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From: Thomas Gleixner <tglx@linutronix.de>
To: Lai Jiangshan <jiangshanlai@gmail.com>, linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.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: Fri, 30 Apr 2021 11:03:25 +0200	[thread overview]
Message-ID: <87y2d0du02.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210426230949.3561-5-jiangshanlai@gmail.com>

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?

Thanks,

        tglx

  reply	other threads:[~2021-04-30  9:03 UTC|newest]

Thread overview: 19+ 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 3/4] KVM/VMX: Invoke NMI non-IST entry instead of IST entry 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 [this message]
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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