[PATCH v2 0/16] cxl: Add CXL feature commands support via fwctl

[PATCH v2 0/16] cxl: Add CXL feature commands support via fwctl

[Dave Jiang]

v2:
- Drop features device and driver. Move features enabling to cxl_memdev. (Dan)
- Drop sysfs attribute of number of features. (Dan)
- Drop moving of include/uapi/linux/cxl_mem.h. (Dan)
- Set get driver info ioctl to return reserved 32bit. Set behavior of issue
  ioctl successful as indicating Feature commands supported.
- Set 'Set Feature Size' to 0 for kernel exclusive Features.
- See individual patches for detailed changes from v1.
- Hide FWCTL bits behind CONFIG_CXL_FWCTL. (Dan)

v1:
- Create a CXL features driver to handle all feature command related bits
  including FWCTL support. (Dan)
- Tested against CXL CLI unit tests for FWCTL.
- See individual patches for detailed changes from RFC v2.

RFC v2:
- Dropped 1/13 and 2/13 from previous version. Merged upstream already.
- Combined changes from Shiju for "get supported features"
- Addressed comments from Jonathan and Jason
- See specific changes in individual patch revision history
- Added hardware command info to FWCTL
- Added filtering to set feature command
- Added documentation

This series add support for CXL feature commands using the FWCTL framework [1].
The code has been tested with CXL CLI unit tests for FWCTL.

Patches 1-7 are shared with EDAC series [1] and there will be an immutable branch
once accepted post review.

CXL Features support is added behind the CXL mem driver. The 3 mailbox commands
"Get Supported Features", "Get Feature", and "Set Feature" are implemented. The
"Get" commands are under the FWCTL_RPC_CONFIGURATION policy, the "Set" command
checks the policy depending on the set effects of the feature defined by the
device via the Feature set effects field. All mailbox commands for CXL provides
an effects table that describes the effects of a command when performed on the
device.  For CXL features, there is also an effects field that describes the
effects a feature set operation has on the device per feature. The security
policy is checked against this feature specific effects field. 

The code is based off of v3 of FWCTL series [2] posted by Jason and rebased on top of
v6.13-rc5.

[1]: https://lore.kernel.org/linux-cxl/20250106121017.1620-1-shiju.jose@huawei.com/T/#t
[2]: https://lore.kernel.org/linux-cxl/0-v3-960f17f90f17+516-fwctl_jgg@nvidia.com/#r
---

Dave Jiang (14):
      cxl: Refactor user ioctl command path from mds to mailbox
      cxl: Enumerate feature commands
      cxl: Add Get Supported Features command for kernel usage
      cxl/test: Add Get Supported Features mailbox command support
      cxl: Setup exclusive CXL features that are reserved for the kernel
      cxl: Add FWCTL support to the CXL memdev driver
      cxl: Add support for FWCTL get driver information callback
      cxl: Move cxl feature command structs to user header
      cxl: Add support for fwctl RPC command to enable CXL feature commands
      cxl: Add support to handle user feature commands for get feature
      cxl: Add support to handle user feature commands for set feature
      cxl/test: Add Get Feature support to cxl_test
      cxl/test: Add Set Feature support to cxl_test
      fwctl/cxl: Add documentation to FWCTL CXL

Shiju Jose (2):
      cxl/mbox: Add GET_FEATURE mailbox command
      cxl/mbox: Add SET_FEATURE mailbox command

 Documentation/userspace-api/fwctl/fwctl-cxl.rst | 135 +++++++++++
 Documentation/userspace-api/fwctl/index.rst     |   1 +
 drivers/cxl/Kconfig                             |   1 +
 drivers/cxl/Makefile                            |   2 +-
 drivers/cxl/core/Makefile                       |   1 +
 drivers/cxl/core/core.h                         |   6 +-
 drivers/cxl/core/features.c                     | 175 ++++++++++++++
 drivers/cxl/core/mbox.c                         | 128 ++++++----
 drivers/cxl/core/memdev.c                       |  22 +-
 drivers/cxl/cxl.h                               |   3 +
 drivers/cxl/cxlmem.h                            |  45 +---
 drivers/cxl/features.c                          | 567 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/features.h                          |  15 ++
 drivers/cxl/mem.c                               |   5 +
 include/cxl/features.h                          |  80 +++++++
 include/cxl/mailbox.h                           |  44 +++-
 include/uapi/cxl/features.h                     | 128 ++++++++++
 include/uapi/fwctl/cxl.h                        |  56 +++++
 include/uapi/fwctl/fwctl.h                      |   1 +
 tools/testing/cxl/Kbuild                        |   3 +-
 tools/testing/cxl/test/mem.c                    | 174 ++++++++++++++
 21 files changed, 1494 insertions(+), 98 deletions(-)

[PATCH v2 01/16] cxl: Refactor user ioctl command path from mds to mailbox

[Dave Jiang]

With 'struct cxl_mailbox' context introduced, the helper functions
cxl_query_cmd() and cxl_send_cmd() can take a cxl_mailbox directly
rather than a cxl_memdev parameter. Refactor to use cxl_mailbox
directly.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/core.h   |  6 ++-
 drivers/cxl/core/mbox.c   | 89 +++++++++++++++++++--------------------
 drivers/cxl/core/memdev.c | 22 +++++++---
 drivers/cxl/cxlmem.h      | 40 ------------------
 include/cxl/mailbox.h     | 41 +++++++++++++++++-
 5 files changed, 102 insertions(+), 96 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 800466f96a68..23761340e65c 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -4,6 +4,8 @@
 #ifndef __CXL_CORE_H__
 #define __CXL_CORE_H__
 
+#include <cxl/mailbox.h>
+
 extern const struct device_type cxl_nvdimm_bridge_type;
 extern const struct device_type cxl_nvdimm_type;
 extern const struct device_type cxl_pmu_type;
@@ -65,9 +67,9 @@ static inline void cxl_region_exit(void)
 
 struct cxl_send_command;
 struct cxl_mem_query_commands;
-int cxl_query_cmd(struct cxl_memdev *cxlmd,
+int cxl_query_cmd(struct cxl_mailbox *cxl_mbox,
 		  struct cxl_mem_query_commands __user *q);
-int cxl_send_cmd(struct cxl_memdev *cxlmd, struct cxl_send_command __user *s);
+int cxl_send_cmd(struct cxl_mailbox *cxl_mailbox, struct cxl_send_command __user *s);
 void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
 				   resource_size_t length);
 
diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 548564c770c0..bdb8f060f2c1 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -349,40 +349,40 @@ static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in)
 	return true;
 }
 
-static int cxl_mbox_cmd_ctor(struct cxl_mbox_cmd *mbox,
-			     struct cxl_memdev_state *mds, u16 opcode,
+static int cxl_mbox_cmd_ctor(struct cxl_mbox_cmd *mbox_cmd,
+			     struct cxl_mailbox *cxl_mbox, u16 opcode,
 			     size_t in_size, size_t out_size, u64 in_payload)
 {
-	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
-	*mbox = (struct cxl_mbox_cmd) {
+	*mbox_cmd = (struct cxl_mbox_cmd) {
 		.opcode = opcode,
 		.size_in = in_size,
 	};
 
 	if (in_size) {
-		mbox->payload_in = vmemdup_user(u64_to_user_ptr(in_payload),
-						in_size);
-		if (IS_ERR(mbox->payload_in))
-			return PTR_ERR(mbox->payload_in);
+		mbox_cmd->payload_in = vmemdup_user(u64_to_user_ptr(in_payload),
+						    in_size);
+		if (IS_ERR(mbox_cmd->payload_in))
+			return PTR_ERR(mbox_cmd->payload_in);
 
-		if (!cxl_payload_from_user_allowed(opcode, mbox->payload_in)) {
-			dev_dbg(mds->cxlds.dev, "%s: input payload not allowed\n",
+		if (!cxl_payload_from_user_allowed(opcode,
+						   mbox_cmd->payload_in)) {
+			dev_dbg(cxl_mbox->host, "%s: input payload not allowed\n",
 				cxl_mem_opcode_to_name(opcode));
-			kvfree(mbox->payload_in);
+			kvfree(mbox_cmd->payload_in);
 			return -EBUSY;
 		}
 	}
 
 	/* Prepare to handle a full payload for variable sized output */
 	if (out_size == CXL_VARIABLE_PAYLOAD)
-		mbox->size_out = cxl_mbox->payload_size;
+		mbox_cmd->size_out = cxl_mbox->payload_size;
 	else
-		mbox->size_out = out_size;
+		mbox_cmd->size_out = out_size;
 
-	if (mbox->size_out) {
-		mbox->payload_out = kvzalloc(mbox->size_out, GFP_KERNEL);
-		if (!mbox->payload_out) {
-			kvfree(mbox->payload_in);
+	if (mbox_cmd->size_out) {
+		mbox_cmd->payload_out = kvzalloc(mbox_cmd->size_out, GFP_KERNEL);
+		if (!mbox_cmd->payload_out) {
+			kvfree(mbox_cmd->payload_in);
 			return -ENOMEM;
 		}
 	}
@@ -397,10 +397,8 @@ static void cxl_mbox_cmd_dtor(struct cxl_mbox_cmd *mbox)
 
 static int cxl_to_mem_cmd_raw(struct cxl_mem_command *mem_cmd,
 			      const struct cxl_send_command *send_cmd,
-			      struct cxl_memdev_state *mds)
+			      struct cxl_mailbox *cxl_mbox)
 {
-	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
-
 	if (send_cmd->raw.rsvd)
 		return -EINVAL;
 
@@ -415,7 +413,7 @@ static int cxl_to_mem_cmd_raw(struct cxl_mem_command *mem_cmd,
 	if (!cxl_mem_raw_command_allowed(send_cmd->raw.opcode))
 		return -EPERM;
 
-	dev_WARN_ONCE(mds->cxlds.dev, true, "raw command path used\n");
+	dev_WARN_ONCE(cxl_mbox->host, true, "raw command path used\n");
 
 	*mem_cmd = (struct cxl_mem_command) {
 		.info = {
@@ -431,7 +429,7 @@ static int cxl_to_mem_cmd_raw(struct cxl_mem_command *mem_cmd,
 
 static int cxl_to_mem_cmd(struct cxl_mem_command *mem_cmd,
 			  const struct cxl_send_command *send_cmd,
-			  struct cxl_memdev_state *mds)
+			  struct cxl_mailbox *cxl_mbox)
 {
 	struct cxl_mem_command *c = &cxl_mem_commands[send_cmd->id];
 	const struct cxl_command_info *info = &c->info;
@@ -446,11 +444,11 @@ static int cxl_to_mem_cmd(struct cxl_mem_command *mem_cmd,
 		return -EINVAL;
 
 	/* Check that the command is enabled for hardware */
-	if (!test_bit(info->id, mds->enabled_cmds))
+	if (!test_bit(info->id, cxl_mbox->enabled_cmds))
 		return -ENOTTY;
 
 	/* Check that the command is not claimed for exclusive kernel use */
-	if (test_bit(info->id, mds->exclusive_cmds))
+	if (test_bit(info->id, cxl_mbox->exclusive_cmds))
 		return -EBUSY;
 
 	/* Check the input buffer is the expected size */
@@ -479,7 +477,7 @@ static int cxl_to_mem_cmd(struct cxl_mem_command *mem_cmd,
 /**
  * cxl_validate_cmd_from_user() - Check fields for CXL_MEM_SEND_COMMAND.
  * @mbox_cmd: Sanitized and populated &struct cxl_mbox_cmd.
- * @mds: The driver data for the operation
+ * @cxl_mbox: CXL mailbox context
  * @send_cmd: &struct cxl_send_command copied in from userspace.
  *
  * Return:
@@ -494,10 +492,9 @@ static int cxl_to_mem_cmd(struct cxl_mem_command *mem_cmd,
  * safe to send to the hardware.
  */
 static int cxl_validate_cmd_from_user(struct cxl_mbox_cmd *mbox_cmd,
-				      struct cxl_memdev_state *mds,
+				      struct cxl_mailbox *cxl_mbox,
 				      const struct cxl_send_command *send_cmd)
 {
-	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
 	struct cxl_mem_command mem_cmd;
 	int rc;
 
@@ -514,24 +511,23 @@ static int cxl_validate_cmd_from_user(struct cxl_mbox_cmd *mbox_cmd,
 
 	/* Sanitize and construct a cxl_mem_command */
 	if (send_cmd->id == CXL_MEM_COMMAND_ID_RAW)
-		rc = cxl_to_mem_cmd_raw(&mem_cmd, send_cmd, mds);
+		rc = cxl_to_mem_cmd_raw(&mem_cmd, send_cmd, cxl_mbox);
 	else
-		rc = cxl_to_mem_cmd(&mem_cmd, send_cmd, mds);
+		rc = cxl_to_mem_cmd(&mem_cmd, send_cmd, cxl_mbox);
 
 	if (rc)
 		return rc;
 
 	/* Sanitize and construct a cxl_mbox_cmd */
-	return cxl_mbox_cmd_ctor(mbox_cmd, mds, mem_cmd.opcode,
+	return cxl_mbox_cmd_ctor(mbox_cmd, cxl_mbox, mem_cmd.opcode,
 				 mem_cmd.info.size_in, mem_cmd.info.size_out,
 				 send_cmd->in.payload);
 }
 
-int cxl_query_cmd(struct cxl_memdev *cxlmd,
+int cxl_query_cmd(struct cxl_mailbox *cxl_mbox,
 		  struct cxl_mem_query_commands __user *q)
 {
-	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
-	struct device *dev = &cxlmd->dev;
+	struct device *dev = cxl_mbox->host;
 	struct cxl_mem_command *cmd;
 	u32 n_commands;
 	int j = 0;
@@ -552,9 +548,9 @@ int cxl_query_cmd(struct cxl_memdev *cxlmd,
 	cxl_for_each_cmd(cmd) {
 		struct cxl_command_info info = cmd->info;
 
-		if (test_bit(info.id, mds->enabled_cmds))
+		if (test_bit(info.id, cxl_mbox->enabled_cmds))
 			info.flags |= CXL_MEM_COMMAND_FLAG_ENABLED;
-		if (test_bit(info.id, mds->exclusive_cmds))
+		if (test_bit(info.id, cxl_mbox->exclusive_cmds))
 			info.flags |= CXL_MEM_COMMAND_FLAG_EXCLUSIVE;
 
 		if (copy_to_user(&q->commands[j++], &info, sizeof(info)))
@@ -569,7 +565,7 @@ int cxl_query_cmd(struct cxl_memdev *cxlmd,
 
 /**
  * handle_mailbox_cmd_from_user() - Dispatch a mailbox command for userspace.
- * @mds: The driver data for the operation
+ * @cxl_mbox: The mailbox context for the operation.
  * @mbox_cmd: The validated mailbox command.
  * @out_payload: Pointer to userspace's output payload.
  * @size_out: (Input) Max payload size to copy out.
@@ -590,13 +586,12 @@ int cxl_query_cmd(struct cxl_memdev *cxlmd,
  *
  * See cxl_send_cmd().
  */
-static int handle_mailbox_cmd_from_user(struct cxl_memdev_state *mds,
+static int handle_mailbox_cmd_from_user(struct cxl_mailbox *cxl_mbox,
 					struct cxl_mbox_cmd *mbox_cmd,
 					u64 out_payload, s32 *size_out,
 					u32 *retval)
 {
-	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
-	struct device *dev = mds->cxlds.dev;
+	struct device *dev = cxl_mbox->host;
 	int rc;
 
 	dev_dbg(dev,
@@ -633,10 +628,9 @@ static int handle_mailbox_cmd_from_user(struct cxl_memdev_state *mds,
 	return rc;
 }
 
