[libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Yi Min Zhao posted 12 patches 10 weeks ago
Failed in applying to current master (apply log)
Test syntax-check passed
docs/formatdomain.html.in                          |   9 +-
docs/news.xml                                      |  11 +
docs/schemas/basictypes.rng                        |  31 ++
docs/schemas/domaincommon.rng                      |   1 +
src/conf/device_conf.c                             |  73 +++++
src/conf/device_conf.h                             |   1 +
src/conf/domain_addr.c                             | 346 +++++++++++++++++++++
src/conf/domain_addr.h                             |  29 ++
src/conf/domain_conf.c                             |   6 +
src/libvirt_private.syms                           |   4 +
src/qemu/qemu_capabilities.c                       |   6 +
src/qemu/qemu_capabilities.h                       |   1 +
src/qemu/qemu_command.c                            | 115 +++++++
src/qemu/qemu_command.h                            |   4 +
src/qemu/qemu_domain.c                             |   1 +
src/qemu/qemu_domain_address.c                     | 181 ++++++++++-
src/qemu/qemu_hotplug.c                            | 182 ++++++++++-
src/util/virpci.h                                  |  13 +
tests/qemucapabilitiesdata/caps_2.10.0.s390x.xml   |   1 +
tests/qemucapabilitiesdata/caps_2.11.0.s390x.xml   |   1 +
tests/qemucapabilitiesdata/caps_2.12.0.s390x.xml   |   1 +
tests/qemucapabilitiesdata/caps_2.7.0.s390x.xml    |   1 +
tests/qemucapabilitiesdata/caps_2.8.0.s390x.xml    |   1 +
tests/qemucapabilitiesdata/caps_2.9.0.s390x.xml    |   1 +
tests/qemuxml2argvdata/disk-virtio-s390-zpci.args  |  27 ++
tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml   |  17 +
.../hostdev-vfio-zpci-autogenerate.args            |  26 ++
.../hostdev-vfio-zpci-autogenerate.xml             |  18 ++
.../hostdev-vfio-zpci-boundaries.args              |  30 ++
.../hostdev-vfio-zpci-boundaries.xml               |  26 ++
.../hostdev-vfio-zpci-multidomain-many.args        |  40 +++
.../hostdev-vfio-zpci-multidomain-many.xml         |  67 ++++
tests/qemuxml2argvdata/hostdev-vfio-zpci.args      |  26 ++
tests/qemuxml2argvdata/hostdev-vfio-zpci.xml       |  19 ++
tests/qemuxml2argvtest.c                           |  14 +
tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml |  29 ++
tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml     |  30 ++
tests/qemuxml2xmltest.c                            |   3 +
38 files changed, 1377 insertions(+), 15 deletions(-)
create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.args
create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.args
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.xml
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.args
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.xml
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.args
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.xml
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.args
create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.xml
create mode 100644 tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml
create mode 100644 tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml

[libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 10 weeks ago
Abstract
========
The PCI representation in QEMU has recently been extended for S390
allowing configuration of zPCI attributes like uid (user-defined
identifier) and fid (PCI function identifier).
The details can be found here:
https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html

To support the new zPCI feature of the S390 platform, two new XML
attributes, @uid and @fid, are introduced for device addresses of type
'pci', i.e.:
  <hostdev mode='subsystem' type='pci'>
    <driver name='vfio'/>
    <source>
      <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
    </source>
    <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
      uid='0x0003' fid='0x00000027'/>
  </hostdev>

uid and fid are optional attributes. If they are defined by the user,
unique values within the guest domain must be used. If they are not
specified and the architecture requires them, they are automatically
generated with non-conflicting values.

Current implementation is the most seamless one for the user as it
unites the address specific data of a PCI device on one XML element.
It could accommodate both specifying our special parameters (uid and fid)
and re-using standard statements (domain, bus, slot and function) for
PCI devices. User can still specify bus/slot/function for the virtualized
PCI devices in the XML.

Thus uid/fid act as an extension to the PCI address and are stored in
a new structure 'virZPCIDeviceAddress' which is a member of common PCI
Address structure. Additionally, two hashtables are used for assignment
and reservation of uid/fid.

In support of extending the PCI address, a new PCI address extension flag is
introduced. This extension flag allows is not only dedicated for the S390
platform but also other architectures needing certain extensions to PCI
address space.

Code Base
=========
commit in master:
767f9e1449b1a36111532847f0c62dc758263c42
qemu: validate: Enforce compile time switch type checking for videos

Change Log
==========
v1->v2:
1. Separate test commit and merge testcases into corresponding commits that
   introduce the functionalities firstly.
2. Spare some checks for zpci device.
3. Add vsock and controller support.
4. Add uin32 type schema.
5. Rename zpciuid and zpcifid to zpci_uid and zpci_fid.
6. Always return multibus support on S390.

Yi Min Zhao (12):
  conf: Add definitions for 'uid' and 'fid' PCI address attributes
  qemu: Introduce zPCI capability
  conf: Introduce a new PCI address extension flag
  qemu: Enable PCI multi bus for S390 guests
  qemu: Auto add pci-root for s390/s390x guests
  conf: Introduce address caching for PCI extensions
  conf: Introduce parser, formatter for uid and fid
  conf: Allocate/release 'uid' and 'fid' in PCI address
  qemu: Generate and use zPCI device in QEMU command line
  qemu: Add hotpluging support for PCI devices on S390 guests
  docs: Add 'uid' and 'fid' information
  news: Update news for PCI address extension attributes

 docs/formatdomain.html.in                          |   9 +-
 docs/news.xml                                      |  11 +
 docs/schemas/basictypes.rng                        |  31 ++
 docs/schemas/domaincommon.rng                      |   1 +
 src/conf/device_conf.c                             |  73 +++++
 src/conf/device_conf.h                             |   1 +
 src/conf/domain_addr.c                             | 346 +++++++++++++++++++++
 src/conf/domain_addr.h                             |  29 ++
 src/conf/domain_conf.c                             |   6 +
 src/libvirt_private.syms                           |   4 +
 src/qemu/qemu_capabilities.c                       |   6 +
 src/qemu/qemu_capabilities.h                       |   1 +
 src/qemu/qemu_command.c                            | 115 +++++++
 src/qemu/qemu_command.h                            |   4 +
 src/qemu/qemu_domain.c                             |   1 +
 src/qemu/qemu_domain_address.c                     | 181 ++++++++++-
 src/qemu/qemu_hotplug.c                            | 182 ++++++++++-
 src/util/virpci.h                                  |  13 +
 tests/qemucapabilitiesdata/caps_2.10.0.s390x.xml   |   1 +
 tests/qemucapabilitiesdata/caps_2.11.0.s390x.xml   |   1 +
 tests/qemucapabilitiesdata/caps_2.12.0.s390x.xml   |   1 +
 tests/qemucapabilitiesdata/caps_2.7.0.s390x.xml    |   1 +
 tests/qemucapabilitiesdata/caps_2.8.0.s390x.xml    |   1 +
 tests/qemucapabilitiesdata/caps_2.9.0.s390x.xml    |   1 +
 tests/qemuxml2argvdata/disk-virtio-s390-zpci.args  |  27 ++
 tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml   |  17 +
 .../hostdev-vfio-zpci-autogenerate.args            |  26 ++
 .../hostdev-vfio-zpci-autogenerate.xml             |  18 ++
 .../hostdev-vfio-zpci-boundaries.args              |  30 ++
 .../hostdev-vfio-zpci-boundaries.xml               |  26 ++
 .../hostdev-vfio-zpci-multidomain-many.args        |  40 +++
 .../hostdev-vfio-zpci-multidomain-many.xml         |  67 ++++
 tests/qemuxml2argvdata/hostdev-vfio-zpci.args      |  26 ++
 tests/qemuxml2argvdata/hostdev-vfio-zpci.xml       |  19 ++
 tests/qemuxml2argvtest.c                           |  14 +
 tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml |  29 ++
 tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml     |  30 ++
 tests/qemuxml2xmltest.c                            |   3 +
 38 files changed, 1377 insertions(+), 15 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.args
 create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.args
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.xml
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.args
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.xml
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.args
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.xml
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.args
 create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.xml
 create mode 100644 tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml
 create mode 100644 tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml

-- 
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Cornelia Huck 9 weeks ago
On Tue, 10 Jul 2018 16:02:14 +0800
Yi Min Zhao <zyimin@linux.ibm.com> wrote:

> Abstract
> ========
> The PCI representation in QEMU has recently been extended for S390
> allowing configuration of zPCI attributes like uid (user-defined
> identifier) and fid (PCI function identifier).
> The details can be found here:
> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
> 
> To support the new zPCI feature of the S390 platform, two new XML
> attributes, @uid and @fid, are introduced for device addresses of type
> 'pci', i.e.:
>   <hostdev mode='subsystem' type='pci'>
>     <driver name='vfio'/>
>     <source>
>       <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>     </source>
>     <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
>       uid='0x0003' fid='0x00000027'/>
>   </hostdev>
> 
> uid and fid are optional attributes. If they are defined by the user,
> unique values within the guest domain must be used. If they are not
> specified and the architecture requires them, they are automatically
> generated with non-conflicting values.
> 
> Current implementation is the most seamless one for the user as it
> unites the address specific data of a PCI device on one XML element.
> It could accommodate both specifying our special parameters (uid and fid)
> and re-using standard statements (domain, bus, slot and function) for
> PCI devices. User can still specify bus/slot/function for the virtualized
> PCI devices in the XML.
> 
> Thus uid/fid act as an extension to the PCI address and are stored in
> a new structure 'virZPCIDeviceAddress' which is a member of common PCI
> Address structure. Additionally, two hashtables are used for assignment
> and reservation of uid/fid.
> 
> In support of extending the PCI address, a new PCI address extension flag is
> introduced. This extension flag allows is not only dedicated for the S390
> platform but also other architectures needing certain extensions to PCI
> address space.

FWIW, from my QEMU POV there's nothing obviously wrong in here, but I'm
not familiar with the libvirt code base. So I'll leave this to the
libvirt developers.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 9 weeks ago

在 2018/7/17 下午8:35, Cornelia Huck 写道:
> On Tue, 10 Jul 2018 16:02:14 +0800
> Yi Min Zhao <zyimin@linux.ibm.com> wrote:
>
>> Abstract
>> ========
>> The PCI representation in QEMU has recently been extended for S390
>> allowing configuration of zPCI attributes like uid (user-defined
>> identifier) and fid (PCI function identifier).
>> The details can be found here:
>> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
>>
>> To support the new zPCI feature of the S390 platform, two new XML
>> attributes, @uid and @fid, are introduced for device addresses of type
>> 'pci', i.e.:
>>    <hostdev mode='subsystem' type='pci'>
>>      <driver name='vfio'/>
>>      <source>
>>        <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>>      </source>
>>      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
>>        uid='0x0003' fid='0x00000027'/>
>>    </hostdev>
>>
>> uid and fid are optional attributes. If they are defined by the user,
>> unique values within the guest domain must be used. If they are not
>> specified and the architecture requires them, they are automatically
>> generated with non-conflicting values.
>>
>> Current implementation is the most seamless one for the user as it
>> unites the address specific data of a PCI device on one XML element.
>> It could accommodate both specifying our special parameters (uid and fid)
>> and re-using standard statements (domain, bus, slot and function) for
>> PCI devices. User can still specify bus/slot/function for the virtualized
>> PCI devices in the XML.
>>
>> Thus uid/fid act as an extension to the PCI address and are stored in
>> a new structure 'virZPCIDeviceAddress' which is a member of common PCI
>> Address structure. Additionally, two hashtables are used for assignment
>> and reservation of uid/fid.
>>
>> In support of extending the PCI address, a new PCI address extension flag is
>> introduced. This extension flag allows is not only dedicated for the S390
>> platform but also other architectures needing certain extensions to PCI
>> address space.
> FWIW, from my QEMU POV there's nothing obviously wrong in here, but I'm
> not familiar with the libvirt code base. So I'll leave this to the
> libvirt developers.
>
>
Thanks! Libvirt developers have not given any comment on v2 until now.
I'm afraid the end of this month is coming soon.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 9 weeks ago
Hi all,

The next release is coming soon. I'm really expecting the comments from 
all of you.

Hope you could consider a review before the next review.

Thank you very much!

