KVM: x86: Refactor guest debug IOCTL handling

Much of so far vendor-specific code for setting up guest debug can
actually be handled by the generic code. This also fixes a minor deficit
in the SVM part /wrt processing KVM_GUESTDBG_ENABLE.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 02a4269..279a2ae 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1065,26 +1065,16 @@
 		vcpu->guest_debug = 0;
 }
 
-static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
+static void svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
 {
-	int old_debug = vcpu->guest_debug;
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	vcpu->guest_debug = dbg->control;
-
-	update_db_intercept(vcpu);
-
 	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
 		svm->vmcb->save.dr7 = dbg->arch.debugreg[7];
 	else
 		svm->vmcb->save.dr7 = vcpu->arch.dr7;
 
-	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
-		svm->vmcb->save.rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
-	else if (old_debug & KVM_GUESTDBG_SINGLESTEP)
-		svm->vmcb->save.rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
-
-	return 0;
+	update_db_intercept(vcpu);
 }
 
 static void load_host_msrs(struct kvm_vcpu *vcpu)