[PATCH v3 0/6] Hyper-V: kexec fixes for L1VH (mshv)

Jork Loeser
2026-04-08T01:37:03Z

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 v2:
- Rebased onto linux-next/master to adapt to the upstream SynIC
refactor (commit 5a674ef871fe, "mshv: refactor synic init and
cleanup").

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_synic.c | 146 +++++++++++++++++++++------------
drivers/hv/vmbus_drv.c | 2 -
include/asm-generic/mshyperv.h | 10 +++
include/hyperv/hvgdk_mini.h | 1 +
include/hyperv/hvhdk_mini.h | 12 +++
8 files changed, 184 insertions(+), 56 deletions(-)

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2.43.0