cxl fixes for v7.0-rc2

- Fix incorrect usages of decoder flags.
 cxl/region: Test CXL_DECODER_F_NORMALIZED_ADDRESSING as a bitmask
 cxl: Test CXL_DECODER_F_LOCK as a bitmask
 
 cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()
 
 - Moving of devm_cxl_add_nvdimm_bridge() is required for the race fix.
 cxl: Fix race of nvdimm_bus object when creating nvdimm objects
 cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko
 
 - The port_to_host() is used to fix the race window without host lock.
 cxl/port: Hold port host lock during dport adding.
 cxl/port: Introduce port_to_host() helper
 
 cxl/memdev: fix deadlock in cxl_memdev_autoremove() on attach failure
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Merge tag 'cxl-fixes-7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl

Pull cxl fixes from Dave Jiang:

 - Fix incorrect usages of decoder flags

 - Validate payload size before accessing contents

 - Fix race condition when creating nvdimm objects

 - Fix deadlock on attach failure

* tag 'cxl-fixes-7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
  cxl/region: Test CXL_DECODER_F_NORMALIZED_ADDRESSING as a bitmask
  cxl: Test CXL_DECODER_F_LOCK as a bitmask
  cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()
  cxl: Fix race of nvdimm_bus object when creating nvdimm objects
  cxl: Move devm_cxl_add_nvdimm_bridge() to cxl_pmem.ko
  cxl/port: Hold port host lock during dport adding.
  cxl/port: Introduce port_to_host() helper
  cxl/memdev: fix deadlock in cxl_memdev_autoremove() on attach failure

drivers/cxl/core/core.h

@@ -152,6 +152,24 @@ int cxl_pci_get_bandwidth(struct pci_dev *pdev, struct access_coordinate *c);
 int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 					struct access_coordinate *c);
 
+static inline struct device *port_to_host(struct cxl_port *port)
+{
+	struct cxl_port *parent = is_cxl_root(port) ? NULL :
+				  to_cxl_port(port->dev.parent);
+
+	/*
+	 * The host of CXL root port and the first level of ports is
+	 * the platform firmware device, the host of all other ports
+	 * is their parent port.
+	 */
+	if (!parent)
+		return port->uport_dev;
+	else if (is_cxl_root(parent))
+		return parent->uport_dev;
+	else
+		return &parent->dev;
+}
+
 static inline struct device *dport_to_host(struct cxl_dport *dport)
 {
 	struct cxl_port *port = dport->port;

drivers/cxl/core/hdm.c

@@ -904,7 +904,7 @@ static void cxl_decoder_reset(struct cxl_decoder *cxld)
 	if ((cxld->flags & CXL_DECODER_F_ENABLE) == 0)
 		return;
 
-	if (test_bit(CXL_DECODER_F_LOCK, &cxld->flags))
+	if (cxld->flags & CXL_DECODER_F_LOCK)
 		return;
 
 	if (port->commit_end == id)

drivers/cxl/core/mbox.c

@@ -311,6 +311,7 @@ static bool cxl_mem_raw_command_allowed(u16 opcode)
  * cxl_payload_from_user_allowed() - Check contents of in_payload.
  * @opcode: The mailbox command opcode.
  * @payload_in: Pointer to the input payload passed in from user space.
+ * @in_size: Size of @payload_in in bytes.
  *
  * Return:
  *  * true	- payload_in passes check for @opcode.
@@ -325,12 +326,15 @@ static bool cxl_mem_raw_command_allowed(u16 opcode)
  *
  * The specific checks are determined by the opcode.
  */
-static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in)
+static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in,
+					  size_t in_size)
 {
 	switch (opcode) {
 	case CXL_MBOX_OP_SET_PARTITION_INFO: {
 		struct cxl_mbox_set_partition_info *pi = payload_in;
 
+		if (in_size < sizeof(*pi))
+			return false;
 		if (pi->flags & CXL_SET_PARTITION_IMMEDIATE_FLAG)
 			return false;
 		break;
@@ -338,6 +342,8 @@ static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in)
 	case CXL_MBOX_OP_CLEAR_LOG: {
 		const uuid_t *uuid = (uuid_t *)payload_in;
 
