Subject: Re: [PATCH mlx5-next v8 0/4] Dynamically assign MSI-X vectors count

From: Leon Romanovsky <[email-masked]>
Date: Thu, 25 Mar 2021 09:57:07 +0200

Bjorn,

Can you please help us progress with the series?

It needs to go from mlx5-next to net-next and maybe to rdma-next too
and we need enough time to keep the series for automatic testing in
all those branches.

The code was posted on -rc1 [1] while we are in -rc4 already.

[1] https://lore.kernel.org/linux-pci/[email-masked]/

Thanks

On Sat, Mar 20, 2021 at 11:13:44AM +0200, Leon Romanovsky wrote:
> Gentle reminder
> 
> Thanks
> 
> On Sun, Mar 14, 2021 at 02:42:52PM +0200, Leon Romanovsky wrote:
> > ---------------------------------------------------------------------------------
> > Changelog
> > v8:
> >  * Added "physical/virtual function" words near PF and VF acronyms.
> > v7: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Rebase on top v5.12-rc1
> >  * More english fixes
> >  * Returned to static sysfs creation model as was implemented in v0/v1.
> > v6: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Patch 1:
> >    * English fixes
> >    * Moved pci_vf_set_msix_vec_count() from msi.c to iov.c
> >    * Embedded pci_vf_set_msix_vec_count() into sriov_vf_msix_count_store
> >    * Deleted sriov_vf_msix_count_show
> >    * Deleted vfs_overlay folder
> >    * Renamed functions *_vfs_overlay_* to be *_vf_overlay_*
> >    * Deleted is_supported and attribute_group because it confused people more than
> >      it gave advantage.
> >    * Changed vf_total_msix to be callback
> >  * Patch 3:
> >    * Fixed english as suggested by Bjorn
> >    * Added more explanations to the commit message
> >  * Patch 4:
> >    * Protected enable/disable with capability check
> > v5: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Patch 1:
> >   * Added forgotten "inline" keyword when declaring empty functions.
> > v4: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Used sysfs_emit() instead of sprintf() in new sysfs entries.
> >  * Changed EXPORT_SYMBOL to be EXPORT_SYMBOL_GPL for pci_iov_virtfn_devfn().
> >  * Rewrote sysfs registration code to be driven by PF that wants to enable VF
> >    overlay instead of creating to all SR-IOV devices.
> >  * Grouped all such functionality under new "vfs_overlay" folder.
> >  * Combined two PCI patches into one.
> > v3: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Renamed pci_set_msix_vec_count to be pci_vf_set_msix_vec_count.
> >  * Added VF msix_cap check to hide sysfs entry if device doesn't support msix.
> >  * Changed "-" to be ":" in the mlx5 patch to silence CI warnings about missing
> >    kdoc description.
> >  * Split differently error print in mlx5 driver to avoid checkpatch warning.
> > v2: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Patch 1:
> >   * Renamed vf_msix_vec sysfs knob to be sriov_vf_msix_count
> >   * Added PF and VF device locks during set MSI-X call to protect from parallel
> >     driver bind/unbind operations.
> >   * Removed extra checks when reading sriov_vf_msix, because users will
> >     be able to distinguish between supported/not supported by looking on
> >     sriov_vf_total_msix count.
> >   * Changed all occurrences of "numb" to be "count"
> >   * Changed returned error from EOPNOTSUPP to be EBUSY if user tries to set
> >     MSI-X count after driver already bound to the VF.
> >   * Added extra comment in pci_set_msix_vec_count() to emphasize that driver
> >     should not be bound.
> >  * Patch 2:
> >   * Changed vf_total_msix from int to be u32 and updated function signatures
> >     accordingly.
> >   * Improved patch title
> > v1: https://lore.kernel.org/linux-pci/[email-masked]
> >  * Improved wording and commit messages of first PCI patch
> >  * Added extra PCI patch to provide total number of MSI-X vectors
> >  * Prohibited read of vf_msix_vec sysfs file if driver doesn't support write
> >  * Removed extra function definition in pci.h
> > v0: https://lore.kernel.org/linux-pci/[email-masked]
> > 
> > --------------------------------------------------------------------
> > Hi,
> > 
> > The number of MSI-X vectors is PCI property visible through lspci, that
> > field is read-only and configured by the device.
> > 
> > The static assignment of an amount of MSI-X vectors doesn't allow utilize
> > the newly created VF because it is not known to the device the future load
> > and configuration where that VF will be used.
> > 
> > The VFs are created on the hypervisor and forwarded to the VMs that have
> > different properties (for example number of CPUs).
> > 
> > To overcome the inefficiency in the spread of such MSI-X vectors, we
> > allow the kernel to instruct the device with the needed number of such
> > vectors, before VF is initialized and bounded to the driver.
> > 
> > Before this series:
> > [root@server ~]# lspci -vs 0000:08:00.2
> > 08:00.2 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
> > ....
> >         Capabilities: [9c] MSI-X: Enable- Count=12 Masked-
> > 
> > Configuration script:
> > 1. Start fresh
> > echo 0 > /sys/bus/pci/devices/0000\:08\:00.0/sriov_numvfs
> > modprobe -q -r mlx5_ib mlx5_core
> > 2. Ensure that driver doesn't run and it is safe to change MSI-X
> > echo 0 > /sys/bus/pci/devices/0000\:08\:00.0/sriov_drivers_autoprobe
> > 3. Load driver for the PF
> > modprobe mlx5_core
> > 4. Configure one of the VFs with new number
> > echo 2 > /sys/bus/pci/devices/0000\:08\:00.0/sriov_numvfs
> > echo 21 > /sys/bus/pci/devices/0000\:08\:00.2/sriov_vf_msix_count
> > 
> > After this series:
> > [root@server ~]# lspci -vs 0000:08:00.2
> > 08:00.2 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
> > ....
> >         Capabilities: [9c] MSI-X: Enable- Count=21 Masked-
> > 
> > Thanks
> > 
> > Leon Romanovsky (4):
> >   PCI: Add a sysfs file to change the MSI-X table size of SR-IOV VFs
> >   net/mlx5: Add dynamic MSI-X capabilities bits
> >   net/mlx5: Dynamically assign MSI-X vectors count
> >   net/mlx5: Implement sriov_get_vf_total_msix/count() callbacks
> > 
> >  Documentation/ABI/testing/sysfs-bus-pci       |  29 +++++
> >  .../net/ethernet/mellanox/mlx5/core/main.c    |   6 ++
> >  .../ethernet/mellanox/mlx5/core/mlx5_core.h   |  12 +++
> >  .../net/ethernet/mellanox/mlx5/core/pci_irq.c |  73 +++++++++++++
> >  .../net/ethernet/mellanox/mlx5/core/sriov.c   |  48 ++++++++-
> >  drivers/pci/iov.c                             | 102 ++++++++++++++++--
> >  drivers/pci/pci-sysfs.c                       |   3 +-
> >  drivers/pci/pci.h                             |   3 +-
> >  include/linux/mlx5/mlx5_ifc.h                 |  11 +-
> >  include/linux/pci.h                           |   8 ++
> >  10 files changed, 284 insertions(+), 11 deletions(-)
> > 
> > --
> > 2.30.2
> >