Yi Min

在 2018/7/10 下午4:02, Yi Min Zhao 写道:
> Abstract
> ========
> The PCI representation in QEMU has recently been extended for S390
> allowing configuration of zPCI attributes like uid (user-defined
> identifier) and fid (PCI function identifier).
> The details can be found here:
> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
>
> To support the new zPCI feature of the S390 platform, two new XML
> attributes, @uid and @fid, are introduced for device addresses of type
> 'pci', i.e.:
>    <hostdev mode='subsystem' type='pci'>
>      <driver name='vfio'/>
>      <source>
>        <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>      </source>
>      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
>        uid='0x0003' fid='0x00000027'/>
>    </hostdev>
>
> uid and fid are optional attributes. If they are defined by the user,
> unique values within the guest domain must be used. If they are not
> specified and the architecture requires them, they are automatically
> generated with non-conflicting values.
>
> Current implementation is the most seamless one for the user as it
> unites the address specific data of a PCI device on one XML element.
> It could accommodate both specifying our special parameters (uid and fid)
> and re-using standard statements (domain, bus, slot and function) for
> PCI devices. User can still specify bus/slot/function for the virtualized
> PCI devices in the XML.
>
> Thus uid/fid act as an extension to the PCI address and are stored in
> a new structure 'virZPCIDeviceAddress' which is a member of common PCI
> Address structure. Additionally, two hashtables are used for assignment
> and reservation of uid/fid.
>
> In support of extending the PCI address, a new PCI address extension flag is
> introduced. This extension flag allows is not only dedicated for the S390
> platform but also other architectures needing certain extensions to PCI
> address space.
>
> Code Base
> =========
> commit in master:
> 767f9e1449b1a36111532847f0c62dc758263c42
> qemu: validate: Enforce compile time switch type checking for videos
>
> Change Log
> ==========
> v1->v2:
> 1. Separate test commit and merge testcases into corresponding commits that
>     introduce the functionalities firstly.
> 2. Spare some checks for zpci device.
> 3. Add vsock and controller support.
> 4. Add uin32 type schema.
> 5. Rename zpciuid and zpcifid to zpci_uid and zpci_fid.
> 6. Always return multibus support on S390.
>
> Yi Min Zhao (12):
>    conf: Add definitions for 'uid' and 'fid' PCI address attributes
>    qemu: Introduce zPCI capability
>    conf: Introduce a new PCI address extension flag
>    qemu: Enable PCI multi bus for S390 guests
>    qemu: Auto add pci-root for s390/s390x guests
>    conf: Introduce address caching for PCI extensions
>    conf: Introduce parser, formatter for uid and fid
>    conf: Allocate/release 'uid' and 'fid' in PCI address
>    qemu: Generate and use zPCI device in QEMU command line
>    qemu: Add hotpluging support for PCI devices on S390 guests
>    docs: Add 'uid' and 'fid' information
>    news: Update news for PCI address extension attributes
>
>   docs/formatdomain.html.in                          |   9 +-
>   docs/news.xml                                      |  11 +
>   docs/schemas/basictypes.rng                        |  31 ++
>   docs/schemas/domaincommon.rng                      |   1 +
>   src/conf/device_conf.c                             |  73 +++++
>   src/conf/device_conf.h                             |   1 +
>   src/conf/domain_addr.c                             | 346 +++++++++++++++++++++
>   src/conf/domain_addr.h                             |  29 ++
>   src/conf/domain_conf.c                             |   6 +
>   src/libvirt_private.syms                           |   4 +
>   src/qemu/qemu_capabilities.c                       |   6 +
>   src/qemu/qemu_capabilities.h                       |   1 +
>   src/qemu/qemu_command.c                            | 115 +++++++
>   src/qemu/qemu_command.h                            |   4 +
>   src/qemu/qemu_domain.c                             |   1 +
>   src/qemu/qemu_domain_address.c                     | 181 ++++++++++-
>   src/qemu/qemu_hotplug.c                            | 182 ++++++++++-
>   src/util/virpci.h                                  |  13 +
>   tests/qemucapabilitiesdata/caps_2.10.0.s390x.xml   |   1 +
>   tests/qemucapabilitiesdata/caps_2.11.0.s390x.xml   |   1 +
>   tests/qemucapabilitiesdata/caps_2.12.0.s390x.xml   |   1 +
>   tests/qemucapabilitiesdata/caps_2.7.0.s390x.xml    |   1 +
>   tests/qemucapabilitiesdata/caps_2.8.0.s390x.xml    |   1 +
>   tests/qemucapabilitiesdata/caps_2.9.0.s390x.xml    |   1 +
>   tests/qemuxml2argvdata/disk-virtio-s390-zpci.args  |  27 ++
>   tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml   |  17 +
>   .../hostdev-vfio-zpci-autogenerate.args            |  26 ++
>   .../hostdev-vfio-zpci-autogenerate.xml             |  18 ++
>   .../hostdev-vfio-zpci-boundaries.args              |  30 ++
>   .../hostdev-vfio-zpci-boundaries.xml               |  26 ++
>   .../hostdev-vfio-zpci-multidomain-many.args        |  40 +++
>   .../hostdev-vfio-zpci-multidomain-many.xml         |  67 ++++
>   tests/qemuxml2argvdata/hostdev-vfio-zpci.args      |  26 ++
>   tests/qemuxml2argvdata/hostdev-vfio-zpci.xml       |  19 ++
>   tests/qemuxml2argvtest.c                           |  14 +
>   tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml |  29 ++
>   tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml     |  30 ++
>   tests/qemuxml2xmltest.c                            |   3 +
>   38 files changed, 1377 insertions(+), 15 deletions(-)
>   create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.args
>   create mode 100644 tests/qemuxml2argvdata/disk-virtio-s390-zpci.xml
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.args
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-autogenerate.xml
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.args
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-boundaries.xml
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.args
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci-multidomain-many.xml
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.args
>   create mode 100644 tests/qemuxml2argvdata/hostdev-vfio-zpci.xml
>   create mode 100644 tests/qemuxml2xmloutdata/disk-virtio-s390-zpci.xml
>   create mode 100644 tests/qemuxml2xmloutdata/hostdev-vfio-zpci.xml
>

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Ján Tomko 9 weeks ago
On Tue, Jul 10, 2018 at 04:02:14PM +0800, Yi Min Zhao wrote:
>Abstract
>========
>The PCI representation in QEMU has recently been extended for S390
>allowing configuration of zPCI attributes like uid (user-defined
>identifier) and fid (PCI function identifier).
>The details can be found here:
>https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
>
>To support the new zPCI feature of the S390 platform, two new XML
>attributes, @uid and @fid, are introduced for device addresses of type
>'pci', i.e.:
>  <hostdev mode='subsystem' type='pci'>
>    <driver name='vfio'/>
>    <source>
>      <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>    </source>
>    <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
>      uid='0x0003' fid='0x00000027'/>
>  </hostdev>
>
>uid and fid are optional attributes. If they are defined by the user,
>unique values within the guest domain must be used. If they are not
>specified and the architecture requires them, they are automatically
>generated with non-conflicting values.
>
>Current implementation is the most seamless one for the user as it
>unites the address specific data of a PCI device on one XML element.
>It could accommodate both specifying our special parameters (uid and fid)
>and re-using standard statements (domain, bus, slot and function) for
>PCI devices. User can still specify bus/slot/function for the virtualized
>PCI devices in the XML.
>
>Thus uid/fid act as an extension to the PCI address and are stored in
>a new structure 'virZPCIDeviceAddress' which is a member of common PCI
>Address structure. Additionally, two hashtables are used for assignment
>and reservation of uid/fid.
>
>In support of extending the PCI address, a new PCI address extension flag is
>introduced. This extension flag allows is not only dedicated for the S390
>platform but also other architectures needing certain extensions to PCI
>address space.
>
>Code Base
>=========
>commit in master:
>767f9e1449b1a36111532847f0c62dc758263c42
>qemu: validate: Enforce compile time switch type checking for videos
>
>Change Log
>==========
>v1->v2:
>1. Separate test commit and merge testcases into corresponding commits that
>   introduce the functionalities firstly.
>2. Spare some checks for zpci device.
>3. Add vsock and controller support.
>4. Add uin32 type schema.
>5. Rename zpciuid and zpcifid to zpci_uid and zpci_fid.
>6. Always return multibus support on S390.
>
>Yi Min Zhao (12):
>  conf: Add definitions for 'uid' and 'fid' PCI address attributes
>  qemu: Introduce zPCI capability
>  conf: Introduce a new PCI address extension flag
>  qemu: Enable PCI multi bus for S390 guests
>  qemu: Auto add pci-root for s390/s390x guests
>  conf: Introduce address caching for PCI extensions
>  conf: Introduce parser, formatter for uid and fid
>  conf: Allocate/release 'uid' and 'fid' in PCI address
>  qemu: Generate and use zPCI device in QEMU command line
>  qemu: Add hotpluging support for PCI devices on S390 guests
>  docs: Add 'uid' and 'fid' information
>  news: Update news for PCI address extension attributes
>

The patches look OK to me, therefore:

Reviewed-by: J�n Tomko <jtomko@redhat.com>

But I'd like to hear from some other developer who touched the PCI code
last (Laine? Andrea?)

