[PATCH v4 0/9] support CPU hot-unplug

["Ankur Arora" <ankur.a.arora@oracle.com>]

Hi,

This series adds support for CPU hot-unplug with OVMF.

Please see this in conjunction with the QEMU secureboot hot-unplug v2
series posted here (now upstreamed):
  https://lore.kernel.org/qemu-devel/20201207140739.3829993-1-imammedo@redhat.com/

Patches 1 and 3,
  ("OvmfPkg/CpuHotplugSmm: refactor hotplug logic")
  ("OvmfPkg/CpuHotplugSmm: add Qemu Cpu Status helper")
are either refactors or add support functions.

  OvmfPkg/CpuHotplugSmm: introduce UnplugCpus()
  OvmfPkg/CpuHotplugSmm: add CpuEject()
  OvmfPkg/CpuHotplugSmm: add worker to do CPU ejection

Patch 2 and 9,
  ("OvmfPkg/CpuHotplugSmm: collect hot-unplug events")
  ("OvmfPkg/SmmControl2Dxe: negotiate CPU hot-unplug")
handle the QEMU protocol logic for collection of CPU hot-unplug events
or the protocol negotiation.

Patch 4,
  ("OvmfPkg/CpuHotplugSmm: introduce UnplugCpus()")
adds the MMI logic for CPU hot-unplug handling and informing
the PiSmmCpuDxeSmm of CPU removal.

Patches 5 and 6,
  ("OvmfPkg/CpuHotplugSmm: define CPU_HOT_EJECT_DATA")
  ("OvmfPkg/SmmCpuFeaturesLib: init CPU ejection state")
sets up state for doing the CPU ejection as part of hot-unplug.

Patches 7, and 8,
  ("OvmfPkg/CpuHotplugSmm: introduce UnplugCpus()")
  ("OvmfPkg/CpuHotplugSmm: add worker to do CPU ejection")
add the CPU ejection logic.

Testing (with QEMU 5.2.50):
 - Stable with randomized CPU plug/unplug (guest maxcpus=1,8,128)
 - Synthetic tests with simultaneous multi CPU hot-unplug
 - Negotiation with/without CPU hotplug enabled

Also at:
  github.com/terminus/edk2/ hot-unplug-v4

Changelog:
v4:
  - Gets rid of unnecessary UefiCpuPkg changes

v3:
  - Use a saner PCD based interface to share state between PiSmmCpuDxeSmm
    and OvmfPkg/CpuHotplugSmm
  - Cleaner split of the hot-unplug code
  URL: https://patchew.org/EDK2/20210115074533.277448-1-ankur.a.arora@oracle.com/

v2:
  - Do the ejection via SmmCpuFeaturesRendezvousExit()
  URL: https://patchew.org/EDK2/20210107195515.106158-1-ankur.a.arora@oracle.com/

RFC:
  URL: https://patchew.org/EDK2/20201208053432.2690694-1-ankur.a.arora@oracle.com/


Please review.

Thanks
Ankur

Ankur Arora (9):
  OvmfPkg/CpuHotplugSmm: refactor hotplug logic
  OvmfPkg/CpuHotplugSmm: collect hot-unplug events
  OvmfPkg/CpuHotplugSmm: add Qemu Cpu Status helper
  OvmfPkg/CpuHotplugSmm: introduce UnplugCpus()
  OvmfPkg/CpuHotplugSmm: define CPU_HOT_EJECT_DATA
  OvmfPkg/SmmCpuFeaturesLib: init CPU ejection state
  OvmfPkg/CpuHotplugSmm: add CpuEject()
  OvmfPkg/CpuHotplugSmm: add worker to do CPU ejection
  OvmfPkg/SmmControl2Dxe: negotiate CPU hot-unplug

 OvmfPkg/CpuHotplugSmm/CpuHotplug.c                 | 435 ++++++++++++++++-----
 OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf            |   1 +
 OvmfPkg/CpuHotplugSmm/QemuCpuhp.c                  |  58 ++-
 OvmfPkg/CpuHotplugSmm/QemuCpuhp.h                  |   6 +
 OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h  |   2 +
 OvmfPkg/Include/Library/CpuHotEjectData.h          |  31 ++
 .../Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c  |  62 +++
 .../SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf        |   3 +
 OvmfPkg/OvmfPkg.dec                                |   6 +
 OvmfPkg/SmmControl2Dxe/SmiFeatures.c               |  25 +-
 10 files changed, 527 insertions(+), 102 deletions(-)
 create mode 100644 OvmfPkg/Include/Library/CpuHotEjectData.h

-- 
2.9.3