-int cxl_send_cmd(struct cxl_memdev *cxlmd, struct cxl_send_command __user *s)
+int cxl_send_cmd(struct cxl_mailbox *cxl_mbox, struct cxl_send_command __user *s)
 {
-	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
-	struct device *dev = &cxlmd->dev;
+	struct device *dev = cxl_mbox->host;
 	struct cxl_send_command send;
 	struct cxl_mbox_cmd mbox_cmd;
 	int rc;
@@ -646,11 +640,11 @@ int cxl_send_cmd(struct cxl_memdev *cxlmd, struct cxl_send_command __user *s)
 	if (copy_from_user(&send, s, sizeof(send)))
 		return -EFAULT;
 
-	rc = cxl_validate_cmd_from_user(&mbox_cmd, mds, &send);
+	rc = cxl_validate_cmd_from_user(&mbox_cmd, cxl_mbox, &send);
 	if (rc)
 		return rc;
 
-	rc = handle_mailbox_cmd_from_user(mds, &mbox_cmd, send.out.payload,
+	rc = handle_mailbox_cmd_from_user(cxl_mbox, &mbox_cmd, send.out.payload,
 					  &send.out.size, &send.retval);
 	if (rc)
 		return rc;
@@ -724,6 +718,7 @@ static int cxl_xfer_log(struct cxl_memdev_state *mds, uuid_t *uuid,
  */
 static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
 {
+	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
 	struct cxl_cel_entry *cel_entry;
 	const int cel_entries = size / sizeof(*cel_entry);
 	struct device *dev = mds->cxlds.dev;
@@ -737,7 +732,7 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
 		int enabled = 0;
 
 		if (cmd) {
-			set_bit(cmd->info.id, mds->enabled_cmds);
+			set_bit(cmd->info.id, cxl_mbox->enabled_cmds);
 			enabled++;
 		}
 
@@ -807,6 +802,7 @@ static const uuid_t log_uuid[] = {
  */
 int cxl_enumerate_cmds(struct cxl_memdev_state *mds)
 {
+	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
 	struct cxl_mbox_get_supported_logs *gsl;
 	struct device *dev = mds->cxlds.dev;
 	struct cxl_mem_command *cmd;
@@ -845,7 +841,7 @@ int cxl_enumerate_cmds(struct cxl_memdev_state *mds)
 		/* In case CEL was bogus, enable some default commands. */
 		cxl_for_each_cmd(cmd)
 			if (cmd->flags & CXL_CMD_FLAG_FORCE_ENABLE)
-				set_bit(cmd->info.id, mds->enabled_cmds);
+				set_bit(cmd->info.id, cxl_mbox->enabled_cmds);
 
 		/* Found the required CEL */
 		rc = 0;
@@ -1448,6 +1444,7 @@ struct cxl_memdev_state *cxl_memdev_state_create(struct device *dev)
 	mutex_init(&mds->event.log_lock);
 	mds->cxlds.dev = dev;
 	mds->cxlds.reg_map.host = dev;
+	mds->cxlds.cxl_mbox.host = dev;
 	mds->cxlds.reg_map.resource = CXL_RESOURCE_NONE;
 	mds->cxlds.type = CXL_DEVTYPE_CLASSMEM;
 	mds->ram_perf.qos_class = CXL_QOS_CLASS_INVALID;
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index ae3dfcbe8938..2e2e035abdaa 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -564,9 +564,11 @@ EXPORT_SYMBOL_NS_GPL(is_cxl_memdev, "CXL");
 void set_exclusive_cxl_commands(struct cxl_memdev_state *mds,
 				unsigned long *cmds)
 {
+	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
+
 	down_write(&cxl_memdev_rwsem);
-	bitmap_or(mds->exclusive_cmds, mds->exclusive_cmds, cmds,
-		  CXL_MEM_COMMAND_ID_MAX);
+	bitmap_or(cxl_mbox->exclusive_cmds, cxl_mbox->exclusive_cmds,
+		  cmds, CXL_MEM_COMMAND_ID_MAX);
 	up_write(&cxl_memdev_rwsem);
 }
 EXPORT_SYMBOL_NS_GPL(set_exclusive_cxl_commands, "CXL");
@@ -579,9 +581,11 @@ EXPORT_SYMBOL_NS_GPL(set_exclusive_cxl_commands, "CXL");
 void clear_exclusive_cxl_commands(struct cxl_memdev_state *mds,
 				  unsigned long *cmds)
 {
+	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
+
 	down_write(&cxl_memdev_rwsem);
-	bitmap_andnot(mds->exclusive_cmds, mds->exclusive_cmds, cmds,
-		      CXL_MEM_COMMAND_ID_MAX);
+	bitmap_andnot(cxl_mbox->exclusive_cmds, cxl_mbox->exclusive_cmds,
+		      cmds, CXL_MEM_COMMAND_ID_MAX);
 	up_write(&cxl_memdev_rwsem);
 }
 EXPORT_SYMBOL_NS_GPL(clear_exclusive_cxl_commands, "CXL");
@@ -656,11 +660,14 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 static long __cxl_memdev_ioctl(struct cxl_memdev *cxlmd, unsigned int cmd,
 			       unsigned long arg)
 {
+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
+
 	switch (cmd) {
 	case CXL_MEM_QUERY_COMMANDS:
-		return cxl_query_cmd(cxlmd, (void __user *)arg);
+		return cxl_query_cmd(cxl_mbox, (void __user *)arg);
 	case CXL_MEM_SEND_COMMAND:
-		return cxl_send_cmd(cxlmd, (void __user *)arg);
+		return cxl_send_cmd(cxl_mbox, (void __user *)arg);
 	default:
 		return -ENOTTY;
 	}
@@ -994,10 +1001,11 @@ static void cxl_remove_fw_upload(void *fwl)
 int devm_cxl_setup_fw_upload(struct device *host, struct cxl_memdev_state *mds)
 {
 	struct cxl_dev_state *cxlds = &mds->cxlds;
+	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
 	struct device *dev = &cxlds->cxlmd->dev;
 	struct fw_upload *fwl;
 
-	if (!test_bit(CXL_MEM_COMMAND_ID_GET_FW_INFO, mds->enabled_cmds))
+	if (!test_bit(CXL_MEM_COMMAND_ID_GET_FW_INFO, cxl_mbox->enabled_cmds))
 		return 0;
 
 	fwl = firmware_upload_register(THIS_MODULE, dev, dev_name(dev),
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 2a25d1957ddb..a0a49809cd76 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -106,42 +106,6 @@ static inline struct cxl_ep *cxl_ep_load(struct cxl_port *port,
 	return xa_load(&port->endpoints, (unsigned long)&cxlmd->dev);
 }
 
-/**
- * struct cxl_mbox_cmd - A command to be submitted to hardware.
- * @opcode: (input) The command set and command submitted to hardware.
- * @payload_in: (input) Pointer to the input payload.
- * @payload_out: (output) Pointer to the output payload. Must be allocated by
- *		 the caller.
- * @size_in: (input) Number of bytes to load from @payload_in.
- * @size_out: (input) Max number of bytes loaded into @payload_out.
- *            (output) Number of bytes generated by the device. For fixed size
- *            outputs commands this is always expected to be deterministic. For
- *            variable sized output commands, it tells the exact number of bytes
- *            written.
- * @min_out: (input) internal command output payload size validation
- * @poll_count: (input) Number of timeouts to attempt.
- * @poll_interval_ms: (input) Time between mailbox background command polling
- *                    interval timeouts.
- * @return_code: (output) Error code returned from hardware.
- *
- * This is the primary mechanism used to send commands to the hardware.
- * All the fields except @payload_* correspond exactly to the fields described in
- * Command Register section of the CXL 2.0 8.2.8.4.5. @payload_in and
- * @payload_out are written to, and read from the Command Payload Registers
- * defined in CXL 2.0 8.2.8.4.8.
- */
-struct cxl_mbox_cmd {
-	u16 opcode;
-	void *payload_in;
-	void *payload_out;
-	size_t size_in;
-	size_t size_out;
-	size_t min_out;
-	int poll_count;
-	int poll_interval_ms;
-	u16 return_code;
-};
-
 /*
  * Per CXL 3.0 Section 8.2.8.4.5.1
  */
@@ -461,8 +425,6 @@ static inline struct cxl_dev_state *mbox_to_cxlds(struct cxl_mailbox *cxl_mbox)
  * @lsa_size: Size of Label Storage Area
  *                (CXL 2.0 8.2.9.5.1.1 Identify Memory Device)
  * @firmware_version: Firmware version for the memory device.
- * @enabled_cmds: Hardware commands found enabled in CEL.
- * @exclusive_cmds: Commands that are kernel-internal only
  * @total_bytes: sum of all possible capacities
  * @volatile_only_bytes: hard volatile capacity
  * @persistent_only_bytes: hard persistent capacity
@@ -485,8 +447,6 @@ struct cxl_memdev_state {
 	struct cxl_dev_state cxlds;
 	size_t lsa_size;
 	char firmware_version[0x10];
-	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
-	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
 	u64 total_bytes;
 	u64 volatile_only_bytes;
 	u64 persistent_only_bytes;
diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h
index bacd111e75f1..cc894f07a435 100644
--- a/include/cxl/mailbox.h
+++ b/include/cxl/mailbox.h
@@ -3,12 +3,49 @@
 #ifndef __CXL_MBOX_H__
 #define __CXL_MBOX_H__
 #include <linux/rcuwait.h>
+#include <uapi/linux/cxl_mem.h>
 
-struct cxl_mbox_cmd;
+/**
+ * struct cxl_mbox_cmd - A command to be submitted to hardware.
+ * @opcode: (input) The command set and command submitted to hardware.
+ * @payload_in: (input) Pointer to the input payload.
+ * @payload_out: (output) Pointer to the output payload. Must be allocated by
+ *		 the caller.
+ * @size_in: (input) Number of bytes to load from @payload_in.
+ * @size_out: (input) Max number of bytes loaded into @payload_out.
+ *            (output) Number of bytes generated by the device. For fixed size
+ *            outputs commands this is always expected to be deterministic. For
+ *            variable sized output commands, it tells the exact number of bytes
+ *            written.
+ * @min_out: (input) internal command output payload size validation
+ * @poll_count: (input) Number of timeouts to attempt.
+ * @poll_interval_ms: (input) Time between mailbox background command polling
+ *                    interval timeouts.
+ * @return_code: (output) Error code returned from hardware.
+ *
+ * This is the primary mechanism used to send commands to the hardware.
+ * All the fields except @payload_* correspond exactly to the fields described in
+ * Command Register section of the CXL 2.0 8.2.8.4.5. @payload_in and
+ * @payload_out are written to, and read from the Command Payload Registers
+ * defined in CXL 2.0 8.2.8.4.8.
+ */
+struct cxl_mbox_cmd {
+	u16 opcode;
+	void *payload_in;
+	void *payload_out;
+	size_t size_in;
+	size_t size_out;
+	size_t min_out;
+	int poll_count;
+	int poll_interval_ms;
+	u16 return_code;
+};
 
 /**
  * struct cxl_mailbox - context for CXL mailbox operations
  * @host: device that hosts the mailbox
+ * @enabled_cmds: mailbox commands that are enabled by the driver
+ * @exclusive_cmds: mailbox commands that are exclusive to the kernel
  * @payload_size: Size of space for payload
  *                (CXL 3.1 8.2.8.4.3 Mailbox Capabilities Register)
  * @mbox_mutex: mutex protects device mailbox and firmware
@@ -17,6 +54,8 @@ struct cxl_mbox_cmd;
  */
 struct cxl_mailbox {
 	struct device *host;
+	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
+	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
 	size_t payload_size;
 	struct mutex mbox_mutex; /* lock to protect mailbox context */
 	struct rcuwait mbox_wait;
-- 
2.48.1

[PATCH v2 02/16] cxl: Enumerate feature commands

[Dave Jiang]

Add feature commands enumeration code in order to detect and enumerate
the 3 feature related commands "get supported features", "get feature",
and "set feature". The enumeration will help determine whether the driver
can issue any of the 3 commands to the device.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Setup allocation of cxlfs and move enumeration of commands to
  the setup function.
- Introduce features_capability enum. (Dan)
- Name the setup function devm_cxl_add_features(). (Dan)
- Drop 'cxl_mem_command' support. (Dan)
- Move feature support to mem probe. (Dan)
- Remove comma at last entry of data structs. (Jonathan)
---
 drivers/cxl/Makefile     |  2 +-
 drivers/cxl/core/mbox.c  | 30 ++++++++++++++++++++++
 drivers/cxl/cxl.h        |  2 ++
 drivers/cxl/cxlmem.h     |  5 ++++
 drivers/cxl/features.c   | 55 ++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/features.h   |  8 ++++++
 drivers/cxl/mem.c        |  5 ++++
 include/cxl/features.h   | 35 +++++++++++++++++++++++++
 include/cxl/mailbox.h    |  2 ++
 tools/testing/cxl/Kbuild |  2 +-
 10 files changed, 144 insertions(+), 2 deletions(-)
 create mode 100644 drivers/cxl/features.c
 create mode 100644 drivers/cxl/features.h
 create mode 100644 include/cxl/features.h

diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index 2caa90fa4bf2..12fbc35081bb 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -17,5 +17,5 @@ obj-$(CONFIG_CXL_PCI) += cxl_pci.o
 cxl_port-y := port.o
 cxl_acpi-y := acpi.o
 cxl_pmem-y := pmem.o security.o
-cxl_mem-y := mem.o
+cxl_mem-y := mem.o features.o
 cxl_pci-y := pci.o
diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index bdb8f060f2c1..25fb7bd770b3 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -69,6 +69,29 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
 	CXL_CMD(GET_TIMESTAMP, 0, 0x8, 0),
 };
 
