[PATCH v2 14/31] PCI/TSM: Report active IDE streams per host bridge

Xu Yilun
2026-03-27T16:23:25Z

From: Dan Williams <dan.j.williams@intel.com>

The first attempt at an ABI for this failed to account for naming
collisions across host bridges:

Commit a4438f06b1db ("PCI/TSM: Report active IDE streams")

Revive this ABI with a per host bridge link that appears at first stream
creation for a given host bridge and disappears after the last stream is
removed.

For systems with many host bridge objects it allows:

ls /sys/class/tsm/tsmN/pci*/stream*

...to find all the host bridges with active streams without first iterating
over all host bridges. Yilun notes that is handy to have this short cut [1]
and from an administrator perspective it helps with inventory for
constrained stream resources.

Link: http://lore.kernel.org/aXLtILY85oMU5qlb@yilunxu-OptiPlex-7050 [1]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
Documentation/ABI/testing/sysfs-class-tsm | 13 +++
include/linux/pci-ide.h | 2 +
include/linux/tsm.h | 3 +
drivers/pci/ide.c | 4 +
drivers/virt/coco/tsm-core.c | 97 +++++++++++++++++++++++
5 files changed, 119 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-tsm b/Documentation/ABI/testing/sysfs-class-tsm
index 2949468deaf7..1ddb8f357961 100644
--- a/Documentation/ABI/testing/sysfs-class-tsm
+++ b/Documentation/ABI/testing/sysfs-class-tsm
@@ -7,3 +7,16 @@ 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/pciDDDD:BB
+Contact: linux-pci@vger.kernel.org
+Description:
+ (RO) When a PCIe host bridge has established a secure connection
+ via a TSM to an endpoint, this symlink appears. It facilitates a
+ TSM instance scoped view of PCIe Link Encryption and Secure
+ Session resource consumption across host bridges. The symlink
+ appears when a host bridge has 1 or more IDE streams established
+ with this TSM, and disappears when that number returns to 0. See
+ Documentation/ABI/testing/sysfs-devices-pci-host-bridge for the
+ description of the pciDDDD:BB/streamH.R.E symlink and the
+ pciDDDD:BB/available_secure_streams attribute.
diff --git a/include/linux/pci-ide.h b/include/linux/pci-ide.h
index ae07d9f699c0..381a1bf22a95 100644
--- a/include/linux/pci-ide.h
+++ b/include/linux/pci-ide.h
@@ -82,6 +82,7 @@ struct pci_ide_regs {
* @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
@@ -93,6 +94,7 @@ struct pci_ide {
u8 host_bridge_stream;
int stream_id;
const char *name;
+ struct tsm_dev *tsm_dev;
};

/*
diff --git a/include/linux/tsm.h b/include/linux/tsm.h
index 381c53244c83..7f72a154b6b2 100644
--- a/include/linux/tsm.h
+++ b/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 */
diff --git a/drivers/pci/ide.c b/drivers/pci/ide.c
index be74e8f0ae21..b35e8aba7ecb 100644
--- a/drivers/pci/ide.c
+++ b/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"

@@ -372,6 +373,9 @@ 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);

diff --git a/drivers/virt/coco/tsm-core.c b/drivers/virt/coco/tsm-core.c
index 98dcf7d836df..ece7cd7ea9d8 100644
--- a/drivers/virt/coco/tsm-core.c
+++ b/drivers/virt/coco/tsm-core.c
@@ -4,10 +4,12 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/tsm.h>
+#include <linux/pci.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 DEFINE_IDA(tsm_ida);
@@ -104,6 +106,100 @@ void tsm_unregister(struct tsm_dev *tsm_dev)
}
EXPORT_SYMBOL_GPL(tsm_unregister);

+static DEFINE_XARRAY(tsm_ide_streams);
+static DEFINE_MUTEX(tsm_ide_streams_lock);
+
+/* tracker for the bridge symlink when the bridge has any streams */
+struct tsm_ide_stream {
+ struct tsm_dev *tsm_dev;
+ struct pci_host_bridge *bridge;
+ struct kref kref;
+};
+
+static struct tsm_ide_stream *create_streams(struct tsm_dev *tsm_dev,
+ struct pci_host_bridge *bridge)
+{
+ int rc;
+
+ struct tsm_ide_stream *streams __free(kfree) =
+ kzalloc(sizeof(*streams), GFP_KERNEL);
+ if (!streams)
+ return NULL;
+
+ streams->tsm_dev = tsm_dev;
+ streams->bridge = bridge;
+ kref_init(&streams->kref);
+ rc = xa_insert(&tsm_ide_streams, (unsigned long)bridge, streams,
+ GFP_KERNEL);
+ if (rc)
+ return NULL;
+
+ rc = sysfs_create_link(&tsm_dev->dev.kobj, &bridge->dev.kobj,
+ dev_name(&bridge->dev));
+ if (rc) {
+ xa_erase(&tsm_ide_streams, (unsigned long)bridge);
+ return NULL;
+ }
+
+ return no_free_ptr(streams);
+}
+
+int tsm_ide_stream_register(struct pci_ide *ide)
+{
+ struct tsm_ide_stream *streams;
+ struct pci_dev *pdev = ide->pdev;
+ struct pci_tsm *tsm = pdev->tsm;
+ struct tsm_dev *tsm_dev = tsm->tsm_dev;
+ struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+
+ guard(mutex)(&tsm_ide_streams_lock);
+ streams = xa_load(&tsm_ide_streams, (unsigned long)bridge);
+ if (streams)
+ kref_get(&streams->kref);
+ else
+ streams = create_streams(tsm_dev, bridge);
+
+ if (!streams)
+ return -ENOMEM;
+ ide->tsm_dev = tsm_dev;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_ide_stream_register);
+
+static void destroy_streams(struct kref *kref)
+{
+ struct tsm_ide_stream *streams =
+ container_of(kref, struct tsm_ide_stream, kref);
+ struct tsm_dev *tsm_dev = streams->tsm_dev;
+ struct pci_host_bridge *bridge = streams->bridge;
+
+ lockdep_assert_held(&tsm_ide_streams_lock);
+ sysfs_remove_link(&tsm_dev->dev.kobj, dev_name(&bridge->dev));
+ xa_erase(&tsm_ide_streams, (unsigned long)bridge);
+ kfree(streams);
+}
+
+void tsm_ide_stream_unregister(struct pci_ide *ide)
+{
+ struct tsm_ide_stream *streams;
+ struct tsm_dev *tsm_dev = ide->tsm_dev;
+ struct pci_dev *pdev = ide->pdev;
+ struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+
+ guard(mutex)(&tsm_ide_streams_lock);
+ streams = xa_load(&tsm_ide_streams, (unsigned long)bridge);
+ /* catch API abuse */
+ if (dev_WARN_ONCE(&tsm_dev->dev,
+ !streams || streams->tsm_dev != tsm_dev,
+ "no IDE streams associated with %s\n",
+ dev_name(&bridge->dev)))
+ return;
+ kref_put(&streams->kref, destroy_streams);
+ ide->tsm_dev = NULL;
+}
+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);
@@ -126,6 +222,7 @@ module_init(tsm_init)
static void __exit tsm_exit(void)
{
class_destroy(tsm_class);
+ xa_destroy(&tsm_ide_streams);
}
module_exit(tsm_exit)

--
2.25.1