On 1 October 2026 14:21:25 BST, Shradha Gupta <[email protected]> wrote: >Kexec reboot fails on ARM64 Hyper-V guests because the VMBus >connection and SynIC CPU hotplug state are not torn down before the >secondary CPUs are stopped. The kexec kernel consequently starts with >the previous kernel's VMBus state still active. > >The previous version added an ARM64-specific syscore shutdown >implementation. This version follows Michael Kelley's review and moves >the cleanup into the existing architecture-independent VMBus syscore >operations. This removes the separate x86 handler dispatch and gives >x86 and ARM64 the same ordering: > > device_shutdown() > syscore_shutdown() > VMBus UNLOAD and SynIC CPU hotplug teardown > machine_shutdown() > >On x86, VMBus teardown now runs before hv_stimer_global_cleanup(). >This ordering is safe after commit be0cfab740e5 ("clocksource: hyper-v: >Remove support for stimer interrupts in message mode") removed the >VMBus dependency from synthetic timer handling. > >Patch 1 adds a read-only helper that reports whether a kexec reboot is >in progress. The helper is exported because HYPERV_VMBUS is tristate >and the common syscore callback must also link when VMBus is a module. >Patch 2 moves the cleanup into the common callback and removes the >obsolete architecture-specific setup/remove interface. > >For stable kernels that still support message-mode stimers, an >ARM64-specific backport will be needed to preserve the existing x86 >ordering. > >Changes in v3: > - Use the existing common VMBus syscore operations on all > architectures, as suggested by Michael. > - Remove the x86 handler pointer and the weak setup/remove interface. > - Add an exported read-only helper for modular VMBus builds. > - Correct the Fixes tag to the commit that enabled Hyper-V on ARM64. > >Changes in v2: > - Use syscore shutdown instead of an ARM64 machine_shutdown() hook, as > suggested by Catalin. > >Shradha Gupta (2): > kexec: Add helper to report an active kexec reboot > Drivers: hv: Run VMBus kexec cleanup from syscore shutdown > > arch/x86/kernel/cpu/mshyperv.c | 17 +---------------- > drivers/hv/hv_common.c | 10 ---------- > drivers/hv/vmbus_drv.c | 22 ++++++++++++++-------- > include/asm-generic/mshyperv.h | 2 -- > include/linux/kexec.h | 2 ++ > kernel/kexec_core.c | 7 +++++++ > 6 files changed, 24 insertions(+), 36 deletions(-) > > >base-commit: be0cfab740e58b70047ef6e7e3d578f00ed5d258 >
Wow! Great!!! Whole series: Reviewed-by: Bradley Morgan <[email protected]> --- Thanks! "I'm not a very positive person" - Linus torvalds