+static u16 cxl_feature_commands[] = {
+	CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
+	CXL_MBOX_OP_GET_FEATURE,
+	CXL_MBOX_OP_SET_FEATURE
+};
+
+/**
+ * cxl_get_feature_command_id() - Get the index id for a feature command
+ * @opcode: The device opcode for the feature command
+ *
+ * Return the index id on success or -errno on failure
+ */
+int cxl_get_feature_command_id(u16 opcode)
+{
+	for (int i = 0; i < ARRAY_SIZE(cxl_feature_commands); i++) {
+		if (cxl_feature_commands[i] == opcode)
+			return i;
+	}
+
+	return -ENOENT;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_feature_command_id, "CXL");
+
 /*
  * Commands that RAW doesn't permit. The rationale for each:
  *
@@ -734,6 +757,13 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
 		if (cmd) {
 			set_bit(cmd->info.id, cxl_mbox->enabled_cmds);
 			enabled++;
+		} else {
+			int fid = cxl_get_feature_command_id(opcode);
+
+			if (fid >= 0) {
+				set_bit(fid, cxl_mbox->feature_cmds);
+				enabled++;
+			}
 		}
 
 		if (cxl_is_poison_command(opcode)) {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f6015f24ad38..2d6f7c87e5e8 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -911,6 +911,8 @@ void cxl_coordinates_combine(struct access_coordinate *out,
 
 bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
 
+int cxl_get_feature_command_id(u16 opcode);
+
 /*
  * Unit test builds overrides this to __weak, find the 'strong' version
  * of these symbols in tools/testing/cxl/.
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index a0a49809cd76..4a42cdb64b5c 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -39,6 +39,7 @@
  * @dev: driver core device object
  * @cdev: char dev core object for ioctl operations
  * @cxlds: The device state backing this device
+ * @cxlfs: The features state for the device
  * @detach_work: active memdev lost a port in its ancestry
  * @cxl_nvb: coordinate removal of @cxl_nvd if present
  * @cxl_nvd: optional bridge to an nvdimm if the device supports pmem
@@ -50,6 +51,7 @@ struct cxl_memdev {
 	struct device dev;
 	struct cdev cdev;
 	struct cxl_dev_state *cxlds;
+	struct cxl_features_state *cxlfs;
 	struct work_struct detach_work;
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	struct cxl_nvdimm *cxl_nvd;
@@ -490,6 +492,9 @@ enum cxl_opcode {
 	CXL_MBOX_OP_GET_LOG_CAPS	= 0x0402,
 	CXL_MBOX_OP_CLEAR_LOG           = 0x0403,
 	CXL_MBOX_OP_GET_SUP_LOG_SUBLIST = 0x0405,
+	CXL_MBOX_OP_GET_SUPPORTED_FEATURES	= 0x0500,
+	CXL_MBOX_OP_GET_FEATURE		= 0x0501,
+	CXL_MBOX_OP_SET_FEATURE		= 0x0502,
 	CXL_MBOX_OP_IDENTIFY		= 0x4000,
 	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,
 	CXL_MBOX_OP_SET_PARTITION_INFO	= 0x4101,
diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
new file mode 100644
index 000000000000..13b0b29ee102
--- /dev/null
+++ b/drivers/cxl/features.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+#include <linux/device.h>
+#include <cxl/mailbox.h>
+#include <cxl/features.h>
+#include "cxl.h"
+#include "cxlmem.h"
+#include "features.h"
+
+static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
+{
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
+	struct cxl_features_state *cxlfs = cxlds->cxlmd->cxlfs;
+	int fid;
+
+	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
+	if (!test_bit(fid, cxl_mbox->feature_cmds))
+		return;
+
+	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_FEATURE);
+	if (!test_bit(fid, cxl_mbox->feature_cmds))
+		return;
+
+	cxlfs->cap = CXL_FEATURES_RO;
+
+	fid = cxl_get_feature_command_id(CXL_MBOX_OP_SET_FEATURE);
+	if (!test_bit(fid, cxl_mbox->feature_cmds))
+		return;
+
+	cxlfs->cap = CXL_FEATURES_RW;
+}
+
+/**
+ * devm_cxl_add_features() - Allocate and initialize features context
+ * @cxlmd: CXL memory device
+ *
+ * Return 0 on success or -errno on failure.
+ */
+int devm_cxl_add_features(struct cxl_memdev *cxlmd)
+{
+	struct cxl_features_state *cxlfs;
+	struct device *dev = &cxlmd->dev;
+
+	cxlfs = devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
+	if (!cxlfs)
+		return -ENOMEM;
+
+	cxlmd->cxlfs = cxlfs;
+	cxlfs->cxlmd = cxlmd;
+	enumerate_feature_cmds(cxlmd);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");
diff --git a/drivers/cxl/features.h b/drivers/cxl/features.h
new file mode 100644
index 000000000000..0cc6d9e6c441
--- /dev/null
+++ b/drivers/cxl/features.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2025 Intel Corporation. */
+#ifndef __CXL_FEATURES_LOCAL__
+#define __CXL_FEATURES_LOCAL__
+
+int devm_cxl_add_features(struct cxl_memdev *cxlmd);
+
+#endif
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 2f03a4d5606e..47348a52bc05 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -7,6 +7,7 @@
 
 #include "cxlmem.h"
 #include "cxlpci.h"
+#include "features.h"
 
 /**
  * DOC: cxl mem
@@ -180,6 +181,10 @@ static int cxl_mem_probe(struct device *dev)
 			return rc;
 	}
 
+	rc = devm_cxl_add_features(cxlmd);
+	if (rc)
+		dev_dbg(dev, "No CXL Features enumerated.\n");
+
 	/*
 	 * The kernel may be operating out of CXL memory on this device,
 	 * there is no spec defined way to determine whether this device
diff --git a/include/cxl/features.h b/include/cxl/features.h
new file mode 100644
index 000000000000..eadf0d56553f
--- /dev/null
+++ b/include/cxl/features.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2024-2025 Intel Corporation. */
+#ifndef __CXL_FEATURES_H__
+#define __CXL_FEATURES_H__
+
+struct cxl_mailbox;
+
+/* Index IDs for CXL mailbox Feature commands */
+enum feature_cmds {
+	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
+	CXL_FEATURE_ID_GET_FEATURE,
+	CXL_FEATURE_ID_SET_FEATURE,
+	CXL_FEATURE_ID_MAX
+};
+
+/* Feature commands capability supported by a device */
+enum cxl_features_capability {
+	CXL_FEATURES_NONE = 0,
+	CXL_FEATURES_RO,
+	CXL_FEATURES_RW
+};
+
+/**
+ * struct cxl_features_state - The Features state for the device
+ * @cxlmd: Pointer to cxl mem device
+ * @cap: Feature commands capability
+ * @num_features: total Features supported by the device
+ */
+struct cxl_features_state {
+	struct cxl_memdev *cxlmd;
+	enum cxl_features_capability cap;
+	int num_features;
+};
+
+#endif
diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h
index cc894f07a435..99d3bbe1ba2a 100644
--- a/include/cxl/mailbox.h
+++ b/include/cxl/mailbox.h
@@ -3,6 +3,7 @@
 #ifndef __CXL_MBOX_H__
 #define __CXL_MBOX_H__
 #include <linux/rcuwait.h>
+#include <cxl/features.h>
 #include <uapi/linux/cxl_mem.h>
 
 /**
@@ -56,6 +57,7 @@ struct cxl_mailbox {
 	struct device *host;
 	DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
 	DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
+	DECLARE_BITMAP(feature_cmds, CXL_FEATURE_ID_MAX);
 	size_t payload_size;
 	struct mutex mbox_mutex; /* lock to protect mailbox context */
 	struct rcuwait mbox_wait;
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index b1256fee3567..47be82a2dd5b 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -46,7 +46,7 @@ cxl_port-y += cxl_port_test.o
 
 obj-m += cxl_mem.o
 
-cxl_mem-y := $(CXL_SRC)/mem.o
+cxl_mem-y := $(CXL_SRC)/mem.o $(CXL_SRC)/features.o
 cxl_mem-y += config_check.o
 cxl_mem-y += cxl_mem_test.o
 
-- 
2.48.1

[PATCH v2 03/16] cxl: Add Get Supported Features command for kernel usage

[Dave Jiang]

CXL spec r3.2 8.2.9.6.1 Get Supported Features (Opcode 0500h)
The command retrieve the list of supported device-specific features
(identified by UUID) and general information about each Feature.

The driver will retrieve the feature entries in order to make checks and
provide information for the Get Feature and Set Feature command. One of
the main piece of information retrieved are the effects a Set Feature
command would have for a particular feature.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Move to memdev driver and drop features driver support. (Dan)
- Use features_capability to check what's supported. (Dan)
- Drop cxl_get_supported_feature_entry() as no usage (Dan, Jonathan)
- Drop Shiju sign off tags per requested. (Shiju)
- Rename EXTEND bit(9) to VALID. (Jonathan)
---
 drivers/cxl/features.c | 159 +++++++++++++++++++++++++++++++++++++++--
 include/cxl/features.h |  57 +++++++++++++++
 2 files changed, 210 insertions(+), 6 deletions(-)

diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
index 13b0b29ee102..be6c19b01b90 100644
--- a/drivers/cxl/features.c
+++ b/drivers/cxl/features.c
@@ -7,11 +7,144 @@
 #include "cxlmem.h"
 #include "features.h"
 
-static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
+static void cxl_free_feature_entries(void *entries)
+{
+	kvfree(entries);
+}
+
+static int cxl_get_supported_features_count(struct cxl_mailbox *cxl_mbox)
+{
+	struct cxl_mbox_get_sup_feats_out mbox_out;
+	struct cxl_mbox_get_sup_feats_in mbox_in;
+	struct cxl_mbox_cmd mbox_cmd;
+	int rc;
+
+	memset(&mbox_in, 0, sizeof(mbox_in));
+	mbox_in.count = cpu_to_le32(sizeof(mbox_out));
+	memset(&mbox_out, 0, sizeof(mbox_out));
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
+		.size_in = sizeof(mbox_in),
+		.payload_in = &mbox_in,
+		.size_out = sizeof(mbox_out),
+		.payload_out = &mbox_out,
+		.min_out = sizeof(mbox_out),
+	};
+	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
+	if (rc < 0)
+		return rc;
+
+	return le16_to_cpu(mbox_out.supported_feats);
+}
+
+static int get_supported_features(struct cxl_memdev *cxlmd,
+				  struct cxl_features_state *cxlfs)
+{
+	int remain_feats, max_size, max_feats, start, rc, hdr_size;
+	struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
+	int feat_size = sizeof(struct cxl_feat_entry);
+	struct cxl_mbox_get_sup_feats_in mbox_in;
+	struct cxl_feat_entry *entry;
+	struct cxl_mbox_cmd mbox_cmd;
+	int count;
+
+	if (cxlfs->cap < CXL_FEATURES_RO)
+		return -EOPNOTSUPP;
+
+	count = cxl_get_supported_features_count(cxl_mbox);
+	if (count == 0)
+		return 0;
+	if (count < 0)
+		return -ENXIO;
+
+	struct cxl_feat_entry *entries __free(kvfree) =
+		kvmalloc(count * sizeof(*entries), GFP_KERNEL);
+	if (!entries)
+		return -ENOMEM;
+
+	struct cxl_mbox_get_sup_feats_out *mbox_out __free(kvfree) =
+		kvmalloc(cxl_mbox->payload_size, GFP_KERNEL);
+	if (!mbox_out)
+		return -ENOMEM;
+
+	hdr_size = sizeof(*mbox_out);
+	max_size = cxl_mbox->payload_size - hdr_size;
+	/* max feat entries that can fit in mailbox max payload size */
+	max_feats = max_size / feat_size;
+	entry = entries;
+
+	start = 0;
+	remain_feats = count;
+	do {
+		int retrieved, alloc_size, copy_feats;
+		int num_entries;
+
+		if (remain_feats > max_feats) {
+			alloc_size = sizeof(*mbox_out) + max_feats * feat_size;
+			remain_feats = remain_feats - max_feats;
+			copy_feats = max_feats;
+		} else {
+			alloc_size = sizeof(*mbox_out) + remain_feats * feat_size;
+			copy_feats = remain_feats;
+			remain_feats = 0;
+		}
+
+		memset(&mbox_in, 0, sizeof(mbox_in));
+		mbox_in.count = cpu_to_le32(alloc_size);
+		mbox_in.start_idx = cpu_to_le16(start);
+		memset(mbox_out, 0, alloc_size);
+		mbox_cmd = (struct cxl_mbox_cmd) {
+			.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
+			.size_in = sizeof(mbox_in),
+			.payload_in = &mbox_in,
+			.size_out = alloc_size,
+			.payload_out = mbox_out,
+			.min_out = hdr_size,
+		};
+		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
+		if (rc < 0)
+			return rc;
+
+		if (mbox_cmd.size_out <= hdr_size)
+			return -ENXIO;
+
+		/*
+		 * Make sure retrieved out buffer is multiple of feature
+		 * entries.
+		 */
+		retrieved = mbox_cmd.size_out - hdr_size;
+		if (retrieved % feat_size)
+			return -ENXIO;
+
+		num_entries = le16_to_cpu(mbox_out->num_entries);
+		/*
+		 * If the reported output entries * defined entry size !=
+		 * retrieved output bytes, then the output package is incorrect.
+		 */
+		if (num_entries * feat_size != retrieved)
+			return -ENXIO;
+
+		memcpy(entry, mbox_out->ents, retrieved);
+		entry++;
+		/*
+		 * If the number of output entries is less than expected, add the
+		 * remaining entries to the next batch.
+		 */
+		remain_feats += copy_feats - num_entries;
+		start += num_entries;
+	} while (remain_feats);
+
+	cxlfs->num_features = count;
+	cxlfs->entries = no_free_ptr(entries);
+	return devm_add_action_or_reset(&cxlmd->dev, cxl_free_feature_entries,
+					cxlfs->entries);
+}
+
+static void enumerate_feature_cmds(struct cxl_memdev *cxlmd,
+				   struct cxl_features_state *cxlfs)
 {
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
-	struct cxl_features_state *cxlfs = cxlds->cxlmd->cxlfs;
 	int fid;
 
 	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
@@ -31,6 +164,15 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
 	cxlfs->cap = CXL_FEATURES_RW;
 }
 
+static void cxl_cxlfs_free(struct cxl_features_state *cxlfs)
+{
+	struct device *dev = &cxlfs->cxlmd->dev;
+
+	devm_kfree(dev, cxlfs);
+}
+
+DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
+
 /**
  * devm_cxl_add_features() - Allocate and initialize features context
  * @cxlmd: CXL memory device
@@ -39,16 +181,21 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
  */
 int devm_cxl_add_features(struct cxl_memdev *cxlmd)
 {
-	struct cxl_features_state *cxlfs;
 	struct device *dev = &cxlmd->dev;
+	int rc;
 
-	cxlfs = devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
+	struct cxl_features_state *cxlfs __free(free_cxlfs) =
+		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
 	if (!cxlfs)
 		return -ENOMEM;
 
-	cxlmd->cxlfs = cxlfs;
 	cxlfs->cxlmd = cxlmd;
-	enumerate_feature_cmds(cxlmd);
+	enumerate_feature_cmds(cxlmd, cxlfs);
+	rc = get_supported_features(cxlmd, cxlfs);
+	if (rc)
+		return rc;
+
+	cxlmd->cxlfs = no_free_ptr(cxlfs);
 
 	return 0;
 }
diff --git a/include/cxl/features.h b/include/cxl/features.h
index eadf0d56553f..56dc3b78c725 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -3,6 +3,8 @@
 #ifndef __CXL_FEATURES_H__
 #define __CXL_FEATURES_H__
 
+#include <linux/uuid.h>
+
 struct cxl_mailbox;
 
 /* Index IDs for CXL mailbox Feature commands */
@@ -25,11 +27,66 @@ enum cxl_features_capability {
  * @cxlmd: Pointer to cxl mem device
  * @cap: Feature commands capability
  * @num_features: total Features supported by the device
+ * @entries: Feature detail entries fetched from the device
  */
 struct cxl_features_state {
 	struct cxl_memdev *cxlmd;
 	enum cxl_features_capability cap;
 	int num_features;
+	struct cxl_feat_entry *entries;
 };
 
