KVM: SVM: Create trace events for VMGEXIT processing

Add trace events for entry to and exit from VMGEXIT processing. The vCPU
id and the exit reason will be common for the trace events. The exit info
fields will represent the input and output values for the entry and exit
events, respectively.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <25357dca49a38372e8f483753fb0c1c2a70a6898.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -15,10 +15,12 @@
 #include <linux/pagemap.h>
 #include <linux/swap.h>
 #include <linux/processor.h>
+#include <linux/trace_events.h>
 
 #include "x86.h"
 #include "svm.h"
 #include "cpuid.h"
+#include "trace.h"
 
 static u8 sev_enc_bit;
 static int sev_flush_asids(void);
@@ -1468,6 +1470,8 @@ static void pre_sev_es_run(struct vcpu_svm *svm)
 	if (!svm->ghcb)
 		return;
 
+	trace_kvm_vmgexit_exit(svm->vcpu.vcpu_id, svm->ghcb);
+
 	sev_es_sync_to_ghcb(svm);
 
 	kvm_vcpu_unmap(&svm->vcpu, &svm->ghcb_map, true);
@@ -1617,6 +1621,8 @@ int sev_handle_vmgexit(struct vcpu_svm *svm)
 	svm->ghcb = svm->ghcb_map.hva;
 	ghcb = svm->ghcb_map.hva;
 
+	trace_kvm_vmgexit_enter(svm->vcpu.vcpu_id, ghcb);
+
 	exit_code = ghcb_get_sw_exit_code(ghcb);
 
 	ret = sev_es_validate_vmgexit(svm);

arch/x86/kvm/trace.h

@@ -1578,6 +1578,59 @@ TRACE_EVENT(kvm_hv_syndbg_get_msr,
 		  __entry->vcpu_id, __entry->vp_index, __entry->msr,
 		  __entry->data)
 );
+
+/*
+ * Tracepoint for the start of VMGEXIT processing
+ */
+TRACE_EVENT(kvm_vmgexit_enter,
+	TP_PROTO(unsigned int vcpu_id, struct ghcb *ghcb),
+	TP_ARGS(vcpu_id, ghcb),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, vcpu_id)
+		__field(u64, exit_reason)
+		__field(u64, info1)
+		__field(u64, info2)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_id     = vcpu_id;
+		__entry->exit_reason = ghcb->save.sw_exit_code;
+		__entry->info1       = ghcb->save.sw_exit_info_1;
+		__entry->info2       = ghcb->save.sw_exit_info_2;
+	),
+
+	TP_printk("vcpu %u, exit_reason %llx, exit_info1 %llx, exit_info2 %llx",
+		  __entry->vcpu_id, __entry->exit_reason,
+		  __entry->info1, __entry->info2)
+);
+
+/*
+ * Tracepoint for the end of VMGEXIT processing
+ */
+TRACE_EVENT(kvm_vmgexit_exit,
+	TP_PROTO(unsigned int vcpu_id, struct ghcb *ghcb),
+	TP_ARGS(vcpu_id, ghcb),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, vcpu_id)
+		__field(u64, exit_reason)
+		__field(u64, info1)
+		__field(u64, info2)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_id     = vcpu_id;
+		__entry->exit_reason = ghcb->save.sw_exit_code;
+		__entry->info1       = ghcb->save.sw_exit_info_1;
+		__entry->info2       = ghcb->save.sw_exit_info_2;
+	),
+
+	TP_printk("vcpu %u, exit_reason %llx, exit_info1 %llx, exit_info2 %llx",
+		  __entry->vcpu_id, __entry->exit_reason,
+		  __entry->info1, __entry->info2)
+);
+
 #endif /* _TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH

arch/x86/kvm/x86.c

@@ -11314,3 +11314,5 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_unaccelerated_access);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_incomplete_ipi);
 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);