KVM: Add instruction-set-specific exit qualifications to kvm_exit trace

The exit reason alone is insufficient to understand exactly why an exit
occured; add ISA-specific trace parameters for additional information.

Because fetching these parameters is expensive on vmx, and because these
parameters are fetched even if tracing is disabled, we fetch the
parameters via a callback instead of as traditional trace arguments.
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -594,6 +594,7 @@ struct kvm_x86_ops {
 
 	void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
+	void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
 	const struct trace_print_flags *exit_reasons_str;
 };
 

arch/x86/kvm/svm.c

@@ -2974,6 +2974,14 @@ void dump_vmcb(struct kvm_vcpu *vcpu)
 
 }
 
+static void svm_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2)
+{
+	struct vmcb_control_area *control = &to_svm(vcpu)->vmcb->control;
+
+	*info1 = control->exit_info_1;
+	*info2 = control->exit_info_2;
+}
+
 static int handle_exit(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -3684,7 +3692,9 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.get_tdp_level = get_npt_level,
 	.get_mt_mask = svm_get_mt_mask,
 
+	.get_exit_info = svm_get_exit_info,
 	.exit_reasons_str = svm_exit_reasons_str,
+
 	.get_lpage_level = svm_get_lpage_level,
 
 	.cpuid_update = svm_cpuid_update,

arch/x86/kvm/trace.h

@@ -192,18 +192,22 @@ TRACE_EVENT(kvm_exit,
 		__field(	unsigned int,	exit_reason	)
 		__field(	unsigned long,	guest_rip	)
 		__field(	u32,	        isa             )
+		__field(	u64,	        info1           )
+		__field(	u64,	        info2           )
 	),
 
 	TP_fast_assign(
 		__entry->exit_reason	= exit_reason;
 		__entry->guest_rip	= kvm_rip_read(vcpu);
 		__entry->isa            = isa;
+		kvm_x86_ops->get_exit_info(vcpu, &__entry->info1,
+					   &__entry->info2);
 	),
 
-	TP_printk("reason %s rip 0x%lx",
+	TP_printk("reason %s rip 0x%lx info %llx %llx",
 		 ftrace_print_symbols_seq(p, __entry->exit_reason,
 					  kvm_x86_ops->exit_reasons_str),
-		 __entry->guest_rip)
+		 __entry->guest_rip, __entry->info1, __entry->info2)
 );
 
 /*

arch/x86/kvm/vmx.c

@@ -3690,6 +3690,12 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 static const int kvm_vmx_max_exit_handlers =
 	ARRAY_SIZE(kvm_vmx_exit_handlers);
 
+static void vmx_get_exit_info(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2)
+{
+	*info1 = vmcs_readl(EXIT_QUALIFICATION);
+	*info2 = vmcs_read32(VM_EXIT_INTR_INFO);
+}
+
 /*
  * The guest has exited.  See if we can fix it or if we need userspace
  * assistance.
@@ -4334,7 +4340,9 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.get_tdp_level = get_ept_level,
 	.get_mt_mask = vmx_get_mt_mask,
 
+	.get_exit_info = vmx_get_exit_info,
 	.exit_reasons_str = vmx_exit_reasons_str,
+
 	.get_lpage_level = vmx_get_lpage_level,
 
 	.cpuid_update = vmx_cpuid_update,