+/* Get Supported Features (0x500h) CXL r3.2 8.2.9.6.1 */
+struct cxl_mbox_get_sup_feats_in {
+	__le32 count;
+	__le16 start_idx;
+	u8 reserved[2];
+} __packed;
+
+/* CXL spec r3.2 Table 8-87 command effects */
+#define CXL_CMD_CONFIG_CHANGE_COLD_RESET	BIT(0)
+#define CXL_CMD_CONFIG_CHANGE_IMMEDIATE		BIT(1)
+#define CXL_CMD_DATA_CHANGE_IMMEDIATE		BIT(2)
+#define CXL_CMD_POLICY_CHANGE_IMMEDIATE		BIT(3)
+#define CXL_CMD_LOG_CHANGE_IMMEDIATE		BIT(4)
+#define CXL_CMD_SECURITY_STATE_CHANGE		BIT(5)
+#define CXL_CMD_BACKGROUND			BIT(6)
+#define CXL_CMD_BGCMD_ABORT_SUPPORTED		BIT(7)
+#define CXL_CMD_EFFECTS_VALID			BIT(9)
+#define CXL_CMD_CONFIG_CHANGE_CONV_RESET	BIT(10)
+#define CXL_CMD_CONFIG_CHANGE_CXL_RESET		BIT(11)
+
+/*
+ * CXL spec r3.2 Table 8-109
+ * Get Supported Features Supported Feature Entry
+ */
+struct cxl_feat_entry {
+	uuid_t uuid;
+	__le16 id;
+	__le16 get_feat_size;
+	__le16 set_feat_size;
+	__le32 flags;
+	u8 get_feat_ver;
+	u8 set_feat_ver;
+	__le16 effects;
+	u8 reserved[18];
+} __packed;
+
+/* @flags field for 'struct cxl_feat_entry' */
+#define CXL_FEATURE_F_CHANGEABLE		BIT(0)
+#define CXL_FEATURE_F_PERSIST_FW_UPDATE		BIT(4)
+#define CXL_FEATURE_F_DEFAULT_SEL		BIT(5)
+#define CXL_FEATURE_F_SAVED_SEL			BIT(6)
+
+/*
+ * CXL spec r3.2 Table 8-108
+ * Get supported Features Output Payload
+ */
+struct cxl_mbox_get_sup_feats_out {
+	__le16 num_entries;
+	__le16 supported_feats;
+	u8 reserved[4];
+	struct cxl_feat_entry ents[] __counted_by_le(num_entries);
+} __packed;
+
 #endif
-- 
2.48.1

[PATCH v2 04/16] cxl/test: Add Get Supported Features mailbox command support

[Dave Jiang]

Add cxl-test emulation of Get Supported Features mailbox command.
Currently only adding a test feature with feature identifier of
all f's for testing.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v1:
- Fix setting of num_entries endieness issue. (Jonathan)
---
 tools/testing/cxl/test/mem.c | 68 ++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 347c1e7b37bd..9394c48cf38e 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -44,6 +44,10 @@ static struct cxl_cel_entry mock_cel[] = {
 		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_SUPPORTED_LOGS),
 		.effect = CXL_CMD_EFFECT_NONE,
 	},
+	{
+		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_SUPPORTED_FEATURES),
+		.effect = CXL_CMD_EFFECT_NONE,
+	},
 	{
 		.opcode = cpu_to_le16(CXL_MBOX_OP_IDENTIFY),
 		.effect = CXL_CMD_EFFECT_NONE,
@@ -1337,6 +1341,67 @@ static int mock_activate_fw(struct cxl_mockmem_data *mdata,
 	return -EINVAL;
 }
 
+#define CXL_VENDOR_FEATURE_TEST							\
+	UUID_INIT(0xffffffff, 0xffff, 0xffff, 0xff, 0xff, 0xff, 0xff, 0xff,	\
+		  0xff, 0xff, 0xff)
+
+static void fill_feature_vendor_test(struct cxl_feat_entry *feat)
+{
+	feat->uuid = CXL_VENDOR_FEATURE_TEST;
+	feat->id = 0;
+	feat->get_feat_size = cpu_to_le16(0x4);
+	feat->set_feat_size = cpu_to_le16(0x4);
+	feat->flags = cpu_to_le32(CXL_FEATURE_F_CHANGEABLE |
+				  CXL_FEATURE_F_DEFAULT_SEL |
+				  CXL_FEATURE_F_SAVED_SEL);
+	feat->get_feat_ver = 1;
+	feat->set_feat_ver = 1;
+	feat->effects = cpu_to_le16(CXL_CMD_CONFIG_CHANGE_COLD_RESET |
+				    CXL_CMD_EFFECTS_VALID);
+}
+
+static int mock_get_supported_features(struct cxl_mockmem_data *mdata,
+				       struct cxl_mbox_cmd *cmd)
+{
+	struct cxl_mbox_get_sup_feats_in *in = cmd->payload_in;
+	struct cxl_mbox_get_sup_feats_out *out = cmd->payload_out;
+	struct cxl_feat_entry *feat;
+	u16 start_idx, count;
+
+	if (cmd->size_out < sizeof(*out)) {
+		cmd->return_code = CXL_MBOX_CMD_RC_PAYLOADLEN;
+		return -EINVAL;
+	}
+
+	/*
+	 * Current emulation only supports 1 feature
+	 */
+	start_idx = le16_to_cpu(in->start_idx);
+	if (start_idx != 0) {
+		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
+		return -EINVAL;
+	}
+
+	count = le16_to_cpu(in->count);
+	if (count < sizeof(*out)) {
+		cmd->return_code = CXL_MBOX_CMD_RC_PAYLOADLEN;
+		return -EINVAL;
+	}
+
+	out->supported_feats = cpu_to_le16(1);
+	cmd->return_code = 0;
+	if (count < sizeof(*out) + sizeof(*feat)) {
+		out->num_entries = 0;
+		return 0;
+	}
+
+	out->num_entries = cpu_to_le16(1);
+	feat = out->ents;
+	fill_feature_vendor_test(feat);
+
+	return 0;
+}
+
 static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
 			      struct cxl_mbox_cmd *cmd)
 {
@@ -1422,6 +1487,9 @@ static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
 	case CXL_MBOX_OP_ACTIVATE_FW:
 		rc = mock_activate_fw(mdata, cmd);
 		break;
+	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
+		rc = mock_get_supported_features(mdata, cmd);
+		break;
 	default:
 		break;
 	}
-- 
2.48.1

[PATCH v2 05/16] cxl/mbox: Add GET_FEATURE mailbox command

[Dave Jiang]

From: Shiju Jose <shiju.jose@huawei.com>

Add support for GET_FEATURE mailbox command.

CXL spec r3.2 section 8.2.9.6 describes optional device specific features.
The settings of a feature can be retrieved using Get Feature command.
CXL spec r3.2 section 8.2.9.6.2 describes Get Feature command.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Set input as 'struct cxl_mailbox' for cxl_get_feature() (Dan)
- Set feat_uuid as 'uuid_t *' (Dan)
- Use uuid_copy() to assign uuid
---
 drivers/cxl/core/Makefile   |  1 +
 drivers/cxl/core/features.c | 59 +++++++++++++++++++++++++++++++++++++
 include/cxl/features.h      | 29 ++++++++++++++++++
 tools/testing/cxl/Kbuild    |  1 +
 4 files changed, 90 insertions(+)
 create mode 100644 drivers/cxl/core/features.c

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 9259bcc6773c..73b6348afd67 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -14,5 +14,6 @@ cxl_core-y += pci.o
 cxl_core-y += hdm.o
 cxl_core-y += pmu.o
 cxl_core-y += cdat.o
+cxl_core-y += features.o
 cxl_core-$(CONFIG_TRACING) += trace.o
 cxl_core-$(CONFIG_CXL_REGION) += region.o
diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
new file mode 100644
index 000000000000..b01dc5ebb24d
--- /dev/null
+++ b/drivers/cxl/core/features.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+#include <linux/device.h>
+#include <cxl/mailbox.h>
+#include <cxl/features.h>
+#include "cxl.h"
+#include "core.h"
+#include "cxlmem.h"
+#include "features.h"
+
+size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
+		       enum cxl_get_feat_selection selection,
+		       void *feat_out, size_t feat_out_size, u16 offset,
+		       u16 *return_code)
+{
+	size_t data_to_rd_size, size_out;
+	struct cxl_mbox_get_feat_in pi;
+	struct cxl_mbox_cmd mbox_cmd;
+	size_t data_rcvd_size = 0;
+	int rc;
+
+	if (return_code)
+		*return_code = CXL_MBOX_CMD_RC_INPUT;
+
+	if (!feat_out || !feat_out_size)
+		return 0;
+
+	size_out = min(feat_out_size, cxl_mbox->payload_size);
+	uuid_copy(&pi.uuid, feat_uuid);
+	pi.selection = selection;
+	do {
+		data_to_rd_size = min(feat_out_size - data_rcvd_size,
+				      cxl_mbox->payload_size);
+		pi.offset = cpu_to_le16(offset + data_rcvd_size);
+		pi.count = cpu_to_le16(data_to_rd_size);
+
+		mbox_cmd = (struct cxl_mbox_cmd) {
+			.opcode = CXL_MBOX_OP_GET_FEATURE,
+			.size_in = sizeof(pi),
+			.payload_in = &pi,
+			.size_out = size_out,
+			.payload_out = feat_out + data_rcvd_size,
+			.min_out = data_to_rd_size,
+		};
+		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
+		if (rc < 0 || !mbox_cmd.size_out) {
+			if (return_code)
+				*return_code = mbox_cmd.return_code;
+			return 0;
+		}
+		data_rcvd_size += mbox_cmd.size_out;
+	} while (data_rcvd_size < feat_out_size);
+
+	if (return_code)
+		*return_code = CXL_MBOX_CMD_RC_SUCCESS;
+
+	return data_rcvd_size;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_feature, "CXL");
diff --git a/include/cxl/features.h b/include/cxl/features.h
index 56dc3b78c725..b80164fa18ef 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -89,4 +89,33 @@ struct cxl_mbox_get_sup_feats_out {
 	struct cxl_feat_entry ents[] __counted_by_le(num_entries);
 } __packed;
 
+/*
+ * Get Feature CXL spec r3.2 Spec 8.2.9.6.2
+ */
+
+/*
+ * Get Feature input payload
+ * CXL spec r3.2 section 8.2.9.6.2 Table 8-99
+ */
+struct cxl_mbox_get_feat_in {
+	uuid_t uuid;
+	__le16 offset;
+	__le16 count;
+	u8 selection;
+}  __packed;
+
+/* Selection field for 'struct cxl_mbox_get_feat_in' */
+enum cxl_get_feat_selection {
+	CXL_GET_FEAT_SEL_CURRENT_VALUE,
+	CXL_GET_FEAT_SEL_DEFAULT_VALUE,
+	CXL_GET_FEAT_SEL_SAVED_VALUE,
+	CXL_GET_FEAT_SEL_MAX
+};
+
+struct cxl_mailbox;
+size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
+		       enum cxl_get_feat_selection selection,
+		       void *feat_out, size_t feat_out_size, u16 offset,
+		       u16 *return_code);
+
 #endif
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 47be82a2dd5b..6b0a992af4a7 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -61,6 +61,7 @@ cxl_core-y += $(CXL_CORE_SRC)/pci.o
 cxl_core-y += $(CXL_CORE_SRC)/hdm.o
 cxl_core-y += $(CXL_CORE_SRC)/pmu.o
 cxl_core-y += $(CXL_CORE_SRC)/cdat.o
+cxl_core-y += $(CXL_CORE_SRC)/features.o
 cxl_core-$(CONFIG_TRACING) += $(CXL_CORE_SRC)/trace.o
 cxl_core-$(CONFIG_CXL_REGION) += $(CXL_CORE_SRC)/region.o
 cxl_core-y += config_check.o
-- 
2.48.1

[PATCH v2 06/16] cxl/mbox: Add SET_FEATURE mailbox command

[Dave Jiang]

From: Shiju Jose <shiju.jose@huawei.com>

Add support for SET_FEATURE mailbox command.

CXL spec r3.2 section 8.2.9.6 describes optional device specific features.
CXL devices supports features with changeable attributes.
The settings of a feature can be optionally modified using Set Feature
command.
CXL spec r3.2 section 8.2.9.6.3 describes Set Feature command.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Set input as 'struct cxl_mailbox' for cxl_get_feature() (Dan)
- Set feat_uuid as 'uuid_t *' (Dan)
- Use uuid_copy() to assign uuid
- Fix tab alignment. (Jonathan)
- Update kmalloc() to kzalloc(). (Dan)
---
 drivers/cxl/core/features.c | 81 +++++++++++++++++++++++++++++++++++++
 include/cxl/features.h      | 33 +++++++++++++++
 2 files changed, 114 insertions(+)

diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index b01dc5ebb24d..7dd3b64b6976 100644
--- a/drivers/cxl/core/features.c
+++ b/drivers/cxl/core/features.c
@@ -57,3 +57,84 @@ size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 	return data_rcvd_size;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_get_feature, "CXL");
+
+/*
+ * FEAT_DATA_MIN_PAYLOAD_SIZE - min extra number of bytes should be
+ * available in the mailbox for storing the actual feature data so that
+ * the feature data transfer would work as expected.
+ */
+#define FEAT_DATA_MIN_PAYLOAD_SIZE 10
+int cxl_set_feature(struct cxl_mailbox *cxl_mbox,
+		    const uuid_t *feat_uuid, u8 feat_version,
+		    void *feat_data, size_t feat_data_size,
+		    u32 feat_flag, u16 offset, u16 *return_code)
+{
+	struct cxl_memdev_set_feat_pi {
+		struct cxl_mbox_set_feat_hdr hdr;
+		u8 feat_data[];
+	}  __packed;
+	size_t data_in_size, data_sent_size = 0;
+	struct cxl_mbox_cmd mbox_cmd;
+	size_t hdr_size;
+	int rc = 0;
+
+	if (return_code)
+		*return_code = CXL_MBOX_CMD_RC_INPUT;
+
+	struct cxl_memdev_set_feat_pi *pi __free(kfree) =
+			kzalloc(cxl_mbox->payload_size, GFP_KERNEL);
+	uuid_copy(&pi->hdr.uuid, feat_uuid);
+	pi->hdr.version = feat_version;
+	feat_flag &= ~CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK;
+	feat_flag |= CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET;
+	hdr_size = sizeof(pi->hdr);
+	/*
+	 * Check minimum mbox payload size is available for
+	 * the feature data transfer.
+	 */
+	if (hdr_size + FEAT_DATA_MIN_PAYLOAD_SIZE > cxl_mbox->payload_size)
+		return -ENOMEM;
+
+	if ((hdr_size + feat_data_size) <= cxl_mbox->payload_size) {
+		pi->hdr.flags = cpu_to_le32(feat_flag |
+				       CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER);
+		data_in_size = feat_data_size;
+	} else {
+		pi->hdr.flags = cpu_to_le32(feat_flag |
+				       CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER);
+		data_in_size = cxl_mbox->payload_size - hdr_size;
+	}
+
+	do {
+		pi->hdr.offset = cpu_to_le16(offset + data_sent_size);
+		memcpy(pi->feat_data, feat_data + data_sent_size, data_in_size);
+		mbox_cmd = (struct cxl_mbox_cmd) {
+			.opcode = CXL_MBOX_OP_SET_FEATURE,
+			.size_in = hdr_size + data_in_size,
+			.payload_in = pi,
+		};
+		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
+		if (rc < 0) {
+			if (return_code)
+				*return_code = mbox_cmd.return_code;
+			return rc;
+		}
+
+		data_sent_size += data_in_size;
+		if (data_sent_size >= feat_data_size) {
+			if (return_code)
+				*return_code = CXL_MBOX_CMD_RC_SUCCESS;
+			return 0;
+		}
+
+		if ((feat_data_size - data_sent_size) <= (cxl_mbox->payload_size - hdr_size)) {
+			data_in_size = feat_data_size - data_sent_size;
+			pi->hdr.flags = cpu_to_le32(feat_flag |
+					       CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER);
+		} else {
+			pi->hdr.flags = cpu_to_le32(feat_flag |
+					       CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER);
+		}
+	} while (true);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_set_feature, "CXL");
diff --git a/include/cxl/features.h b/include/cxl/features.h
index b80164fa18ef..d10ef2b54f45 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -112,10 +112,43 @@ enum cxl_get_feat_selection {
 	CXL_GET_FEAT_SEL_MAX
 };
 
