Merging upstream version 6.7.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 844 insertions, 13 deletions

diff --git a/drivers/virt/coco/Kconfig b/drivers/virt/coco/Kconfig
new file mode 100644
index 0000000000..87d142c1f9
--- /dev/null
+++ b/drivers/virt/coco/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Confidential computing related collateral
+#
+
+config TSM_REPORTS
+	select CONFIGFS_FS
+	tristate
+
+source "drivers/virt/coco/efi_secret/Kconfig"
+
+source "drivers/virt/coco/sev-guest/Kconfig"
+
+source "drivers/virt/coco/tdx-guest/Kconfig"
diff --git a/drivers/virt/coco/Makefile b/drivers/virt/coco/Makefile
new file mode 100644
index 0000000000..18c1aba5ed
--- /dev/null
+++ b/drivers/virt/coco/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Confidential computing related collateral
+#
+obj-$(CONFIG_TSM_REPORTS)	+= tsm.o
+obj-$(CONFIG_EFI_SECRET)	+= efi_secret/
+obj-$(CONFIG_SEV_GUEST)		+= sev-guest/
+obj-$(CONFIG_INTEL_TDX_GUEST)	+= tdx-guest/
diff --git a/drivers/virt/coco/sev-guest/Kconfig b/drivers/virt/coco/sev-guest/Kconfig
index da2d7ca531..1cffc72c41 100644
--- a/drivers/virt/coco/sev-guest/Kconfig
+++ b/drivers/virt/coco/sev-guest/Kconfig
@@ -5,6 +5,7 @@ config SEV_GUEST
 	select CRYPTO
 	select CRYPTO_AEAD2
 	select CRYPTO_GCM
+	select TSM_REPORTS
 	help
 	  SEV-SNP firmware provides the guest a mechanism to communicate with
 	  the PSP without risk from a malicious hypervisor who wishes to read,
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 5bee58ef5f..bc564adcf4 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -16,9 +16,13 @@
 #include <linux/miscdevice.h>
 #include <linux/set_memory.h>
 #include <linux/fs.h>
+#include <linux/tsm.h>
 #include <crypto/aead.h>
 #include <linux/scatterlist.h>
 #include <linux/psp-sev.h>
+#include <linux/sockptr.h>
+#include <linux/cleanup.h>
+#include <linux/uuid.h>
 #include <uapi/linux/sev-guest.h>
 #include <uapi/linux/psp-sev.h>
 
@@ -475,6 +479,11 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
 	return 0;
 }
 
+struct snp_req_resp {
+	sockptr_t req_data;
+	sockptr_t resp_data;
+};
+
 static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
 	struct snp_guest_crypto *crypto = snp_dev->crypto;
@@ -555,22 +564,25 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	return rc;
 }
 
-static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
+static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg,
+			  struct snp_req_resp *io)
+
 {
 	struct snp_ext_report_req *req = &snp_dev->req.ext_report;
 	struct snp_guest_crypto *crypto = snp_dev->crypto;
 	struct snp_report_resp *resp;
 	int ret, npages = 0, resp_len;
+	sockptr_t certs_address;
 
 	lockdep_assert_held(&snp_cmd_mutex);
 
-	if (!arg->req_data || !arg->resp_data)
+	if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
 		return -EINVAL;
 
-	if (copy_from_user(req, (void __user *)arg->req_data, sizeof(*req)))
+	if (copy_from_sockptr(req, io->req_data, sizeof(*req)))
 		return -EFAULT;
 
-	/* userspace does not want certificate data */
+	/* caller does not want certificate data */
 	if (!req->certs_len || !req->certs_address)
 		goto cmd;
 
@@ -578,8 +590,13 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 	    !IS_ALIGNED(req->certs_len, PAGE_SIZE))
 		return -EINVAL;
 
-	if (!access_ok((const void __user *)req->certs_address, req->certs_len))
-		return -EFAULT;
+	if (sockptr_is_kernel(io->resp_data)) {
+		certs_address = KERNEL_SOCKPTR((void *)req->certs_address);
+	} else {
+		certs_address = USER_SOCKPTR((void __user *)req->certs_address);
+		if (!access_ok(certs_address.user, req->certs_len))
+			return -EFAULT;
+	}
 
 	/*
 	 * Initialize the intermediate buffer with all zeros. This buffer
@@ -609,21 +626,19 @@ cmd:
 	if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
 		req->certs_len = snp_dev->input.data_npages << PAGE_SHIFT;
 
-		if (copy_to_user((void __user *)arg->req_data, req, sizeof(*req)))
+		if (copy_to_sockptr(io->req_data, req, sizeof(*req)))
 			ret = -EFAULT;
 	}
 
 	if (ret)
 		goto e_free;
 
-	if (npages &&
-	    copy_to_user((void __user *)req->certs_address, snp_dev->certs_data,
-			 req->certs_len)) {
+	if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, req->certs_len)) {
 		ret = -EFAULT;
 		goto e_free;
 	}
 
-	if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp)))
+	if (copy_to_sockptr(io->resp_data, resp, sizeof(*resp)))
 		ret = -EFAULT;
 
 e_free:
@@ -636,6 +651,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
 	struct snp_guest_dev *snp_dev = to_snp_dev(file);
 	void __user *argp = (void __user *)arg;
 	struct snp_guest_request_ioctl input;
+	struct snp_req_resp io;
 	int ret = -ENOTTY;
 
 	if (copy_from_user(&input, argp, sizeof(input)))
@@ -664,7 +680,14 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
 		ret = get_derived_key(snp_dev, &input);
 		break;
 	case SNP_GET_EXT_REPORT:
-		ret = get_ext_report(snp_dev, &input);
+		/*
+		 * As get_ext_report() may be called from the ioctl() path and a
+		 * kernel internal path (configfs-tsm), decorate the passed
+		 * buffers as user pointers.
+		 */
+		io.req_data = USER_SOCKPTR((void __user *)input.req_data);
+		io.resp_data = USER_SOCKPTR((void __user *)input.resp_data);
+		ret = get_ext_report(snp_dev, &input, &io);
 		break;
 	default:
 		break;
@@ -748,6 +771,130 @@ static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno
 	return key;
 }
 
+struct snp_msg_report_resp_hdr {
+	u32 status;
+	u32 report_size;
+	u8 rsvd[24];
+};
+
+struct snp_msg_cert_entry {
+	guid_t guid;
+	u32 offset;
+	u32 length;
+};
+
+static int sev_report_new(struct tsm_report *report, void *data)
+{
+	struct snp_msg_cert_entry *cert_table;
+	struct tsm_desc *desc = &report->desc;
+	struct snp_guest_dev *snp_dev = data;
+	struct snp_msg_report_resp_hdr hdr;
+	const u32 report_size = SZ_4K;
+	const u32 ext_size = SEV_FW_BLOB_MAX_SIZE;
+	u32 certs_size, i, size = report_size + ext_size;
+	int ret;
+
+	if (desc->inblob_len != SNP_REPORT_USER_DATA_SIZE)
+		return -EINVAL;
+
+	void *buf __free(kvfree) = kvzalloc(size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	guard(mutex)(&snp_cmd_mutex);
+
+	/* Check if the VMPCK is not empty */
+	if (is_vmpck_empty(snp_dev)) {
+		dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n");
+		return -ENOTTY;
+	}
+
+	cert_table = buf + report_size;
+	struct snp_ext_report_req ext_req = {
+		.data = { .vmpl = desc->privlevel },
+		.certs_address = (__u64)cert_table,
+		.certs_len = ext_size,
+	};
+	memcpy(&ext_req.data.user_data, desc->inblob, desc->inblob_len);
+
+	struct snp_guest_request_ioctl input = {
+		.msg_version = 1,
+		.req_data = (__u64)&ext_req,
+		.resp_data = (__u64)buf,
+		.exitinfo2 = 0xff,
+	};
+	struct snp_req_resp io = {
+		.req_data = KERNEL_SOCKPTR(&ext_req),
+		.resp_data = KERNEL_SOCKPTR(buf),
+	};
+
+	ret = get_ext_report(snp_dev, &input, &io);
+	if (ret)
+		return ret;
+
+	memcpy(&hdr, buf, sizeof(hdr));
+	if (hdr.status == SEV_RET_INVALID_PARAM)
+		return -EINVAL;
+	if (hdr.status == SEV_RET_INVALID_KEY)
+		return -EINVAL;
+	if (hdr.status)
+		return -ENXIO;
+	if ((hdr.report_size + sizeof(hdr)) > report_size)
+		return -ENOMEM;
+
+	void *rbuf __free(kvfree) = kvzalloc(hdr.report_size, GFP_KERNEL);
+	if (!rbuf)
+		return -ENOMEM;
+
+	memcpy(rbuf, buf + sizeof(hdr), hdr.report_size);
+	report->outblob = no_free_ptr(rbuf);
+	report->outblob_len = hdr.report_size;
+
+	certs_size = 0;
+	for (i = 0; i < ext_size / sizeof(struct snp_msg_cert_entry); i++) {
+		struct snp_msg_cert_entry *ent = &cert_table[i];
+
+		if (guid_is_null(&ent->guid) && !ent->offset && !ent->length)
+			break;
+		certs_size = max(certs_size, ent->offset + ent->length);
+	}
+
+	/* Suspicious that the response populated entries without populating size */
+	if (!certs_size && i)
+		dev_warn_ratelimited(snp_dev->dev, "certificate slots conveyed without size\n");
+
+	/* No certs to report */
+	if (!certs_size)
+		return 0;
+
+	/* Suspicious that the certificate blob size contract was violated
+	 */
+	if (certs_size > ext_size) {
+		dev_warn_ratelimited(snp_dev->dev, "certificate data truncated\n");
+		certs_size = ext_size;
+	}
+
+	void *cbuf __free(kvfree) = kvzalloc(certs_size, GFP_KERNEL);
+	if (!cbuf)
+		return -ENOMEM;
+
+	memcpy(cbuf, cert_table, certs_size);
+	report->auxblob = no_free_ptr(cbuf);
+	report->auxblob_len = certs_size;
+
+	return 0;
+}
+
+static const struct tsm_ops sev_tsm_ops = {
+	.name = KBUILD_MODNAME,
+	.report_new = sev_report_new,
+};
+
+static void unregister_sev_tsm(void *data)
+{
+	tsm_unregister(&sev_tsm_ops);
+}
+
 static int __init sev_guest_probe(struct platform_device *pdev)
 {
 	struct snp_secrets_page_layout *layout;
@@ -821,6 +968,14 @@ static int __init sev_guest_probe(struct platform_device *pdev)
 	snp_dev->input.resp_gpa = __pa(snp_dev->response);
 	snp_dev->input.data_gpa = __pa(snp_dev->certs_data);
 
+	ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type);
+	if (ret)
+		goto e_free_cert_data;
+
+	ret = devm_add_action_or_reset(&pdev->dev, unregister_sev_tsm, NULL);
+	if (ret)
+		goto e_free_cert_data;
+
 	ret =  misc_register(misc);
 	if (ret)
 		goto e_free_cert_data;
diff --git a/drivers/virt/coco/tdx-guest/Kconfig b/drivers/virt/coco/tdx-guest/Kconfig
index 14246fc2fb..22dd59e194 100644
--- a/drivers/virt/coco/tdx-guest/Kconfig
+++ b/drivers/virt/coco/tdx-guest/Kconfig
@@ -1,6 +1,7 @@
 config TDX_GUEST_DRIVER
 	tristate "TDX Guest driver"
 	depends on INTEL_TDX_GUEST
+	select TSM_REPORTS
 	help
 	  The driver provides userspace interface to communicate with
 	  the TDX module to request the TDX guest details like attestation
diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/tdx-guest.c
index 5e44a0fa69..1253bf76b5 100644
--- a/drivers/virt/coco/tdx-guest/tdx-guest.c
+++ b/drivers/virt/coco/tdx-guest/tdx-guest.c
@@ -12,12 +12,60 @@
 #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/tsm.h>
+#include <linux/sizes.h>
 
