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Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos
From: |
Radim Krcmar |
Subject: |
Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos |
Date: |
Tue, 15 Dec 2015 19:53:39 +0100 |
2015-12-15 05:43-0500, Paolo Bonzini:
>> Hi Paolo,
>>
>> /* for KVM_GET/SET_VCPU_EVENTS */
>> struct kvm_vcpu_events {
>> ...
>> struct {
>> __u8 injected;
>> __u8 pending;
>> __u8 masked;
>> __u8 pad;
>> } nmi;
>> ...
>>
>> I found that the nmi.masked property does these enable or disable NMI jobs.
>> So, I think we don't need to add a new bit. Right?
>
> nmi.masked says whether the CPU is accepting the NMIs, and is cleared
> by the next IRET instruction. This is a different thing; it probably
> shouldn't affect NMI IPIs, and it definitely should remain set until
> cleared via the RTC. So it should be something like
>
> _u8 external_nmi_disabled;
>
> or similar.
>
> *However* I found this in the ICH9 datasheet:
>
> The ICH9's I/O APIC can only send interrupts due to interrupts which
> do not include SMI, NMI or INIT. This means that in IA-32/Intel ® 64
> based platforms, Front Side Bus interrupt message format delivery modes
> 010 (SMI/PMI), 100 (NMI), and 101 (INIT) as indicated in this section,
> must not be used and is not supported.
>
> In theory the PIIX4 could deliver such messages, but perhaps we could
> disable them in the KVM IOAPIC. If we do this, there is no need for a
> change to struct kvm_vcpu_events, because all external NMI sources will
> be in userspace.
>
> Radim, what do you think?
I looked at the 440fx, piix, and 82083aa(ioapic) datasheets and the
NMI_EN bit doesn't seem to be propagated into the IOAPIC.
The IOAPIC datasheet doesn't mention a thing about NMI masking and PIIX4
generates NMI on SERR# or IOCHK# so it seems that the NMI_EN feature
only changes the behavior of those two ...
I think it's best to do nothing in KVM.
(q35 guests shouldn't configure IOAPIC to send unsupported messages and
disabling SMI/NMI/INIT in the in-kernel IOAPIC for piix is risky.)
- [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei, 2015/12/12
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/14
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/15
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/15
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos,
Radim Krcmar <=
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/16
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/16
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/16
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/16
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/17
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Paolo Bonzini, 2015/12/17
- Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Gonglei (Arei), 2015/12/17
Re: [Qemu-devel] [PATCH] rtc: introduce nmi disable bit handler for cmos, Eduardo Habkost, 2015/12/14