+		if (in_size < sizeof(uuid_t))
+			return false;
 		/*
 		 * Restrict the ‘Clear log’ action to only apply to
 		 * Vendor debug logs.
@@ -365,7 +371,8 @@ static int cxl_mbox_cmd_ctor(struct cxl_mbox_cmd *mbox_cmd,
 		if (IS_ERR(mbox_cmd->payload_in))
 			return PTR_ERR(mbox_cmd->payload_in);
 
-		if (!cxl_payload_from_user_allowed(opcode, mbox_cmd->payload_in)) {
+		if (!cxl_payload_from_user_allowed(opcode, mbox_cmd->payload_in,
+						  in_size)) {
 			dev_dbg(cxl_mbox->host, "%s: input payload not allowed\n",
 				cxl_mem_opcode_to_name(opcode));
 			kvfree(mbox_cmd->payload_in);

drivers/cxl/core/memdev.c

@@ -1089,10 +1089,8 @@ static int cxlmd_add(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds)
 DEFINE_FREE(put_cxlmd, struct cxl_memdev *,
 	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))
 
-static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd)
+static bool cxl_memdev_attach_failed(struct cxl_memdev *cxlmd)
 {
-	int rc;
-
 	/*
 	 * If @attach is provided fail if the driver is not attached upon
 	 * return. Note that failure here could be the result of a race to
@@ -1100,7 +1098,14 @@ static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd)
 	 * succeeded and then cxl_mem unbound before the lock is acquired.
 	 */
 	guard(device)(&cxlmd->dev);
-	if (cxlmd->attach && !cxlmd->dev.driver) {
+	return (cxlmd->attach && !cxlmd->dev.driver);
+}
+
+static struct cxl_memdev *cxl_memdev_autoremove(struct cxl_memdev *cxlmd)
+{
+	int rc;
+
+	if (cxl_memdev_attach_failed(cxlmd)) {
 		cxl_memdev_unregister(cxlmd);
 		return ERR_PTR(-ENXIO);
 	}

drivers/cxl/core/pmem.c

@@ -115,15 +115,17 @@ static void unregister_nvb(void *_cxl_nvb)
 	device_unregister(&cxl_nvb->dev);
 }
 
-/**
- * devm_cxl_add_nvdimm_bridge() - add the root of a LIBNVDIMM topology
- * @host: platform firmware root device
- * @port: CXL port at the root of a CXL topology
- *
- * Return: bridge device that can host cxl_nvdimm objects
- */
-struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
-						     struct cxl_port *port)
+static bool cxl_nvdimm_bridge_failed_attach(struct cxl_nvdimm_bridge *cxl_nvb)
+{
+	struct device *dev = &cxl_nvb->dev;
+
+	guard(device)(dev);
+	/* If the device has no driver, then it failed to attach. */
+	return dev->driver == NULL;
+}
+
+struct cxl_nvdimm_bridge *__devm_cxl_add_nvdimm_bridge(struct device *host,
+						       struct cxl_port *port)
 {
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	struct device *dev;
@@ -145,6 +147,11 @@ struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
 	if (rc)
 		goto err;
 
+	if (cxl_nvdimm_bridge_failed_attach(cxl_nvb)) {
+		unregister_nvb(cxl_nvb);
+		return ERR_PTR(-ENODEV);
+	}
+
 	rc = devm_add_action_or_reset(host, unregister_nvb, cxl_nvb);
 	if (rc)
 		return ERR_PTR(rc);
@@ -155,7 +162,7 @@ err:
 	put_device(dev);
 	return ERR_PTR(rc);
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_add_nvdimm_bridge, "CXL");
+EXPORT_SYMBOL_FOR_MODULES(__devm_cxl_add_nvdimm_bridge, "cxl_pmem");
 
 static void cxl_nvdimm_release(struct device *dev)
 {
@@ -255,6 +262,21 @@ int devm_cxl_add_nvdimm(struct device *host, struct cxl_port *port,
 	if (!cxl_nvb)
 		return -ENODEV;
 