+/*
+ * Set Feature CXL spec r3.2  8.2.9.6.3
+ */
+
+/*
+ * Set Feature input payload
+ * CXL spec r3.2 section 8.2.9.6.3 Table 8-101
+ */
+struct cxl_mbox_set_feat_hdr {
+	uuid_t uuid;
+	__le32 flags;
+	__le16 offset;
+	u8 version;
+	u8 rsvd[9];
+}  __packed;
+
+/* Set Feature flags field */
+enum cxl_set_feat_flag_data_transfer {
+	CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER = 0,
+	CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_ABORT_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_DATA_TRANSFER_MAX
+};
+
+#define CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK	GENMASK(2, 0)
+
+#define CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET	BIT(3)
+
 struct cxl_mailbox;
 size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 		       enum cxl_get_feat_selection selection,
 		       void *feat_out, size_t feat_out_size, u16 offset,
 		       u16 *return_code);
+int cxl_set_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
+		    u8 feat_version, void *feat_data, size_t feat_data_size,
+		    u32 feat_flag, u16 offset, u16 *return_code);
 
 #endif
-- 
2.48.1

[PATCH v2 07/16] cxl: Setup exclusive CXL features that are reserved for the kernel

[Dave Jiang]

Certain features will be exclusively used by components such as in
kernel RAS driver. Setup an exclusion list that can be later filtered
out before exposing to user space.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/features.c | 29 +++++++++++++++++++++++++++++
 drivers/cxl/features.c      |  4 ++++
 drivers/cxl/features.h      |  3 +++
 include/cxl/features.h      | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)

diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index 7dd3b64b6976..132f93050d1c 100644
--- a/drivers/cxl/core/features.c
+++ b/drivers/cxl/core/features.c
@@ -8,6 +8,35 @@
 #include "cxlmem.h"
 #include "features.h"
 
+/* All the features below are exclusive to the kernel */
+static const uuid_t cxl_exclusive_feats[] = {
+	CXL_FEAT_PATROL_SCRUB_UUID,
+	CXL_FEAT_ECS_UUID,
+	CXL_FEAT_SPPR_UUID,
+	CXL_FEAT_HPPR_UUID,
+	CXL_FEAT_CACHELINE_SPARING_UUID,
+	CXL_FEAT_ROW_SPARING_UUID,
+	CXL_FEAT_BANK_SPARING_UUID,
+	CXL_FEAT_RANK_SPARING_UUID,
+};
+
+/**
+ * is_cxl_feature_exclusive() - Check if a CXL feature is exclusive to kernel
+ * @entry: cxl feature entry
+ *
+ * Return true if feature is exclusive to kernel, otherwise false
+ */
+bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry)
+{
+	for (int i = 0; i < ARRAY_SIZE(cxl_exclusive_feats); i++) {
+		if (uuid_equal(&entry->uuid, &cxl_exclusive_feats[i]))
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_NS_GPL(is_cxl_feature_exclusive, "CXL");
+
 size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 		       enum cxl_get_feat_selection selection,
 		       void *feat_out, size_t feat_out_size, u16 offset,
diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
index be6c19b01b90..82598a409acc 100644
--- a/drivers/cxl/features.c
+++ b/drivers/cxl/features.c
@@ -46,6 +46,7 @@ static int get_supported_features(struct cxl_memdev *cxlmd,
 	struct cxl_mbox_get_sup_feats_in mbox_in;
 	struct cxl_feat_entry *entry;
 	struct cxl_mbox_cmd mbox_cmd;
+	int user_feats = 0;
 	int count;
 
 	if (cxlfs->cap < CXL_FEATURES_RO)
@@ -125,6 +126,8 @@ static int get_supported_features(struct cxl_memdev *cxlmd,
 			return -ENXIO;
 
 		memcpy(entry, mbox_out->ents, retrieved);
+		if (!is_cxl_feature_exclusive(entry))
+			user_feats++;
 		entry++;
 		/*
 		 * If the number of output entries is less than expected, add the
@@ -135,6 +138,7 @@ static int get_supported_features(struct cxl_memdev *cxlmd,
 	} while (remain_feats);
 
 	cxlfs->num_features = count;
+	cxlfs->num_user_features = user_feats;
 	cxlfs->entries = no_free_ptr(entries);
 	return devm_add_action_or_reset(&cxlmd->dev, cxl_free_feature_entries,
 					cxlfs->entries);
diff --git a/drivers/cxl/features.h b/drivers/cxl/features.h
index 0cc6d9e6c441..8706f944b476 100644
--- a/drivers/cxl/features.h
+++ b/drivers/cxl/features.h
@@ -3,6 +3,9 @@
 #ifndef __CXL_FEATURES_LOCAL__
 #define __CXL_FEATURES_LOCAL__
 
+struct cxl_feat_entry;
+
 int devm_cxl_add_features(struct cxl_memdev *cxlmd);
+bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);
 
 #endif
diff --git a/include/cxl/features.h b/include/cxl/features.h
index d10ef2b54f45..7ae84696d6dd 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -5,6 +5,39 @@
 
 #include <linux/uuid.h>
 
+/* Feature UUIDs used by the kernel */
+#define CXL_FEAT_PATROL_SCRUB_UUID						\
+	UUID_INIT(0x96dad7d6, 0xfde8, 0x482b, 0xa7, 0x33, 0x75, 0x77, 0x4e,	\
+		  0x06, 0xdb, 0x8a)
+
+#define CXL_FEAT_ECS_UUID							\
+	UUID_INIT(0xe5b13f22, 0x2328, 0x4a14, 0xb8, 0xba, 0xb9, 0x69, 0x1e,	\
+		  0x89, 0x33, 0x86)
+
+#define CXL_FEAT_SPPR_UUID							\
+	UUID_INIT(0x892ba475, 0xfad8, 0x474e, 0x9d, 0x3e, 0x69, 0x2c, 0x91,	\
+		  0x75, 0x68, 0xbb)
+
+#define CXL_FEAT_HPPR_UUID							\
+	UUID_INIT(0x80ea4521, 0x786f, 0x4127, 0xaf, 0xb1, 0xec, 0x74, 0x59,	\
+		  0xfb, 0x0e, 0x24)
+
+#define CXL_FEAT_CACHELINE_SPARING_UUID						\
+	UUID_INIT(0x96C33386, 0x91dd, 0x44c7, 0x9e, 0xcb, 0xfd, 0xaf, 0x65,	\
+		  0x03, 0xba, 0xc4)
+
+#define CXL_FEAT_ROW_SPARING_UUID						\
+	UUID_INIT(0x450ebf67, 0xb135, 0x4f97, 0xa4, 0x98, 0xc2, 0xd5, 0x7f,	\
+		  0x27, 0x9b, 0xed)
+
+#define CXL_FEAT_BANK_SPARING_UUID						\
+	UUID_INIT(0x78b79636, 0x90ac, 0x4b64, 0xa4, 0xef, 0xfa, 0xac, 0x5d,	\
+		  0x18, 0xa8, 0x63)
+
+#define CXL_FEAT_RANK_SPARING_UUID						\
+	UUID_INIT(0x34dbaff5, 0x0552, 0x4281, 0x8f, 0x76, 0xda, 0x0b, 0x5e,	\
+		  0x7a, 0x76, 0xa7)
+
 struct cxl_mailbox;
 
 /* Index IDs for CXL mailbox Feature commands */
@@ -27,12 +60,14 @@ enum cxl_features_capability {
  * @cxlmd: Pointer to cxl mem device
  * @cap: Feature commands capability
  * @num_features: total Features supported by the device
+ * @num_user_features: total Features not kernel exclusive
  * @entries: Feature detail entries fetched from the device
  */
 struct cxl_features_state {
 	struct cxl_memdev *cxlmd;
 	enum cxl_features_capability cap;
 	int num_features;
+	int num_user_features;
 	struct cxl_feat_entry *entries;
 };
 
-- 
2.48.1

[PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Dave Jiang]

Add fwctl support code to allow sending of CXL feature commands from
userspace through as ioctls via FWCTL. Provide initial setup bits.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Associate FWCTL with the 'cxl_memdev' through the memdev driver. (Dan)
- I'm leaving Jonathan's tag off to get this looked at again.
- Hide FWCTL code behind CONFIG_CXL_FWCTL (Dan)
---
 drivers/cxl/Kconfig        | 15 +++++++
 drivers/cxl/Makefile       |  1 +
 drivers/cxl/features.c     | 35 ++++++++++++---
 drivers/cxl/features.h     |  2 +
 drivers/cxl/fwctl.c        | 88 ++++++++++++++++++++++++++++++++++++++
 include/cxl/features.h     |  3 ++
 include/uapi/fwctl/fwctl.h |  1 +
 tools/testing/cxl/Kbuild   |  1 +
 8 files changed, 140 insertions(+), 6 deletions(-)
 create mode 100644 drivers/cxl/fwctl.c

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index 876469e23f7a..34731890bc8e 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -102,6 +102,21 @@ config CXL_MEM
 
 	  If unsure say 'm'.
 
+config CXL_FWCTL
+	bool "CXL: Firmware Control support"
+	depends on CXL_MEM
+	select FWCTL
+	help
+	  Enable support for firmware control of CXL devices. This allows
+	  a FWCTL char device to be created in order to issue ioctls from
+	  user space to exercise the CXL Features commands supported by
+	  a CXL mailbox. There are some Features defined in the CXL spec
+	  such as memory sparing. However a lof of those features are
+	  exclusive to the kernel. Most likely the Features maniulated
+	  by CXL_FWCTL will be vendor defined Features.
+
+	  If unsure say 'n'.
+
 config CXL_PORT
 	default CXL_BUS
 	tristate
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index 12fbc35081bb..cd28fb3bf855 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -18,4 +18,5 @@ cxl_port-y := port.o
 cxl_acpi-y := acpi.o
 cxl_pmem-y := pmem.o security.o
 cxl_mem-y := mem.o features.o
+cxl_mem-$(CONFIG_CXL_FWCTL) += fwctl.o
 cxl_pci-y := pci.o
diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
index 82598a409acc..2dcfefdfa6b3 100644
--- a/drivers/cxl/features.c
+++ b/drivers/cxl/features.c
@@ -1,8 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+#include <linux/pci.h>
 #include <linux/device.h>
+#include <linux/module.h>
 #include <cxl/mailbox.h>
 #include <cxl/features.h>
+
 #include "cxl.h"
 #include "cxlmem.h"
 #include "features.h"
@@ -168,11 +171,31 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd,
 	cxlfs->cap = CXL_FEATURES_RW;
 }
 
+/* The __weak symbol gets replaced by FWCTL allocation function in fwctl.c */
+struct cxl_features_state * __weak devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
+{
+	struct device *dev = &cxlmd->dev;
+	struct cxl_features_state *cxlfs =
+		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
+
+	if (!cxlfs)
+		return ERR_PTR(-ENOMEM);
+
+	cxlfs->cxlmd = cxlmd;
+
+	return cxlfs;
+}
+
+/* The __weak symbol gets replaced by FWCTL free function in fwctl.c */
+void __weak devm_cxlfs_free(struct cxl_memdev *cxlmd)
+{
+	devm_kfree(&cxlmd->dev, cxlmd->cxlfs);
+	cxlmd->cxlfs = NULL;
+}
+
 static void cxl_cxlfs_free(struct cxl_features_state *cxlfs)
 {
-	struct device *dev = &cxlfs->cxlmd->dev;
-
-	devm_kfree(dev, cxlfs);
+	devm_cxlfs_free(cxlfs->cxlmd);
 }
 
 DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
@@ -185,15 +208,13 @@ DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
  */
 int devm_cxl_add_features(struct cxl_memdev *cxlmd)
 {
-	struct device *dev = &cxlmd->dev;
 	int rc;
 
 	struct cxl_features_state *cxlfs __free(free_cxlfs) =
-		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
+		devm_cxlfs_allocate(cxlmd);
 	if (!cxlfs)
 		return -ENOMEM;
 
-	cxlfs->cxlmd = cxlmd;
 	enumerate_feature_cmds(cxlmd, cxlfs);
 	rc = get_supported_features(cxlmd, cxlfs);
 	if (rc)
@@ -204,3 +225,5 @@ int devm_cxl_add_features(struct cxl_memdev *cxlmd)
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");
+
+MODULE_IMPORT_NS("CXL");
diff --git a/drivers/cxl/features.h b/drivers/cxl/features.h
index 8706f944b476..e487c24ff06f 100644
--- a/drivers/cxl/features.h
+++ b/drivers/cxl/features.h
@@ -5,6 +5,8 @@
 
 struct cxl_feat_entry;
 
+struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd);
+void devm_cxlfs_free(struct cxl_memdev *cxlmd);
 int devm_cxl_add_features(struct cxl_memdev *cxlmd);
 bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);
 
diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
new file mode 100644
index 000000000000..d8fd68ac8982
--- /dev/null
+++ b/drivers/cxl/fwctl.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2025 Intel Corporation. All rights reserved. */
+#include <linux/fwctl.h>
+#include <linux/device.h>
+#include <cxl/features.h>
+#include "cxlmem.h"
+#include "features.h"
+
+static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
+{
+	return 0;
+}
+
+static void cxlctl_close_uctx(struct fwctl_uctx *uctx)
+{
+}
+
+static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
+{
+	/* Place holder */
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
+			   void *rpc_in, size_t in_len, size_t *out_len)
+{
+	/* Place holder */
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static const struct fwctl_ops cxlctl_ops = {
+	.device_type = FWCTL_DEVICE_TYPE_CXL,
+	.uctx_size = sizeof(struct fwctl_uctx),
+	.open_uctx = cxlctl_open_uctx,
+	.close_uctx = cxlctl_close_uctx,
+	.info = cxlctl_info,
+	.fw_rpc = cxlctl_fw_rpc,
+};
+
+static void remove_cxlfs(void *_cxlfs)
+{
+	struct cxl_features_state *cxlfs = _cxlfs;
+	struct cxl_memdev *cxlmd = cxlfs->cxlmd;
+	struct fwctl_device *fwctl = &cxlfs->fwctl;
+
+	cxlmd->cxlfs = NULL;
+	fwctl_unregister(fwctl);
+	fwctl_put(fwctl);
+}
+
+DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) fwctl_put(&_T->fwctl))
+
+static struct cxl_features_state *
+__devm_cxl_cfs_allocate(struct cxl_memdev *cxlmd, const struct fwctl_ops *ops)
+{
+	struct device *dev = &cxlmd->dev;
+	int rc;
+
+	struct cxl_features_state *cxlfs __free(free_cxlfs) =
+		fwctl_alloc_device(dev, ops, struct cxl_features_state, fwctl);
+	if (!cxlfs)
+		return ERR_PTR(-ENOMEM);
+
+	cxlfs->cxlmd = cxlmd;
+	rc = fwctl_register(&cxlfs->fwctl);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = devm_add_action_or_reset(dev, remove_cxlfs, cxlfs);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return no_free_ptr(cxlfs);
+}
+
+struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
+{
+	return __devm_cxl_cfs_allocate(cxlmd, &cxlctl_ops);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxlfs_allocate, "CXL");
+
+void devm_cxlfs_free(struct cxl_memdev *cxlmd)
+{
+	devm_release_action(&cxlmd->dev, remove_cxlfs, cxlmd);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxlfs_free, "CXL");
+
+MODULE_IMPORT_NS("FWCTL");
diff --git a/include/cxl/features.h b/include/cxl/features.h
index 7ae84696d6dd..7c43ac021a8c 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -4,6 +4,7 @@
 #define __CXL_FEATURES_H__
 
