[PATCH 0/3] system: Don't leak CPU AddressSpaces

[Peter Maydell <peter.maydell@linaro.org>]

When a vCPU is created, it typically calls cpu_address_space_init()
one or more times to set up its address spaces. We don't currently
do anything to destroy these address spaces, which means that we
will leak them on a vcpu hot-plug -> hot-unplug cycle.

This patchset fixes the leak by replacing the current
cpu_address_space_destroy() (which has an awkward API, includes
a bug, and is never called from anywhere) with a new
cpu_destroy_address_spaces() which cleans up all the ASes a CPU
has and is called from generic unrealize code.

Patch 1 is just a comment improvement to clarify that
address_space_destroy() defers most of its work to RCU and you
can't free the memory for the AS struct itself until it's done.

Patch 2 is from Peter Xu; we need to be able to do "destroy and
free an AS" via RCU, and at the moment you can't do that.

Patch 3 is the bugfix proper.

thanks
-- PMM

Peter Maydell (2):
  include/system/memory.h: Clarify address_space_destroy() behaviour
  physmem: Destroy all CPU AddressSpaces on unrealize

Peter Xu (1):
  memory: New AS helper to serialize destroy+free

 include/exec/cpu-common.h          | 10 ++++-----
 include/hw/core/cpu.h              |  1 -
 include/system/memory.h            | 24 ++++++++++++++++++---
 hw/core/cpu-common.c               |  1 +
 stubs/cpu-destroy-address-spaces.c | 15 +++++++++++++
 system/memory.c                    | 20 +++++++++++++++++-
 system/physmem.c                   | 34 ++++++++++++++----------------
 stubs/meson.build                  |  1 +
 8 files changed, 78 insertions(+), 28 deletions(-)
 create mode 100644 stubs/cpu-destroy-address-spaces.c

-- 
2.43.0