Jano
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Laine Stump 9 weeks ago
On Mon, Jul 23, 2018, 2:37 PM Ján Tomko <jtomko@redhat.com> wrote:

>
> But I'd like to hear from some other developer who touched the PCI code
> last (Laine? Andrea?)
>

I'm looking at this on the screen of my phone as I stare out the hotel
window at an afternoon rainstorm over Razgrad, Bulgaria, and won't be back
to my office for another week, so I'm afraid I'm not in much of a position
to make any useful comment :-)

>
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Mon, 2018-07-23 at 13:37 +0200, Ján Tomko wrote:
> On Tue, Jul 10, 2018 at 04:02:14PM +0800, Yi Min Zhao wrote:
> > Abstract
> > ========
> > The PCI representation in QEMU has recently been extended for S390
> > allowing configuration of zPCI attributes like uid (user-defined
> > identifier) and fid (PCI function identifier).
> > The details can be found here:
> > https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
> > 
> > To support the new zPCI feature of the S390 platform, two new XML
> > attributes, @uid and @fid, are introduced for device addresses of type
> > 'pci', i.e.:
> >  <hostdev mode='subsystem' type='pci'>
> >    <driver name='vfio'/>
> >    <source>
> >      <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
> >    </source>
> >    <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
> >      uid='0x0003' fid='0x00000027'/>
> >  </hostdev>
> > 
> > uid and fid are optional attributes. If they are defined by the user,
> > unique values within the guest domain must be used. If they are not
> > specified and the architecture requires them, they are automatically
> > generated with non-conflicting values.
> > 
> > Current implementation is the most seamless one for the user as it
> > unites the address specific data of a PCI device on one XML element.
> > It could accommodate both specifying our special parameters (uid and fid)
> > and re-using standard statements (domain, bus, slot and function) for
> > PCI devices. User can still specify bus/slot/function for the virtualized
> > PCI devices in the XML.
> > 
> > Thus uid/fid act as an extension to the PCI address and are stored in
> > a new structure 'virZPCIDeviceAddress' which is a member of common PCI
> > Address structure. Additionally, two hashtables are used for assignment
> > and reservation of uid/fid.
> > 
> > In support of extending the PCI address, a new PCI address extension flag is
> > introduced. This extension flag allows is not only dedicated for the S390
> > platform but also other architectures needing certain extensions to PCI
> > address space.
[...]
> 
> The patches look OK to me, therefore:
> 
> Reviewed-by: Ján Tomko <jtomko@redhat.com>
> 
> But I'd like to hear from some other developer who touched the PCI code
> last (Laine? Andrea?)

Thanks for bringing this to my attention - it had somehow managed
to escape my radar so far :)

I've quickly gone through the patches and spotted some minor code
style issues that I'd like to see addressed (I'll point them out
separately); first, though, I have a couple of questions about the
general idea behind the feature.

Looking at both the generated QEMU command line and the qemu-devel
message linked above, I seem to understand the zpci device is
basically some sort of adapter that sits between a regular PCI
device (emulated or otherwise) and an s390 guest and presents an
ID-based interface to the latter; so IIUC the s390 guest doesn't
actually see a PCI device, but a couple of IDs that can (somehow)
be used to access the underlying PCI device.

>From whatever little s390 knowledge I have, I recall the
architecture using peculiar ways to address and access devices, so
PCI not being usable wouldn't surprise me that much; what I find
odd, however, is that regular PCI seems to be available at least
on the host side, because otherwise stuff like

  -device zpci,uid=1,fid=1,target=vpci0
  -device vfio-pci,host=0000:00:00.0,id=vpci0

wouldn't be possible. So, would anyone with s390 knowledge please
spend a few words explaining how the various pieces fit together?

Assuming the above is a correct reading of the situation, it
would seem the IDs are the only guest-visible part that we need
to make sure doesn't change during the lifetime of the guest,
while the usual bus/slot/function triplet assigned to the
underlying PCI device doesn't actually matter. And if that's the
case, wouldn't something like

  <address type='zpci' uid='1' fid='1'/>

be a better representation of the arrangement? We could leave it
up to QEMU to assign addresses to the PCI devices in this case...
But maybe they still matter for things such as migration? Or maybe
I've just gotten it wrong altogether? :)

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Cornelia Huck 8 weeks ago
On Tue, 24 Jul 2018 10:20:48 +0200
Andrea Bolognani <abologna@redhat.com> wrote:

> Looking at both the generated QEMU command line and the qemu-devel
> message linked above, I seem to understand the zpci device is
> basically some sort of adapter that sits between a regular PCI
> device (emulated or otherwise) and an s390 guest and presents an
> ID-based interface to the latter; so IIUC the s390 guest doesn't
> actually see a PCI device, but a couple of IDs that can (somehow)
> be used to access the underlying PCI device.
> 
> From whatever little s390 knowledge I have, I recall the
> architecture using peculiar ways to address and access devices, so
> PCI not being usable wouldn't surprise me that much; what I find
> odd, however, is that regular PCI seems to be available at least
> on the host side, because otherwise stuff like
> 
>   -device zpci,uid=1,fid=1,target=vpci0
>   -device vfio-pci,host=0000:00:00.0,id=vpci0
> 
> wouldn't be possible. So, would anyone with s390 knowledge please
> spend a few words explaining how the various pieces fit together?

For some hints, let me point to
https://virtualpenguins.blogspot.de/2018/02/notes-on-pci-on-s390x.html
-- for implementation details, I'll point to the IBM folks :)

> 
> Assuming the above is a correct reading of the situation, it
> would seem the IDs are the only guest-visible part that we need
> to make sure doesn't change during the lifetime of the guest,
> while the usual bus/slot/function triplet assigned to the
> underlying PCI device doesn't actually matter. And if that's the
> case, wouldn't something like
> 
>   <address type='zpci' uid='1' fid='1'/>
> 
> be a better representation of the arrangement? We could leave it
> up to QEMU to assign addresses to the PCI devices in this case...
> But maybe they still matter for things such as migration? Or maybe
> I've just gotten it wrong altogether? :)
> 

