1 files changed, 441 insertions, 0 deletions
diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/tdx-guest.c
new file mode 100644
index 000000000000..4e239ec960c9
--- /dev/null
+++ b/drivers/virt/coco/tdx-guest/tdx-guest.c
@@ -0,0 +1,441 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TDX guest user interface driver
+ *
+ * Copyright (C) 2022 Intel Corporation
+ */
+
+#define pr_fmt(fmt)			KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/set_memory.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/sockptr.h>
+#include <linux/tsm.h>
+#include <linux/tsm-mr.h>
+
+#include <uapi/linux/tdx-guest.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/tdx.h>
+
+/* TDREPORT buffer */
+static u8 *tdx_report_buf;
+
+/* Lock to serialize TDG.MR.REPORT and TDG.MR.RTMR.EXTEND TDCALLs */
+static DEFINE_MUTEX(mr_lock);
+
+/* TDREPORT fields */
+enum {
+	TDREPORT_reportdata = 128,
+	TDREPORT_tee_tcb_info = 256,
+	TDREPORT_tdinfo = TDREPORT_tee_tcb_info + 256,
+	TDREPORT_attributes = TDREPORT_tdinfo,
+	TDREPORT_xfam = TDREPORT_attributes + sizeof(u64),
+	TDREPORT_mrtd = TDREPORT_xfam + sizeof(u64),
+	TDREPORT_mrconfigid = TDREPORT_mrtd + SHA384_DIGEST_SIZE,
+	TDREPORT_mrowner = TDREPORT_mrconfigid + SHA384_DIGEST_SIZE,
+	TDREPORT_mrownerconfig = TDREPORT_mrowner + SHA384_DIGEST_SIZE,
+	TDREPORT_rtmr0 = TDREPORT_mrownerconfig + SHA384_DIGEST_SIZE,
+	TDREPORT_rtmr1 = TDREPORT_rtmr0 + SHA384_DIGEST_SIZE,
+	TDREPORT_rtmr2 = TDREPORT_rtmr1 + SHA384_DIGEST_SIZE,
+	TDREPORT_rtmr3 = TDREPORT_rtmr2 + SHA384_DIGEST_SIZE,
+	TDREPORT_servtd_hash = TDREPORT_rtmr3 + SHA384_DIGEST_SIZE,
+};
+
+static int tdx_do_report(sockptr_t data, sockptr_t tdreport)
+{
+	scoped_cond_guard(mutex_intr, return -EINTR, &mr_lock) {
+		u8 *reportdata = tdx_report_buf + TDREPORT_reportdata;
+		int ret;
+
+		if (!sockptr_is_null(data) &&
+		    copy_from_sockptr(reportdata, data, TDX_REPORTDATA_LEN))
+			return -EFAULT;
+
+		ret = tdx_mcall_get_report0(reportdata, tdx_report_buf);
+		if (WARN_ONCE(ret, "tdx_mcall_get_report0() failed: %d", ret))
+			return ret;
+
+		if (!sockptr_is_null(tdreport) &&
+		    copy_to_sockptr(tdreport, tdx_report_buf, TDX_REPORT_LEN))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+static int tdx_do_extend(u8 mr_ind, const u8 *data)
+{
+	scoped_cond_guard(mutex_intr, return -EINTR, &mr_lock) {
+		/*
+		 * TDX requires @extend_buf to be 64-byte aligned.
+		 * It's safe to use REPORTDATA buffer for that purpose because
+		 * tdx_mr_report/extend_lock() are mutually exclusive.