 #include <linux/uuid.h>
+#include <linux/fwctl.h>
 
 /* Feature UUIDs used by the kernel */
 #define CXL_FEAT_PATROL_SCRUB_UUID						\
@@ -57,6 +58,7 @@ enum cxl_features_capability {
 
 /**
  * struct cxl_features_state - The Features state for the device
+ * @fwctl: FWCTL device
  * @cxlmd: Pointer to cxl mem device
  * @cap: Feature commands capability
  * @num_features: total Features supported by the device
@@ -64,6 +66,7 @@ enum cxl_features_capability {
  * @entries: Feature detail entries fetched from the device
  */
 struct cxl_features_state {
+	struct fwctl_device fwctl;
 	struct cxl_memdev *cxlmd;
 	enum cxl_features_capability cap;
 	int num_features;
diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h
index f9b27fb5c161..4e4d30104667 100644
--- a/include/uapi/fwctl/fwctl.h
+++ b/include/uapi/fwctl/fwctl.h
@@ -43,6 +43,7 @@ enum {
 enum fwctl_device_type {
 	FWCTL_DEVICE_TYPE_ERROR = 0,
 	FWCTL_DEVICE_TYPE_MLX5 = 1,
+	FWCTL_DEVICE_TYPE_CXL = 2,
 };
 
 /**
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 6b0a992af4a7..6396d1296cef 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -47,6 +47,7 @@ cxl_port-y += cxl_port_test.o
 obj-m += cxl_mem.o
 
 cxl_mem-y := $(CXL_SRC)/mem.o $(CXL_SRC)/features.o
+cxl_mem-$(CONFIG_CXL_FWCTL) += $(CXL_SRC)/fwctl.o
 cxl_mem-y += config_check.o
 cxl_mem-y += cxl_mem_test.o
 
-- 
2.48.1

[PATCH v2 09/16] cxl: Add support for FWCTL get driver information callback

[Dave Jiang]

Add definition for fwctl_ops->info() to return driver information. The
function will return a data structure with a reserved u32. This is setup
for future usages.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Set command_info to reserved. (Dan)
---
 drivers/cxl/fwctl.c      | 18 ++++++++++++++++--
 include/cxl/mailbox.h    |  1 +
 include/uapi/fwctl/cxl.h | 19 +++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 include/uapi/fwctl/cxl.h

diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
index d8fd68ac8982..b7984c98645c 100644
--- a/drivers/cxl/fwctl.c
+++ b/drivers/cxl/fwctl.c
@@ -6,6 +6,8 @@
 #include "cxlmem.h"
 #include "features.h"
 
+#define to_cxl_features_state(fwctl) container_of(fwctl, struct cxl_features_state, fwctl)
+
 static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
 {
 	return 0;
@@ -17,8 +19,20 @@ static void cxlctl_close_uctx(struct fwctl_uctx *uctx)
 
 static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
 {
-	/* Place holder */
-	return ERR_PTR(-EOPNOTSUPP);
+	struct fwctl_device *fwctl = uctx->fwctl;
+	struct cxl_features_state *cxlfs = to_cxl_features_state(fwctl);
+	struct fwctl_info_cxl *info;
+
+	if (!cxlfs->num_user_features)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	*length = sizeof(*info);
+
+	return info;
 }
 
 static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h
index 99d3bbe1ba2a..bbbbff3af61f 100644
--- a/include/cxl/mailbox.h
+++ b/include/cxl/mailbox.h
@@ -4,6 +4,7 @@
 #define __CXL_MBOX_H__
 #include <linux/rcuwait.h>
 #include <cxl/features.h>
+#include <uapi/fwctl/cxl.h>
 #include <uapi/linux/cxl_mem.h>
 
 /**
diff --git a/include/uapi/fwctl/cxl.h b/include/uapi/fwctl/cxl.h
new file mode 100644
index 000000000000..4e766ffb1388
--- /dev/null
+++ b/include/uapi/fwctl/cxl.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2024, Intel Corporation
+ *
+ * These are definitions for the mailbox command interface of CXL subsystem.
+ */
+#ifndef _UAPI_FWCTL_CXL_H_
+#define _UAPI_FWCTL_CXL_H_
+
+#include <linux/types.h>
+
+/**
+ * struct fwctl_info_cxl - ioctl(FWCTL_INFO) out_device_data
+ * @reserved: Place older for future usages
+ */
+struct fwctl_info_cxl {
+	__u32 reserved;
+};
+#endif
-- 
2.48.1

[PATCH v2 10/16] cxl: Move cxl feature command structs to user header

[Dave Jiang]

In preparation for cxl fwctl enabling, move data structures related to
cxl feature commands to a user header file.

Reviewed-by; Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 include/cxl/features.h      | 107 +------------------------------
 include/uapi/cxl/features.h | 122 ++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+), 106 deletions(-)
 create mode 100644 include/uapi/cxl/features.h

diff --git a/include/cxl/features.h b/include/cxl/features.h
index 7c43ac021a8c..eb13d7ee64f0 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -5,6 +5,7 @@
 
 #include <linux/uuid.h>
 #include <linux/fwctl.h>
+#include <uapi/cxl/features.h>
 
 /* Feature UUIDs used by the kernel */
 #define CXL_FEAT_PATROL_SCRUB_UUID						\
@@ -74,112 +75,6 @@ struct cxl_features_state {
 	struct cxl_feat_entry *entries;
 };
 
-/* Get Supported Features (0x500h) CXL r3.2 8.2.9.6.1 */
-struct cxl_mbox_get_sup_feats_in {
-	__le32 count;
-	__le16 start_idx;
-	u8 reserved[2];
-} __packed;
-
-/* CXL spec r3.2 Table 8-87 command effects */
-#define CXL_CMD_CONFIG_CHANGE_COLD_RESET	BIT(0)
-#define CXL_CMD_CONFIG_CHANGE_IMMEDIATE		BIT(1)
-#define CXL_CMD_DATA_CHANGE_IMMEDIATE		BIT(2)
-#define CXL_CMD_POLICY_CHANGE_IMMEDIATE		BIT(3)
-#define CXL_CMD_LOG_CHANGE_IMMEDIATE		BIT(4)
-#define CXL_CMD_SECURITY_STATE_CHANGE		BIT(5)
-#define CXL_CMD_BACKGROUND			BIT(6)
-#define CXL_CMD_BGCMD_ABORT_SUPPORTED		BIT(7)
-#define CXL_CMD_EFFECTS_VALID			BIT(9)
-#define CXL_CMD_CONFIG_CHANGE_CONV_RESET	BIT(10)
-#define CXL_CMD_CONFIG_CHANGE_CXL_RESET		BIT(11)
-
-/*
- * CXL spec r3.2 Table 8-109
- * Get Supported Features Supported Feature Entry
- */
-struct cxl_feat_entry {
-	uuid_t uuid;
-	__le16 id;
-	__le16 get_feat_size;
-	__le16 set_feat_size;
-	__le32 flags;
-	u8 get_feat_ver;
-	u8 set_feat_ver;
-	__le16 effects;
-	u8 reserved[18];
-} __packed;
-
-/* @flags field for 'struct cxl_feat_entry' */
-#define CXL_FEATURE_F_CHANGEABLE		BIT(0)
-#define CXL_FEATURE_F_PERSIST_FW_UPDATE		BIT(4)
-#define CXL_FEATURE_F_DEFAULT_SEL		BIT(5)
-#define CXL_FEATURE_F_SAVED_SEL			BIT(6)
-
-/*
- * CXL spec r3.2 Table 8-108
- * Get supported Features Output Payload
- */
-struct cxl_mbox_get_sup_feats_out {
-	__le16 num_entries;
-	__le16 supported_feats;
-	u8 reserved[4];
-	struct cxl_feat_entry ents[] __counted_by_le(num_entries);
-} __packed;
-
-/*
- * Get Feature CXL spec r3.2 Spec 8.2.9.6.2
- */
-
-/*
- * Get Feature input payload
- * CXL spec r3.2 section 8.2.9.6.2 Table 8-99
- */
-struct cxl_mbox_get_feat_in {
-	uuid_t uuid;
-	__le16 offset;
-	__le16 count;
-	u8 selection;
-}  __packed;
-
-/* Selection field for 'struct cxl_mbox_get_feat_in' */
-enum cxl_get_feat_selection {
-	CXL_GET_FEAT_SEL_CURRENT_VALUE,
-	CXL_GET_FEAT_SEL_DEFAULT_VALUE,
-	CXL_GET_FEAT_SEL_SAVED_VALUE,
-	CXL_GET_FEAT_SEL_MAX
-};
-
-/*
- * Set Feature CXL spec r3.2  8.2.9.6.3
- */
-
-/*
- * Set Feature input payload
- * CXL spec r3.2 section 8.2.9.6.3 Table 8-101
- */
-struct cxl_mbox_set_feat_hdr {
-	uuid_t uuid;
-	__le32 flags;
-	__le16 offset;
-	u8 version;
-	u8 rsvd[9];
-}  __packed;
-
-/* Set Feature flags field */
-enum cxl_set_feat_flag_data_transfer {
-	CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER = 0,
-	CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER,
-	CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER,
-	CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER,
-	CXL_SET_FEAT_FLAG_ABORT_DATA_TRANSFER,
-	CXL_SET_FEAT_FLAG_DATA_TRANSFER_MAX
-};
-
-#define CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK	GENMASK(2, 0)
-
-#define CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET	BIT(3)
-
 struct cxl_mailbox;
 size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 		       enum cxl_get_feat_selection selection,
diff --git a/include/uapi/cxl/features.h b/include/uapi/cxl/features.h
new file mode 100644
index 000000000000..2e98efb9abf1
--- /dev/null
+++ b/include/uapi/cxl/features.h
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2024,2025, Intel Corporation
+ *
+ * These are definitions for the mailbox command interface of CXL subsystem.
+ */
+#ifndef _UAPI_CXL_FEATURES_H_
+#define _UAPI_CXL_FEATURES_H_
+
+#include <linux/types.h>
+#ifndef __KERNEL__
+#include <uuid/uuid.h>
+#else
+#include <linux/uuid.h>
+#endif
+
+/* Get Supported Features (0x500h) CXL r3.2 8.2.9.6.1 */
+struct cxl_mbox_get_sup_feats_in {
+	__le32 count;
+	__le16 start_idx;
+	__u8 reserved[2];
+} __attribute__ ((__packed__));
+
+/* CXL spec r3.2 Table 8-87 command effects */
+#define CXL_CMD_CONFIG_CHANGE_COLD_RESET	BIT(0)
+#define CXL_CMD_CONFIG_CHANGE_IMMEDIATE		BIT(1)
+#define CXL_CMD_DATA_CHANGE_IMMEDIATE		BIT(2)
+#define CXL_CMD_POLICY_CHANGE_IMMEDIATE		BIT(3)
+#define CXL_CMD_LOG_CHANGE_IMMEDIATE		BIT(4)
+#define CXL_CMD_SECURITY_STATE_CHANGE		BIT(5)
+#define CXL_CMD_BACKGROUND			BIT(6)
+#define CXL_CMD_BGCMD_ABORT_SUPPORTED		BIT(7)
+#define CXL_CMD_EFFECTS_VALID			BIT(9)
+#define CXL_CMD_CONFIG_CHANGE_CONV_RESET	BIT(10)
+#define CXL_CMD_CONFIG_CHANGE_CXL_RESET		BIT(11)
+
+/*
+ * CXL spec r3.2 Table 8-109
+ * Get Supported Features Supported Feature Entry
+ */
+struct cxl_feat_entry {
+	uuid_t uuid;
+	__le16 id;
+	__le16 get_feat_size;
+	__le16 set_feat_size;
+	__le32 flags;
+	__u8 get_feat_ver;
+	__u8 set_feat_ver;
+	__le16 effects;
+	__u8 reserved[18];
+} __attribute__ ((__packed__));
+
+/* @flags field for 'struct cxl_feat_entry' */
+#define CXL_FEATURE_F_CHANGEABLE		BIT(0)
+#define CXL_FEATURE_F_PERSIST_FW_UPDATE		BIT(4)
+#define CXL_FEATURE_F_DEFAULT_SEL		BIT(5)
+#define CXL_FEATURE_F_SAVED_SEL			BIT(6)
+
+/*
+ * CXL spec r3.2 Table 8-108
+ * Get supported Features Output Payload
+ */
+struct cxl_mbox_get_sup_feats_out {
+	__le16 num_entries;
+	__le16 supported_feats;
+	__u8 reserved[4];
+	struct cxl_feat_entry ents[] __counted_by_le(num_entries);
+} __attribute__ ((__packed__));
+
+/*
+ * Get Feature CXL spec r3.2 Spec 8.2.9.6.2
+ */
+
+/*
+ * Get Feature input payload
+ * CXL spec r3.2 section 8.2.9.6.2 Table 8-99
+ */
+struct cxl_mbox_get_feat_in {
+	uuid_t uuid;
+	__le16 offset;
+	__le16 count;
+	__u8 selection;
+} __attribute__ ((__packed__));
+
+/* Selection field for 'struct cxl_mbox_get_feat_in' */
+enum cxl_get_feat_selection {
+	CXL_GET_FEAT_SEL_CURRENT_VALUE,
+	CXL_GET_FEAT_SEL_DEFAULT_VALUE,
+	CXL_GET_FEAT_SEL_SAVED_VALUE,
+	CXL_GET_FEAT_SEL_MAX
+};
+
+/*
+ * Set Feature CXL spec r3.2  8.2.9.6.3
+ */
+
+/*
+ * Set Feature input payload
+ * CXL spec r3.2 section 8.2.9.6.3 Table 8-101
+ */
+struct cxl_mbox_set_feat_hdr {
+	uuid_t uuid;
+	__le32 flags;
+	__le16 offset;
+	__u8 version;
+	__u8 rsvd[9];
+} __attribute__ ((__packed__));
+
+/* Set Feature flags field */
+enum cxl_set_feat_flag_data_transfer {
+	CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER = 0,
+	CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_ABORT_DATA_TRANSFER,
+	CXL_SET_FEAT_FLAG_DATA_TRANSFER_MAX
+};
+
+#define CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK		GENMASK(2, 0)
+#define CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET	BIT(3)
+
+#endif
-- 
2.48.1

[PATCH v2 11/16] cxl: Add support for fwctl RPC command to enable CXL feature commands

[Dave Jiang]

fwctl provides a fwctl_ops->fw_rpc() callback in order to issue ioctls
to a device. The cxl fwctl driver will start by supporting the CXL
feature commands: Get Supported Features, Get Feature, and Set Feature.

The fw_rpc() callback provides 'enum fwctl_rpc_scope' parameter where
it indicates the security scope of the call. The Get Supported Features
and Get Feature calls can be executed with the scope of
FWCTL_RPC_CONFIGRATION. The Set Feature call is gated by the effects
of the feature reported by Get Supported Features call for the specific
feature.

