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[PATCH v2 0/2] spapr: Fix device unplug vs CAS or migration

From: Greg Kurz
Subject: [PATCH v2 0/2] spapr: Fix device unplug vs CAS or migration
Date: Fri, 14 Feb 2020 16:01:16 +0100
User-agent: StGit/unknown-version

While working on getting rid of CAS reboot, I realized that we currently
don't handle device hot unplug properly in the following situations:

1) if the device is unplugged between boot and CAS, SLOF doesn't handle
   the even, which is a known limitation. The device hence stays around
   forever (specifically, until some other event is emitted and the guest
   eventually completes the unplug or a reboot). Until we can teach SLOF
   to correctly process the full FDT at CAS, we should trigger a CAS reboot,
   like we already do for hotplug.

2) if the guest is migrated after the even was emitted but before the
   guest could process it, the destination is unaware of the pending
   unplug operation and doesn't remove the device when the guests
   releases it. The 'unplug_requested' field of the DRC is actually state
   that should be migrated.

Changes since v1:
   - new spapr_drc_transient() helper that covers pending plug and unplug
     situations for both CAS and migration
   - as a mechanical consequence, fix unplug for CAS an migration in the
     same patch



Greg Kurz (2):
      spapr: Don't use spapr_drc_needed() in CAS code
      spapr: Fix handling of unplugged devices during CAS and migration

 hw/ppc/spapr_drc.c         |   43 ++++++++++++++++++++++++++++++++++++-------
 hw/ppc/spapr_hcall.c       |   14 +++++++++-----
 include/hw/ppc/spapr_drc.h |    4 +++-
 3 files changed, 48 insertions(+), 13 deletions(-)

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