[PATCH v2 00/28] partition suspend updates

From: Nathan Lynch <nathanl@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: tyreld@linux.ibm.com, ajd@linux.ibm.com, mmc@linux.vnet.ibm.com,
	cforno12@linux.vnet.ibm.com, drt@linux.vnet.ibm.com,
	brking@linux.ibm.com
Subject: [PATCH v2 00/28] partition suspend updates
Date: Mon,  7 Dec 2020 15:51:32 -0600	[thread overview]
Message-ID: <20201207215200.1785968-1-nathanl@linux.ibm.com> (raw)

This series aims to improve the pseries-specific partition migration
and hibernation implementation, part of which has been living in
kernel/rtas.c. Most of that code is eliminated or moved to
platforms/pseries, and the following major functional changes are
made:

- Use stop_machine() instead of on_each_cpu() to avoid deadlock in the
  join/suspend sequence.

- Retry the join/suspend sequence on errors that are likely to be
  transient. This is a mitigation for the fact that drivers currently
  have no way to prepare for an impending partition suspension,
  sometimes resulting in a virtual adapter being in a state which
  causes the platform to fail the suspend call.

- Request cancellation of the migration via H_VASI_SIGNAL if Linux is
  going to error out of the suspend attempt. This allows the
  management console and other entities to promptly clean up their
  operations instead of relying on long timeouts to fail the
  migration.

- Little-endian users of ibm,suspend-me, ibm,update-nodes and
  ibm,update-properties via sys_rtas are blocked when
  CONFIG_PPC_RTAS_FILTERS is enabled.

- Legacy user space code (drmgr) historically has driven the migration
  process by using sys_rtas to separately call ibm,suspend-me,
  ibm,activate-firmware, and ibm,update-nodes/properties, in that
  order. With these changes, when sys_rtas() dispatches
  ibm,suspend-me, the kernel performs the device tree update and
  firmware activation before returning. This is more reliable, and
  drmgr does not seem bothered by it.

- If the H_VASI_STATE hcall is absent, the implementation proceeds
  with the suspend instead of erroring out. This allows us to exercise
  these code paths in QEMU.

Changes since v1:
- Drop "powerpc/rtas: move rtas_call_reentrant() out of pseries
  guards". rtas_call_reentrant() actually is pseries-specific and this
  broke builds without CONFIG_PPC_PSERIES set.
- Simplify polling logic in wait_for_vasi_session_suspending().
  ("powerpc/pseries/mobility: extract VASI session polling logic")
- Use direct return instead of goto in pseries_migrate_partition().
  ("powerpc/pseries/mobility: use stop_machine for join/suspend")
- Change dispatch of ibm,suspend-me in rtas syscall path to use
  conventional config symbol guards instead of a weak function.
  ("powerpc/rtas: dispatch partition migration requests to pseries")
- Fix refcount imbalance in add_dt_node() error path.
  ("powerpc/pseries/mobility: refactor node lookup during DT update")

Nathan Lynch (28):
  powerpc/rtas: prevent suspend-related sys_rtas use on LE
  powerpc/rtas: complete ibm,suspend-me status codes
  powerpc/rtas: rtas_ibm_suspend_me -> rtas_ibm_suspend_me_unsafe
  powerpc/rtas: add rtas_ibm_suspend_me()
  powerpc/rtas: add rtas_activate_firmware()
  powerpc/hvcall: add token and codes for H_VASI_SIGNAL
  powerpc/pseries/mobility: don't error on absence of ibm,update-nodes
  powerpc/pseries/mobility: add missing break to default case
  powerpc/pseries/mobility: error message improvements
  powerpc/pseries/mobility: use rtas_activate_firmware() on resume
  powerpc/pseries/mobility: extract VASI session polling logic
  powerpc/pseries/mobility: use stop_machine for join/suspend
  powerpc/pseries/mobility: signal suspend cancellation to platform
  powerpc/pseries/mobility: retry partition suspend after error
  powerpc/rtas: dispatch partition migration requests to pseries
  powerpc/rtas: remove rtas_ibm_suspend_me_unsafe()
  powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend
    ops
  powerpc/pseries/hibernation: pass stream id via function arguments
  powerpc/pseries/hibernation: remove pseries_suspend_cpu()
  powerpc/machdep: remove suspend_disable_cpu()
  powerpc/rtas: remove rtas_suspend_cpu()
  powerpc/pseries/hibernation: switch to rtas_ibm_suspend_me()
  powerpc/rtas: remove unused rtas_suspend_last_cpu()
  powerpc/pseries/hibernation: remove redundant cacheinfo update
  powerpc/pseries/hibernation: perform post-suspend fixups later
  powerpc/pseries/hibernation: remove prepare_late() callback
  powerpc/rtas: remove unused rtas_suspend_me_data
  powerpc/pseries/mobility: refactor node lookup during DT update

 arch/powerpc/include/asm/hvcall.h         |   9 +
 arch/powerpc/include/asm/machdep.h        |   1 -
 arch/powerpc/include/asm/rtas-types.h     |   8 -
 arch/powerpc/include/asm/rtas.h           |  17 +-
 arch/powerpc/kernel/rtas.c                | 243 ++++++---------
 arch/powerpc/platforms/pseries/mobility.c | 358 ++++++++++++++++++----
 arch/powerpc/platforms/pseries/suspend.c  |  79 +----
 7 files changed, 415 insertions(+), 300 deletions(-)

-- 
2.28.0