 #include <uapi/linux/tdx-guest.h>
 
 #include <asm/cpu_device_id.h>
 #include <asm/tdx.h>
 
+/*
+ * 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)
 {
 	u8 *reportdata, *tdreport;
@@ -53,6 +101,154 @@ out:
 	return ret;
 }
 
+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)) {
+		free_pages_exact(addr, len);
+		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(struct tsm_report *report, void *data)
+{
+	u8 *buf, *reportdata = NULL, *tdreport = NULL;
+	struct tdx_quote_buf *quote_buf = quote_data;
+	struct tsm_desc *desc = &report->desc;
+	int ret;
+	u64 err;
+
+	/* TODO: switch to guard(mutex_intr) */
+	if (mutex_lock_interruptible(&quote_lock))
+		return -EINTR;
+
+	/*
+	 * 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) {
+		ret = -EBUSY;
+		goto done;
+	}
+
+	if (desc->inblob_len != TDX_REPORTDATA_LEN) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
+	if (!reportdata) {
+		ret = -ENOMEM;
+		goto done;
+	}
+
+	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
+	if (!tdreport) {
+		ret = -ENOMEM;
+		goto done;
+	}
+
+	memcpy(reportdata, desc->inblob, desc->inblob_len);
+
+	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
+	ret = tdx_mcall_get_report0(reportdata, tdreport);
+	if (ret) {
+		pr_err("GetReport call failed\n");
+		goto done;
+	}
+
+	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;
+
+	memcpy(quote_buf->data, tdreport, TDX_REPORT_LEN);
+
+	err = tdx_hcall_get_quote(quote_data, GET_QUOTE_BUF_SIZE);
+	if (err) {
+		pr_err("GetQuote hypercall failed, status:%llx\n", err);
+		ret = -EIO;
+		goto done;
+	}
+
+	ret = wait_for_quote_completion(quote_buf, getquote_timeout);
+	if (ret) {
+		pr_err("GetQuote request timedout\n");
+		goto done;
+	}
+
+	buf = kvmemdup(quote_buf->data, quote_buf->out_len, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto done;
+	}
+
+	report->outblob = buf;
+	report->outblob_len = quote_buf->out_len;
+
+	/*
+	 * TODO: parse the PEM-formatted cert chain out of the quote buffer when
+	 * provided
+	 */
+done:
+	mutex_unlock(&quote_lock);
+	kfree(reportdata);
+	kfree(tdreport);
+
+	return ret;
+}
+
 static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
 			    unsigned long arg)
 {
@@ -82,17 +278,48 @@ static const struct x86_cpu_id tdx_guest_ids[] = {
 };
 MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);
 
+static const struct tsm_ops tdx_tsm_ops = {
+	.name = KBUILD_MODNAME,
+	.report_new = tdx_report_new,
+};
+
 static int __init tdx_guest_init(void)
 {
+	int ret;
+
 	if (!x86_match_cpu(tdx_guest_ids))
 		return -ENODEV;
 
-	return misc_register(&tdx_misc_dev);
+	ret = misc_register(&tdx_misc_dev);
+	if (ret)
+		return ret;
+
+	quote_data = alloc_quote_buf();
+	if (!quote_data) {
+		pr_err("Failed to allocate Quote buffer\n");
+		ret = -ENOMEM;
+		goto free_misc;
+	}
+
+	ret = tsm_register(&tdx_tsm_ops, NULL, NULL);
+	if (ret)
+		goto free_quote;
+
+	return 0;
+
+free_quote:
+	free_quote_buf(quote_data);
+free_misc:
+	misc_deregister(&tdx_misc_dev);
+
+	return ret;
 }
 module_init(tdx_guest_init);
 