+		 */
+		u8 *extend_buf = tdx_report_buf + TDREPORT_reportdata;
+		int ret;
+
+		memcpy(extend_buf, data, SHA384_DIGEST_SIZE);
+
+		ret = tdx_mcall_extend_rtmr(mr_ind, extend_buf);
+		if (WARN_ONCE(ret, "tdx_mcall_extend_rtmr(%u) failed: %d", mr_ind, ret))
+			return ret;
+	}
+	return 0;
+}
+
+#define TDX_MR_(r) .mr_value = (void *)TDREPORT_##r, TSM_MR_(r, SHA384)
+static struct tsm_measurement_register tdx_mrs[] = {
+	{ TDX_MR_(rtmr0) | TSM_MR_F_RTMR },
+	{ TDX_MR_(rtmr1) | TSM_MR_F_RTMR },
+	{ TDX_MR_(rtmr2) | TSM_MR_F_RTMR },
+	{ TDX_MR_(rtmr3) | TSM_MR_F_RTMR },
+	{ TDX_MR_(mrtd) },
+	{ TDX_MR_(mrconfigid) | TSM_MR_F_NOHASH },
+	{ TDX_MR_(mrowner) | TSM_MR_F_NOHASH },
+	{ TDX_MR_(mrownerconfig) | TSM_MR_F_NOHASH },
+};
+#undef TDX_MR_
+
+static int tdx_mr_refresh(const struct tsm_measurements *tm)
+{
+	return tdx_do_report(KERNEL_SOCKPTR(NULL), KERNEL_SOCKPTR(NULL));
+}
+
+static int tdx_mr_extend(const struct tsm_measurements *tm,
+			 const struct tsm_measurement_register *mr,
+			 const u8 *data)
+{
+	return tdx_do_extend(mr - tm->mrs, data);
+}
+
+static struct tsm_measurements tdx_measurements = {
+	.mrs = tdx_mrs,
+	.nr_mrs = ARRAY_SIZE(tdx_mrs),
+	.refresh = tdx_mr_refresh,
+	.write = tdx_mr_extend,
+};
+
+static const struct attribute_group *tdx_mr_init(void)
+{
+	const struct attribute_group *g;
+	int rc;
+
+	u8 *buf __free(kfree) = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	tdx_report_buf = buf;
+	rc = tdx_mr_refresh(&tdx_measurements);
+	if (rc)
+		return ERR_PTR(rc);
+
+	/*
+	 * @mr_value was initialized with the offset only, while the base
+	 * address is being added here.
+	 */
+	for (size_t i = 0; i < ARRAY_SIZE(tdx_mrs); ++i)
+		*(long *)&tdx_mrs[i].mr_value += (long)buf;
+
+	g = tsm_mr_create_attribute_group(&tdx_measurements);
+	if (!IS_ERR(g))
+		tdx_report_buf = no_free_ptr(buf);
+
+	return g;
+}
+
+static void tdx_mr_deinit(const struct attribute_group *mr_grp)
+{
+	tsm_mr_free_attribute_group(mr_grp);
+	kfree(tdx_report_buf);
+}
+
+/*
+ * Intel's SGX QE implementation generally uses Quote size less
+ * than 8K (2K Quote data + ~5K of certificate blob).
+ */
+#define GET_QUOTE_BUF_SIZE		SZ_8K
+
+#define GET_QUOTE_CMD_VER		1
+
+/* TDX GetQuote status codes */
+#define GET_QUOTE_SUCCESS		0
+#define GET_QUOTE_IN_FLIGHT		0xffffffffffffffff
+
+/* struct tdx_quote_buf: Format of Quote request buffer.
+ * @version: Quote format version, filled by TD.
+ * @status: Status code of Quote request, filled by VMM.
+ * @in_len: Length of TDREPORT, filled by TD.
+ * @out_len: Length of Quote data, filled by VMM.
+ * @data: Quote data on output or TDREPORT on input.
+ *
+ * More details of Quote request buffer can be found in TDX
+ * Guest-Host Communication Interface (GHCI) for Intel TDX 1.0,
+ * section titled "TDG.VP.VMCALL<GetQuote>"
+ */
+struct tdx_quote_buf {
+	u64 version;
+	u64 status;
+	u32 in_len;
+	u32 out_len;
+	u8 data[];
+};
+
+/* Quote data buffer */
+static void *quote_data;
+
+/* Lock to streamline quote requests */
+static DEFINE_MUTEX(quote_lock);
+
+/*
+ * GetQuote request timeout in seconds. Expect that 30 seconds
+ * is enough time for QE to respond to any Quote requests.
