PCI/TSM: Report active IDE streams

Given that the platform TSM owns IDE Stream ID allocation, report the
active streams via the TSM class device. Establish a symlink from the
class device to the PCI endpoint device consuming the stream, named by
the Stream ID.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Link: https://patch.msgid.link/20251031212902.2256310-10-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Documentation/ABI/testing/sysfs-class-tsm

@@ -7,3 +7,13 @@ Description:
 		signals when the PCI layer is able to support establishment of
 		link encryption and other device-security features coordinated
 		through a platform tsm.
+
+What:		/sys/class/tsm/tsmN/streamH.R.E
+Contact:	linux-pci@vger.kernel.org
+Description:
+		(RO) When a host bridge has established a secure connection via
+		the platform TSM, symlink appears. The primary function of this
+		is have a system global review of TSM resource consumption
+		across host bridges. The link points to the endpoint PCI device
+		and matches the same link published by the host bridge. See
+		Documentation/ABI/testing/sysfs-devices-pci-host-bridge.

drivers/pci/ide.c

@@ -11,6 +11,7 @@
 #include <linux/pci_regs.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
+#include <linux/tsm.h>
 
 #include "pci.h"
 
@@ -261,6 +262,9 @@ void pci_ide_stream_release(struct pci_ide *ide)
 	if (ide->partner[PCI_IDE_EP].enable)
 		pci_ide_stream_disable(pdev, ide);
 
+	if (ide->tsm_dev)
+		tsm_ide_stream_unregister(ide);
+
 	if (ide->partner[PCI_IDE_RP].setup)
 		pci_ide_stream_teardown(rp, ide);
 

drivers/virt/coco/tsm-core.c

@@ -4,11 +4,13 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/tsm.h>
+#include <linux/pci.h>
 #include <linux/rwsem.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/cleanup.h>
 #include <linux/pci-tsm.h>
+#include <linux/pci-ide.h>
 
 static struct class *tsm_class;
 static DECLARE_RWSEM(tsm_rwsem);
@@ -106,6 +108,32 @@ void tsm_unregister(struct tsm_dev *tsm_dev)
 }
 EXPORT_SYMBOL_GPL(tsm_unregister);
 
+/* must be invoked between tsm_register / tsm_unregister */
+int tsm_ide_stream_register(struct pci_ide *ide)
+{
+	struct pci_dev *pdev = ide->pdev;
+	struct pci_tsm *tsm = pdev->tsm;
+	struct tsm_dev *tsm_dev = tsm->tsm_dev;
+	int rc;
+
+	rc = sysfs_create_link(&tsm_dev->dev.kobj, &pdev->dev.kobj, ide->name);
+	if (rc)
+		return rc;
+
+	ide->tsm_dev = tsm_dev;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_ide_stream_register);
+
+void tsm_ide_stream_unregister(struct pci_ide *ide)
+{
+	struct tsm_dev *tsm_dev = ide->tsm_dev;
+
+	ide->tsm_dev = NULL;
+	sysfs_remove_link(&tsm_dev->dev.kobj, ide->name);
+}
+EXPORT_SYMBOL_GPL(tsm_ide_stream_unregister);
+
 static void tsm_release(struct device *dev)
 {
 	struct tsm_dev *tsm_dev = container_of(dev, typeof(*tsm_dev), dev);

include/linux/pci-ide.h

@@ -50,6 +50,7 @@ struct pci_ide_partner {
  * @host_bridge_stream: allocated from host bridge @ide_stream_ida pool
  * @stream_id: unique Stream ID (within Partner Port pairing)
  * @name: name of the established Selective IDE Stream in sysfs
+ * @tsm_dev: For TSM established IDE, the TSM device context
  *
  * Negative @stream_id values indicate "uninitialized" on the
  * expectation that with TSM established IDE the TSM owns the stream_id
@@ -61,6 +62,7 @@ struct pci_ide {
 	u8 host_bridge_stream;
 	int stream_id;
 	const char *name;
+	struct tsm_dev *tsm_dev;
 };
 
 void pci_ide_set_nr_streams(struct pci_host_bridge *hb, u16 nr);

include/linux/tsm.h

@@ -123,4 +123,7 @@ int tsm_report_unregister(const struct tsm_report_ops *ops);
 struct tsm_dev *tsm_register(struct device *parent, struct pci_tsm_ops *ops);
 void tsm_unregister(struct tsm_dev *tsm_dev);
 struct tsm_dev *find_tsm_dev(int id);
+struct pci_ide;
+int tsm_ide_stream_register(struct pci_ide *ide);
+void tsm_ide_stream_unregister(struct pci_ide *ide);
 #endif /* __TSM_H */