 static void __exit tdx_guest_exit(void)
 {
+	tsm_unregister(&tdx_tsm_ops);
+	free_quote_buf(quote_data);
 	misc_deregister(&tdx_misc_dev);
 }
 module_exit(tdx_guest_exit);
diff --git a/drivers/virt/coco/tsm.c b/drivers/virt/coco/tsm.c
new file mode 100644
index 0000000000..d1c2db83a8
--- /dev/null
+++ b/drivers/virt/coco/tsm.c
@@ -0,0 +1,425 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/tsm.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/cleanup.h>
+#include <linux/configfs.h>
+
+static struct tsm_provider {
+	const struct tsm_ops *ops;
+	const struct config_item_type *type;
+	void *data;
+} provider;
+static DECLARE_RWSEM(tsm_rwsem);
+
+/**
+ * DOC: Trusted Security Module (TSM) Attestation Report Interface
+ *
+ * The TSM report interface is a common provider of blobs that facilitate
+ * attestation of a TVM (confidential computing guest) by an attestation
+ * service. A TSM report combines a user-defined blob (likely a public-key with
+ * a nonce for a key-exchange protocol) with a signed attestation report. That
+ * combined blob is then used to obtain secrets provided by an agent that can
+ * validate the attestation report. The expectation is that this interface is
+ * invoked infrequently, however configfs allows for multiple agents to
+ * own their own report generation instances to generate reports as
+ * often as needed.
+ *
+ * The attestation report format is TSM provider specific, when / if a standard
+ * materializes that can be published instead of the vendor layout. Until then
+ * the 'provider' attribute indicates the format of 'outblob', and optionally
+ * 'auxblob'.
+ */
+
+struct tsm_report_state {
+	struct tsm_report report;
+	unsigned long write_generation;
+	unsigned long read_generation;
+	struct config_item cfg;
+};
+
+enum tsm_data_select {
+	TSM_REPORT,
+	TSM_CERTS,
+};
+
+static struct tsm_report *to_tsm_report(struct config_item *cfg)
+{
+	struct tsm_report_state *state =
+		container_of(cfg, struct tsm_report_state, cfg);
+
+	return &state->report;
+}
+
+static struct tsm_report_state *to_state(struct tsm_report *report)
+{
+	return container_of(report, struct tsm_report_state, report);
+}
+
+static int try_advance_write_generation(struct tsm_report *report)
+{
+	struct tsm_report_state *state = to_state(report);
+
+	lockdep_assert_held_write(&tsm_rwsem);
+
+	/*
+	 * Malicious or broken userspace has written enough times for
+	 * read_generation == write_generation by modular arithmetic without an
+	 * interim read. Stop accepting updates until the current report
+	 * configuration is read.
+	 */
+	if (state->write_generation == state->read_generation - 1)
+		return -EBUSY;
+	state->write_generation++;
+	return 0;
+}
+
+static ssize_t tsm_report_privlevel_store(struct config_item *cfg,
+					  const char *buf, size_t len)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	unsigned int val;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	/*
+	 * The valid privilege levels that a TSM might accept, if it accepts a
+	 * privilege level setting at all, are a max of TSM_PRIVLEVEL_MAX (see
+	 * SEV-SNP GHCB) and a minimum of a TSM selected floor value no less
+	 * than 0.
+	 */
+	if (provider.ops->privlevel_floor > val || val > TSM_PRIVLEVEL_MAX)
+		return -EINVAL;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+	report->desc.privlevel = val;
+
+	return len;
+}
+CONFIGFS_ATTR_WO(tsm_report_, privlevel);
+
+static ssize_t tsm_report_privlevel_floor_show(struct config_item *cfg,
+					       char *buf)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+	return sysfs_emit(buf, "%u\n", provider.ops->privlevel_floor);
+}
+CONFIGFS_ATTR_RO(tsm_report_, privlevel_floor);
+
+static ssize_t tsm_report_inblob_write(struct config_item *cfg,
+				       const void *buf, size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	int rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+
+	report->desc.inblob_len = count;
+	memcpy(report->desc.inblob, buf, count);
+	return count;
+}
+CONFIGFS_BIN_ATTR_WO(tsm_report_, inblob, NULL, TSM_INBLOB_MAX);
+
+static ssize_t tsm_report_generation_show(struct config_item *cfg, char *buf)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	struct tsm_report_state *state = to_state(report);
+
+	guard(rwsem_read)(&tsm_rwsem);
+	return sysfs_emit(buf, "%lu\n", state->write_generation);
+}
+CONFIGFS_ATTR_RO(tsm_report_, generation);
+
+static ssize_t tsm_report_provider_show(struct config_item *cfg, char *buf)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+	return sysfs_emit(buf, "%s\n", provider.ops->name);
+}
+CONFIGFS_ATTR_RO(tsm_report_, provider);
+
+static ssize_t __read_report(struct tsm_report *report, void *buf, size_t count,
+			     enum tsm_data_select select)
+{
+	loff_t offset = 0;
+	ssize_t len;
+	u8 *out;
+
+	if (select == TSM_REPORT) {
+		out = report->outblob;
+		len = report->outblob_len;
+	} else {
+		out = report->auxblob;
+		len = report->auxblob_len;
+	}
+
+	/*
+	 * Recall that a NULL @buf is configfs requesting the size of
+	 * the buffer.
+	 */
+	if (!buf)
+		return len;
+	return memory_read_from_buffer(buf, count, &offset, out, len);
+}
+
+static ssize_t read_cached_report(struct tsm_report *report, void *buf,
+				  size_t count, enum tsm_data_select select)
+{
+	struct tsm_report_state *state = to_state(report);
+
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!report->desc.inblob_len)
+		return -EINVAL;
+
+	/*
+	 * A given TSM backend always fills in ->outblob regardless of
+	 * whether the report includes an auxblob or not.
+	 */
+	if (!report->outblob ||
+	    state->read_generation != state->write_generation)
+		return -EWOULDBLOCK;
+
+	return __read_report(report, buf, count, select);
+}
+
+static ssize_t tsm_report_read(struct tsm_report *report, void *buf,
+			       size_t count, enum tsm_data_select select)
+{
+	struct tsm_report_state *state = to_state(report);
+	const struct tsm_ops *ops;
+	ssize_t rc;
+
+	/* try to read from the existing report if present and valid... */
+	rc = read_cached_report(report, buf, count, select);
+	if (rc >= 0 || rc != -EWOULDBLOCK)
+		return rc;
+
+	/* slow path, report may need to be regenerated... */
+	guard(rwsem_write)(&tsm_rwsem);
+	ops = provider.ops;
+	if (!ops)
+		return -ENOTTY;
+	if (!report->desc.inblob_len)
+		return -EINVAL;
+
+	/* did another thread already generate this report? */
+	if (report->outblob &&
+	    state->read_generation == state->write_generation)
+		goto out;
+
+	kvfree(report->outblob);
+	kvfree(report->auxblob);
+	report->outblob = NULL;
+	report->auxblob = NULL;
+	rc = ops->report_new(report, provider.data);
+	if (rc < 0)
+		return rc;
+	state->read_generation = state->write_generation;
+out:
+	return __read_report(report, buf, count, select);
+}
+
+static ssize_t tsm_report_outblob_read(struct config_item *cfg, void *buf,
+				       size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+
+	return tsm_report_read(report, buf, count, TSM_REPORT);
+}
+CONFIGFS_BIN_ATTR_RO(tsm_report_, outblob, NULL, TSM_OUTBLOB_MAX);
+
+static ssize_t tsm_report_auxblob_read(struct config_item *cfg, void *buf,
+				       size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+
+	return tsm_report_read(report, buf, count, TSM_CERTS);
+}
+CONFIGFS_BIN_ATTR_RO(tsm_report_, auxblob, NULL, TSM_OUTBLOB_MAX);
+
+#define TSM_DEFAULT_ATTRS() \
+	&tsm_report_attr_generation, \
+	&tsm_report_attr_provider
+
+static struct configfs_attribute *tsm_report_attrs[] = {
+	TSM_DEFAULT_ATTRS(),
+	NULL,
+};
+
+static struct configfs_attribute *tsm_report_extra_attrs[] = {
+	TSM_DEFAULT_ATTRS(),
+	&tsm_report_attr_privlevel,
+	&tsm_report_attr_privlevel_floor,
+	NULL,
+};
+
+#define TSM_DEFAULT_BIN_ATTRS() \
+	&tsm_report_attr_inblob, \
+	&tsm_report_attr_outblob
+
+static struct configfs_bin_attribute *tsm_report_bin_attrs[] = {
+	TSM_DEFAULT_BIN_ATTRS(),
+	NULL,
+};
+
+static struct configfs_bin_attribute *tsm_report_bin_extra_attrs[] = {
+	TSM_DEFAULT_BIN_ATTRS(),
+	&tsm_report_attr_auxblob,
+	NULL,
+};
+
+static void tsm_report_item_release(struct config_item *cfg)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	struct tsm_report_state *state = to_state(report);
+
+	kvfree(report->auxblob);
+	kvfree(report->outblob);
+	kfree(state);
+}
+
+static struct configfs_item_operations tsm_report_item_ops = {
+	.release = tsm_report_item_release,
+};
+
+const struct config_item_type tsm_report_default_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_bin_attrs = tsm_report_bin_attrs,
+	.ct_attrs = tsm_report_attrs,
+	.ct_item_ops = &tsm_report_item_ops,
+};
+EXPORT_SYMBOL_GPL(tsm_report_default_type);
+
+const struct config_item_type tsm_report_extra_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_bin_attrs = tsm_report_bin_extra_attrs,
+	.ct_attrs = tsm_report_extra_attrs,
+	.ct_item_ops = &tsm_report_item_ops,
+};
+EXPORT_SYMBOL_GPL(tsm_report_extra_type);
+
+static struct config_item *tsm_report_make_item(struct config_group *group,
+						const char *name)
+{
+	struct tsm_report_state *state;
+
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!provider.ops)
+		return ERR_PTR(-ENXIO);
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&state->cfg, name, provider.type);
+	return &state->cfg;
+}
+
+static struct configfs_group_operations tsm_report_group_ops = {
+	.make_item = tsm_report_make_item,
+};
+
+static const struct config_item_type tsm_reports_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_group_ops = &tsm_report_group_ops,
+};
+
+static const struct config_item_type tsm_root_group_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem tsm_configfs = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "tsm",
+			.ci_type = &tsm_root_group_type,
+		},
+	},
+	.su_mutex = __MUTEX_INITIALIZER(tsm_configfs.su_mutex),
+};
+
+int tsm_register(const struct tsm_ops *ops, void *priv,
+		 const struct config_item_type *type)
+{
+	const struct tsm_ops *conflict;
+
+	if (!type)
+		type = &tsm_report_default_type;
+	if (!(type == &tsm_report_default_type || type == &tsm_report_extra_type))
+		return -EINVAL;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	conflict = provider.ops;
+	if (conflict) {
+		pr_err("\"%s\" ops already registered\n", conflict->name);
+		return -EBUSY;
+	}
+
+	provider.ops = ops;
+	provider.data = priv;
+	provider.type = type;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_register);
+
+int tsm_unregister(const struct tsm_ops *ops)
+{
+	guard(rwsem_write)(&tsm_rwsem);
+	if (ops != provider.ops)
+		return -EBUSY;
+	provider.ops = NULL;
+	provider.data = NULL;
+	provider.type = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_unregister);
+
+static struct config_group *tsm_report_group;
+
+static int __init tsm_init(void)
+{
+	struct config_group *root = &tsm_configfs.su_group;
+	struct config_group *tsm;
+	int rc;
+
+	config_group_init(root);
+	rc = configfs_register_subsystem(&tsm_configfs);
+	if (rc)
+		return rc;
+
+	tsm = configfs_register_default_group(root, "report",
+					      &tsm_reports_type);
+	if (IS_ERR(tsm)) {
+		configfs_unregister_subsystem(&tsm_configfs);
+		return PTR_ERR(tsm);
+	}
+	tsm_report_group = tsm;
+
+	return 0;
+}
+module_init(tsm_init);
+
+static void __exit tsm_exit(void)
+{
+	configfs_unregister_default_group(tsm_report_group);
+	configfs_unregister_subsystem(&tsm_configfs);
+}
+module_exit(tsm_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Provide Trusted Security Module attestation reports via configfs");