Only "get supported features" is supported in this patch. Additional
commands will be added in follow on patches. "Get supported features"
will filter the features that are exclusive to the kernel and only
report out features that are not kernel only.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Return -EINVAL for get_support_feature_info() instead of -ENOENT. (Dan)
- Set set_feat_size to 0 for kernel exclusive features.
- Just don't bother checking the valid (9) bit. (Dan)
- Reject if the reserved bits are set. (Dan)
---
 drivers/cxl/core/mbox.c     |   9 ++
 drivers/cxl/cxl.h           |   1 +
 drivers/cxl/fwctl.c         | 204 +++++++++++++++++++++++++++++++++++-
 include/cxl/features.h      |   9 +-
 include/uapi/cxl/features.h |   1 +
 include/uapi/fwctl/cxl.h    |  37 +++++++
 6 files changed, 250 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 25fb7bd770b3..71ab331830bf 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -92,6 +92,15 @@ int cxl_get_feature_command_id(u16 opcode)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_get_feature_command_id, "CXL");
 
+u16 cxl_get_feature_command_opcode(int feature_id)
+{
+	if (feature_id >= ARRAY_SIZE(cxl_feature_commands))
+		return 0xffff;
+
+	return cxl_feature_commands[feature_id];
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_feature_command_opcode, "CXL");
+
 /*
  * Commands that RAW doesn't permit. The rationale for each:
  *
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 2d6f7c87e5e8..451b2c7e995b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -912,6 +912,7 @@ void cxl_coordinates_combine(struct access_coordinate *out,
 bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
 
 int cxl_get_feature_command_id(u16 opcode);
+u16 cxl_get_feature_command_opcode(int feature_id);
 
 /*
  * Unit test builds overrides this to __weak, find the 'strong' version
diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
index b7984c98645c..93c6174ded20 100644
--- a/drivers/cxl/fwctl.c
+++ b/drivers/cxl/fwctl.c
@@ -35,11 +35,209 @@ static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
 	return info;
 }
 
+static struct cxl_feat_entry *
+get_support_feature_info(struct cxl_features_state *cxlfs,
+			 const struct fwctl_rpc_cxl *rpc_in)
+{
+	struct cxl_feat_entry *feat;
+	uuid_t uuid;
+
+	if (rpc_in->op_size < sizeof(uuid))
+		return ERR_PTR(-EINVAL);
+
+	if (copy_from_user(&uuid, u64_to_user_ptr(rpc_in->in_payload),
+			   sizeof(uuid)))
+		return ERR_PTR(-EFAULT);
+
+	for (int i = 0; i < cxlfs->num_features; i++) {
+		feat = &cxlfs->entries[i];
+		if (uuid_equal(&uuid, &feat->uuid))
+			return feat;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+static void *cxlctl_get_supported_features(struct cxl_features_state *cxlfs,
+					   const struct fwctl_rpc_cxl *rpc_in,
+					   size_t *out_len)
+{
+	struct cxl_mbox_get_sup_feats_out *feat_out;
+	struct cxl_mbox_get_sup_feats_in feat_in;
+	struct cxl_feat_entry *pos;
+	int requested, copied;
+	size_t out_size;
+	u32 count;
+	u16 start;
+
+	if (rpc_in->op_size != sizeof(feat_in))
+		return ERR_PTR(-EINVAL);
+
+	if (copy_from_user(&feat_in, u64_to_user_ptr(rpc_in->in_payload),
+			   rpc_in->op_size))
+		return ERR_PTR(-EFAULT);
+
+	count = le32_to_cpu(feat_in.count);
+	start = le16_to_cpu(feat_in.start_idx);
+	requested = count / sizeof(*pos);
+
+	/*
+	 * Make sure that the total requested number of entries is not greater
+	 * than the total number of supported features allowed for userspace.
+	 */
+	if (start >= cxlfs->num_user_features)
+		return ERR_PTR(-EINVAL);
+
+	requested = min_t(int, requested, cxlfs->num_user_features - start);
+
+	out_size = sizeof(struct fwctl_rpc_cxl_out) + sizeof(*feat_out) +
+		   requested * sizeof(*pos);
+
+	struct fwctl_rpc_cxl_out *rpc_out __free(kvfree) =
+		kvzalloc(out_size, GFP_KERNEL);
+	if (!rpc_out)
+		return ERR_PTR(-ENOMEM);
+
+	rpc_out->size = sizeof(*feat_out) + requested * sizeof(*pos);
+	feat_out = (struct cxl_mbox_get_sup_feats_out *)rpc_out->payload;
+	if (requested == 0) {
+		feat_out->num_entries = cpu_to_le16(requested);
+		feat_out->supported_feats =
+			cpu_to_le16(cxlfs->num_user_features);
+		rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
+		*out_len = out_size;
+		return no_free_ptr(rpc_out);
+	}
+
+	pos = &feat_out->ents[0];
+
+	copied = 0;
+	for (int i = 0; i < cxlfs->num_features; i++, pos++) {
+		memcpy(pos, &cxlfs->entries[i], sizeof(*pos));
+		/*
+		 * If the feature is exclusive, set the set_feat_size to 0 to
+		 * indicate that the feature is not changeable.
+		 */
+		if (is_cxl_feature_exclusive(pos))
+			pos->set_feat_size = 0;
+
+		copied++;
+		if (copied == requested)
+			break;
+	}
+
+	feat_out->num_entries = cpu_to_le16(requested);
+	feat_out->supported_feats = cpu_to_le16(cxlfs->num_features);
+	rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
+	*out_len = out_size;
+
+	return no_free_ptr(rpc_out);
+}
+
+static bool cxlctl_validate_set_features(struct cxl_features_state *cxlfs,
+					 const struct fwctl_rpc_cxl *rpc_in,
+					 enum fwctl_rpc_scope scope)
+{
+	struct cxl_feat_entry *feat;
+	u16 effects, mask;
+	u32 flags;
+
+	feat = get_support_feature_info(cxlfs, rpc_in);
+	if (IS_ERR(feat))
+		return false;
+
+	/* Ensure that the attribute is changeable */
+	flags = le32_to_cpu(feat->flags);
+	if (!(flags & CXL_FEATURE_F_CHANGEABLE))
+		return false;
+
+	effects = le16_to_cpu(feat->effects);
+
+	/*
+	 * Reserved bits are set, rejecting since the effects is not
+	 * comprehended by the driver.
+	 */
+	if (effects & CXL_CMD_EFFECTS_RESERVED) {
+		dev_warn_once(&cxlfs->cxlmd->dev,
+			      "Reserved bits set in the Feature effects field!\n");
+		return false;
+	}
+
+	/* Currently no user background command support */
+	if (effects & CXL_CMD_BACKGROUND)
+		return false;
+
+	/* Effects cause immediate change, highest security scope is needed */
+	mask = CXL_CMD_CONFIG_CHANGE_IMMEDIATE |
+	       CXL_CMD_DATA_CHANGE_IMMEDIATE |
+	       CXL_CMD_POLICY_CHANGE_IMMEDIATE |
+	       CXL_CMD_LOG_CHANGE_IMMEDIATE;
+	if (effects & mask && scope >= FWCTL_RPC_DEBUG_WRITE_FULL)
+		return true;
+
+	/* These effects supported for all WRITE scope */
+	if ((effects & CXL_CMD_CONFIG_CHANGE_COLD_RESET ||
+	     effects & CXL_CMD_CONFIG_CHANGE_CONV_RESET ||
+	     effects & CXL_CMD_CONFIG_CHANGE_CXL_RESET) &&
+	    scope >= FWCTL_RPC_DEBUG_WRITE)
+		return true;
+
+	return false;
+}
+
+static bool cxlctl_validate_hw_command(struct cxl_features_state *cxlfs,
+				       const struct fwctl_rpc_cxl *rpc_in,
+				       enum fwctl_rpc_scope scope,
+				       u16 opcode)
+{
+	if (!cxlfs->num_features)
+		return false;
+
+	switch (opcode) {
+	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
+	case CXL_MBOX_OP_GET_FEATURE:
+		if (cxlfs->cap < CXL_FEATURES_RO)
+			return false;
+		if (scope >= FWCTL_RPC_CONFIGURATION)
+			return true;
+		return false;
+	case CXL_MBOX_OP_SET_FEATURE:
+		return cxlctl_validate_set_features(cxlfs, rpc_in, scope);
+	default:
+		return false;
+	}
+}
+
+static void *cxlctl_handle_commands(struct cxl_features_state *cxlfs,
+				    const struct fwctl_rpc_cxl *rpc_in,
+				    size_t *out_len, u16 opcode)
+{
+	switch (opcode) {
+	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
+		return cxlctl_get_supported_features(cxlfs, rpc_in, out_len);
+	case CXL_MBOX_OP_GET_FEATURE:
+	case CXL_MBOX_OP_SET_FEATURE:
+	default:
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+}
+
 static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
-			   void *rpc_in, size_t in_len, size_t *out_len)
+			   void *in, size_t in_len, size_t *out_len)
 {
-	/* Place holder */
-	return ERR_PTR(-EOPNOTSUPP);
+	struct fwctl_device *fwctl = uctx->fwctl;
+	struct cxl_features_state *cxlfs = to_cxl_features_state(fwctl);
+	const struct fwctl_rpc_cxl *rpc_in = in;
+	u16 opcode;
+
+	opcode = cxl_get_feature_command_opcode(rpc_in->command_id);
+	if (opcode == 0xffff)
+		return ERR_PTR(-EINVAL);
+
+	if (!cxlctl_validate_hw_command(cxlfs, rpc_in, scope, opcode))
+		return ERR_PTR(-EINVAL);
+
+	return cxlctl_handle_commands(cxlfs, rpc_in, out_len, opcode);
 }
 
 static const struct fwctl_ops cxlctl_ops = {
diff --git a/include/cxl/features.h b/include/cxl/features.h
index eb13d7ee64f0..f43aa761a7ee 100644
--- a/include/cxl/features.h
+++ b/include/cxl/features.h
@@ -42,14 +42,6 @@
 
 struct cxl_mailbox;
 
-/* Index IDs for CXL mailbox Feature commands */
-enum feature_cmds {
-	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
-	CXL_FEATURE_ID_GET_FEATURE,
-	CXL_FEATURE_ID_SET_FEATURE,
-	CXL_FEATURE_ID_MAX
-};
-
 /* Feature commands capability supported by a device */
 enum cxl_features_capability {
 	CXL_FEATURES_NONE = 0,
@@ -83,5 +75,6 @@ size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 int cxl_set_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
 		    u8 feat_version, void *feat_data, size_t feat_data_size,
 		    u32 feat_flag, u16 offset, u16 *return_code);
+bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);
 
 #endif
diff --git a/include/uapi/cxl/features.h b/include/uapi/cxl/features.h
index 2e98efb9abf1..05c8a06a5dff 100644
--- a/include/uapi/cxl/features.h
+++ b/include/uapi/cxl/features.h
@@ -33,6 +33,7 @@ struct cxl_mbox_get_sup_feats_in {
 #define CXL_CMD_EFFECTS_VALID			BIT(9)
 #define CXL_CMD_CONFIG_CHANGE_CONV_RESET	BIT(10)
 #define CXL_CMD_CONFIG_CHANGE_CXL_RESET		BIT(11)
+#define CXL_CMD_EFFECTS_RESERVED		GENMASK(15, 12)
 
 /*
  * CXL spec r3.2 Table 8-109
diff --git a/include/uapi/fwctl/cxl.h b/include/uapi/fwctl/cxl.h
index 4e766ffb1388..3b95e0903856 100644
--- a/include/uapi/fwctl/cxl.h
+++ b/include/uapi/fwctl/cxl.h
@@ -16,4 +16,41 @@
 struct fwctl_info_cxl {
 	__u32 reserved;
 };
+
+/**
+ * struct fwctl_rpc_cxl - ioctl(FWCTL_RPC) input for CXL
+ * @command_id: the defined command id by 'enum feature_cmds'
+ * @flags: Flags for the command (input).
+ * @op_size: Size of input payload.
+ * @reserved1: Reserved. Must be 0s.
+ * @in_payload: User address of the hardware op input structure
+ */
+struct fwctl_rpc_cxl {
+	__u32 command_id;
+	__u32 flags;
+	__u32 op_size;
+	__u32 reserved1;
+	__aligned_u64 in_payload;
+};
+
+/* command_id for CXL mailbox Feature commands */
+enum feature_cmds {
+	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
+	CXL_FEATURE_ID_GET_FEATURE,
+	CXL_FEATURE_ID_SET_FEATURE,
+	CXL_FEATURE_ID_MAX
+};
+
+/**
+ * struct fwctl_rpc_cxl_out - ioctl(FWCTL_RPC) output for CXL
+ * @size: Size of the output payload
+ * @retval: Return value from device
+ * @payload: Return data from device
+ */
+struct fwctl_rpc_cxl_out {
+	__u32 size;
+	__u32 retval;
+	__u8 payload[] __counted_by(size);
+};
+
 #endif
-- 
2.48.1

[PATCH v2 12/16] cxl: Add support to handle user feature commands for get feature

[Dave Jiang]

Add helper function to parse the user data from fwctl RPC ioctl and
send the parsed input parameters to cxl_get_feature() call.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Use rpc_out->payload inline. (Jonathan)
- Adjust to new cxl_get_feature() input params.
---
 drivers/cxl/fwctl.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
index 93c6174ded20..b1d4ca8786c4 100644
--- a/drivers/cxl/fwctl.c
+++ b/drivers/cxl/fwctl.c
@@ -134,6 +134,51 @@ static void *cxlctl_get_supported_features(struct cxl_features_state *cxlfs,
 	return no_free_ptr(rpc_out);
 }
 
+static void *cxlctl_get_feature(struct cxl_features_state *cxlfs,
+				const struct fwctl_rpc_cxl *rpc_in,
+				size_t *out_len)
+{
+	struct cxl_dev_state *cxlds = cxlfs->cxlmd->cxlds;
+	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
+	struct cxl_mbox_get_feat_in feat_in;
+	u16 offset, count, return_code;
+	size_t out_size = *out_len;
+
+	if (rpc_in->op_size != sizeof(feat_in))
+		return ERR_PTR(-EINVAL);
+
+	if (copy_from_user(&feat_in, u64_to_user_ptr(rpc_in->in_payload),
+			   rpc_in->op_size))
+		return ERR_PTR(-EFAULT);
+
+	offset = le16_to_cpu(feat_in.offset);
+	count = le16_to_cpu(feat_in.count);
+
+	if (!count)
+		return ERR_PTR(-EINVAL);
+
+	struct fwctl_rpc_cxl_out *rpc_out __free(kvfree) =
+		kvzalloc(out_size, GFP_KERNEL);
+	if (!rpc_out)
+		return ERR_PTR(-ENOMEM);
+
+	out_size = cxl_get_feature(cxl_mbox, &feat_in.uuid,
+				   feat_in.selection, rpc_out->payload,
+				   count, offset, &return_code);
+	*out_len = sizeof(struct fwctl_rpc_cxl_out);
+	if (!out_size) {
+		rpc_out->size = 0;
+		rpc_out->retval = return_code;
+		return no_free_ptr(rpc_out);
+	}
+
+	rpc_out->size = out_size;
+	rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
+	*out_len += out_size;
+
+	return no_free_ptr(rpc_out);
+}
+
 static bool cxlctl_validate_set_features(struct cxl_features_state *cxlfs,
 					 const struct fwctl_rpc_cxl *rpc_in,
 					 enum fwctl_rpc_scope scope)
@@ -216,6 +261,7 @@ static void *cxlctl_handle_commands(struct cxl_features_state *cxlfs,
 	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
 		return cxlctl_get_supported_features(cxlfs, rpc_in, out_len);
 	case CXL_MBOX_OP_GET_FEATURE:
+		return cxlctl_get_feature(cxlfs, rpc_in, out_len);
 	case CXL_MBOX_OP_SET_FEATURE:
 	default:
 		return ERR_PTR(-EOPNOTSUPP);
-- 
2.48.1

