Re: [PATCH v3 2/4] KVM: x86: add more information to the kvm_entry tracepoint

[Paolo Bonzini]

On 9/28/23 12:36, Maxim Levitsky wrote:
> Add VMX/SVM specific interrupt injection info to vm entry tracepoint.
> Also add a flag showing that immediate vm exit is set to happen after
> the entry.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> ---
>   arch/x86/include/asm/kvm-x86-ops.h |  1 +
>   arch/x86/include/asm/kvm_host.h    |  5 ++++-
>   arch/x86/kvm/svm/svm.c             | 17 +++++++++++++++++
>   arch/x86/kvm/trace.h               | 15 +++++++++++++--
>   arch/x86/kvm/vmx/vmx.c             | 12 ++++++++++++
>   5 files changed, 47 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index f654a7f4cc8c0c..346fed6e3c33aa 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -99,6 +99,7 @@ KVM_X86_OP(get_l2_tsc_multiplier)
>   KVM_X86_OP(write_tsc_offset)
>   KVM_X86_OP(write_tsc_multiplier)
>   KVM_X86_OP(get_exit_info)
> +KVM_X86_OP(get_entry_info)
>   KVM_X86_OP(check_intercept)
>   KVM_X86_OP(handle_exit_irqoff)
>   KVM_X86_OP(sched_in)
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 383a1d0cc0743b..321721813474f7 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1679,13 +1679,16 @@ struct kvm_x86_ops {
>   	void (*write_tsc_multiplier)(struct kvm_vcpu *vcpu);
>   
>   	/*
> -	 * Retrieve somewhat arbitrary exit information.  Intended to
> +	 * Retrieve somewhat arbitrary exit/entry information.  Intended to
>   	 * be used only from within tracepoints or error paths.
>   	 */
>   	void (*get_exit_info)(struct kvm_vcpu *vcpu, u32 *reason,
>   			      u64 *info1, u64 *info2,
>   			      u32 *exit_int_info, u32 *exit_int_info_err_code);
>   
> +	void (*get_entry_info)(struct kvm_vcpu *vcpu,
> +				u32 *inj_info, u32 *inj_info_error_code);
> +
>   	int (*check_intercept)(struct kvm_vcpu *vcpu,
>   			       struct x86_instruction_info *info,
>   			       enum x86_intercept_stage stage,
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 60b130b7f9d510..cd65c04be3d0e2 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3504,6 +3504,22 @@ static void svm_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
>   		*error_code = 0;
>   }
>   
> +static void svm_get_entry_info(struct kvm_vcpu *vcpu,
> +			u32 *inj_info,
> +			u32 *inj_info_error_code)
> +{
> +	struct vmcb_control_area *control = &to_svm(vcpu)->vmcb->control;
> +
> +	*inj_info = control->event_inj;
> +
> +	if ((*inj_info & SVM_EXITINTINFO_VALID) &&
> +	    (*inj_info & SVM_EXITINTINFO_VALID_ERR))
> +		*inj_info_error_code = control->event_inj_err;
> +	else
> +		*inj_info_error_code = 0;
> +
> +}
> +
>   static int svm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>   {
>   	struct vcpu_svm *svm = to_svm(vcpu);
> @@ -4992,6 +5008,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
>   	.required_apicv_inhibits = AVIC_REQUIRED_APICV_INHIBITS,
>   
>   	.get_exit_info = svm_get_exit_info,
> +	.get_entry_info = svm_get_entry_info,
>   
>   	.vcpu_after_set_cpuid = svm_vcpu_after_set_cpuid,
>   
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index 83843379813ee3..28e8a63368cc02 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -21,14 +21,25 @@ TRACE_EVENT(kvm_entry,
>   	TP_STRUCT__entry(
>   		__field(	unsigned int,	vcpu_id		)
>   		__field(	unsigned long,	rip		)
> -	),
> +		__field(	u32,		inj_info	)
> +		__field(	u32,		inj_info_err	)
> +		__field(	bool,		req_imm_exit	)
> +		),
>   
>   	TP_fast_assign(
>   		__entry->vcpu_id        = vcpu->vcpu_id;
>   		__entry->rip		= kvm_rip_read(vcpu);
> +		__entry->req_imm_exit	= vcpu->arch.req_immediate_exit;
> +
> +		static_call(kvm_x86_get_entry_info)(vcpu,
> +					  &__entry->inj_info,
> +					  &__entry->inj_info_err);
>   	),
>   
> -	TP_printk("vcpu %u, rip 0x%lx", __entry->vcpu_id, __entry->rip)
> +	TP_printk("vcpu %u, rip 0x%lx inj 0x%08x inj_error_code 0x%08x%s",
> +			__entry->vcpu_id, __entry->rip,
> +			__entry->inj_info, __entry->inj_info_err,
> +			__entry->req_imm_exit ? " [req_imm_exit]" : "")
>   );
>   
>   /*
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index eb7e42235e8811..9dd13f52d4999c 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6156,6 +6156,17 @@ static void vmx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
>   	}
>   }
>   
> +static void vmx_get_entry_info(struct kvm_vcpu *vcpu,
> +			      u32 *inj_info,
> +			      u32 *inj_info_error_code)
> +{
> +	*inj_info = vmcs_read32(VM_ENTRY_INTR_INFO_FIELD);
> +	if (is_exception_with_error_code(*inj_info))
> +		*inj_info_error_code = vmcs_read32(VM_ENTRY_EXCEPTION_ERROR_CODE);
> +	else
> +		*inj_info_error_code = 0;
> +}
> +
>   static void vmx_destroy_pml_buffer(struct vcpu_vmx *vmx)
>   {
>   	if (vmx->pml_pg) {
> @@ -8297,6 +8308,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
>   	.get_mt_mask = vmx_get_mt_mask,
>   
>   	.get_exit_info = vmx_get_exit_info,
> +	.get_entry_info = vmx_get_entry_info,
>   
>   	.vcpu_after_set_cpuid = vmx_vcpu_after_set_cpuid,
>   

Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>