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Boris Fiuczynski 8 weeks ago
On 07/24/2018 10:20 AM, Andrea Bolognani wrote:
> On Mon, 2018-07-23 at 13:37 +0200, Ján Tomko wrote:
>> On Tue, Jul 10, 2018 at 04:02:14PM +0800, Yi Min Zhao wrote:
>>> Abstract
>>> ========
>>> The PCI representation in QEMU has recently been extended for S390
>>> allowing configuration of zPCI attributes like uid (user-defined
>>> identifier) and fid (PCI function identifier).
>>> The details can be found here:
>>> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
>>>
>>> To support the new zPCI feature of the S390 platform, two new XML
>>> attributes, @uid and @fid, are introduced for device addresses of type
>>> 'pci', i.e.:
>>>   <hostdev mode='subsystem' type='pci'>
>>>     <driver name='vfio'/>
>>>     <source>
>>>       <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>>>     </source>
>>>     <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'
>>>       uid='0x0003' fid='0x00000027'/>
>>>   </hostdev>
>>>
>>> uid and fid are optional attributes. If they are defined by the user,
>>> unique values within the guest domain must be used. If they are not
>>> specified and the architecture requires them, they are automatically
>>> generated with non-conflicting values.
>>>
>>> Current implementation is the most seamless one for the user as it
>>> unites the address specific data of a PCI device on one XML element.
>>> It could accommodate both specifying our special parameters (uid and fid)
>>> and re-using standard statements (domain, bus, slot and function) for
>>> PCI devices. User can still specify bus/slot/function for the virtualized
>>> PCI devices in the XML.
>>>
>>> Thus uid/fid act as an extension to the PCI address and are stored in
>>> a new structure 'virZPCIDeviceAddress' which is a member of common PCI
>>> Address structure. Additionally, two hashtables are used for assignment
>>> and reservation of uid/fid.
>>>
>>> In support of extending the PCI address, a new PCI address extension flag is
>>> introduced. This extension flag allows is not only dedicated for the S390
>>> platform but also other architectures needing certain extensions to PCI
>>> address space.
> [...]
>>
>> The patches look OK to me, therefore:
>>
>> Reviewed-by: Ján Tomko <jtomko@redhat.com>
>>
>> But I'd like to hear from some other developer who touched the PCI code
>> last (Laine? Andrea?)
> 
> Thanks for bringing this to my attention - it had somehow managed
> to escape my radar so far :)
> 
> I've quickly gone through the patches and spotted some minor code
> style issues that I'd like to see addressed (I'll point them out
> separately); first, though, I have a couple of questions about the
> general idea behind the feature.
> 
> Looking at both the generated QEMU command line and the qemu-devel
> message linked above, I seem to understand the zpci device is
> basically some sort of adapter that sits between a regular PCI
> device (emulated or otherwise) and an s390 guest and presents an
> ID-based interface to the latter; so IIUC the s390 guest doesn't
> actually see a PCI device, but a couple of IDs that can (somehow)
> be used to access the underlying PCI device.
> 
>>From whatever little s390 knowledge I have, I recall the
> architecture using peculiar ways to address and access devices, so
> PCI not being usable wouldn't surprise me that much; what I find
> odd, however, is that regular PCI seems to be available at least
> on the host side, because otherwise stuff like
> 
>    -device zpci,uid=1,fid=1,target=vpci0
>    -device vfio-pci,host=0000:00:00.0,id=vpci0
> 
> wouldn't be possible. So, would anyone with s390 knowledge please
> spend a few words explaining how the various pieces fit together?
> 
> Assuming the above is a correct reading of the situation, it
> would seem the IDs are the only guest-visible part that we need
> to make sure doesn't change during the lifetime of the guest,
> while the usual bus/slot/function triplet assigned to the
> underlying PCI device doesn't actually matter. And if that's the
> case, wouldn't something like
> 
>    <address type='zpci' uid='1' fid='1'/>

Then a pci device on s390 would need a special address type zpci in 
libvirt and the design idea for libvirt is to stay compatible with pci.
Therefore uid and fid are optional attributes and if not specified on 
s390 they are generated. The patch series also allows on s390 to specify 
the pci address type just with attributes uid and/or fid causing the 
rest of the pci address attributes to be generated.
That means
<address type='pci' uid='1' fid='1'/>
is a valid pci address on s390 but would get expanded during definition 
into e.g.
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' 
function='0x0' uid='1' fid='1'/>
Also
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'>
is a valid pci address on s390 and is would be expanded during 
definition into e.g.
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' 
function='0x0' uid='1' fid='1'/>


> 
> be a better representation of the arrangement? We could leave it
> up to QEMU to assign addresses to the PCI devices in this case...
> But maybe they still matter for things such as migration? Or maybe
> I've just gotten it wrong altogether? :)
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martina Köderitz
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Tue, 2018-07-24 at 11:31 +0200, Boris Fiuczynski wrote:
> On 07/24/2018 10:20 AM, Andrea Bolognani wrote:
> > Assuming the above is a correct reading of the situation, it
> > would seem the IDs are the only guest-visible part that we need
> > to make sure doesn't change during the lifetime of the guest,
> > while the usual bus/slot/function triplet assigned to the
> > underlying PCI device doesn't actually matter. And if that's the
> > case, wouldn't something like
> > 
> >    <address type='zpci' uid='1' fid='1'/>
> 
> Then a pci device on s390 would need a special address type zpci in 
> libvirt and the design idea for libvirt is to stay compatible with pci.

Being compatible with the existing PCI machinery is certainly a
good idea when it makes sense to do so, but I'm not quite convinced
that is the case here.

According to Cornelia's blog post on the subject, the PCI topology
inside the guest will be determined entirely by the IDs. Is there
even a way to eg. use bridges to create a non-flat PCI hierarchy?
Or to have several PCI devices share the same bus or slot?

If none of the above applies, then that doesn't look a whole lot
like PCI to me :)

Moreover, we already have several address types in addition to PCI
such as USB, virtio-mmio, spapr-vio, ccw... Adding yet another one
is not a problem if it makes the interface more sensible.

More concrete questions: one of the zPCI test cases includes

    <controller type='pci' index='1' model='pci-bridge'/>
    <hostdev mode='subsystem' type='pci' managed='no'>
      <driver name='vfio'/>
      <source>
        <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
               function='0x0' uid='0xffff' fid='0xffffffff'/>
    </hostdev>

which translates to

  -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
  -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
  -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
  -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \

How does the pci-bridge controller show up in the guest, if at all?

Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
example above matter eg. for migration purposes?

> Therefore uid and fid are optional attributes and if not specified on 
> s390 they are generated. The patch series also allows on s390 to specify 
> the pci address type just with attributes uid and/or fid causing the 
> rest of the pci address attributes to be generated.

This goes without saying: users should not have to worry about
addresses at all unless they have very specific needs.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Boris Fiuczynski 8 weeks ago
On 07/24/2018 03:41 PM, Andrea Bolognani wrote:
> On Tue, 2018-07-24 at 11:31 +0200, Boris Fiuczynski wrote:
>> On 07/24/2018 10:20 AM, Andrea Bolognani wrote:
>>> Assuming the above is a correct reading of the situation, it
>>> would seem the IDs are the only guest-visible part that we need
>>> to make sure doesn't change during the lifetime of the guest,
>>> while the usual bus/slot/function triplet assigned to the
>>> underlying PCI device doesn't actually matter. And if that's the
>>> case, wouldn't something like
>>>
>>>     <address type='zpci' uid='1' fid='1'/>
>>
>> Then a pci device on s390 would need a special address type zpci in
>> libvirt and the design idea for libvirt is to stay compatible with pci.
> 
> Being compatible with the existing PCI machinery is certainly a
> good idea when it makes sense to do so, but I'm not quite convinced
> that is the case here.

 From a user perspective:
I take your example below and reduce it to pci only like this:

     <controller type='pci' index='1' model='pci-bridge'/>
     <hostdev mode='subsystem' type='pci' managed='no'>
       <driver name='vfio'/>
       <source>
         <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
       </source>
       <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
                function='0x0'/>
     </hostdev>

This works on x86 as well as on s390 where as your suggested zpci 
address type would not allow this. This is what I wanted to express with 
the word "compatible".
As I wrote before: It would also be valid for a user to not care about 
the attributes domain, bus, slot and function and reduce the specified 
set of attributes to e.g. <address type='pci' uid='0xffff'/>

> 
> According to Cornelia's blog post on the subject, the PCI topology
> inside the guest will be determined entirely by the IDs. Is there
> even a way to eg. use bridges to create a non-flat PCI hierarchy?
> Or to have several PCI devices share the same bus or slot?
> 
> If none of the above applies, then that doesn't look a whole lot
> like PCI to me :)
> 
> Moreover, we already have several address types in addition to PCI
> such as USB, virtio-mmio, spapr-vio, ccw... Adding yet another one
> is not a problem if it makes the interface more sensible.
Sure you can add one more but wouldn't you end up with e.g. a hostdev 
model vfio-pci with an address type of pci on all pci supporting 
architectures but s390 where you need to use zpci? What would be the 
benefit for the user or higher level management software? Actually I 
would not like to introduce special handling unless required.

