linux-kernel - Re: [PATCH v2 11/13] KVM: x86: Add helper to "handle" internal emulation error

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Date:   Wed, 26 Feb 2020 18:52:14 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 11/13] KVM: x86: Add helper to "handle" internal emulation error

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Add a helper to set the appropriate error codes in vcpu->run when
> emulation fails (future patches will add additional failure scenarios).
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/x86.c | 32 ++++++++++++++------------------
>  1 file changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e1eaca65756b..7bffdc6f9e1b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6491,6 +6491,14 @@ void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip)
>  }
>  EXPORT_SYMBOL_GPL(kvm_inject_realmode_interrupt);
>  
> +static int internal_emulation_error(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
> +	vcpu->run->internal.ndata = 0;
> +	return 0;
> +}
> +
>  static int handle_emulation_failure(struct x86_emulate_ctxt *ctxt,
>  				    int emulation_type)
>  {
> @@ -6504,21 +6512,13 @@ static int handle_emulation_failure(struct x86_emulate_ctxt *ctxt,
>  		return 1;
>  	}
>  
> -	if (emulation_type & EMULTYPE_SKIP) {
> -		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
> -		vcpu->run->internal.ndata = 0;
> -		return 0;
> -	}
> +	if (emulation_type & EMULTYPE_SKIP)
> +		return internal_emulation_error(vcpu);
>  
>  	kvm_queue_exception(vcpu, UD_VECTOR);
>  
> -	if (!is_guest_mode(vcpu) && kvm_x86_ops->get_cpl(vcpu) == 0) {
> -		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
> -		vcpu->run->internal.ndata = 0;
> -		return 0;
> -	}
> +	if (!is_guest_mode(vcpu) && kvm_x86_ops->get_cpl(vcpu) == 0)
> +		return internal_emulation_error(vcpu);
>  
>  	return 1;
>  }
> @@ -8986,12 +8986,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
>  
>  	ret = emulator_task_switch(ctxt, tss_selector, idt_index, reason,
>  				   has_error_code, error_code);
> -	if (ret) {
> -		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
> -		vcpu->run->internal.ndata = 0;
> -		return 0;
> -	}
> +	if (ret)
> +		return internal_emulation_error(vcpu);
>  
>  	kvm_rip_write(vcpu, ctxt->eip);
>  	kvm_set_rflags(vcpu, ctxt->eflags);

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly