> changelog:
>>
>> v6: rebased to latest. capabilities have been renamed as per suggestions
>> that
>>     were made here:
>>
>> https://listman.redhat.com/archives/libvir-list/2021-October/msg00061.html
>> v5: rebased the patchset with the latest master.
>> v4: split the original series into two - pci-root controller specific one
>>     (https://www.mail-archive.com/libvir-list@redhat.com/msg221645.html)
>>     and this one specific to pci bridges.
>>     The conf xml has been introduced as per suggestion by Berrange here:
>>     https://patchew.org/Libvirt/20210912032631.2853520-1-ani@anisinha.ca
>>     Changes has been introduced to parse and validate the xml accordingly
>>     as well as to add backend qemu commandline option.
>> v3: reorganized the patches as per Laine's suggestion. Added more
>>     details in commit messages. Added conf description in
>> formatdomain.rst.
>>     Added changelog for next release.
>> v2: fixed bugs and added additional missing unit tests.
>> v1: initial implementation. Had some bugs and missed some unit tests
>>
>> This change introduces a new libvirt sub-element <pci> under <features>
>> that
>> can be used to configure all pci related features.
>> Currently the only sub-sub element supported by this sub-element is
>> 'acpi-bridge-hotplug' as shown below:
>>
>> <features>
>>   <pci>
>>     <acpi-bridge-hotplug state='on|off'/>
>>   </pci>
>> </features>
>>
>> The above option is only available for qemu driver and that too for x86
>> guests
>> only. It is a global option.
>>
>> 'acpi-bridge-hotplug' option enables or disables ACPI hotplug support for
>> cold-plugged pci bridges. Examples of bridges include PCI-PCI bridge
>> (pci-bridge controller) or PCIe-PCI bridges for pc machines and
>> pcie-root-port controller for q35 machines. Being global option, no other
>> bridge specific option are required. For pc machine type in x86, this
>> option
>> is available in qemu for a long time, from version 2.1.
>> Please see the following changes in qemu repo:
>>
>> 9e047b982452c6 ("piix4: add acpi pci hotplug support")
>> 133a2da488062e ("pc: acpi: generate AML only for PCI0 devices if PCI
>> bridge hotplug is disabled")
>>
>> For q35 machine type, this was introduced in qemu 6.1 with the following
>> changes in qemu repo:
>>
>> (a) c0e427d6eb5fef ("hw/acpi/ich9: Enable ACPI PCI hot-plug")
>> (b) 17858a16950860 ("hw/acpi/ich9: Set ACPI PCI hot-plug as default on
>> Q35")
>>
>> The reasons for enabling ACPI based hotplug for PCIe (q35) based machines
>> (as
>> opposed to native hotplug) are outlined in (b). There are use cases where
>> users
>> would still want to use native hotplug (see notes). Therefore, this
>> config option
>> enables users to choose either ACPI based hotplug or native hotplug for
>> bridges
>> (for example for pcie root port controller in q35 machines).
>>
>> Notes:
>> One concrete example of why one might still want to use native hotplug
>> with
>> pcie-root-port controller is the fact that we are still discovering
>> issues with
>> acpi hotplug on PCIE. One such issue is:
>> https://lists.gnu.org/archive/html/qemu-devel/2021-09/msg02146.html
>> Another reason is that users have been using native hotplug on pcie root
>> ports
>> up until now. They have built and tested their systems based on native
>> hotplug.
>> They may not want to suddenly move to acpi based hotplug just because it
>> is now
>> the default in qemu. Supporting the option to chose one or the other
>> through
>> libvirt makes things simpler for end users.