+	/*
+	 * Take the uport_dev lock to guard against race of nvdimm_bus object.
+	 * cxl_acpi_probe() registers the nvdimm_bus and is done under the
+	 * root port uport_dev lock.
+	 *
+	 * Take the cxl_nvb device lock to ensure that cxl_nvb driver is in a
+	 * consistent state. And the driver registers nvdimm_bus.
+	 */
+	guard(device)(cxl_nvb->port->uport_dev);
+	guard(device)(&cxl_nvb->dev);
+	if (!cxl_nvb->nvdimm_bus) {
+		rc = -ENODEV;
+		goto err_alloc;
+	}
+
 	cxl_nvd = cxl_nvdimm_alloc(cxl_nvb, cxlmd);
 	if (IS_ERR(cxl_nvd)) {
 		rc = PTR_ERR(cxl_nvd);

drivers/cxl/core/port.c

@@ -615,22 +615,8 @@ struct cxl_port *parent_port_of(struct cxl_port *port)
 static void unregister_port(void *_port)
 {
 	struct cxl_port *port = _port;
-	struct cxl_port *parent = parent_port_of(port);
-	struct device *lock_dev;
 
-	/*
-	 * CXL root port's and the first level of ports are unregistered
-	 * under the platform firmware device lock, all other ports are
-	 * unregistered while holding their parent port lock.
-	 */
-	if (!parent)
-		lock_dev = port->uport_dev;
-	else if (is_cxl_root(parent))
-		lock_dev = parent->uport_dev;
-	else
-		lock_dev = &parent->dev;
-
-	device_lock_assert(lock_dev);
+	device_lock_assert(port_to_host(port));
 	port->dead = true;
 	device_unregister(&port->dev);
 }
@@ -1427,20 +1413,11 @@ static struct device *grandparent(struct device *dev)
 	return NULL;
 }
 
-static struct device *endpoint_host(struct cxl_port *endpoint)
-{
-	struct cxl_port *port = to_cxl_port(endpoint->dev.parent);
-
-	if (is_cxl_root(port))
-		return port->uport_dev;
-	return &port->dev;
-}
-
 static void delete_endpoint(void *data)
 {
 	struct cxl_memdev *cxlmd = data;
 	struct cxl_port *endpoint = cxlmd->endpoint;
-	struct device *host = endpoint_host(endpoint);
+	struct device *host = port_to_host(endpoint);
 
 	scoped_guard(device, host) {
 		if (host->driver && !endpoint->dead) {
@@ -1456,7 +1433,7 @@ static void delete_endpoint(void *data)
 
 int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint)
 {
-	struct device *host = endpoint_host(endpoint);
+	struct device *host = port_to_host(endpoint);
 	struct device *dev = &cxlmd->dev;
 
 	get_device(host);
@@ -1790,7 +1767,16 @@ static struct cxl_dport *find_or_add_dport(struct cxl_port *port,
 {
 	struct cxl_dport *dport;
 
-	device_lock_assert(&port->dev);
+	/*
+	 * The port is already visible in CXL hierarchy, but it may still
+	 * be in the process of binding to the CXL port driver at this point.
+	 *
+	 * port creation and driver binding are protected by the port's host
+	 * lock, so acquire the host lock here to ensure the port has completed
+	 * driver binding before proceeding with dport addition.
+	 */
+	guard(device)(port_to_host(port));
+	guard(device)(&port->dev);
 	dport = cxl_find_dport_by_dev(port, dport_dev);
 	if (!dport) {
 		dport = probe_dport(port, dport_dev);
@@ -1857,13 +1843,11 @@ retry:
 			 * RP port enumerated by cxl_acpi without dport will
 			 * have the dport added here.
 			 */
-			scoped_guard(device, &port->dev) {
-				dport = find_or_add_dport(port, dport_dev);
-				if (IS_ERR(dport)) {
-					if (PTR_ERR(dport) == -EAGAIN)
-						goto retry;
-					return PTR_ERR(dport);
-				}
+			dport = find_or_add_dport(port, dport_dev);
+			if (IS_ERR(dport)) {
+				if (PTR_ERR(dport) == -EAGAIN)
+					goto retry;
+				return PTR_ERR(dport);
 			}
 
 			rc = cxl_add_ep(dport, &cxlmd->dev);

drivers/cxl/core/region.c

@@ -1100,12 +1100,12 @@ static int cxl_rr_assign_decoder(struct cxl_port *port, struct cxl_region *cxlr,
 static void cxl_region_setup_flags(struct cxl_region *cxlr,
 				   struct cxl_decoder *cxld)
 {
-	if (test_bit(CXL_DECODER_F_LOCK, &cxld->flags)) {
+	if (cxld->flags & CXL_DECODER_F_LOCK) {
 		set_bit(CXL_REGION_F_LOCK, &cxlr->flags);
 		clear_bit(CXL_REGION_F_NEEDS_RESET, &cxlr->flags);
 	}
 
