KVM: x86: move kvm_inject_gp up from kvm_set_dr to callers

Push the injection of #GP up to the callers, so that they can just use
kvm_complete_insn_gp. __kvm_set_dr is pretty much what the callers can use
together with kvm_complete_insn_gp, so rename it to kvm_set_dr and drop
the old kvm_set_dr wrapper.

This also allows nested VMX code, which really wanted to use __kvm_set_dr,
to use the right function.

While at it, remove the kvm_require_dr() check from the SVM interception.
The APM states:

All normal exception checks take precedence over the SVM intercepts.

which includes the CR4.DE=1 #UD.

Signed-off-by: Paolo Bonzini <[e-mail]>

arch/x86/kvm/svm/svm.c

···
 {
 	int reg, dr;
 	unsigned long val;
+	int err = 0;
 
 	if (svm->vcpu.guest_debug == 0) {
 		/*
···
 
 	reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
 	dr = svm->vmcb->control.exit_code - SVM_EXIT_READ_DR0;
-
-	if (dr >= 16) { /* mov to DRn */
-		if (!kvm_require_dr(&svm->vcpu, dr - 16))
-			return 1;
+	if (dr >= 16) { /* mov to DRn  */
+		dr -= 16;
 		val = kvm_register_read(&svm->vcpu, reg);
-		kvm_set_dr(&svm->vcpu, dr - 16, val);
+		err = kvm_set_dr(&svm->vcpu, dr, val);
 	} else {
-		if (!kvm_require_dr(&svm->vcpu, dr))
-			return 1;
 		kvm_get_dr(&svm->vcpu, dr, &val);
 		kvm_register_write(&svm->vcpu, reg, val);
 	}
 
-	return kvm_skip_emulated_instruction(&svm->vcpu);
+	return kvm_complete_insn_gp(&svm->vcpu, err);
 }
 
 static int cr8_write_interception(struct vcpu_svm *svm)

arch/x86/kvm/vmx/vmx.c

···
 {
 	unsigned long exit_qualification;
 	int dr, dr7, reg;
+	int err = 1;
 
 	exit_qualification = vmx_get_exit_qual(vcpu);
 	dr = exit_qualification & DEBUG_REG_ACCESS_NUM;
···
 	if (!kvm_require_dr(vcpu, dr))
 		return 1;
 
-	/* Do not handle if the CPL > 0, will trigger GP on re-entry */
-	if (!kvm_require_cpl(vcpu, 0))
-		return 1;
+	if (kvm_x86_ops.get_cpl(vcpu) > 0)
+		goto out;
+
 	dr7 = vmcs_readl(GUEST_DR7);
 	if (dr7 & DR7_GD) {
 		/*
···
 
 		kvm_get_dr(vcpu, dr, &val);
 		kvm_register_write(vcpu, reg, val);
-	} else
-		if (kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg)))
-			return 1;
+		err = 0;
+	} else {
+		err = kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg));
+	}
 
-	return kvm_skip_emulated_instruction(vcpu);
+out:
+	return kvm_complete_insn_gp(vcpu, err);
 }
 
 static void vmx_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)

arch/x86/kvm/x86.c

···
 	return fixed;
 }
 
-static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
+int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
 {
 	size_t size = ARRAY_SIZE(vcpu->arch.db);
 
···
 	case 4:
 	case 6:
 		if (!kvm_dr6_valid(val))
-			return -1; /* #GP */
+			return 1; /* #GP */
 		vcpu->arch.dr6 = (val & DR6_VOLATILE) | kvm_dr6_fixed(vcpu);
 		break;
 	case 5:
 	default: /* 7 */
 		if (!kvm_dr7_valid(val))
-			return -1; /* #GP */
+			return 1; /* #GP */
 		vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1;
 		kvm_update_dr7(vcpu);
 		break;
 	}
 
-	return 0;
-}
-
-int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
-{
-	if (__kvm_set_dr(vcpu, dr, val)) {
-		kvm_inject_gp(vcpu, 0);
-		return 1;
-	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_set_dr);
···
 			   unsigned long value)
 {
 
-	return __kvm_set_dr(emul_to_vcpu(ctxt), dr, value);
+	return kvm_set_dr(emul_to_vcpu(ctxt), dr, value);
 }
 
 static u64 mk_cr_64(u64 curr_cr, u32 new_val)
···
 	dt.address = dt.size = 0;
 	static_call(kvm_x86_set_idt)(vcpu, &dt);
 
-	__kvm_set_dr(vcpu, 7, DR7_FIXED_1);
+	kvm_set_dr(vcpu, 7, DR7_FIXED_1);
 
 	cs.selector = (vcpu->arch.smbase >> 4) & 0xffff;
 	cs.base = vcpu->arch.smbase;