Re: [PATCH v17 02/13] perf/x86, KVM: Prevent host debug register leak into guest OS on NMI
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From: Peter Zijlstra <peterz@infradead.org>
Date: 2026-09-23 08:51:51
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On Tue, Sep 22, 2026 at 01:25:07PM +0900, Masami Hiramatsu (Google) wrote:
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> 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.