Re: [PATCH 8/9] VMX: work around lacking VNMI support

[Gleb Natapov <gleb@qumranet.com>]

Hi Jan,

On Fri, Sep 19, 2008 at 02:04:37PM +0200, Jan Kiszka wrote:
>  static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
>  {
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -2356,6 +2384,29 @@ static void vmx_inject_nmi(struct kvm_vc
>  {
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>  
> +	if (!cpu_has_virtual_nmis()) {
> +		int desc_size = is_long_mode(vcpu) ? 16 : 8;
> +		struct descriptor_table dt;
> +		gpa_t gpa;
> +		u64 desc;
> +
> +		/*
> +		 * Deny delivery if the NMI will not be handled by an
> +		 * interrupt gate (workaround depends on IRQ masking).
> +		 */
> +		vmx_get_idt(vcpu, &dt);
> +		if (!vcpu->arch.rmode.active && dt.limit
> +		    >= desc_size * (NMI_VECTOR + 1) - 1) {
> +			gpa = vcpu->arch.mmu.gva_to_gpa(vcpu,
> +					dt.base + desc_size * NMI_VECTOR);
> +			if (kvm_read_guest(vcpu->kvm, gpa, &desc, 8) == 0
> +			    && ((desc >> 40) & 0x7) != 0x6)
> +				return;
> +		}

Windows2003 sets NMI entry in IDT as a task gate (0x5) during hibernation and this check
prevents it from shutting down itself. It hangs in "It is save to turn
your computer now" screen.
If I replace this part by:
    if(vmx->soft_vnmi_blocked)
	  return;
It shut itself down properly.

> +		vmx->soft_vnmi_blocked = 1;
> +		vmx->vnmi_blocked_time = 0;
> +	}
> +

--
			Gleb.