Re: [PATCH for-10.1 v9 0/9] virtio-net: add support for SR-IOV emulation

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2025/03/21 13:34, Yui Washizu wrote:
> 
> I tested the following features with this patch series, and there were 
> not  issues:
> - Creation and deletion of VFs
> - Communication with an external machine through VFs
> 
> Thank you.

Can you reply with:

Tested-by: Your Name <youraddress@example.com>

This tag means:
- you have tested changes you found significant,
- you found no problems with them, and
- you are fine to record that in Git commit logs

Pasha Tatashin (who told me they tried the patches), it would be nice if 
you do the same.

Regards,
Akihiko Odaki

> 
> 
> Yui
> 
> 
> On 2025/03/14 15:14, Akihiko Odaki wrote:
>> Based-on:<20250104-reuse-v18-0-c349eafd8673@daynix.com>
>> ("[PATCH v18 00/14] hw/pci: SR-IOV related fixes and improvements")
>>
>> Introduction
>> ------------
>>
>> This series is based on the RFC series submitted by Yui Washizu[1].
>> See also [2] for the context.
>>
>> This series enables SR-IOV emulation for virtio-net. It is useful
>> to test SR-IOV support on the guest, or to expose several vDPA devices
>> in a VM. vDPA devices can also provide L2 switching feature for
>> offloading though it is out of scope to allow the guest to configure
>> such a feature.
>>
>> The PF side code resides in virtio-pci. The VF side code resides in
>> the PCI common infrastructure, but it is restricted to work only for
>> virtio-net-pci because of lack of validation.
>>
>> User Interface
>> --------------
>>
>> A user can configure a SR-IOV capable virtio-net device by adding
>> virtio-net-pci functions to a bus. Below is a command line example:
>>    -netdev user,id=n -netdev user,id=o
>>    -netdev user,id=p -netdev user,id=q
>>    -device pcie-root-port,id=b
>>    -device virtio-net-pci,bus=b,addr=0x0.0x3,netdev=q,sriov-pf=f
>>    -device virtio-net-pci,bus=b,addr=0x0.0x2,netdev=p,sriov-pf=f
>>    -device virtio-net-pci,bus=b,addr=0x0.0x1,netdev=o,sriov-pf=f
>>    -device virtio-net-pci,bus=b,addr=0x0.0x0,netdev=n,id=f
>>
>> The VFs specify the paired PF with "sriov-pf" property. The PF must be
>> added after all VFs. It is user's responsibility to ensure that VFs have
>> function numbers larger than one of the PF, and the function numbers
>> have a consistent stride.
>>
>> Keeping VF instances
>> --------------------
>>
>> A problem with SR-IOV emulation is that it needs to hotplug the VFs as
>> the guest requests. Previously, this behavior was implemented by
>> realizing and unrealizing VFs at runtime. However, this strategy does
>> not work well for the proposed virtio-net emulation; in this proposal,
>> device options passed in the command line must be maintained as VFs
>> are hotplugged, but they are consumed when the machine starts and not
>> available after that, which makes realizing VFs at runtime impossible.
>>
>> As an strategy alternative to runtime realization/unrealization, this
>> series proposes to reuse the code to power down PCI Express devices.
>> When a PCI Express device is powered down, it will be hidden from the
>> guest but will be kept realized. This effectively implements the
>> behavior we need for the SR-IOV emulation.
