Messages in this thread | | | Date | Mon, 27 Jan 2014 21:22:52 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH] x86: Plug racy xAPIC access of CPU hotplug code |
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On Mon, Jan 27, 2014 at 08:14:06PM +0100, Jan Kiszka wrote: > apic_icr_write and its users in smpboot.c were apparently written under > the assumption that this code would only run during early boot. But > nowadays we also execute it when onlining a CPU later on while the > system is fully running. That will make wakeup_cpu_via_init_nmi and, > thus, also native_apic_icr_write run in plain process context. If we > migrate the caller to a different CPU at the wrong time or interrupt it > and write to ICR/ICR2 to send unrelated IPIs, we can end up sending > INIT, SIPI or NMIs to wrong CPUs. > > Fix this by disabling interrupts during the write to the ICR halves and > disable preemption around waiting for ICR availability and using it.
If you just want to disable migration use get_cpu()/put_cpu()
-Andi
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