[RFC,for-5.1,0/4] Better handling of attempt NVLink2 unplug

Message

David Gibson March 26, 2020, 5:40 a.m. UTC

Currently, attempting to unplug an NVLink2 device will generally
result in the guest crashing.  If you're lucky, it instead simply
won't work and remain in a "pending unplug" state indefinitely.

There is code we could we could theoretically improve in qemu to tear
these devices down better.  However since NVLink2 devices aren't hot
pluggable in hardware, the guest side drivers usually don't cope with
that anyway.

So, patch 4/4 blocks attempts to unplug NVLink2 devices.  The others
are some preliminary cleanups to get us towards there.

David Gibson (4):
  spapr: Refactor locating NVLink2 devices for device tree creation
  spapr: Helper to determine if a device is NVLink2 related
  spapr: Fix failure path for attempting to hot unplug PCI bridges
  spapr: Don't allow unplug of NVLink2 devices

 hw/ppc/spapr_pci.c          |   6 ++
 hw/ppc/spapr_pci_nvlink2.c  | 120 +++++++++++++++++++++++++-----------
 include/hw/pci-host/spapr.h |   1 +
 3 files changed, 91 insertions(+), 36 deletions(-)