On 03/17/2010 11:28 AM, Sheng Yang wrote:
I'm not sure if vmexit does break NMI context or not. Hardware NMI context
isn't reentrant till a IRET. YangSheng would like to double check it.
After more check, I think VMX won't remained NMI block state for host. That's
means, if NMI happened and processor is in VMX non-root mode, it would only
result in VMExit, with a reason indicate that it's due to NMI happened, but no
more state change in the host.
So in that meaning, there _is_ a window between VMExit and KVM handle the NMI.
Moreover, I think we _can't_ stop the re-entrance of NMI handling code because
"int $2" don't have effect to block following NMI.
That's pretty bad, as NMI runs on a separate stack (via IST). So if
another NMI happens while our int $2 is running, the stack will be
corrupted.
And if the NMI sequence is not important(I think so), then we need to generate
a real NMI in current vmexit-after code. Seems let APIC send a NMI IPI to
itself is a good idea.
I am debugging a patch based on apic->send_IPI_self(NMI_VECTOR) to replace
"int $2". Something unexpected is happening...
I think you need DM_NMI for that to work correctly.
An alternative is to call the NMI handler directly.
--
error compiling committee.c: too many arguments to function
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