coco/tsm: Introduce a core device for TEE Security Managers

A "TSM" is a platform component that provides an API for securely
provisioning resources for a confidential guest (TVM) to consume. The
name originates from the PCI specification for platform agent that
carries out operations for PCIe TDISP (TEE Device Interface Security
Protocol).

Instances of this core device are parented by a device representing the
platform security function like CONFIG_CRYPTO_DEV_CCP or
CONFIG_INTEL_TDX_HOST.

This device interface is a frontend to the aspects of a TSM and TEE I/O
that are cross-architecture common. This includes mechanisms like
enumerating available platform TEE I/O capabilities and provisioning
connections between the platform TSM and device DSMs (Device Security
Manager (TDISP)).

For now this is just the scaffolding for registering a TSM device sysfs
interface.

Cc: Xu Yilun <yilun.xu@linux.intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Co-developed-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Link: https://patch.msgid.link/20251031212902.2256310-2-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 93 insertions, 0 deletions

diff --git a/drivers/virt/coco/tsm-core.c b/drivers/virt/coco/tsm-core.c
new file mode 100644
index 000000000000..347507cc5e3f
--- /dev/null
+++ b/drivers/virt/coco/tsm-core.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/tsm.h>
+#include <linux/rwsem.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/cleanup.h>
+
+static struct class *tsm_class;
+static DECLARE_RWSEM(tsm_rwsem);
+static DEFINE_IDA(tsm_ida);
+
+static struct tsm_dev *alloc_tsm_dev(struct device *parent)
+{
+	struct device *dev;
+	int id;
+
+	struct tsm_dev *tsm_dev __free(kfree) =
+		kzalloc(sizeof(*tsm_dev), GFP_KERNEL);
+	if (!tsm_dev)
+		return ERR_PTR(-ENOMEM);
+
+	id = ida_alloc(&tsm_ida, GFP_KERNEL);
+	if (id < 0)
+		return ERR_PTR(id);
+
+	tsm_dev->id = id;
+	dev = &tsm_dev->dev;
+	dev->parent = parent;
+	dev->class = tsm_class;
+	device_initialize(dev);
+
+	return no_free_ptr(tsm_dev);
+}
+
+struct tsm_dev *tsm_register(struct device *parent)
+{
+	struct tsm_dev *tsm_dev __free(put_tsm_dev) = alloc_tsm_dev(parent);
+	struct device *dev;
+	int rc;
+
+	if (IS_ERR(tsm_dev))
+		return tsm_dev;
+
+	dev = &tsm_dev->dev;
+	rc = dev_set_name(dev, "tsm%d", tsm_dev->id);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = device_add(dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return no_free_ptr(tsm_dev);
+}
+EXPORT_SYMBOL_GPL(tsm_register);
+
+void tsm_unregister(struct tsm_dev *tsm_dev)
+{
+	device_unregister(&tsm_dev->dev);
+}
+EXPORT_SYMBOL_GPL(tsm_unregister);
+
+static void tsm_release(struct device *dev)
+{
+	struct tsm_dev *tsm_dev = container_of(dev, typeof(*tsm_dev), dev);
+
+	ida_free(&tsm_ida, tsm_dev->id);
+	kfree(tsm_dev);
+}
+
+static int __init tsm_init(void)
+{
+	tsm_class = class_create("tsm");
+	if (IS_ERR(tsm_class))
+		return PTR_ERR(tsm_class);
+
+	tsm_class->dev_release = tsm_release;
+	return 0;
+}
+module_init(tsm_init)
+
+static void __exit tsm_exit(void)
+{
+	class_destroy(tsm_class);
+}
+module_exit(tsm_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TEE Security Manager Class Device");