On Fri, 2023-10-27 at 21:14 +0200, Peter Zijlstra wrote: > On Fri, Oct 27, 2023 at 07:36:51PM +0100, David Woodhouse wrote: > > From: David Woodhouse <[email protected]> > > > > Xen HVM guests were observed taking triple-faults when attempting to > > online a previously offlined vCPU. > > > > Investigation showed that the fault was coming from a failing call > > to lockdep_assert_irqs_disabled(), in load_current_idt() which was > > too early in the CPU bringup to actually catch the exception and > > report the failure cleanly. > > > > This was a false positive, caused by acpi_idle_play_dead() setting > > the per-cpu hardirqs_enabled flag by calling safe_halt(). Switch it > > to use raw_safe_halt() instead, which doesn't do so. > > > > Signed-off-by: David Woodhouse <[email protected]> > > --- > > We might {also,instead} explicitly set the hardirqs_enabled flag to > > zero when bringing up an AP? > > So I fixed up the idle paths the other day (see all that __cpuidle > stuff) but I've not yet gone through the whole hotplug thing :/ > > This seems right, at this point everything, including RCU is very much > gone, any instrumentation is undesired. > > Acked-by: Peter Zijlstra (Intel) <[email protected]>
Ping? Who's taking this? Needs a Cc:[email protected] now too, to fix 6.6.x.
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