+ */
+static u32 getquote_timeout = 30;
+
+static long tdx_get_report0(struct tdx_report_req __user *req)
+{
+	return tdx_do_report(USER_SOCKPTR(req->reportdata),
+			     USER_SOCKPTR(req->tdreport));
+}
+
+static void free_quote_buf(void *buf)
+{
+	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
+	unsigned int count = len >> PAGE_SHIFT;
+
+	if (set_memory_encrypted((unsigned long)buf, count)) {
+		pr_err("Failed to restore encryption mask for Quote buffer, leak it\n");
+		return;
+	}
+
+	free_pages_exact(buf, len);
+}
+
+static void *alloc_quote_buf(void)
+{
+	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
+	unsigned int count = len >> PAGE_SHIFT;
+	void *addr;
+
+	addr = alloc_pages_exact(len, GFP_KERNEL | __GFP_ZERO);
+	if (!addr)
+		return NULL;
+
+	if (set_memory_decrypted((unsigned long)addr, count))
+		return NULL;
+
+	return addr;
+}
+
+/*
+ * wait_for_quote_completion() - Wait for Quote request completion
+ * @quote_buf: Address of Quote buffer.
+ * @timeout: Timeout in seconds to wait for the Quote generation.
+ *
+ * As per TDX GHCI v1.0 specification, sec titled "TDG.VP.VMCALL<GetQuote>",
+ * the status field in the Quote buffer will be set to GET_QUOTE_IN_FLIGHT
+ * while VMM processes the GetQuote request, and will change it to success
+ * or error code after processing is complete. So wait till the status
+ * changes from GET_QUOTE_IN_FLIGHT or the request being timed out.
+ */
+static int wait_for_quote_completion(struct tdx_quote_buf *quote_buf, u32 timeout)
+{
+	int i = 0;
+
+	/*
+	 * Quote requests usually take a few seconds to complete, so waking up
+	 * once per second to recheck the status is fine for this use case.
+	 */
+	while (quote_buf->status == GET_QUOTE_IN_FLIGHT && i++ < timeout) {
+		if (msleep_interruptible(MSEC_PER_SEC))
+			return -EINTR;
+	}
+
+	return (i == timeout) ? -ETIMEDOUT : 0;
+}
+
+static int tdx_report_new_locked(struct tsm_report *report, void *data)
+{
+	u8 *buf;
+	struct tdx_quote_buf *quote_buf = quote_data;
+	struct tsm_report_desc *desc = &report->desc;
+	int ret;
+	u64 err;
+
+	/*
+	 * If the previous request is timedout or interrupted, and the
+	 * Quote buf status is still in GET_QUOTE_IN_FLIGHT (owned by
+	 * VMM), don't permit any new request.