> 
> More concrete questions: one of the zPCI test cases includes
> 
>      <controller type='pci' index='1' model='pci-bridge'/>
>      <hostdev mode='subsystem' type='pci' managed='no'>
>        <driver name='vfio'/>
>        <source>
>          <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>        </source>
>        <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
>                 function='0x0' uid='0xffff' fid='0xffffffff'/>
>      </hostdev>
> 
> which translates to
> 
>    -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
>    -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
>    -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
>    -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \
> 
> How does the pci-bridge controller show up in the guest, if at all?
> 
> Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
> example above matter eg. for migration purposes?
> 
>> Therefore uid and fid are optional attributes and if not specified on
>> s390 they are generated. The patch series also allows on s390 to specify
>> the pci address type just with attributes uid and/or fid causing the
>> rest of the pci address attributes to be generated.
> 
> This goes without saying: users should not have to worry about
> addresses at all unless they have very specific needs.
> 


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    Boris Fiuczynski

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Tue, 2018-07-24 at 17:15 +0200, Boris Fiuczynski wrote:
> On 07/24/2018 03:41 PM, Andrea Bolognani wrote:
> > Being compatible with the existing PCI machinery is certainly a
> > good idea when it makes sense to do so, but I'm not quite convinced
> > that is the case here.
> 
>  From a user perspective:
> I take your example below and reduce it to pci only like this:
> 
>      <controller type='pci' index='1' model='pci-bridge'/>
>      <hostdev mode='subsystem' type='pci' managed='no'>
>        <driver name='vfio'/>
>        <source>
>          <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>        </source>
>        <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
>                 function='0x0'/>
>      </hostdev>
> 
> This works on x86 as well as on s390 where as your suggested zpci 
> address type would not allow this. This is what I wanted to express with 
> the word "compatible".
> As I wrote before: It would also be valid for a user to not care about 
> the attributes domain, bus, slot and function and reduce the specified 
> set of attributes to e.g. <address type='pci' uid='0xffff'/>

That's not really what users and management applications pass to
libvirt, though: a more realistic example would be

  <hostdev mode='subsystem' type='pci'>
    <driver name='vfio'/>
    <source>
      <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
    </source>
  </hostdev>

eg. you specify the host address and leave coming up with a
suitable guest address entirely up to libvirt, in which case
whether the resulting address is type=pci or type=zpci hardly
matters.

If you want to take device address assignment upon yourself, then
you're gonna have to assign addresses to controllers as well, not
to mention specify the entire PCI topology with all which that
entails... Not exactly a common scenario.

> > According to Cornelia's blog post on the subject, the PCI topology
> > inside the guest will be determined entirely by the IDs. Is there
> > even a way to eg. use bridges to create a non-flat PCI hierarchy?
> > Or to have several PCI devices share the same bus or slot?
> > 
> > If none of the above applies, then that doesn't look a whole lot
> > like PCI to me :)
> > 
> > Moreover, we already have several address types in addition to PCI
> > such as USB, virtio-mmio, spapr-vio, ccw... Adding yet another one
> > is not a problem if it makes the interface more sensible.
> 
> Sure you can add one more but wouldn't you end up with e.g. a hostdev 
> model vfio-pci with an address type of pci on all pci supporting 
> architectures but s390 where you need to use zpci? What would be the 
> benefit for the user or higher level management software? Actually I 
> would not like to introduce special handling unless required.

I'm all for offering users an interface that abstracts as many
platform-specific quirks as possible, but there's a balance to be
found and we should be careful not to lean too much the opposite
way.

With my current understanding, it doesn't look to me like zPCI
behaves similarly enough to how PCI behaves on other platforms
for us to sensibly describe both using the same interface, and
the fact that QEMU had to come up with a specific middleware
device seems to confirm my suspicion...

In any case, would you mind answering the questions below? That
would certainly help me gain a better understanding of the whole
issue.

> > More concrete questions: one of the zPCI test cases includes
> > 
> >      <controller type='pci' index='1' model='pci-bridge'/>
> >      <hostdev mode='subsystem' type='pci' managed='no'>
> >        <driver name='vfio'/>
> >        <source>
> >          <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
> >        </source>
> >        <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
> >                 function='0x0' uid='0xffff' fid='0xffffffff'/>
> >      </hostdev>
> > 
> > which translates to
> > 
> >    -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
> >    -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
> >    -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
> >    -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \
> > 
> > How does the pci-bridge controller show up in the guest, if at all?
> > 
> > Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
> > example above matter eg. for migration purposes?

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 8 weeks ago

在 2018/7/24 下午11:43, Andrea Bolognani 写道:
> On Tue, 2018-07-24 at 17:15 +0200, Boris Fiuczynski wrote:
>> On 07/24/2018 03:41 PM, Andrea Bolognani wrote:
>>> Being compatible with the existing PCI machinery is certainly a
>>> good idea when it makes sense to do so, but I'm not quite convinced
>>> that is the case here.
>>   From a user perspective:
>> I take your example below and reduce it to pci only like this:
>>
>>       <controller type='pci' index='1' model='pci-bridge'/>
>>       <hostdev mode='subsystem' type='pci' managed='no'>
>>         <driver name='vfio'/>
>>         <source>
>>           <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>>         </source>
>>         <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
>>                  function='0x0'/>
>>       </hostdev>
>>
>> This works on x86 as well as on s390 where as your suggested zpci
>> address type would not allow this. This is what I wanted to express with
>> the word "compatible".
>> As I wrote before: It would also be valid for a user to not care about
>> the attributes domain, bus, slot and function and reduce the specified
>> set of attributes to e.g. <address type='pci' uid='0xffff'/>
> That's not really what users and management applications pass to
> libvirt, though: a more realistic example would be
>
>    <hostdev mode='subsystem' type='pci'>
>      <driver name='vfio'/>
>      <source>
>        <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>      </source>
>    </hostdev>
>
> eg. you specify the host address and leave coming up with a
> suitable guest address entirely up to libvirt, in which case
> whether the resulting address is type=pci or type=zpci hardly
> matters.
>
> If you want to take device address assignment upon yourself, then
> you're gonna have to assign addresses to controllers as well, not
> to mention specify the entire PCI topology with all which that
> entails... Not exactly a common scenario.
>
>>> According to Cornelia's blog post on the subject, the PCI topology
>>> inside the guest will be determined entirely by the IDs. Is there
>>> even a way to eg. use bridges to create a non-flat PCI hierarchy?
>>> Or to have several PCI devices share the same bus or slot?
>>>
>>> If none of the above applies, then that doesn't look a whole lot
>>> like PCI to me :)
>>>
>>> Moreover, we already have several address types in addition to PCI
>>> such as USB, virtio-mmio, spapr-vio, ccw... Adding yet another one
>>> is not a problem if it makes the interface more sensible.
>> Sure you can add one more but wouldn't you end up with e.g. a hostdev
>> model vfio-pci with an address type of pci on all pci supporting
>> architectures but s390 where you need to use zpci? What would be the
>> benefit for the user or higher level management software? Actually I
>> would not like to introduce special handling unless required.
> I'm all for offering users an interface that abstracts as many
> platform-specific quirks as possible, but there's a balance to be
> found and we should be careful not to lean too much the opposite
> way.
>
> With my current understanding, it doesn't look to me like zPCI
> behaves similarly enough to how PCI behaves on other platforms
> for us to sensibly describe both using the same interface, and
> the fact that QEMU had to come up with a specific middleware
> device seems to confirm my suspicion...
>
> In any case, would you mind answering the questions below? That
> would certainly help me gain a better understanding of the whole
> issue.
>
>>> More concrete questions: one of the zPCI test cases includes
>>>
>>>       <controller type='pci' index='1' model='pci-bridge'/>
>>>       <hostdev mode='subsystem' type='pci' managed='no'>
>>>         <driver name='vfio'/>
>>>         <source>
>>>           <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>>>         </source>
>>>         <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
>>>                  function='0x0' uid='0xffff' fid='0xffffffff'/>
>>>       </hostdev>
>>>
>>> which translates to
>>>
>>>     -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
>>>     -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
>>>     -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
>>>     -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \
>>>
>>> How does the pci-bridge controller show up in the guest, if at all?
Qemu hides pci-bridge devices and just exposes pci devices to the guest.
In above example, indeed, qemu will generate a pci-bridge device and it will
be existing in pci topology. But the guest can't see it. This is very 
special.
>>>
>>> Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
>>> example above matter eg. for migration purposes?
Do you mean we leave attribute generation for bus and addr to qemu?

