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>

6 files changed, 118 insertions, 1 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-tsm b/Documentation/ABI/testing/sysfs-class-tsm
new file mode 100644
index 000000000000..2949468deaf7
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-tsm
@@ -0,0 +1,9 @@
+What:		/sys/class/tsm/tsmN
+Contact:	linux-coco@lists.linux.dev
+Description:
+		"tsmN" is a device that represents the generic attributes of a
+		platform TEE Security Manager.  It is typically a child of a
+		platform enumerated TSM device. /sys/class/tsm/tsmN/uevent
+		signals when the PCI layer is able to support establishment of
+		link encryption and other device-security features coordinated
+		through a platform tsm.
diff --git a/MAINTAINERS b/MAINTAINERS
index 46bd8e033042..b8c9929532ed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26112,7 +26112,7 @@ M:	David Lechner <dlechner@baylibre.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/trigger-source/*
 
-TRUSTED SECURITY MODULE (TSM) INFRASTRUCTURE
+TRUSTED EXECUTION ENVIRONMENT SECURITY MANAGER (TSM)
 M:	Dan Williams <dan.j.williams@intel.com>
 L:	linux-coco@lists.linux.dev
 S:	Maintained
diff --git a/drivers/virt/coco/Kconfig b/drivers/virt/coco/Kconfig
index 819a97e8ba99..bb0c6d6ddcc8 100644
--- a/drivers/virt/coco/Kconfig
+++ b/drivers/virt/coco/Kconfig
@@ -14,3 +14,6 @@ source "drivers/virt/coco/tdx-guest/Kconfig"
 source "drivers/virt/coco/arm-cca-guest/Kconfig"
 
 source "drivers/virt/coco/guest/Kconfig"
+
+config TSM
+	bool
diff --git a/drivers/virt/coco/Makefile b/drivers/virt/coco/Makefile
index f918bbb61737..cb52021912b3 100644
--- a/drivers/virt/coco/Makefile
+++ b/drivers/virt/coco/Makefile
@@ -7,4 +7,5 @@ obj-$(CONFIG_ARM_PKVM_GUEST)	+= pkvm-guest/
 obj-$(CONFIG_SEV_GUEST)		+= sev-guest/
 obj-$(CONFIG_INTEL_TDX_GUEST)	+= tdx-guest/
 obj-$(CONFIG_ARM_CCA_GUEST)	+= arm-cca-guest/
+obj-$(CONFIG_TSM) 		+= tsm-core.o
 obj-$(CONFIG_TSM_GUEST)		+= guest/
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");
diff --git a/include/linux/tsm.h b/include/linux/tsm.h
index 431054810dca..cd97c63ffa32 100644
--- a/include/linux/tsm.h
+++ b/include/linux/tsm.h
@@ -5,6 +5,7 @@
 #include <linux/sizes.h>
 #include <linux/types.h>
 #include <linux/uuid.h>
+#include <linux/device.h>
 
 #define TSM_REPORT_INBLOB_MAX 64
 #define TSM_REPORT_OUTBLOB_MAX SZ_32K
@@ -107,6 +108,16 @@ struct tsm_report_ops {
 	bool (*report_bin_attr_visible)(int n);
 };
 
+struct tsm_dev {
+	struct device dev;
+	int id;
+};
+
+DEFINE_FREE(put_tsm_dev, struct tsm_dev *,
+	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))
+
 int tsm_report_register(const struct tsm_report_ops *ops, void *priv);
 int tsm_report_unregister(const struct tsm_report_ops *ops);
+struct tsm_dev *tsm_register(struct device *parent);
+void tsm_unregister(struct tsm_dev *tsm_dev);
 #endif /* __TSM_H */