linux-kernel - Re: [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code

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Message-Id: <AB4F0E37-1E13-4735-BE9F-6C80D13D016D@oracle.com>
Date:   Fri, 23 Aug 2019 16:48:16 +0300
From:   Liran Alon <liran.alon@...cle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...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: [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed
 emulation into emulation code



> On 23 Aug 2019, at 4:07, Sean Christopherson <sean.j.christopherson@...el.com> wrote:
> 
> Immediately inject a #UD and return EMULATE done if emulation fails when
> handling an intercepted #UD.  This helps pave the way for removing
> EMULATE_FAIL altogether.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>

I suggest squashing this commit which previous one.

-Liran

> ---
> arch/x86/kvm/x86.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a1f9e36b2d58..bff3320aa78e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5328,7 +5328,6 @@ EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system);
> int handle_ud(struct kvm_vcpu *vcpu)
> {
> 	int emul_type = EMULTYPE_TRAP_UD;
> -	enum emulation_result er;
> 	char sig[5]; /* ud2; .ascii "kvm" */
> 	struct x86_exception e;
> 
> @@ -5340,12 +5339,7 @@ int handle_ud(struct kvm_vcpu *vcpu)
> 		emul_type = EMULTYPE_TRAP_UD_FORCED;
> 	}
> 
> -	er = kvm_emulate_instruction(vcpu, emul_type);
> -	if (er == EMULATE_USER_EXIT)
> -		return 0;
> -	if (er != EMULATE_DONE)
> -		kvm_queue_exception(vcpu, UD_VECTOR);
> -	return 1;
> +	return kvm_emulate_instruction(vcpu, emul_type) != EMULATE_USER_EXIT;
> }
> EXPORT_SYMBOL_GPL(handle_ud);
> 
> @@ -6533,8 +6527,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
> 		++vcpu->stat.insn_emulation;
> 		if (r != EMULATION_OK)  {
> 			if ((emulation_type & EMULTYPE_TRAP_UD) ||
> -			    (emulation_type & EMULTYPE_TRAP_UD_FORCED))
> -				return EMULATE_FAIL;
> +			    (emulation_type & EMULTYPE_TRAP_UD_FORCED)) {
> +				kvm_queue_exception(vcpu, UD_VECTOR);
> +				return EMULATE_DONE;
> +			}
> 			if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
> 						emulation_type))
> 				return EMULATE_DONE;
> -- 
> 2.22.0
>