[PATCH v4 01/10] coco/tsm: Introduce a core device for TEE Security Managers

[Dan Williams <dan.j.williams@intel.com>]

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: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Isaku Yamahata <isaku.yamahata@intel.com>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Yilun Xu <yilun.xu@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: John Allen <john.allen@amd.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>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 Documentation/ABI/testing/sysfs-class-tsm |   9 ++
 MAINTAINERS                               |   2 +-
 drivers/virt/coco/Kconfig                 |   3 +
 drivers/virt/coco/Makefile                |   2 +
 drivers/virt/coco/tsm-core.c              | 113 ++++++++++++++++++++++
 include/linux/tsm.h                       |   5 +
 6 files changed, 133 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-tsm
 create mode 100644 drivers/virt/coco/tsm-core.c

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 b6219e19a749..cfa3fb8772d2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25241,7 +25241,7 @@ M:	David Lechner <dlechner@baylibre.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
 
-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..c0c3733be165 100644
--- a/drivers/virt/coco/Makefile
+++ b/drivers/virt/coco/Makefile
@@ -2,9 +2,11 @@
 #
 # Confidential computing related collateral
 #
+
 obj-$(CONFIG_EFI_SECRET)	+= efi_secret/
 obj-$(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..1f53b9049e2d
--- /dev/null
+++ b/drivers/virt/coco/tsm-core.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024 Intel Corporation. All rights reserved. */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/tsm.h>
+#include <linux/idr.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_IDR(tsm_idr);
+
+struct tsm_dev {
+	struct device dev;
+	int id;
+};
+
+static struct tsm_dev *alloc_tsm_dev(struct device *parent,
+				     const struct attribute_group **groups)
+{
+	struct tsm_dev *tsm_dev __free(kfree) =
+		kzalloc(sizeof(*tsm_dev), GFP_KERNEL);
+	struct device *dev;
+	int id;
+
+	if (!tsm_dev)
+		return ERR_PTR(-ENOMEM);
+
+	guard(rwsem_write)(&tsm_rwsem);
+	id = idr_alloc(&tsm_idr, tsm_dev, 0, INT_MAX, GFP_KERNEL);
+	if (id < 0)
+		return ERR_PTR(id);
+
+	tsm_dev->id = id;
+	dev = &tsm_dev->dev;
+	dev->parent = parent;
+	dev->groups = groups;
+	dev->class = tsm_class;
+	device_initialize(dev);
+	return no_free_ptr(tsm_dev);
+}
+
+static void put_tsm_dev(struct tsm_dev *tsm_dev)
+{
+	if (!IS_ERR_OR_NULL(tsm_dev))
+		put_device(&tsm_dev->dev);
+}
+
+DEFINE_FREE(put_tsm_dev, struct tsm_dev *,
+	    if (!IS_ERR_OR_NULL(_T)) put_tsm_dev(_T))
+
+struct tsm_dev *tsm_register(struct device *parent,
+			     const struct attribute_group **groups)
+{
+	struct tsm_dev *tsm_dev __free(put_tsm_dev) =
+		alloc_tsm_dev(parent, groups);
+	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);
+
+	guard(rwsem_write)(&tsm_rwsem);
+	idr_remove(&tsm_idr, 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..a90b40b1b13c 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
@@ -109,4 +110,8 @@ struct tsm_report_ops {
 
 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;
+struct tsm_dev *tsm_register(struct device *parent,
+			     const struct attribute_group **groups);
+void tsm_unregister(struct tsm_dev *tsm_dev);
 #endif /* __TSM_H */
-- 
2.50.1