From: Carlos Bilbao <carlos.bilbao@kernel.org>

Provide a priority-based mechanism to set the behavior of the kernel at
the post-panic stage -- the current default is a waste of CPU except for
cases with console that generate insightful output.

In v1 [1], I illustrated the potential to reduce unnecessary CPU usage
with an experiment with VMs. The main delta is that, instead of a weak
function that archs can overwrite, we provide a flexible priority-based
mechanism (following suggestions by Sean Christopherson),
panic_set_handling().

[1] https://lore.kernel.org/all/20250326151204.67898-1-carlos.bilbao@kernel.org/

Carlos:
  panic: Allow for dynamic custom behavior after panic
  x86/panic: Add x86_panic_handler as default post-panic behavior

---
 arch/x86/kernel/setup.c | 12 ++++++++++++
 include/linux/panic.h   |  2 ++
 kernel/panic.c          | 27 +++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)