>>
>> Summary
>> -------
>>
>> Patch 1 disables ROM BAR, which virtio-net-pci enables by default, for
>> VFs.
>> Patch 2 makes zero stride valid for 1 VF configuration.
>> Patch 3 and 4 adds validations.
>> Patch 5 adds user-created SR-IOV VF infrastructure.
>> Patch 6 makes virtio-pci work as SR-IOV PF for user-created VFs.
>> Patch 7 allows user to create SR-IOV VFs with virtio-net-pci.
>>
>> [1]https://patchew.org/QEMU/1689731808-3009-1-git-send-email- 
>> yui.washidu@gmail.com/
>> [2]https://lore.kernel.org/all/5d46f455- 
>> f530-4e5e-9ae7-13a2297d4bc5@daynix.com/
>>
>> Co-developed-by: Yui Washizu<yui.washidu@gmail.com>
>> Signed-off-by: Akihiko Odaki<akihiko.odaki@daynix.com>
>> ---
>> Changes in v9:
>> - Rebased.
>> - Link to v8:https://lore.kernel.org/r/20250104-sriov- 
>> v8-0-56144cfdc7d9@daynix.com
>>
>> Changes in v8:
>> - Rebased.
>> - Link to v7:https://lore.kernel.org/r/20240813-sriov- 
>> v7-0-8515e3774df7@daynix.com
>>
>> Changes in v7:
>> - Removed #include <error-report.h>, which is no longer needed.
>> - Rebased.
>> - Link to v6:https://lore.kernel.org/r/20240802-sriov- 
>> v6-0-0c8ff49c4276@daynix.com
>>
>> Changes in v6:
>> - Added ARI extended capability.
>> - Rebased.
>> - Link to v5:https://lore.kernel.org/r/20240715-sriov- 
>> v5-0-3f5539093ffc@daynix.com
>>
>> Changes in v5:
>> - Dropped the RFC tag.
>> - Fixed device unrealization.
>> - Rebased.
>> - Link to v4:https://lore.kernel.org/r/20240428-sriov-v4-0- 
>> ac8ac6212982@daynix.com
>>
>> Changes in v4:
>> - Added patch "hw/pci: Fix SR-IOV VF number calculation" to fix division
>>    by zero reported by Yui Washizu.
>> - Rebased.
>> - Link to v3:https://lore.kernel.org/r/20240305-sriov-v3-0- 
>> abdb75770372@daynix.com
>>
>> Changes in v3:
>> - Rebased.
>> - Link to v2:https://lore.kernel.org/r/20231210-sriov-v2-0- 
>> b959e8a6dfaf@daynix.com
>>
>> Changes in v2:
>> - Changed to keep VF instances.
>> - Link to v1:https://lore.kernel.org/r/20231202-sriov- 
>> v1-0-32b3570f7bd6@daynix.com
>>
>> ---
>> Akihiko Odaki (9):
>>        hw/pci: Do not add ROM BAR for SR-IOV VF
>>        hw/pci: Fix SR-IOV VF number calculation
>>        pcie_sriov: Ensure PF and VF are mutually exclusive
>>        pcie_sriov: Check PCI Express for SR-IOV PF
>>        pcie_sriov: Allow user to create SR-IOV device
>>        virtio-pci: Implement SR-IOV PF
>>        virtio-net: Implement SR-IOV VF
>>        docs: Document composable SR-IOV device
>>        pcie_sriov: Make a PCI device with user-created VF ARI-capable
>>
>>   MAINTAINERS                    |   1 +
>>   docs/system/index.rst          |   1 +
>>   docs/system/sriov.rst          |  37 ++++++
>>   include/hw/pci/pci_device.h    |   6 +-
>>   include/hw/pci/pcie_sriov.h    |  21 +++
>>   include/hw/virtio/virtio-pci.h |   1 +
>>   hw/pci/pci.c                   |  76 +++++++----
>>   hw/pci/pcie_sriov.c            | 294 +++++++++++++++++++++++++++++++ 
>> ++--------
>>   hw/virtio/virtio-net-pci.c     |   1 +
>>   hw/virtio/virtio-pci.c         |  24 +++-
>>   10 files changed, 378 insertions(+), 84 deletions(-)
>> ---
>> base-commit: 825b96dbcee23d134b691fc75618b59c5f53da32
>> change-id: 20231202-sriov-9402fb262be8
>>
>> Best regards,