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)