On Wed, Sep 23, 2026, Peter Zijlstra wrote:
> On Tue, Sep 22, 2026 at 01:25:07PM +0900, Masami Hiramatsu (Google) wrote:
> > From: Masami Hiramatsu (Google) <[email protected]>
> >
> > When KVM enters a guest OS, host hardware breakpoints are disabled
> > before running the guest. However, an NMI can occur while executing
> > in guest mode or during guest transition, where
> > arch_install_hw_breakpoint() can be invoked from NMI context.
>
> How? AFAICT perf doesn't do that. arch_install_hw_breakpoint() is called
> through pmu::add() which is strictly IPI context.
I assume it's:
kgdb_nmi_handler()
|
-> kgdb_nmicallin()
|
-> kgdb_cpu_enter()
|
-> arch_kgdb_ops.correct_hw_break()
|
-> kgdb_correct_hw_break()
|
-> arch_install_hw_breakpoint()
