4 files changed, 67 insertions, 3 deletions

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 422999740649..82e79da195fa 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -221,6 +221,7 @@ static bool cxl_mem_raw_command_allowed(u16 opcode)
  *  * %-EINVAL	- Reserved fields or invalid values were used.
  *  * %-ENOMEM	- Input or output buffer wasn't sized properly.
  *  * %-EPERM	- Attempted to use a protected command.
+ *  * %-EBUSY	- Kernel has claimed exclusive access to this opcode
  *
  * The result of this command is a fully validated command in @out_cmd that is
  * safe to send to the hardware.
@@ -296,6 +297,10 @@ static int cxl_validate_cmd_from_user(struct cxl_mem *cxlm,
 	if (!test_bit(info->id, cxlm->enabled_cmds))
 		return -ENOTTY;
 
+	/* Check that the command is not claimed for exclusive kernel use */
+	if (test_bit(info->id, cxlm->exclusive_cmds))
+		return -EBUSY;
+
 	/* Check the input buffer is the expected size */
 	if (info->size_in >= 0 && info->size_in != send_cmd->in.size)
 		return -ENOMEM;
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index df2ba87238c2..bf1b04d00ff4 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -134,6 +134,38 @@ static const struct device_type cxl_memdev_type = {
 	.groups = cxl_memdev_attribute_groups,
 };
 
+/**
+ * set_exclusive_cxl_commands() - atomically disable user cxl commands
+ * @cxlm: cxl_mem instance to modify
+ * @cmds: bitmap of commands to mark exclusive
+ *
+ * Grab the cxl_memdev_rwsem in write mode to flush in-flight
+ * invocations of the ioctl path and then disable future execution of
+ * commands with the command ids set in @cmds.
+ */
+void set_exclusive_cxl_commands(struct cxl_mem *cxlm, unsigned long *cmds)
+{
+	down_write(&cxl_memdev_rwsem);
+	bitmap_or(cxlm->exclusive_cmds, cxlm->exclusive_cmds, cmds,
+		  CXL_MEM_COMMAND_ID_MAX);
+	up_write(&cxl_memdev_rwsem);
+}
+EXPORT_SYMBOL_GPL(set_exclusive_cxl_commands);
+
+/**
+ * clear_exclusive_cxl_commands() - atomically enable user cxl commands
+ * @cxlm: cxl_mem instance to modify
+ * @cmds: bitmap of commands to mark available for userspace
+ */
+void clear_exclusive_cxl_commands(struct cxl_mem *cxlm, unsigned long *cmds)
+{
+	down_write(&cxl_memdev_rwsem);
+	bitmap_andnot(cxlm->exclusive_cmds, cxlm->exclusive_cmds, cmds,
+		      CXL_MEM_COMMAND_ID_MAX);
+	up_write(&cxl_memdev_rwsem);
+}
+EXPORT_SYMBOL_GPL(clear_exclusive_cxl_commands);
+
 static void cxl_memdev_shutdown(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 8f59a89a0aab..373add570ef6 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -101,6 +101,7 @@ struct cxl_mbox_cmd {
  * @mbox_mutex: Mutex to synchronize mailbox access.
  * @firmware_version: Firmware version for the memory device.
  * @enabled_cmds: Hardware commands found enabled in CEL.
+ * @exclusive_cmds: Commands that are kernel-internal only
  * @pmem_range: Active Persistent memory capacity configuration
  * @ram_range: Active Volatile memory capacity configuration
  * @total_bytes: sum of all possible capacities
@@ -127,6 +128,7 @@ struct cxl_mem {
 	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
 	char firmware_version[0x10];
 	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
+	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
 
 	struct range pmem_range;
 	struct range ram_range;
@@ -200,4 +202,6 @@ int cxl_mem_identify(struct cxl_mem *cxlm);
 int cxl_mem_enumerate_cmds(struct cxl_mem *cxlm);
 int cxl_mem_create_range_info(struct cxl_mem *cxlm);
 struct cxl_mem *cxl_mem_create(struct device *dev);
+void set_exclusive_cxl_commands(struct cxl_mem *cxlm, unsigned long *cmds);
+void clear_exclusive_cxl_commands(struct cxl_mem *cxlm, unsigned long *cmds);
 #endif /* __CXL_MEM_H__ */
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index 9652c3ee41e7..5629289939af 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -16,6 +16,13 @@
  */
 static struct workqueue_struct *cxl_pmem_wq;
 
+static __read_mostly DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
+
+static void clear_exclusive(void *cxlm)
+{
+	clear_exclusive_cxl_commands(cxlm, exclusive_cmds);
+}
+
 static void unregister_nvdimm(void *nvdimm)
 {
 	nvdimm_delete(nvdimm);
@@ -39,25 +46,37 @@ static struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(void)
 static int cxl_nvdimm_probe(struct device *dev)
 {
 	struct cxl_nvdimm *cxl_nvd = to_cxl_nvdimm(dev);
+	struct cxl_memdev *cxlmd = cxl_nvd->cxlmd;
+	struct cxl_mem *cxlm = cxlmd->cxlm;
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	unsigned long flags = 0;
 	struct nvdimm *nvdimm;
-	int rc = -ENXIO;
+	int rc;
 
 	cxl_nvb = cxl_find_nvdimm_bridge();
 	if (!cxl_nvb)
 		return -ENXIO;
 
 	device_lock(&cxl_nvb->dev);
-	if (!cxl_nvb->nvdimm_bus)
+	if (!cxl_nvb->nvdimm_bus) {
+		rc = -ENXIO;
+		goto out;
+	}
+
+	set_exclusive_cxl_commands(cxlm, exclusive_cmds);
+	rc = devm_add_action_or_reset(dev, clear_exclusive, cxlm);
+	if (rc)
 		goto out;
 
 	set_bit(NDD_LABELING, &flags);
 	nvdimm = nvdimm_create(cxl_nvb->nvdimm_bus, cxl_nvd, NULL, flags, 0, 0,
 			       NULL);
-	if (!nvdimm)
+	if (!nvdimm) {
+		rc = -ENOMEM;
 		goto out;
+	}
 
+	dev_set_drvdata(dev, nvdimm);
 	rc = devm_add_action_or_reset(dev, unregister_nvdimm, nvdimm);
 out:
 	device_unlock(&cxl_nvb->dev);
@@ -194,6 +213,10 @@ static __init int cxl_pmem_init(void)
 {
 	int rc;
 
+	set_bit(CXL_MEM_COMMAND_ID_SET_PARTITION_INFO, exclusive_cmds);
+	set_bit(CXL_MEM_COMMAND_ID_SET_SHUTDOWN_STATE, exclusive_cmds);
+	set_bit(CXL_MEM_COMMAND_ID_SET_LSA, exclusive_cmds);
+
 	cxl_pmem_wq = alloc_ordered_workqueue("cxl_pmem", 0);
 	if (!cxl_pmem_wq)
 		return -ENXIO;