3 files changed, 33 insertions, 55 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a1f0b5dd7d75..d73ed48587e4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -506,9 +506,8 @@ struct kvm_x86_ops {
 	void (*set_idt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
 	void (*get_gdt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
 	void (*set_gdt)(struct kvm_vcpu *vcpu, struct descriptor_table *dt);
-	unsigned long (*get_dr)(struct kvm_vcpu *vcpu, int dr);
-	void (*set_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long value,
-		       int *exception);
+	int (*get_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long *dest);
+	int (*set_dr)(struct kvm_vcpu *vcpu, int dr, unsigned long value);
 	void (*cache_reg)(struct kvm_vcpu *vcpu, enum kvm_reg reg);
 	unsigned long (*get_rflags)(struct kvm_vcpu *vcpu);
 	void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8d7cb62ebef6..4295dfcc6031 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1122,76 +1122,70 @@ static void new_asid(struct vcpu_svm *svm, struct svm_cpu_data *sd)
 	svm->vmcb->control.asid = sd->next_asid++;
 }
 
-static unsigned long svm_get_dr(struct kvm_vcpu *vcpu, int dr)
+static int svm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *dest)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	unsigned long val;
 
 	switch (dr) {
 	case 0 ... 3:
-		val = vcpu->arch.db[dr];
+		*dest = vcpu->arch.db[dr];
 		break;
+	case 4:
+		if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
+			return EMULATE_FAIL; /* will re-inject UD */
+		/* fall through */
 	case 6:
 		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
-			val = vcpu->arch.dr6;
+			*dest = vcpu->arch.dr6;
 		else
-			val = svm->vmcb->save.dr6;
+			*dest = svm->vmcb->save.dr6;
 		break;
+	case 5:
+		if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
+			return EMULATE_FAIL; /* will re-inject UD */
+		/* fall through */
 	case 7:
 		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
-			val = vcpu->arch.dr7;
+			*dest = vcpu->arch.dr7;
 		else
-			val = svm->vmcb->save.dr7;
+			*dest = svm->vmcb->save.dr7;
 		break;
-	default:
-		val = 0;
 	}
 
-	return val;
+	return EMULATE_DONE;
 }
 
-static void svm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long value,
-		       int *exception)
+static int svm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long value)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	*exception = 0;
-
 	switch (dr) {
 	case 0 ... 3:
 		vcpu->arch.db[dr] = value;
 		if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP))
 			vcpu->arch.eff_db[dr] = value;
-		return;
-	case 4 ... 5:
-		if (vcpu->arch.cr4 & X86_CR4_DE)
-			*exception = UD_VECTOR;
-		return;
+		break;
+	case 4:
+		if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
+			return EMULATE_FAIL; /* will re-inject UD */
+		/* fall through */
 	case 6:
-		if (value & 0xffffffff00000000ULL) {
-			*exception = GP_VECTOR;
-			return;
-		}
 		vcpu->arch.dr6 = (value & DR6_VOLATILE) | DR6_FIXED_1;
-		return;
+		break;
+	case 5:
+		if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
+			return EMULATE_FAIL; /* will re-inject UD */
+		/* fall through */
 	case 7:
-		if (value & 0xffffffff00000000ULL) {
-			*exception = GP_VECTOR;
-			return;
-		}
 		vcpu->arch.dr7 = (value & DR7_VOLATILE) | DR7_FIXED_1;
 		if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) {
 			svm->vmcb->save.dr7 = vcpu->arch.dr7;
 			vcpu->arch.switch_db_regs = (value & DR7_BP_EN_MASK);
 		}
-		return;
-	default:
-		/* FIXME: Possible case? */
-		printk(KERN_DEBUG "%s: unexpected dr %u\n",
-		       __func__, dr);
-		*exception = UD_VECTOR;
-		return;
+		break;
 	}
+
+	return EMULATE_DONE;
 }
 
 static int pf_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 322c2c5f9bc4..fd5101b57fa3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3270,29 +3270,14 @@ int emulate_clts(struct kvm_vcpu *vcpu)
 
 int emulator_get_dr(struct x86_emulate_ctxt *ctxt, int dr, unsigned long *dest)
 {
-	struct kvm_vcpu *vcpu = ctxt->vcpu;
-
-	switch (dr) {
-	case 0 ... 3:
-		*dest = kvm_x86_ops->get_dr(vcpu, dr);
-		return X86EMUL_CONTINUE;
-	default:
-		pr_unimpl(vcpu, "%s: unexpected dr %u\n", __func__, dr);
-		return X86EMUL_UNHANDLEABLE;
-	}
+	return kvm_x86_ops->get_dr(ctxt->vcpu, dr, dest);
 }
 
 int emulator_set_dr(struct x86_emulate_ctxt *ctxt, int dr, unsigned long value)
 {
 	unsigned long mask = (ctxt->mode == X86EMUL_MODE_PROT64) ? ~0ULL : ~0U;
-	int exception;
 
-	kvm_x86_ops->set_dr(ctxt->vcpu, dr, value & mask, &exception);
-	if (exception) {
-		/* FIXME: better handling */
-		return X86EMUL_UNHANDLEABLE;
-	}
-	return X86EMUL_CONTINUE;
+	return kvm_x86_ops->set_dr(ctxt->vcpu, dr, value & mask);
 }
 
 void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)