Re: [RFC][PATCH 3/4] KVM: VMX: Enable NMI with in-kernel irqchip

[Avi Kivity <avi@qumranet.com>]

Yang, Sheng wrote:
> From 4942a5c35c97e5edb6fe1303e04fb86f25cac345 Mon Sep 17 00:00:00 2001
> From: Sheng Yang <sheng.yang@intel.com>
> Date: Thu, 8 May 2008 16:00:57 +0800
> Subject: [PATCH 3/4] KVM: VMX: Enable NMI with in-kernel irqchip
>
>
>  static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
>  {
>  	int word_index = __ffs(vcpu->arch.irq_summary);
> @@ -2146,9 +2159,11 @@ static void do_interrupt_requests(struct kvm_vcpu 
> *vcpu,
>  		/*
>  		 * Interrupts blocked.  Wait for unblock.
>  		 */
> -		cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
> +		cpu_based_vm_exec_control |=
> +			CPU_BASED_VIRTUAL_INTR_PENDING;
>  	else
> -		cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
> +		cpu_based_vm_exec_control &=
> +			~CPU_BASED_VIRTUAL_INTR_PENDING;
>   

This seems spurious.

>  	/* We need to handle NMIs before interrupts are enabled */
> -	if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) { /* nmi */
> +	if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) {
>  		KVMTRACE_0D(NMI, vcpu, handler);
> -		asm("int $2");
> +		if (!cpu_has_virtual_nmis())
> +			asm("int $2");
>  	}
>  }
>   

That's a host nmi.  So does the PIN_BASED_VIRTUAL_NMI mean NMIs are 
handled like unacked host interrupts?

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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