Re: [PATCH 1/1] Disable GUEST_INTR_STATE_STI flag before injecting NMI to guest on VMX

[Jan Kiszka <jan.kiszka@siemens.com>]

Gleb Natapov wrote:
> On Fri, Aug 27, 2010 at 12:44:41PM +0300, Avi Kivity wrote:
>>> Thinking about the implications: Independent of virtualization, this
>>> means that no code code can in any way rely on the STI shadow if there
>>> are NMIs present that could "consume" it. Because after return from
>>> those NMIs, interrupts could then be injected on the instruction that
>>> was originally under the shadow.
>>>
>> Wow.  Maybe we should request an interrupt window instead when
>> blocked-by-STI is active instead of clearing it.
>>
> Wow indeed. We can remember blocked by sti state before injecting NMI
> and request nmi window open exit. When we get nmi window open exit we
> can restore blocked by sti flag.

For sure we could. But I still wonder what happens to the shadow in such
a scenario on real HW.

Jan

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