Re: [PATCH 10/11] VMX: work around lacking VNMI support

[Gleb Natapov <gleb@qumranet.com>]

On Tue, Sep 23, 2008 at 10:46:38AM +0200, Jan Kiszka wrote:
> Gleb Natapov wrote:
> > On Mon, Sep 22, 2008 at 09:59:07AM +0200, Jan Kiszka wrote:
> >> @@ -2356,6 +2384,19 @@ static void vmx_inject_nmi(struct kvm_vc
> >>  {
> >>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> >>  
> >> +	if (!cpu_has_virtual_nmis()) {
> >> +		/*
> >> +		 * Tracking the NMI-blocked state in software is built upon
> >> +		 * finding the next open IRQ window. This, in turn, depends on
> >> +		 * well-behaving guests: They have to keep IRQs disabled at
> >> +		 * least as long as the NMI handler runs. Otherwise we may
> >> +		 * cause NMI nesting, maybe breaking the guest. But as this is
> >> +		 * highly unlikely, we can live with the residual risk.
> >> +		 */
> >> +		vmx->soft_vnmi_blocked = 1;
> >> +		vmx->vnmi_blocked_time = 0;
> >> +	}
> >> +
> > We still get here with vmx->soft_vnmi_blocked = 1. Trying to find out
> > how.
> 
> We should only come along here with vnmi blocked on reinjection (after a
> fault on calling the handler).
> 
I see that nmi_injected is never cleared and it is check before calling
vmx_inject_nmi();

--
			Gleb.