Re: [PATCH 3/4] KVM: VMX: Emulated real mode interrupt injection

[Avi Kivity <avi@redhat.com>]

  On 09/20/2010 07:30 PM, Marcelo Tosatti wrote:
> >   static void __vmx_complete_interrupts(struct vcpu_vmx *vmx,
> >   				u32 idt_vectoring_info,
> >   				int instr_len_field,
> >  @@ -3864,9 +3814,6 @@ static void __vmx_complete_interrupts(struct vcpu_vmx *vmx,
> >   	int type;
> >   	bool idtv_info_valid;
> >
> >  -	if (vmx->rmode.irq.pending)
> >  -		fixup_rmode_irq(vmx,&idt_vectoring_info);
> >  -
>
> Don't you have to undo kvm_inject_realmode_interrupt if injection fails?
>
>

Injection cannot fail (at least, in the same sense as the vmx 
injections).  It's actually not about failures, it's about guest entry 
being cancelled due to a signal or some KVM_REQ that needs attention.  
For vmx style injections, we need to undo the injection to keep things 
in a consistent state.  To realmode emulated injection, everything is in 
a consistent state already, so no need to undo anything (it's also 
impossible, since we overwrote memory on the stack).


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.