+	 */
+	if (quote_buf->status == GET_QUOTE_IN_FLIGHT)
+		return -EBUSY;
+
+	if (desc->inblob_len != TDX_REPORTDATA_LEN)
+		return -EINVAL;
+
+	memset(quote_data, 0, GET_QUOTE_BUF_SIZE);
+
+	/* Update Quote buffer header */
+	quote_buf->version = GET_QUOTE_CMD_VER;
+	quote_buf->in_len = TDX_REPORT_LEN;
+
+	ret = tdx_do_report(KERNEL_SOCKPTR(desc->inblob),
+			    KERNEL_SOCKPTR(quote_buf->data));
+	if (ret)
+		return ret;
+
+	err = tdx_hcall_get_quote(quote_data, GET_QUOTE_BUF_SIZE);
+	if (err) {
+		pr_err("GetQuote hypercall failed, status:%llx\n", err);
+		return -EIO;
+	}
+
+	ret = wait_for_quote_completion(quote_buf, getquote_timeout);
+	if (ret) {
+		pr_err("GetQuote request timedout\n");
+		return ret;
+	}
+
+	buf = kvmemdup(quote_buf->data, quote_buf->out_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	report->outblob = buf;
+	report->outblob_len = quote_buf->out_len;
+
+	/*
+	 * TODO: parse the PEM-formatted cert chain out of the quote buffer when
+	 * provided
+	 */
+
+	return ret;
+}
+
+static int tdx_report_new(struct tsm_report *report, void *data)
+{
+	scoped_cond_guard(mutex_intr, return -EINTR, &quote_lock)
+		return tdx_report_new_locked(report, data);
+}
+
+static bool tdx_report_attr_visible(int n)
+{
+	switch (n) {
+	case TSM_REPORT_GENERATION:
+	case TSM_REPORT_PROVIDER:
+		return true;
+	}
+
+	return false;
+}
+
+static bool tdx_report_bin_attr_visible(int n)
+{
+	switch (n) {
+	case TSM_REPORT_INBLOB:
+	case TSM_REPORT_OUTBLOB:
+		return true;
+	}
+
+	return false;
+}
+
+static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	switch (cmd) {
+	case TDX_CMD_GET_REPORT0:
+		return tdx_get_report0((struct tdx_report_req __user *)arg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations tdx_guest_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = tdx_guest_ioctl,
+};
+
+static const struct attribute_group *tdx_attr_groups[] = {
+	NULL, /* measurements */
+	NULL
+};
+
+static struct miscdevice tdx_misc_dev = {
+	.name = KBUILD_MODNAME,
+	.minor = MISC_DYNAMIC_MINOR,
+	.fops = &tdx_guest_fops,
+	.groups = tdx_attr_groups,
+};
+
+static const struct x86_cpu_id tdx_guest_ids[] = {
+	X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL),
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);
+
+static const struct tsm_report_ops tdx_tsm_ops = {
+	.name = KBUILD_MODNAME,
+	.report_new = tdx_report_new,
+	.report_attr_visible = tdx_report_attr_visible,
+	.report_bin_attr_visible = tdx_report_bin_attr_visible,
+};
+
+static int __init tdx_guest_init(void)
+{
+	int ret;
+
+	if (!x86_match_cpu(tdx_guest_ids))
+		return -ENODEV;
+
+	tdx_attr_groups[0] = tdx_mr_init();
+	if (IS_ERR(tdx_attr_groups[0]))
+		return PTR_ERR(tdx_attr_groups[0]);
+
+	ret = misc_register(&tdx_misc_dev);
+	if (ret)
+		goto deinit_mr;
+
+	quote_data = alloc_quote_buf();
+	if (!quote_data) {
+		pr_err("Failed to allocate Quote buffer\n");
+		ret = -ENOMEM;
+		goto free_misc;
+	}
+
+	ret = tsm_report_register(&tdx_tsm_ops, NULL);
+	if (ret)
+		goto free_quote;
+
+	return 0;
+
+free_quote:
+	free_quote_buf(quote_data);
+free_misc:
+	misc_deregister(&tdx_misc_dev);
+deinit_mr:
+	tdx_mr_deinit(tdx_attr_groups[0]);
+
+	return ret;
+}
+module_init(tdx_guest_init);
+
+static void __exit tdx_guest_exit(void)
+{
+	tsm_report_unregister(&tdx_tsm_ops);
+	free_quote_buf(quote_data);
+	misc_deregister(&tdx_misc_dev);
+	tdx_mr_deinit(tdx_attr_groups[0]);
+}
+module_exit(tdx_guest_exit);
+
+MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>");
+MODULE_DESCRIPTION("TDX Guest Driver");
+MODULE_LICENSE("GPL");