-	if (test_bit(CXL_DECODER_F_NORMALIZED_ADDRESSING, &cxld->flags))
+	if (cxld->flags & CXL_DECODER_F_NORMALIZED_ADDRESSING)
 		set_bit(CXL_REGION_F_NORMALIZED_ADDRESSING, &cxlr->flags);
 }
 

drivers/cxl/cxl.h

@@ -574,11 +574,16 @@ struct cxl_nvdimm_bridge {
 
 #define CXL_DEV_ID_LEN 19
 
+enum {
+	CXL_NVD_F_INVALIDATED = 0,
+};
+
 struct cxl_nvdimm {
 	struct device dev;
 	struct cxl_memdev *cxlmd;
 	u8 dev_id[CXL_DEV_ID_LEN]; /* for nvdimm, string of 'serial' */
 	u64 dirty_shutdowns;
+	unsigned long flags;
 };
 
 struct cxl_pmem_region_mapping {
@@ -920,6 +925,8 @@ void cxl_driver_unregister(struct cxl_driver *cxl_drv);
 struct cxl_nvdimm_bridge *to_cxl_nvdimm_bridge(struct device *dev);
 struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
 						     struct cxl_port *port);
+struct cxl_nvdimm_bridge *__devm_cxl_add_nvdimm_bridge(struct device *host,
+						       struct cxl_port *port);
 struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev);
 bool is_cxl_nvdimm(struct device *dev);
 int devm_cxl_add_nvdimm(struct device *host, struct cxl_port *port,

drivers/cxl/pmem.c

@@ -13,6 +13,20 @@
 
 static __read_mostly DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
 
+/**
+ * devm_cxl_add_nvdimm_bridge() - add the root of a LIBNVDIMM topology
+ * @host: platform firmware root device
+ * @port: CXL port at the root of a CXL topology
+ *
+ * Return: bridge device that can host cxl_nvdimm objects
+ */
+struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host,
+						     struct cxl_port *port)
+{
+	return __devm_cxl_add_nvdimm_bridge(host, port);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_add_nvdimm_bridge, "CXL");
+
 static void clear_exclusive(void *mds)
 {
 	clear_exclusive_cxl_commands(mds, exclusive_cmds);
@@ -129,6 +143,9 @@ static int cxl_nvdimm_probe(struct device *dev)
 	struct nvdimm *nvdimm;
 	int rc;
 
+	if (test_bit(CXL_NVD_F_INVALIDATED, &cxl_nvd->flags))
+		return -EBUSY;
+
 	set_exclusive_cxl_commands(mds, exclusive_cmds);
 	rc = devm_add_action_or_reset(dev, clear_exclusive, mds);
 	if (rc)
@@ -309,8 +326,10 @@ static int detach_nvdimm(struct device *dev, void *data)
 	scoped_guard(device, dev) {
 		if (dev->driver) {
 			cxl_nvd = to_cxl_nvdimm(dev);
-			if (cxl_nvd->cxlmd && cxl_nvd->cxlmd->cxl_nvb == data)
+			if (cxl_nvd->cxlmd && cxl_nvd->cxlmd->cxl_nvb == data) {
 				release = true;
+				set_bit(CXL_NVD_F_INVALIDATED, &cxl_nvd->flags);
+			}
 		}
 	}
 	if (release)
@@ -353,6 +372,7 @@ static struct cxl_driver cxl_nvdimm_bridge_driver = {
 	.probe = cxl_nvdimm_bridge_probe,
 	.id = CXL_DEVICE_NVDIMM_BRIDGE,
 	.drv = {
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 		.suppress_bind_attrs = true,
 	},
 };