[PATCH v2 0/6] Hyper-V: kexec fixes for L1VH (mshv)

[Jork Loeser <jloeser@linux.microsoft.com>]

This series fixes kexec support when Linux runs as an L1 Virtual Host
(L1VH) under Hyper-V, using the MSHV driver to manage child VMs.

1. A variable shadowing bug in vmbus that hides the cpuhp state used
   for teardown.

2. Move hv_stimer_global_cleanup() from vmbus's hv_kexec_handler() to
   hv_machine_shutdown(). This ensures stimer cleanup happens before
   the vmbus unload.

3. LP/VP re-creation: after kexec, logical processors and virtual
   processors already exist in the hypervisor. Detect this and skip
   re-adding them.

4-5. SynIC cleanup: the MSHV driver manages its own SynIC resources
     separately from vmbus. Add proper teardown of MSHV-owned SINTs,
     SIMP, and SIEFP on kexec, scoped to only the resources MSHV
     owns.

6. Debugfs stats pages: unmap the VP statistics overlay pages before
   kexec to avoid stale mappings in the new kernel.

Changes since v1:
- Patch 4: account for nested root partitions where VMBus is also
  active (not just L1VH); use a vmbus_active local variable; allocate
  SIRBP L1VH allocation path for when the hypervisor doesn't
  pre-provision the page

Jork Loeser (6):
  Drivers: hv: vmbus: fix hyperv_cpuhp_online variable shadowing
  x86/hyperv: move stimer cleanup to hv_machine_shutdown()
  x86/hyperv: Skip LP/VP creation on kexec
  mshv: limit SynIC management to MSHV-owned resources
  mshv: clean up SynIC state on kexec for L1VH
  mshv: unmap debugfs stats pages on kexec

 arch/x86/kernel/cpu/mshyperv.c |  15 +++-
 drivers/hv/hv_proc.c           |  47 +++++++++++
 drivers/hv/mshv_debugfs.c      |   7 +-
 drivers/hv/mshv_root_main.c    |  22 ++---
 drivers/hv/mshv_synic.c        | 142 ++++++++++++++++++++++-----------
 drivers/hv/vmbus_drv.c         |   2 -
 include/asm-generic/mshyperv.h |  10 +++
 include/hyperv/hvgdk_mini.h    |   1 +
 include/hyperv/hvhdk_mini.h    |  12 +++
 9 files changed, 188 insertions(+), 70 deletions(-)

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2.43.0