KVM: x86: Read guest RIP from within the kvm_nested_vmexit tracepoint

Use kvm_rip_read() to read the guest's RIP for the nested VM-Exit
tracepoint instead of having the caller pass in an argument.  Params
that are passed into a tracepoint are evaluated even if the tracepoint
is disabled, i.e. passing in RIP for VMX incurs a VMREAD and retpoline
to retrieve a value that may never be used, e.g. if the exit is due to a
hardware interrupt.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200923201349.16097-3-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -2989,7 +2989,7 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	if (is_guest_mode(vcpu)) {
 		int vmexit;
 
-		trace_kvm_nested_vmexit(svm->vmcb->save.rip, exit_code,
+		trace_kvm_nested_vmexit(vcpu, exit_code,
 					svm->vmcb->control.exit_info_1,
 					svm->vmcb->control.exit_info_2,
 					svm->vmcb->control.exit_int_info,

arch/x86/kvm/trace.h

@@ -578,10 +578,10 @@ TRACE_EVENT(kvm_nested_intercepts,
  * Tracepoint for #VMEXIT while nested
  */
 TRACE_EVENT(kvm_nested_vmexit,
-	    TP_PROTO(__u64 rip, __u32 exit_code,
+	    TP_PROTO(struct kvm_vcpu *vcpu, __u32 exit_code,
 		     __u64 exit_info1, __u64 exit_info2,
 		     __u32 exit_int_info, __u32 exit_int_info_err, __u32 isa),
-	    TP_ARGS(rip, exit_code, exit_info1, exit_info2,
+	    TP_ARGS(vcpu, exit_code, exit_info1, exit_info2,
 		    exit_int_info, exit_int_info_err, isa),
 
 	TP_STRUCT__entry(
@@ -595,7 +595,7 @@ TRACE_EVENT(kvm_nested_vmexit,
 	),
 
 	TP_fast_assign(
-		__entry->rip			= rip;
+		__entry->rip			= kvm_rip_read(vcpu);
 		__entry->exit_code		= exit_code;
 		__entry->exit_info1		= exit_info1;
 		__entry->exit_info2		= exit_info2;

arch/x86/kvm/vmx/nested.c

@@ -5937,7 +5937,7 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
 	exit_intr_info = vmx_get_intr_info(vcpu);
 	exit_qual = vmx_get_exit_qual(vcpu);
 
-	trace_kvm_nested_vmexit(kvm_rip_read(vcpu), exit_reason, exit_qual,
+	trace_kvm_nested_vmexit(vcpu, exit_reason, exit_qual,
 				vmx->idt_vectoring_info, exit_intr_info,
 				vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
 				KVM_ISA_VMX);