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From: Thomas Gleixner <tglx@linutronix.de>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	kvm@vger.kernel.org
Subject: Re: [PATCH 4/4] KVM/VMX: Fold handle_interrupt_nmi_irqoff() into its solo caller
Date: Sat, 01 May 2021 01:28:14 +0200	[thread overview]
Message-ID: <87im43e4j5.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <ba3f6230-8766-92e5-1189-a114c236fd48@redhat.com>

On Fri, Apr 30 2021 at 11:06, Paolo Bonzini wrote:

> On 30/04/21 11:03, Thomas Gleixner wrote:
>> Lai,
>> 
>> On Tue, Apr 27 2021 at 07:09, Lai Jiangshan wrote:
>>>   	u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
>>> @@ -6427,12 +6417,19 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
>>>   static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>>>   {
>>>   	u32 intr_info = vmx_get_intr_info(vcpu);
>>> +	unsigned int vector;
>>> +	gate_desc *desc;
>>>   
>>>   	if (WARN_ONCE(!is_external_intr(intr_info),
>>>   	    "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
>>>   		return;
>>>   
>>> -	handle_interrupt_nmi_irqoff(vcpu, intr_info);
>>> +	vector = intr_info & INTR_INFO_VECTOR_MASK;
>>> +	desc = (gate_desc *)host_idt_base + vector;
>>> +
>>> +	kvm_before_interrupt(vcpu);
>>> +	vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
>>> +	kvm_after_interrupt(vcpu);
>> 
>> So the previous patch does:
>> 
>> +               kvm_before_interrupt(&vmx->vcpu);
>> +               vmx_do_interrupt_nmi_irqoff((unsigned long)asm_noist_exc_nmi);
>> +               kvm_after_interrupt(&vmx->vcpu);
>> 
>> What is this idt gate descriptor dance for in this code?
>
> NMIs are sent through a different vmexit code (the same one as 
> exceptions).  This one is for interrupts.

Duh. Yes. The ability to read is clearly an advantage...

  reply	other threads:[~2021-04-30 23:28 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
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 [this message]
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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