[Qemu-devel] [PATCH v6 00/12] cpu-exec: Safe work in quiescent state

[Paolo Bonzini]

This is not the code I promised at the beginning of the week.
It's better, and not only in that this one works. :)  Instead of
reinventing the wheel and using the new wheel for linux-user's
start_exclusive/end_exclusive, the linux-user/ code is moved to
cpus-common.c and reused as the synchronization mechanism behind
async_safe_run_on_cpu.

The code works and actually satisfies our needs very well.  The only
disadvantage is that safe work items will run with a mutex taken; the
mutex fits decently in QEMU's hierarchy however, sitting between the
BQL and the tb_lock.

For performance, the last patch changes it to avoid condition variables
in the fast path.  (There are still two memory barriers; if desired they
could be merged with the ones in rcu_read_lock/rcu_read_unlock).  I am
including a formal model of the algorithm; together with new documentation
in include/qom/cpu.h, it accounts for most of the added lines of code.
Still, it is completely optional.

Paolo

Alex Bennée (1):
  cpus: pass CPUState to run_on_cpu helpers

Paolo Bonzini (5):
  cpus-common: move CPU list management to common code
  cpus-common: move exclusive work infrastructure from linux-user
  cpus-common: always defer async_run_on_cpu work items
  cpus-common: Introduce async_safe_run_on_cpu()
  cpus-common: lock-free fast path for cpu_exec_start/end

Sergey Fedorov (6):
  cpus: Move common code out of {async_, }run_on_cpu()
  cpus: Rename flush_queued_work()
  linux-user: Use QemuMutex and QemuCond
  linux-user: Add qemu_cpu_is_self() and qemu_cpu_kick()
  cpus-common: move CPU work item management to common code
  tcg: Make tb_flush() thread safe

 Makefile.target            |   2 +-
 bsd-user/main.c            |  30 +----
 cpu-exec.c                 |  12 +-
 cpus-common.c              | 314 +++++++++++++++++++++++++++++++++++++++++++++
 cpus.c                     |  99 +-------------
 docs/tcg-exclusive.promela | 224 ++++++++++++++++++++++++++++++++
 exec.c                     |  30 +----
 hw/i386/kvm/apic.c         |   3 +-
 hw/i386/kvmvapic.c         |   6 +-
 hw/ppc/ppce500_spin.c      |  31 ++---
 hw/ppc/spapr.c             |   6 +-
 hw/ppc/spapr_hcall.c       |  17 +--
 include/exec/cpu-all.h     |   4 +
 include/exec/cpu-common.h  |   2 +
 include/exec/exec-all.h    |  11 --
 include/exec/tb-context.h  |   2 +-
 include/qom/cpu.h          |  95 +++++++++++++-
 kvm-all.c                  |  21 +--
 linux-user/main.c          | 130 ++++++-------------
 target-i386/helper.c       |  19 ++-
 target-i386/kvm.c          |   6 +-
 target-s390x/cpu.c         |   4 +-
 target-s390x/cpu.h         |   7 +-
 target-s390x/kvm.c         |  98 +++++++-------
 target-s390x/misc_helper.c |   4 +-
 translate-all.c            |  38 ++++--
 vl.c                       |   1 +
 27 files changed, 814 insertions(+), 402 deletions(-)
 create mode 100644 cpus-common.c
 create mode 100644 docs/tcg-exclusive.promela

-- 
2.7.4