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

[Marcelo Tosatti <mtosatti@redhat.com>]

On Sun, Sep 19, 2010 at 02:34:07PM +0200, Avi Kivity wrote:
> From: Mohammed Gamal <m.gamal005@gmail.com>
> 
> Replace the inject-as-software-interrupt hack we currently have with
> emulated injection.
> 
> Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/vmx.c |   65 ++++-----------------------------------------------
>  1 files changed, 6 insertions(+), 59 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 8ef6199..2572153 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -155,11 +155,6 @@ struct vcpu_vmx {
>  			u32 limit;
>  			u32 ar;
>  		} tr, es, ds, fs, gs;
> -		struct {
> -			bool pending;
> -			u8 vector;
> -			unsigned rip;
> -		} irq;
>  	} rmode;
>  	int vpid;
>  	bool emulation_required;
> @@ -1034,16 +1029,8 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
>  	}
>  
>  	if (vmx->rmode.vm86_active) {
> -		vmx->rmode.irq.pending = true;
> -		vmx->rmode.irq.vector = nr;
> -		vmx->rmode.irq.rip = kvm_rip_read(vcpu);
> -		if (kvm_exception_is_soft(nr))
> -			vmx->rmode.irq.rip +=
> -				vmx->vcpu.arch.event_exit_inst_len;
> -		intr_info |= INTR_TYPE_SOFT_INTR;
> -		vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
> -		vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, 1);
> -		kvm_rip_write(vcpu, vmx->rmode.irq.rip - 1);
> +		if (kvm_inject_realmode_interrupt(vcpu, nr) != EMULATE_DONE)
> +			kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>  		return;
>  	}
>  
> @@ -2822,16 +2809,8 @@ static void vmx_inject_irq(struct kvm_vcpu *vcpu)
>  
>  	++vcpu->stat.irq_injections;
>  	if (vmx->rmode.vm86_active) {
> -		vmx->rmode.irq.pending = true;
> -		vmx->rmode.irq.vector = irq;
> -		vmx->rmode.irq.rip = kvm_rip_read(vcpu);
> -		if (vcpu->arch.interrupt.soft)
> -			vmx->rmode.irq.rip +=
> -				vmx->vcpu.arch.event_exit_inst_len;
> -		vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
> -			     irq | INTR_TYPE_SOFT_INTR | INTR_INFO_VALID_MASK);
> -		vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, 1);
> -		kvm_rip_write(vcpu, vmx->rmode.irq.rip - 1);
> +		if (kvm_inject_realmode_interrupt(vcpu, irq) != EMULATE_DONE)
> +			kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>  		return;
>  	}
>  	intr = irq | INTR_INFO_VALID_MASK;
> @@ -2863,14 +2842,8 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
>  
>  	++vcpu->stat.nmi_injections;
>  	if (vmx->rmode.vm86_active) {
> -		vmx->rmode.irq.pending = true;
> -		vmx->rmode.irq.vector = NMI_VECTOR;
> -		vmx->rmode.irq.rip = kvm_rip_read(vcpu);
> -		vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
> -			     NMI_VECTOR | INTR_TYPE_SOFT_INTR |
> -			     INTR_INFO_VALID_MASK);
> -		vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, 1);
> -		kvm_rip_write(vcpu, vmx->rmode.irq.rip - 1);
> +		if (kvm_inject_realmode_interrupt(vcpu, NMI_VECTOR) != EMULATE_DONE)
> +			kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>  		return;
>  	}
>  	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
> @@ -3832,29 +3805,6 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
>  			ktime_to_ns(ktime_sub(ktime_get(), vmx->entry_time));
>  }
>  
> -/*
> - * Failure to inject an interrupt should give us the information
> - * in IDT_VECTORING_INFO_FIELD.  However, if the failure occurs
> - * when fetching the interrupt redirection bitmap in the real-mode
> - * tss, this doesn't happen.  So we do it ourselves.
> - */
> -static void fixup_rmode_irq(struct vcpu_vmx *vmx, u32 *idt_vectoring_info)
> -{
> -	vmx->rmode.irq.pending = 0;
> -	if (kvm_rip_read(&vmx->vcpu) + 1 != vmx->rmode.irq.rip)
> -		return;
> -	kvm_rip_write(&vmx->vcpu, vmx->rmode.irq.rip);
> -	if (*idt_vectoring_info & VECTORING_INFO_VALID_MASK) {
> -		*idt_vectoring_info &= ~VECTORING_INFO_TYPE_MASK;
> -		*idt_vectoring_info |= INTR_TYPE_EXT_INTR;
> -		return;
> -	}
> -	*idt_vectoring_info =
> -		VECTORING_INFO_VALID_MASK
> -		| INTR_TYPE_EXT_INTR
> -		| vmx->rmode.irq.vector;
> -}
> -
>  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?

>  	idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
>  
>  	vmx->vcpu.arch.nmi_injected = false;
> -- 
> 1.7.2.3