>>
>> Ani Sinha (4):
>>   qemu: capablities: detect presence of
>>     acpi-pci-hotplug-with-bridge-support
>>   conf: introduce support for acpi-bridge-hotplug feature
>>   qemu: command: add support for acpi-bridge-hotplug feature
>>   NEWS: add new acpi pci hotplug config option in the release note for
>>     next release
>>
>>  NEWS.rst                                      |  7 ++
>>  docs/formatdomain.rst                         | 11 +++
>>  docs/schemas/domaincommon.rng                 | 15 ++++
>>  src/conf/domain_conf.c                        | 89 ++++++++++++++++++-
>>  src/conf/domain_conf.h                        |  9 ++
>>  src/qemu/qemu_capabilities.c                  |  4 +
>>  src/qemu/qemu_capabilities.h                  |  2 +
>>  src/qemu/qemu_command.c                       | 14 +++
>>  src/qemu/qemu_validate.c                      | 46 ++++++++++
>>  .../caps_2.11.0.x86_64.xml                    |  1 +
>>  .../caps_2.12.0.x86_64.xml                    |  1 +
>>  .../caps_3.0.0.x86_64.xml                     |  1 +
>>  .../caps_3.1.0.x86_64.xml                     |  1 +
>>  .../caps_4.0.0.x86_64.xml                     |  1 +
>>  .../caps_4.1.0.x86_64.xml                     |  1 +
>>  .../caps_4.2.0.x86_64.xml                     |  1 +
>>  .../caps_5.0.0.x86_64.xml                     |  1 +
>>  .../caps_5.1.0.x86_64.xml                     |  1 +
>>  .../caps_5.2.0.x86_64.xml                     |  1 +
>>  .../caps_6.0.0.x86_64.xml                     |  1 +
>>  .../caps_6.1.0.x86_64.xml                     |  2 +
>>  .../aarch64-acpi-hotplug-bridge-disable.err   |  1 +
>>  .../aarch64-acpi-hotplug-bridge-disable.xml   | 33 +++++++
>>  ...pc-i440fx-acpi-hotplug-bridge-disable.args | 31 +++++++
>>  .../pc-i440fx-acpi-hotplug-bridge-disable.err |  1 +
>>  .../pc-i440fx-acpi-hotplug-bridge-disable.xml | 33 +++++++
>>  .../pc-i440fx-acpi-hotplug-bridge-enable.xml  | 33 +++++++
>>  .../q35-acpi-hotplug-bridge-disable.args      | 33 +++++++
>>  .../q35-acpi-hotplug-bridge-disable.err       |  1 +
>>  .../q35-acpi-hotplug-bridge-disable.xml       | 47 ++++++++++
>>  .../q35-acpi-hotplug-bridge-enable.xml        | 47 ++++++++++
>>  tests/qemuxml2argvtest.c                      | 16 ++++
>>  .../pc-i440fx-acpi-hotplug-bridge-disable.xml |  1 +
>>  .../pc-i440fx-acpi-hotplug-bridge-enable.xml  |  1 +
>>  .../q35-acpi-hotplug-bridge-disable.xml       |  1 +
>>  .../q35-acpi-hotplug-bridge-enable.xml        |  1 +
>>  tests/qemuxml2xmltest.c                       | 14 +++
>>  37 files changed, 503 insertions(+), 1 deletion(-)
>>  create mode 100644
>> tests/qemuxml2argvdata/aarch64-acpi-hotplug-bridge-disable.err
>>  create mode 100644
>> tests/qemuxml2argvdata/aarch64-acpi-hotplug-bridge-disable.xml
>>  create mode 100644
>> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-disable.args
>>  create mode 100644
>> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-disable.err
>>  create mode 100644
>> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-disable.xml
>>  create mode 100644
>> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-enable.xml
>>  create mode 100644
>> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-disable.args
>>  create mode 100644
>> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-disable.err
>>  create mode 100644
>> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-disable.xml
>>  create mode 100644
>> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-enable.xml
>>  create mode 120000
>> tests/qemuxml2xmloutdata/pc-i440fx-acpi-hotplug-bridge-disable.xml
>>  create mode 120000
>> tests/qemuxml2xmloutdata/pc-i440fx-acpi-hotplug-bridge-enable.xml
>>  create mode 120000
>> tests/qemuxml2xmloutdata/q35-acpi-hotplug-bridge-disable.xml
>>  create mode 120000
>> tests/qemuxml2xmloutdata/q35-acpi-hotplug-bridge-enable.xml
>>
>> --
>> 2.25.1
>>
>>
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