[PATCH RFC v4 0/9] powerpc/powernv/pci: Make hotplug self-sufficient, independent of FW and DT

[Oliver]

On Sat, Mar 2, 2019 at 3:04 AM Sergey Miroshnichenko
<s.miroshnichenko at yadro.com> wrote:
>
> This patchset allows switching from the pnv_php module to the standard
> pciehp driver for PCIe hotplug functionality, if the platform supports it:
> PowerNV working on on top of the skiboot with the "core/pci: Sync VFs and
> the changes of bdfns between the firmware and the OS" patch serie applied.
>
> The feature is activated by the "pci=realloc" command line argument.
>
> The goal is ability to hotplug bridges full of devices in the future. The
> "Movable BARs" [1] is a platform-independent part of our work in this. The
> final part will be movable bus numbers to support inserting a bridge in the
> middle of an existing PCIe tree.
>
> Tested on POWER8 PowerNV+PHB3 ppc64le (our Vesnin server) with:
>  - the pciehp driver active;
>  - the pnv_php driver disabled;

Cool :)

I've had a brief look at this and it the approach seems reasonable.
I'll have a more detailed look and see how it fares on a P9 system
tomorrow.

>  - The "pci=realloc" argument is passed;
>  - surprise hotplug of an NVME disk works;
>  - controlled hotplug of a network card with SR-IOV works;
>  - activating of SR-IOV on a network card works;
>  - [with extra patches] manually initiated (via sysfs) rescan has found
>    and turned on a hotplugged bridge;
>  - Without "pci=realloc" works just as before.
>
> Changes since v3 [2]:
>  - Subject changed;
>  - Don't disable EEH during rescan anymore - instead just unfreeze the
>    target buses deliberately;
>  - Add synchronization with the firmware when changing the PCIe topology;
>  - Fixed for VFs;
>  - Code cleanup.
>
> Changes since v2:
>  - Don't reassign bus numbers on PowerNV by default (to retain the default
>    behavior), but only when pci=realloc is passed;
>  - Less code affected;
>  - pci_add_device_node_info is refactored with add_one_dev_pci_data;
>  - Minor code cleanup.
>
> Changes since v1:
>  - Fixed build for ppc64le and ppc64be when CONFIG_PCI_IOV is disabled;
>  - Fixed build for ppc64e when CONFIG_EEH is disabled;
>  - Fixed code style warnings.
>
> [1] https://www.spinics.net/lists/linux-pci/msg79995.html
> [2] https://lists.ozlabs.org/pipermail/linuxppc-dev/2018-September/178053.html
>
> Sergey Miroshnichenko (9):
>   powerpc/pci: Access PCI config space directly w/o pci_dn
>   powerpc/powernv/pci: Suppress an EEH error when reading an empty slot
>   powerpc/pci: Create pci_dn on demand
>   powerpc/pci: Reduce code duplication in pci_add_device_node_info
>   powerpc/powernv/ioda: Fix using uninitialized IOMMU group
>   powerpc/pci/IOV: Add support for runtime enabling the VFs
>   powerpc/pci: Don't rely on DT is the PCI_REASSIGN_ALL_BUS is set
>   powerpc/powernv/pci: Hook up the writes to PCI_SECONDARY_BUS register
>   powerpc/powernv/pci: Enable reassigning the bus numbers
>
>  arch/powerpc/include/asm/pci-bridge.h        |   2 +-
>  arch/powerpc/include/asm/ppc-pci.h           |   1 +
>  arch/powerpc/kernel/pci_dn.c                 | 164 +++++++++++----
>  arch/powerpc/kernel/rtas_pci.c               |  97 ++++++---
>  arch/powerpc/platforms/powernv/eeh-powernv.c |   2 +-
>  arch/powerpc/platforms/powernv/pci-ioda.c    |   5 +-
>  arch/powerpc/platforms/powernv/pci.c         | 208 +++++++++++++++++--
>  arch/powerpc/platforms/pseries/pci.c         |   2 +-
>  8 files changed, 381 insertions(+), 100 deletions(-)
>
> --
> 2.20.1
>