KVM: X86: Use kvm_get_linear_rip() in single-step and #DB/#BP interception

The kvm_get_linear_rip() handles x86/long mode cases well and has
better readability, __kvm_set_rflags() also use the paired
function kvm_is_linear_rip() to check the vcpu->arch.singlestep_rip
set in kvm_arch_vcpu_ioctl_set_guest_debug(), so change the
"CS.BASE + RIP" code in kvm_arch_vcpu_ioctl_set_guest_debug() and
handle_exception_nmi() to this one.

Signed-off-by: Yuan Yao <yuan.yao@intel.com>
Message-Id: <20210526063828.1173-1-yuan.yao@linux.intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: YuanYao0329

arch/x86/kvm/vmx/vmx.c

@@ -4843,7 +4843,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct kvm_run *kvm_run = vcpu->run;
 	u32 intr_info, ex_no, error_code;
-	unsigned long cr2, rip, dr6;
+	unsigned long cr2, dr6;
 	u32 vect_info;
 
 	vect_info = vmx->idt_vectoring_info;
@@ -4933,8 +4933,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 		vmx->vcpu.arch.event_exit_inst_len =
 			vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
 		kvm_run->exit_reason = KVM_EXIT_DEBUG;
-		rip = kvm_rip_read(vcpu);
-		kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
+		kvm_run->debug.arch.pc = kvm_get_linear_rip(vcpu);
 		kvm_run->debug.arch.exception = ex_no;
 		break;
 	case AC_VECTOR:

arch/x86/kvm/x86.c

@@ -10120,8 +10120,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 	kvm_update_dr7(vcpu);
 
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
-		vcpu->arch.singlestep_rip = kvm_rip_read(vcpu) +
-			get_segment_base(vcpu, VCPU_SREG_CS);
+		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
 
 	/*
 	 * Trigger an rflags update that will inject or remove the trace