Re: [PATCH v5 1/2] KVM: X86: Introduce handle_ud()

From: David Hildenbrand
Date: Wed Apr 04 2018 - 07:54:43 EST


On 04.04.2018 01:28, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Introduce handle_ud() to handle invalid opcode, this function will be
> used by later patches.
>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Liran Alon <liran.alon@xxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/kvm/svm.c | 9 +--------
> arch/x86/kvm/vmx.c | 10 ++--------
> arch/x86/kvm/x86.c | 13 +++++++++++++
> arch/x86/kvm/x86.h | 2 ++
> 4 files changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f66fc2e..e0a3f56 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2676,14 +2676,7 @@ static int bp_interception(struct vcpu_svm *svm)
>
> static int ud_interception(struct vcpu_svm *svm)
> {
> - int er;
> -
> - er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - if (er != EMULATE_DONE)
> - kvm_queue_exception(&svm->vcpu, UD_VECTOR);
> - return 1;
> + return handle_ud(&svm->vcpu);
> }
>
> static int ac_interception(struct vcpu_svm *svm)
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index b2f8a70..0f11243 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6436,14 +6436,8 @@ static int handle_exception(struct kvm_vcpu *vcpu)
> if (is_nmi(intr_info))
> return 1; /* already handled by vmx_vcpu_run() */
>
> - if (is_invalid_opcode(intr_info)) {
> - er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - if (er != EMULATE_DONE)
> - kvm_queue_exception(vcpu, UD_VECTOR);
> - return 1;
> - }
> + if (is_invalid_opcode(intr_info))
> + return handle_ud(vcpu);

(maybe different on this branch) isn't "er" now unused?

>
> error_code = 0;
> if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7d9a444..1eb495e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4840,6 +4840,19 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt,
> }
> EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system);
>
> +int handle_ud(struct kvm_vcpu *vcpu)
> +{
> + enum emulation_result er;
> +
> + er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
> + if (er == EMULATE_USER_EXIT)
> + return 0;
> + if (er != EMULATE_DONE)
> + kvm_queue_exception(vcpu, UD_VECTOR);
> + return 1;

I would now actually prefer

if (er == EMULATE_DONE)
return 1 ...


Anyhow,

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>


--

Thanks,

David / dhildenb