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Wed, 2018-07-25 at 16:34 +0800, Yi Min Zhao wrote:
> 在 2018/7/24 下午11:43, Andrea Bolognani 写道:
> > > > More concrete questions: one of the zPCI test cases includes
> > > > 
> > > >       <controller type='pci' index='1' model='pci-bridge'/>
> > > >       <hostdev mode='subsystem' type='pci' managed='no'>
> > > >         <driver name='vfio'/>
> > > >         <source>
> > > >           <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
> > > >         </source>
> > > >         <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
> > > >                  function='0x0' uid='0xffff' fid='0xffffffff'/>
> > > >       </hostdev>
> > > > 
> > > > which translates to
> > > > 
> > > >     -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
> > > >     -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
> > > >     -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
> > > >     -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \
> > > > 
> > > > How does the pci-bridge controller show up in the guest, if at all?
> 
> Qemu hides pci-bridge devices and just exposes pci devices to the guest.
> In above example, indeed, qemu will generate a pci-bridge device and it will
> be existing in pci topology. But the guest can't see it. This is very
> special.

Yeah, that's kinda problematic as it violates the principle of least
surprise... If s390 guests can only see a flat PCI topology, then we
should find a way to reject bridges altogether instead of allowing
the user to create them (or even create them automatically) only for
them not to show up in the guest.

> > > > Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
> > > > example above matter eg. for migration purposes?
> 
> Do you mean we leave attribute generation for bus and addr to qemu?

That would be the idea, but of course it can only work if the
address of the underlying PCI device can change without affecting
the guest in any way, including migration. If that's not the case,
and the PCI address needs to be as stable as the IDs, then I don't
think there's a way to avoid storing it in the guest XML, no matter
how confusing that will end up looking.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 8 weeks ago

在 2018/7/25 下午11:44, Andrea Bolognani 写道:
> On Wed, 2018-07-25 at 16:34 +0800, Yi Min Zhao wrote:
>> 在 2018/7/24 下午11:43, Andrea Bolognani 写道:
>>>>> More concrete questions: one of the zPCI test cases includes
>>>>>
>>>>>        <controller type='pci' index='1' model='pci-bridge'/>
>>>>>        <hostdev mode='subsystem' type='pci' managed='no'>
>>>>>          <driver name='vfio'/>
>>>>>          <source>
>>>>>            <address domain='0xffff' bus='0x00' slot='0x00' function='0x0'/>
>>>>>          </source>
>>>>>          <address type='pci' domain='0x0000' bus='0x01' slot='0x1f'
>>>>>                   function='0x0' uid='0xffff' fid='0xffffffff'/>
>>>>>        </hostdev>
>>>>>
>>>>> which translates to
>>>>>
>>>>>      -device zpci,uid=3,fid=2,target=pci.1,id=zpci3 \
>>>>>      -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x1 \
>>>>>      -device zpci,uid=65535,fid=4294967295,target=hostdev0,id=zpci65535 \
>>>>>      -device vfio-pci,host=ffff:00:00.0,id=hostdev0,bus=pci.1,addr=0x1f \
>>>>>
>>>>> How does the pci-bridge controller show up in the guest, if at all?
>> Qemu hides pci-bridge devices and just exposes pci devices to the guest.
>> In above example, indeed, qemu will generate a pci-bridge device and it will
>> be existing in pci topology. But the guest can't see it. This is very
>> special.
> Yeah, that's kinda problematic as it violates the principle of least
> surprise... If s390 guests can only see a flat PCI topology, then we
> should find a way to reject bridges altogether instead of allowing
> the user to create them (or even create them automatically) only for
> them not to show up in the guest.
If we reject bridges, there would be only one pci bus that maximum
32 pci devices could be plugged to. This kind of limitation is more
problematic IMO.
>>>>> Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
>>>>> example above matter eg. for migration purposes?
>> Do you mean we leave attribute generation for bus and addr to qemu?
> That would be the idea, but of course it can only work if the
> address of the underlying PCI device can change without affecting
> the guest in any way, including migration. If that's not the case,
> and the PCI address needs to be as stable as the IDs, then I don't
> think there's a way to avoid storing it in the guest XML, no matter
> how confusing that will end up looking.
>
I think it relies on pci base code. Although we don't expose pci address 
to the guest, any
pci device still exists PCI tree tolopogy in qemu. IIUC, this has effect 
on qemu process itself.
For example, if we hotplug a pci device permanently, it will be 
dynamically assigned with a
pci address, and this address might change after shutdown and start 
again the guest and also
might change in destination during migration.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Thu, 2018-07-26 at 13:43 +0800, Yi Min Zhao wrote:
> 在 2018/7/25 下午11:44, Andrea Bolognani 写道:
> > > > > > How does the pci-bridge controller show up in the guest, if at all?
> > > 
> > > Qemu hides pci-bridge devices and just exposes pci devices to the guest.
> > > In above example, indeed, qemu will generate a pci-bridge device and it will
> > > be existing in pci topology. But the guest can't see it. This is very
> > > special.
> > 
> > Yeah, that's kinda problematic as it violates the principle of least
> > surprise... If s390 guests can only see a flat PCI topology, then we
> > should find a way to reject bridges altogether instead of allowing
> > the user to create them (or even create them automatically) only for
> > them not to show up in the guest.
> 
> If we reject bridges, there would be only one pci bus that maximum
> 32 pci devices could be plugged to. This kind of limitation is more
> problematic IMO.

I see how that would be pretty limiting.

>From the test cases I see a zpci devices, with its own uid and fid,
is created for the pci-bridge as well... Is that intentional?

> > > > > > Do the bus= and addr= attributes of vfio-pci and pci-bridge in the
> > > > > > example above matter eg. for migration purposes?
> > > 
> > > Do you mean we leave attribute generation for bus and addr to qemu?
> > 
> > That would be the idea, but of course it can only work if the
> > address of the underlying PCI device can change without affecting
> > the guest in any way, including migration. If that's not the case,
> > and the PCI address needs to be as stable as the IDs, then I don't
> > think there's a way to avoid storing it in the guest XML, no matter
> > how confusing that will end up looking.
> 
> I think it relies on pci base code. Although we don't expose pci address 
> to the guest, any
> pci device still exists PCI tree tolopogy in qemu. IIUC, this has effect 
> on qemu process itself.
> For example, if we hotplug a pci device permanently, it will be 
> dynamically assigned with a
> pci address, and this address might change after shutdown and start 
> again the guest and also
> might change in destination during migration.

