Re: [PATCH v2 2/3] KVM: nVMX: Ack and write vector info to intr_info if L1 asks us to

[Marcelo Tosatti <mtosatti@redhat.com>]

On Fri, Apr 11, 2014 at 03:17:47PM -0400, Bandan Das wrote:
> Marcelo Tosatti <mtosatti@redhat.com> writes:
> 
> > On Mon, Mar 31, 2014 at 05:00:24PM -0400, Bandan Das wrote:
> >> This feature emulates the "Acknowledge interrupt on exit" behavior.
> >> We can safely emulate it for L1 to run L2 even if L0 itself has it
> >> disabled (to run L1).
> >> 
> >> Signed-off-by: Bandan Das <bsd@redhat.com>
> >> ---
> >>  arch/x86/kvm/irq.c |  1 +
> >>  arch/x86/kvm/vmx.c | 19 +++++++++++++++++++
> >>  2 files changed, 20 insertions(+)
> >> 
> >> diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
> >> index 484bc87..bd0da43 100644
> >> --- a/arch/x86/kvm/irq.c
> >> +++ b/arch/x86/kvm/irq.c
> >> @@ -113,6 +113,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
> >>  
> >>  	return kvm_get_apic_interrupt(v);	/* APIC */
> >>  }
> >> +EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt);
> >>  
> >>  void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
> >>  {
> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> >> index 3e7f60c..bdc8f2d 100644
> >> --- a/arch/x86/kvm/vmx.c
> >> +++ b/arch/x86/kvm/vmx.c
> >> @@ -4489,6 +4489,18 @@ static bool nested_exit_on_intr(struct kvm_vcpu *vcpu)
> >>  		PIN_BASED_EXT_INTR_MASK;
> >>  }
> >>  
> >> +/*
> >> + * In nested virtualization, check if L1 has enabled
> >> + * interrupt acknowledgement that writes the interrupt vector
> >> + * info on vmexit
> >> + * 
> >> + */
> >> +static bool nested_exit_intr_ack_set(struct kvm_vcpu *vcpu)
> >> +{
> >> +	return get_vmcs12(vcpu)->vm_exit_controls &
> >> +		VM_EXIT_ACK_INTR_ON_EXIT;
> >> +}
> >> +
> >>  static bool nested_exit_on_nmi(struct kvm_vcpu *vcpu)
> >>  {
> >>  	return get_vmcs12(vcpu)->pin_based_vm_exec_control &
> >> @@ -8442,6 +8454,13 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
> >>  	prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info,
> >>  		       exit_qualification);
> >>  
> >> +	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
> >> +	    && nested_exit_intr_ack_set(vcpu)) {
> >> +		int irq = kvm_cpu_get_interrupt(vcpu);
> >
> > Can irq be -1 ?
> 
> If it is, I think that's a bug because if we exited for this 
> reason with INTR_ACK set, the hypervisor expects a valid vector 
> number to be available. 
> 
> What about adding a BUG_ON ?

Sounds good.