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

Avi Kivity
2008-05-09T15:49:13Z

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.