Re: [Qemu-devel] [PATCH v2 00/14] spapr: add support for pci hotplug

[Alexey Kardashevskiy <aik@ozlabs.ru>]

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On 12/06/2013 09:32 AM, Michael Roth wrote:
> These patches are based on ppc-next, and can also be obtained from:
> 
> https://github.com/mdroth/qemu/commits/spapr-pci-hotplug-v2-ppc-next
> 
> v2:
>   * re-ordered patches to fix build bisectability (Alexey)
>   * replaced g_warning with DPRINTF in RTAS calls for guest errors (Alexey)
>   * replaced g_warning with fprintf for qemu errors (Alexey)
>   * updated RTAS calls to use pre-existing error/success macros (Alexey)
>   * replaced DR_*/SENSOR_* macros with INDICATOR_* for set-indicator/
>     get-sensor-state (Alexey)
> 
> OVERVIEW
> 
> These patches add support for PCI hotplug for SPAPR guests. We advertise
> each PHB as DR-capable (as defined by PAPR 13.5/13.6) with 32 hotpluggable
> PCI slots per PHB, which models a standard PCI expansion device for Power
> machines where the DRC name/loc-code/index for each slot are generated
> based on bus/slot number.
> 
> This is compatible with existing guest kernel's via the rpaphp hotplug
> module, and existing userspace tools such as drmgr/librtas/rtas_errd for
> managing devices, in theory...
> 
> NOTES / ADDITIONAL DEPENDENCIES
> 
> Due to an issue with rpaphp, a workaround must be used for older guest
> kernels which relies on using bus rescan / remove sysfs interfaces instead
> of rpaphp-provided hotplug interfaces.
> 
> Guest kernel fixes for rpaphp are in progress and available for testing
> here (there's still currently a benign issue with duplicate eeh sysfs
> entries with these, but the full guest-driven hotplug workflow is
> functional):
> 
>   https://github.com/mdroth/linux/commits/pci-hotplug-fixes
> 
> Alternatively, there are updated userspace tools which add a "-v" option
> to drmgr to utilize bus rescan/remove instead of relying on rpaphp:
> 
>   https://github.com/tyreld/powerpc-utils/commits/hotplug
> 
> It's possible to test guest-driven hotplug without either of these using
> a workaround (see USAGE below), but not recommended.
> 
> PAPR does not currently define a mechanism for generating PCI
> hotplug/unplug events, and relies on guest-driven management of devices,
> so as part of this series we also introduce an extension to the existing
> EPOW power event reporting mechanism (where a guest will query for events
> via check-exception RTAS calls in response to an external interrupt) to
> surface hotplug/unplug events with the information needed to manage the
> devices automatically via the rtas_errd guest service. In order to enable
> this qemu-driven hotplug/unplug workflow (for parity with ACPI/SHPC-based
> guests), updated versions of librtas/ppc64-diag are required, which are
> available here:
> 
>   https://github.com/tyreld/ppc64-diag/commits/hotplug
>   https://github.com/tyreld/librtas/commits/hotplug
> 
> Lacking those, users must manage device hotplug/unplug manually.
> 
> Additionally, PAPR requires the presence of additional OF properties
> (ibm,my-drc-index and loc-code) for hotpluggable slots that have already
> been populated at the time of boot to support unplug, so an updated SLOF
> is required to allow for device unplug after a guest reboot. (these
> properties cannot currently be added to boot-time FDT, since they will
> conflict with SLOF-generated device nodes, so we either need to teach
> SLOF to re-use/merge existing entries, or simply have it generate the
> required properties values for board-qemu, which is the approach taken
> here). A patch for SLOF is available below, along with a pre-built
> SLOF binary which includes it (for testing):
> 
>   https://github.com/mdroth/SLOF/commit/2e09a2950db0ce8ed464b80cccfea56dccf85d66
>   https://github.com/mdroth/qemu/blob/19a390e3270a7defc7158ce29e52ff2b27d666ae/pc-bios/slof.bin
> 
> PATCH LAYOUT
> 
> Patches
>         1-3   advertise PHBs and associated slots as hotpluggable to guests
>         4-7   add RTAS interfaces required for device configuration
>         8-10  add helpers and potential fix to deal with QEMU-managed BAR
>               assignments
>         11    enables device_add/device_del for spapr machines and
>               guest-driven hotplug
>         12-14 define hotplug event structure and emit them in response to
>               device_add/device_del
> 
> USAGE
> 
> With unmodified guests:
>   hotplug:
>     qemu:
>       device_add e1000,id=slot0
>     guest:
>       drmgr -c pci -s "Slot 0" -n -a
>       echo 1 >/sys/bus/pci/rescan
>   unplug:
>     guest:
>       drmgr -c pci -s "Slot 0" -n -r
>       echo 1 >/sys/bus/pci/devices/0000:00:00.0/remove
>     qemu:
>       device_del slot0
> 
> With only updated guest kernel:
>   hotplug:
>     qemu:
>       device_add e1000,id=slot0
>     guest:
>       modprobe rpaphp
>       drmgr -c pci -s "Slot 0" -n -a
>   unplug:
>     guest:
>       drmgr -c pci -s "Slot 0" -n -r
>     qemu:
>       device_del slot0
> 
> With only updated powerpc-utils/drmgr:
>   hotplug:
>     qemu:
>       device_add e1000,id=slot0
>     guest:
>       drmgr -c pci -s "Slot 0" -n -v -a
>   unplug:
>     guest:
>       drmgr -c pci -s "Slot 0" -n -v -r
>     qemu:
>       device_del slot0
> 
> With updated librtas/ppc64-diag and either an updated guest kernel or drmgr:
>   hotplug:
>     qemu:
>       device_add e1000,id=slot0
>   unplug:
>     qemu:
>       device_del slot0
> 
>  hw/pci/pci.c                |    5 +-
>  hw/ppc/spapr.c              |  174 +++++++++-
>  hw/ppc/spapr_events.c       |  228 ++++++++++---
>  hw/ppc/spapr_pci.c          |  768 ++++++++++++++++++++++++++++++++++++++++++-
>  include/exec/memory.h       |   34 ++
>  include/hw/pci-host/spapr.h |    1 +
>  include/hw/pci/pci.h        |    1 +
>  include/hw/ppc/spapr.h      |   77 ++++-
>  memory.c                    |   50 +++
>  9 files changed, 1286 insertions(+), 52 deletions(-)
> 
> pickGIT: [PATCH v2 06/14] spapr_pci: add get-sensor-state RTAS interface
> 


-- 
Alexey