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

From: Liran Alon <liran.alon@oracle.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Vitaly Kuznetsov" <vkuznets@redhat.com>,
	"Wanpeng Li" <wanpengli@tencent.com>,
	"Jim Mattson" <jmattson@google.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code
Date: Fri, 23 Aug 2019 16:48:16 +0300	[thread overview]
Message-ID: <AB4F0E37-1E13-4735-BE9F-6C80D13D016D@oracle.com> (raw)
In-Reply-To: <20190823010709.24879-9-sean.j.christopherson@intel.com>

> On 23 Aug 2019, at 4:07, Sean Christopherson <sean.j.christopherson@intel.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@intel.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
> 