1// SPDX-License-Identifier: GPL-2.0
2/*
3 * TDX guest user interface driver
4 *
5 * Copyright (C) 2022 Intel Corporation
6 */
7
8#include <linux/kernel.h>
9#include <linux/miscdevice.h>
10#include <linux/mm.h>
11#include <linux/module.h>
12#include <linux/mod_devicetable.h>
13#include <linux/string.h>
14#include <linux/uaccess.h>
15
16#include <uapi/linux/tdx-guest.h>
17
18#include <asm/cpu_device_id.h>
19#include <asm/tdx.h>
20
21static long tdx_get_report0(struct tdx_report_req __user *req)
22{
23	u8 *reportdata, *tdreport;
24	long ret;
25
26	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
27	if (!reportdata)
28		return -ENOMEM;
29
30	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
31	if (!tdreport) {
32		ret = -ENOMEM;
33		goto out;
34	}
35
36	if (copy_from_user(reportdata, req->reportdata, TDX_REPORTDATA_LEN)) {
37		ret = -EFAULT;
38		goto out;
39	}
40
41	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
42	ret = tdx_mcall_get_report0(reportdata, tdreport);
43	if (ret)
44		goto out;
45
46	if (copy_to_user(req->tdreport, tdreport, TDX_REPORT_LEN))
47		ret = -EFAULT;
48
49out:
50	kfree(reportdata);
51	kfree(tdreport);
52
53	return ret;
54}
55
56static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
57			    unsigned long arg)
58{
59	switch (cmd) {
60	case TDX_CMD_GET_REPORT0:
61		return tdx_get_report0((struct tdx_report_req __user *)arg);
62	default:
63		return -ENOTTY;
64	}
65}
66
67static const struct file_operations tdx_guest_fops = {
68	.owner = THIS_MODULE,
69	.unlocked_ioctl = tdx_guest_ioctl,
70	.llseek = no_llseek,
71};
72
73static struct miscdevice tdx_misc_dev = {
74	.name = KBUILD_MODNAME,
75	.minor = MISC_DYNAMIC_MINOR,
76	.fops = &tdx_guest_fops,
77};
78
79static const struct x86_cpu_id tdx_guest_ids[] = {
80	X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL),
81	{}
82};
83MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);
84
85static int __init tdx_guest_init(void)
86{
87	if (!x86_match_cpu(tdx_guest_ids))
88		return -ENODEV;
89
90	return misc_register(&tdx_misc_dev);
91}
92module_init(tdx_guest_init);
93
94static void __exit tdx_guest_exit(void)
95{
96	misc_deregister(&tdx_misc_dev);
97}
98module_exit(tdx_guest_exit);
99
100MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>");
101MODULE_DESCRIPTION("TDX Guest Driver");
102MODULE_LICENSE("GPL");
103