KVM: SVM: Create trace events for VMGEXIT MSR protocol processing

Add trace events for entry to and exit from VMGEXIT MSR protocol
processing. The vCPU will be common for the trace events. The MSR
protocol processing is guided by the GHCB GPA in the VMCB, so the GHCB
GPA will represent the input and output values for the entry and exit
events, respectively. Additionally, the exit event will contain the
return code for the event.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <c5b3b440c3e0db43ff2fc02813faa94fa54896b0.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -1530,6 +1530,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 
 	ghcb_info = control->ghcb_gpa & GHCB_MSR_INFO_MASK;
 
+	trace_kvm_vmgexit_msr_protocol_enter(svm->vcpu.vcpu_id,
+					     control->ghcb_gpa);
+
 	switch (ghcb_info) {
 	case GHCB_MSR_SEV_INFO_REQ:
 		set_ghcb_msr(svm, GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
@@ -1591,6 +1594,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 		ret = -EINVAL;
 	}
 
+	trace_kvm_vmgexit_msr_protocol_exit(svm->vcpu.vcpu_id,
+					    control->ghcb_gpa, ret);
+
 	return ret;
 }
 

arch/x86/kvm/trace.h

@@ -1631,6 +1631,50 @@ TRACE_EVENT(kvm_vmgexit_exit,
 		  __entry->info1, __entry->info2)
 );
 
+/*
+ * Tracepoint for the start of VMGEXIT MSR procotol processing
+ */
+TRACE_EVENT(kvm_vmgexit_msr_protocol_enter,
+	TP_PROTO(unsigned int vcpu_id, u64 ghcb_gpa),
+	TP_ARGS(vcpu_id, ghcb_gpa),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, vcpu_id)
+		__field(u64, ghcb_gpa)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_id  = vcpu_id;
+		__entry->ghcb_gpa = ghcb_gpa;
+	),
+
+	TP_printk("vcpu %u, ghcb_gpa %016llx",
+		  __entry->vcpu_id, __entry->ghcb_gpa)
+);
+
+/*
+ * Tracepoint for the end of VMGEXIT MSR procotol processing
+ */
+TRACE_EVENT(kvm_vmgexit_msr_protocol_exit,
+	TP_PROTO(unsigned int vcpu_id, u64 ghcb_gpa, int result),
+	TP_ARGS(vcpu_id, ghcb_gpa, result),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, vcpu_id)
+		__field(u64, ghcb_gpa)
+		__field(int, result)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_id  = vcpu_id;
+		__entry->ghcb_gpa = ghcb_gpa;
+		__entry->result   = result;
+	),
+
+	TP_printk("vcpu %u, ghcb_gpa %016llx, result %d",
+		  __entry->vcpu_id, __entry->ghcb_gpa, __entry->result)
+);
+
 #endif /* _TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH

arch/x86/kvm/x86.c

@@ -11316,3 +11316,5 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_ga_log);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_apicv_update_request);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_enter);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_exit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_msr_protocol_enter);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_msr_protocol_exit);