Re: [PATCH] kvm-userspace: Cleanup user space NMI injection

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

Avi Kivity wrote:
> Jan Kiszka wrote:
>> Cleanup redundant check for an open NMI window before injecting. This
>> will no longer be supported by the kernel, and it was broken by design
>> anyway.
>>
>> This change still allows to run the user space against older kernel
>> modules.
>>
>>   
> 
> Hm.  For interrupts we need to check, since the interrupt might be
> deasserted or masked while the window is closed.
> 
> Is there no way that this can happen for NMIs?

In our emulation, but I also think in real life, there is no way to
deassert an NMI. Therefore, our user space API just sets the nmi_pending
flag. Masking of NMIs (due to mov ss etc.) is handled by the NMI
injection code, and this has to happen in kernel anyway as the other NMI
sources (APIC and IOAPIC) do not bother about the NMI windows as well.

Jan

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