Okay, if that's the case we'll definitely have to store the PCI
address in the guest XML :(

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Yi Min Zhao 8 weeks ago

在 2018/7/26 下午7:00, Andrea Bolognani 写道:
>>>>>>> How does the pci-bridge controller show up in the guest, if at all?
>>>> Qemu hides pci-bridge devices and just exposes pci devices to the guest.
>>>> In above example, indeed, qemu will generate a pci-bridge device and it will
>>>> be existing in pci topology. But the guest can't see it. This is very
>>>> special.
>>> Yeah, that's kinda problematic as it violates the principle of least
>>> surprise... If s390 guests can only see a flat PCI topology, then we
>>> should find a way to reject bridges altogether instead of allowing
>>> the user to create them (or even create them automatically) only for
>>> them not to show up in the guest.
>> If we reject bridges, there would be only one pci bus that maximum
>> 32 pci devices could be plugged to. This kind of limitation is more
>> problematic IMO.
> I see how that would be pretty limiting.
>
> >From the test cases I see a zpci devices, with its own uid and fid,
> is created for the pci-bridge as well... Is that intentional?
>
Firstly pci bridge can be auto-generated if a pci device is to be 
plugged to non-existing pci bus.
IIUC, pci-bridge is treated as a controller device in libvirt. So I 
think, it's pretty readable not only
in libvirt xml but also in qtree, if we assign zpci device for it. 
Otherwise address type of pci-bridge
is pci type but has no uid and fid. Isn't it odd?

Of course, we could avoid assigning a zpci device to pci-bridge. 
Actually my old patch did
in this way.

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Daniel P. Berrangé 8 weeks ago
On Thu, Jul 26, 2018 at 07:17:03PM +0800, Yi Min Zhao wrote:
> 
> 
> 在 2018/7/26 下午7:00, Andrea Bolognani 写道:
> > > > > > > > How does the pci-bridge controller show up in the guest, if at all?
> > > > > Qemu hides pci-bridge devices and just exposes pci devices to the guest.
> > > > > In above example, indeed, qemu will generate a pci-bridge device and it will
> > > > > be existing in pci topology. But the guest can't see it. This is very
> > > > > special.
> > > > Yeah, that's kinda problematic as it violates the principle of least
> > > > surprise... If s390 guests can only see a flat PCI topology, then we
> > > > should find a way to reject bridges altogether instead of allowing
> > > > the user to create them (or even create them automatically) only for
> > > > them not to show up in the guest.
> > > If we reject bridges, there would be only one pci bus that maximum
> > > 32 pci devices could be plugged to. This kind of limitation is more
> > > problematic IMO.
> > I see how that would be pretty limiting.
> > 
> > >From the test cases I see a zpci devices, with its own uid and fid,
> > is created for the pci-bridge as well... Is that intentional?
> > 
> Firstly pci bridge can be auto-generated if a pci device is to be plugged to
> non-existing pci bus.
> IIUC, pci-bridge is treated as a controller device in libvirt. So I think,
> it's pretty readable not only
> in libvirt xml but also in qtree, if we assign zpci device for it. Otherwise
> address type of pci-bridge
> is pci type but has no uid and fid. Isn't it odd?

>From the libvirt side we must avoid any scenario where QEMU auto-adds
devices behind our back. If adding a device requires adding a controller
libvirt must do this explicitly and record it in the XML.

Regards,
Daniel
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Thu, 2018-07-26 at 12:22 +0100, Daniel P. Berrangé wrote:
> On Thu, Jul 26, 2018 at 07:17:03PM +0800, Yi Min Zhao wrote:
> > 在 2018/7/26 下午7:00, Andrea Bolognani 写道:
> > > From the test cases I see a zpci devices, with its own uid and fid,
> > > is created for the pci-bridge as well... Is that intentional?
> > 
> > Firstly pci bridge can be auto-generated if a pci device is to be plugged to
> > non-existing pci bus.
> > IIUC, pci-bridge is treated as a controller device in libvirt. So I think,
> > it's pretty readable not only
> > in libvirt xml but also in qtree, if we assign zpci device for it. Otherwise
> > address type of pci-bridge
> > is pci type but has no uid and fid. Isn't it odd?

Everything about zPCI is odd ;)

I guess there's no harm in creating an additional zpci device,
and as you say it will keep things a bit more consistent, which
is good.

> From the libvirt side we must avoid any scenario where QEMU auto-adds
> devices behind our back. If adding a device requires adding a controller
> libvirt must do this explicitly and record it in the XML.

Definitely. My question was whether the corresponding zpci device
should be created as well...

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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Daniel P. Berrangé 8 weeks ago
On Thu, Jul 26, 2018 at 01:47:52PM +0200, Andrea Bolognani wrote:
> On Thu, 2018-07-26 at 12:22 +0100, Daniel P. Berrangé wrote:
> > On Thu, Jul 26, 2018 at 07:17:03PM +0800, Yi Min Zhao wrote:
> > > 在 2018/7/26 下午7:00, Andrea Bolognani 写道:
> > > > From the test cases I see a zpci devices, with its own uid and fid,
> > > > is created for the pci-bridge as well... Is that intentional?
> > > 
> > > Firstly pci bridge can be auto-generated if a pci device is to be plugged to
> > > non-existing pci bus.
> > > IIUC, pci-bridge is treated as a controller device in libvirt. So I think,
> > > it's pretty readable not only
> > > in libvirt xml but also in qtree, if we assign zpci device for it. Otherwise
> > > address type of pci-bridge
> > > is pci type but has no uid and fid. Isn't it odd?
> 
> Everything about zPCI is odd ;)
> 
> I guess there's no harm in creating an additional zpci device,
> and as you say it will keep things a bit more consistent, which
> is good.
> 
> > From the libvirt side we must avoid any scenario where QEMU auto-adds
> > devices behind our back. If adding a device requires adding a controller
> > libvirt must do this explicitly and record it in the XML.
> 
> Definitely. My question was whether the corresponding zpci device
> should be created as well...

I'm not sure I understand it fully, but it sounds like  zpci devices are
providing info that is guest ABI sensitive, which would mean libvirt must
control and record it. So from that POV we should create zpci devices

Regards,
Daniel
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Re: [libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

Posted by Andrea Bolognani 8 weeks ago
On Thu, 2018-07-26 at 12:52 +0100, Daniel P. Berrangé wrote:
> On Thu, Jul 26, 2018 at 01:47:52PM +0200, Andrea Bolognani wrote:
> > On Thu, 2018-07-26 at 12:22 +0100, Daniel P. Berrangé wrote:
> > > From the libvirt side we must avoid any scenario where QEMU auto-adds
> > > devices behind our back. If adding a device requires adding a controller
> > > libvirt must do this explicitly and record it in the XML.
> > 
> > Definitely. My question was whether the corresponding zpci device
> > should be created as well...
> 
> I'm not sure I understand it fully, but it sounds like  zpci devices are
> providing info that is guest ABI sensitive, which would mean libvirt must
> control and record it. So from that POV we should create zpci devices

Making sure the guest-visible address is stable is taken care of
by the additional PCI address attributes uid and fid, which are
then used when creating the zpci device.

PCI controllers such as pci-bridge are, however, not visible to the
guest and as such it would be possible to skip the corresponding
zpci devices; it's been argued, though, that it's better to create
them regardless in order to maintain consistency.

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