From: Thomas Gleixner <tglx@linutronix.de>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Maxim Levitsky <mlevitsk@redhat.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-kernel@vger.kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
Steven Rostedt <rostedt@goodmis.org>,
Andi Kleen <ak@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Uros Bizjak <ubizjak@gmail.com>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Juergen Gross <JGross@suse.com>, Joerg Roedel <jroedel@suse.de>,
Jian Cai <caij2003@gmail.com>
Subject: Re: [PATCH] KVM/VMX: Invoke NMI non-IST entry instead of IST entry
Date: Wed, 05 May 2021 02:00:10 +0200 [thread overview]
Message-ID: <87im3yhwxh.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <5d7ca301-a0b2-d389-3bc2-feb304c9f5b5@redhat.com>
On Tue, May 04 2021 at 23:56, Paolo Bonzini wrote:
> On 04/05/21 23:51, Sean Christopherson wrote:
>> On Tue, May 04, 2021, Paolo Bonzini wrote:
>>> On 04/05/21 23:23, Andy Lutomirski wrote:
>>>>> On May 4, 2021, at 2:21 PM, Sean Christopherson <seanjc@google.com> wrote:
>>>>> FWIW, NMIs are masked if the VM-Exit was due to an NMI.
>>>
>>> Huh, indeed: "An NMI causes subsequent NMIs to be blocked, but only after
>>> the VM exit completes".
>>>
>>>> Then this whole change is busted, since nothing will unmask NMIs. Revert it?
>>> Looks like the easiest way out indeed.
>>
>> I've no objection to reverting to intn, but what does reverting versus handling
>> NMI on the kernel stack have to do with NMIs being blocked on VM-Exit due to NMI?
>> I'm struggling mightily to connect the dots.
>
> Nah, you're right: vmx_do_interrupt_nmi_irqoff will not call the handler
> directly, rather it calls the IDT entrypoint which *will* do an IRET and
> unmask NMIs. I trusted Andy too much on this one. :)
>
> Thomas's posted patch ("[PATCH] KVM/VMX: Invoke NMI non-IST entry
> instead of IST entry") looks good.
Well, looks good is one thing.
It would be more helpful if someone would actually review and/or test it.
Thanks,
tglx
next prev parent reply other threads:[~2021-05-05 0:00 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 23:09 [PATCH 0/4] x86: Don't invoke asm_exc_nmi() on the kernel stack Lai Jiangshan
2021-04-26 23:09 ` [PATCH 1/4] x86/xen/entry: Rename xenpv_exc_nmi to noist_exc_nmi Lai Jiangshan
2021-04-28 21:27 ` Steven Rostedt
2021-04-30 7:15 ` Paolo Bonzini
2021-04-30 12:05 ` Steven Rostedt
2021-05-03 19:05 ` Thomas Gleixner
2021-05-03 19:41 ` Thomas Gleixner
2021-05-10 7:59 ` Juergen Gross
2021-04-26 23:09 ` [PATCH 2/4] x86/entry: Use asm_noist_exc_nmi() for NMI in early booting stage Lai Jiangshan
2021-04-28 21:30 ` Steven Rostedt
2021-05-03 20:13 ` Thomas Gleixner
2021-05-03 20:24 ` Thomas Gleixner
2021-05-03 21:45 ` Thomas Gleixner
2021-05-04 12:43 ` Thomas Gleixner
2021-05-04 19:50 ` [PATCH] KVM/VMX: Invoke NMI non-IST entry instead of IST entry Thomas Gleixner
2021-05-04 21:05 ` Maxim Levitsky
2021-05-04 21:12 ` Paolo Bonzini
2021-05-04 21:21 ` Sean Christopherson
2021-05-04 21:23 ` Andy Lutomirski
2021-05-04 21:25 ` Paolo Bonzini
2021-05-04 21:51 ` Sean Christopherson
2021-05-04 21:56 ` Paolo Bonzini
2021-05-05 0:00 ` Thomas Gleixner [this message]
2021-05-05 15:44 ` Lai Jiangshan
2021-05-05 1:07 ` Lai Jiangshan
2021-05-05 1:11 ` Andy Lutomirski
2021-05-06 12:14 ` [tip: x86/urgent] " tip-bot2 for Lai Jiangshan
2021-04-26 23:09 ` [PATCH 3/4] " Lai Jiangshan
2021-04-30 2:46 ` Lai Jiangshan
2021-05-03 19:37 ` Thomas Gleixner
2021-05-03 20:02 ` Thomas Gleixner
2021-05-04 8:10 ` Paolo Bonzini
2021-04-26 23:09 ` [PATCH 4/4] KVM/VMX: Fold handle_interrupt_nmi_irqoff() into its solo caller Lai Jiangshan
2021-04-30 9:03 ` Thomas Gleixner
2021-04-30 9:06 ` Paolo Bonzini
2021-04-30 23:28 ` Thomas Gleixner
2021-04-30 7:14 ` [PATCH 0/4] x86: Don't invoke asm_exc_nmi() on the kernel stack Paolo Bonzini
2021-05-03 14:36 ` Thomas Gleixner
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