[PATCH v2 13/16] cxl: Add support to handle user feature commands for set feature

[Dave Jiang]

Add helper function to parse the user data from fwctl RPC ioctl and
send the parsed input parameters to cxl_set_feature() call.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Adjust to new cxl_set_feature() input params.
- Add check for exclusive feature during Set Feature call
---
 drivers/cxl/core/features.c | 18 ++++++++-----
 drivers/cxl/features.h      |  1 +
 drivers/cxl/fwctl.c         | 53 +++++++++++++++++++++++++++++++++++++
 include/uapi/cxl/features.h |  5 ++++
 4 files changed, 71 insertions(+), 6 deletions(-)

diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index 132f93050d1c..205594a670d4 100644
--- a/drivers/cxl/core/features.c
+++ b/drivers/cxl/core/features.c
@@ -20,6 +20,17 @@ static const uuid_t cxl_exclusive_feats[] = {
 	CXL_FEAT_RANK_SPARING_UUID,
 };
 
+bool is_cxl_feature_exclusive_by_uuid(uuid_t *uuid)
+{
+	for (int i = 0; i < ARRAY_SIZE(cxl_exclusive_feats); i++) {
+		if (uuid_equal(uuid, &cxl_exclusive_feats[i]))
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_NS_GPL(is_cxl_feature_exclusive_by_uuid, "CXL");
+
 /**
  * is_cxl_feature_exclusive() - Check if a CXL feature is exclusive to kernel
  * @entry: cxl feature entry
@@ -28,12 +39,7 @@ static const uuid_t cxl_exclusive_feats[] = {
  */
 bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry)
 {
-	for (int i = 0; i < ARRAY_SIZE(cxl_exclusive_feats); i++) {
-		if (uuid_equal(&entry->uuid, &cxl_exclusive_feats[i]))
-			return true;
-	}
-
-	return false;
+	return is_cxl_feature_exclusive_by_uuid(&entry->uuid);
 }
 EXPORT_SYMBOL_NS_GPL(is_cxl_feature_exclusive, "CXL");
 
diff --git a/drivers/cxl/features.h b/drivers/cxl/features.h
index e487c24ff06f..e22d7d899253 100644
--- a/drivers/cxl/features.h
+++ b/drivers/cxl/features.h
@@ -8,6 +8,7 @@ struct cxl_feat_entry;
 struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd);
 void devm_cxlfs_free(struct cxl_memdev *cxlmd);
 int devm_cxl_add_features(struct cxl_memdev *cxlmd);
+bool is_cxl_feature_exclusive_by_uuid(uuid_t *uuid);
 bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);
 
 #endif
diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
index b1d4ca8786c4..e0ccf41ff9a5 100644
--- a/drivers/cxl/fwctl.c
+++ b/drivers/cxl/fwctl.c
@@ -179,6 +179,58 @@ static void *cxlctl_get_feature(struct cxl_features_state *cxlfs,
 	return no_free_ptr(rpc_out);
 }
 
+static void *cxlctl_set_feature(struct cxl_features_state *cxlfs,
+				const struct fwctl_rpc_cxl *rpc_in,
+				size_t *out_len)
+{
+	struct cxl_dev_state *cxlds = cxlfs->cxlmd->cxlds;
+	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
+	size_t out_size, data_size;
+	u16 offset, return_code;
+	u32 flags;
+	int rc;
+
+	if (rpc_in->op_size <= sizeof(struct cxl_mbox_set_feat_hdr))
+		return ERR_PTR(-EINVAL);
+
+	struct cxl_mbox_set_feat_in *feat_in __free(kvfree) =
+		kvzalloc(rpc_in->op_size, GFP_KERNEL);
+	if (!feat_in)
+		return ERR_PTR(-ENOMEM);
+
+	if (copy_from_user(feat_in, u64_to_user_ptr(rpc_in->in_payload),
+			   rpc_in->op_size))
+		return ERR_PTR(-EFAULT);
+
+	if (is_cxl_feature_exclusive_by_uuid(&feat_in->hdr.uuid))
+		return ERR_PTR(-EPERM);
+
+	offset = le16_to_cpu(feat_in->hdr.offset);
+	flags = le32_to_cpu(feat_in->hdr.flags);
+	out_size = *out_len;
+
+	struct fwctl_rpc_cxl_out *rpc_out __free(kvfree) =
+		kvzalloc(out_size, GFP_KERNEL);
+	if (!rpc_out)
+		return ERR_PTR(-ENOMEM);
+
+	rpc_out->size = 0;
+
+	data_size = rpc_in->op_size - sizeof(feat_in->hdr);
+	rc = cxl_set_feature(cxl_mbox, &feat_in->hdr.uuid,
+			     feat_in->hdr.version, feat_in->data,
+			     data_size, flags, offset, &return_code);
+	if (rc) {
+		rpc_out->retval = return_code;
+		return no_free_ptr(rpc_out);
+	}
+
+	rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
+	*out_len = sizeof(*rpc_out);
+
+	return no_free_ptr(rpc_out);
+}
+
 static bool cxlctl_validate_set_features(struct cxl_features_state *cxlfs,
 					 const struct fwctl_rpc_cxl *rpc_in,
 					 enum fwctl_rpc_scope scope)
@@ -263,6 +315,7 @@ static void *cxlctl_handle_commands(struct cxl_features_state *cxlfs,
 	case CXL_MBOX_OP_GET_FEATURE:
 		return cxlctl_get_feature(cxlfs, rpc_in, out_len);
 	case CXL_MBOX_OP_SET_FEATURE:
+		return cxlctl_set_feature(cxlfs, rpc_in, out_len);
 	default:
 		return ERR_PTR(-EOPNOTSUPP);
 	}
diff --git a/include/uapi/cxl/features.h b/include/uapi/cxl/features.h
index 05c8a06a5dff..30138506b286 100644
--- a/include/uapi/cxl/features.h
+++ b/include/uapi/cxl/features.h
@@ -107,6 +107,11 @@ struct cxl_mbox_set_feat_hdr {
 	__u8 rsvd[9];
 } __attribute__ ((__packed__));
 
+struct cxl_mbox_set_feat_in {
+	struct cxl_mbox_set_feat_hdr hdr;
+	__u8 data[];
+} __attribute__ ((__packed__));
+
 /* Set Feature flags field */
 enum cxl_set_feat_flag_data_transfer {
 	CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER = 0,
-- 
2.48.1

[PATCH v2 14/16] cxl/test: Add Get Feature support to cxl_test

[Dave Jiang]

Add emulation of Get Feature command to cxl_test. The feature for
device patrol scrub is returned by the emulation code. This is
the only feature currently supported by cxl_test. It returns
the information for the device patrol scrub feature.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 tools/testing/cxl/test/mem.c | 56 ++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 9394c48cf38e..103c7d783c35 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -48,6 +48,10 @@ static struct cxl_cel_entry mock_cel[] = {
 		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_SUPPORTED_FEATURES),
 		.effect = CXL_CMD_EFFECT_NONE,
 	},
+	{
+		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_FEATURE),
+		.effect = CXL_CMD_EFFECT_NONE,
+	},
 	{
 		.opcode = cpu_to_le16(CXL_MBOX_OP_IDENTIFY),
 		.effect = CXL_CMD_EFFECT_NONE,
@@ -149,6 +153,10 @@ struct mock_event_store {
 	u32 ev_status;
 };
 
+struct vendor_test_feat {
+	__le32 data;
+} __packed;
+
 struct cxl_mockmem_data {
 	void *lsa;
 	void *fw;
@@ -165,6 +173,7 @@ struct cxl_mockmem_data {
 	u8 event_buf[SZ_4K];
 	u64 timestamp;
 	unsigned long sanitize_timeout;
+	struct vendor_test_feat test_feat;
 };
 
 static struct mock_event_log *event_find_log(struct device *dev, int log_type)
@@ -1360,6 +1369,44 @@ static void fill_feature_vendor_test(struct cxl_feat_entry *feat)
 				    CXL_CMD_EFFECTS_VALID);
 }
 
+static int mock_get_test_feature(struct cxl_mockmem_data *mdata,
+				 struct cxl_mbox_cmd *cmd)
+{
+	struct vendor_test_feat *output = cmd->payload_out;
+	struct cxl_mbox_get_feat_in *input = cmd->payload_in;
+	u16 offset = le16_to_cpu(input->offset);
+	u16 count = le16_to_cpu(input->count);
+	u8 *ptr;
+
+	if (offset > sizeof(*output)) {
+		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
+		return -EINVAL;
+	}
+
+	if (offset + count > sizeof(*output)) {
+		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
+		return -EINVAL;
+	}
+
+	ptr = (u8 *)&mdata->test_feat + offset;
+	memcpy((u8 *)output + offset, ptr, count);
+
+	return 0;
+}
+
+static int mock_get_feature(struct cxl_mockmem_data *mdata,
+			    struct cxl_mbox_cmd *cmd)
+{
+	struct cxl_mbox_get_feat_in *input = cmd->payload_in;
+
+	if (uuid_equal(&input->uuid, &CXL_VENDOR_FEATURE_TEST))
+		return mock_get_test_feature(mdata, cmd);
+
+	cmd->return_code = CXL_MBOX_CMD_RC_UNSUPPORTED;
+
+	return -EOPNOTSUPP;
+}
+
 static int mock_get_supported_features(struct cxl_mockmem_data *mdata,
 				       struct cxl_mbox_cmd *cmd)
 {
@@ -1490,6 +1537,9 @@ static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
 	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
 		rc = mock_get_supported_features(mdata, cmd);
 		break;
+	case CXL_MBOX_OP_GET_FEATURE:
+		rc = mock_get_feature(mdata, cmd);
+		break;
 	default:
 		break;
 	}
@@ -1537,6 +1587,11 @@ static int cxl_mock_mailbox_create(struct cxl_dev_state *cxlds)
 	return 0;
 }
 
+static void cxl_mock_test_feat_init(struct cxl_mockmem_data *mdata)
+{
+	mdata->test_feat.data = cpu_to_le32(0xdeadbeef);
+}
+
 static int cxl_mock_mem_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1624,6 +1679,7 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 		return rc;
 
 	cxl_mem_get_event_records(mds, CXLDEV_EVENT_STATUS_ALL);
+	cxl_mock_test_feat_init(mdata);
 
 	return 0;
 }
-- 
2.48.1

[PATCH v2 15/16] cxl/test: Add Set Feature support to cxl_test

[Dave Jiang]

Add emulation to support Set Feature mailbox command to cxl_test.
The only feature supported is the device patrol scrub feature. The
set feature allows activation of patrol scrub for the cxl_test
emulated device. The command does not support partial data transfer
even though the spec allows it. This restriction is to reduce complexity
of the emulation given the patrol scrub feature is very minimal.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 tools/testing/cxl/test/mem.c | 50 ++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 103c7d783c35..34699635ca49 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -52,6 +52,10 @@ static struct cxl_cel_entry mock_cel[] = {
 		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_FEATURE),
 		.effect = CXL_CMD_EFFECT_NONE,
 	},
+	{
+		.opcode = cpu_to_le16(CXL_MBOX_OP_SET_FEATURE),
+		.effect = cpu_to_le16(EFFECT(CONF_CHANGE_IMMEDIATE)),
+	},
 	{
 		.opcode = cpu_to_le16(CXL_MBOX_OP_IDENTIFY),
 		.effect = CXL_CMD_EFFECT_NONE,
@@ -1407,6 +1411,49 @@ static int mock_get_feature(struct cxl_mockmem_data *mdata,
 	return -EOPNOTSUPP;
 }
 
+static int mock_set_test_feature(struct cxl_mockmem_data *mdata,
+				 struct cxl_mbox_cmd *cmd)
+{
+	struct cxl_mbox_set_feat_in *input = cmd->payload_in;
+	struct vendor_test_feat *test = (struct vendor_test_feat *)input->data;
+	u32 action;
+
+	action = FIELD_GET(CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK,
+			   le32_to_cpu(input->hdr.flags));
+	/*
+	 * While it is spec compliant to support other set actions, it is not
+	 * necessary to add the complication in the emulation currently. Reject
+	 * anything besides full xfer.
+	 */
+	if (action != CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER) {
+		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
+		return -EINVAL;
+	}
+
+	/* Offset should be reserved when doing full transfer */
+	if (input->hdr.offset) {
+		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
+		return -EINVAL;
+	}
+
+	memcpy(&mdata->test_feat.data, &test->data, sizeof(u32));
+
+	return 0;
+}
+
+static int mock_set_feature(struct cxl_mockmem_data *mdata,
+			    struct cxl_mbox_cmd *cmd)
+{
+	struct cxl_mbox_set_feat_in *input = cmd->payload_in;
+
+	if (uuid_equal(&input->hdr.uuid, &CXL_VENDOR_FEATURE_TEST))
+		return mock_set_test_feature(mdata, cmd);
+
+	cmd->return_code = CXL_MBOX_CMD_RC_UNSUPPORTED;
+
+	return -EOPNOTSUPP;
+}
+
 static int mock_get_supported_features(struct cxl_mockmem_data *mdata,
 				       struct cxl_mbox_cmd *cmd)
 {
@@ -1540,6 +1587,9 @@ static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
 	case CXL_MBOX_OP_GET_FEATURE:
 		rc = mock_get_feature(mdata, cmd);
 		break;
+	case CXL_MBOX_OP_SET_FEATURE:
+		rc = mock_set_feature(mdata, cmd);
+		break;
 	default:
 		break;
 	}
-- 
2.48.1

[PATCH v2 16/16] fwctl/cxl: Add documentation to FWCTL CXL

[Dave Jiang]

Add policy and operational documentation for FWCTL CXL.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v2:
- Various corrections. (Dan)
- Add sample code for ioctl. (Dan)
- Update to reflect changes from driver code review.
---
 .../userspace-api/fwctl/fwctl-cxl.rst         | 135 ++++++++++++++++++
 Documentation/userspace-api/fwctl/index.rst   |   1 +
 MAINTAINERS                                   |   1 +
 3 files changed, 137 insertions(+)
 create mode 100644 Documentation/userspace-api/fwctl/fwctl-cxl.rst

diff --git a/Documentation/userspace-api/fwctl/fwctl-cxl.rst b/Documentation/userspace-api/fwctl/fwctl-cxl.rst
new file mode 100644
index 000000000000..8d9aeb77bc6d
--- /dev/null
+++ b/Documentation/userspace-api/fwctl/fwctl-cxl.rst
@@ -0,0 +1,135 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+fwctl cxl driver
+================
+
+:Author: Dave Jiang
+
+Overview
+========
+
+The CXL spec defines a set of commands that can be issued to the mailbox of a
+CXL device or switch. It also left room for vendor specific commands to be
+issued to the mailbox as well. fwctl provides a path to issue a set of allowed
+mailbox commands from user space to the device moderated by the kernel driver.
+
+The following 3 commands will be used to support CXL Features:
+CXL spec r3.1 8.2.9.6.1 Get Supported Features (Opcode 0500h)
+CXL spec r3.1 8.2.9.6.2 Get Feature (Opcode 0501h)
+CXL spec r3.1 8.2.9.6.3 Set Feature (Opcode 0502h)
+
+The "Get Supported Features" return data may be filtered by the kernel driver to
+drop any features that are forbidden by the kernel or being exclusively used by
+the kernel. The "Get Supported Features" command and the "Get Features" falls
+under the fwctl policy of FWCTL_RPC_CONFIGURATION.
+
+For "Set Feature" command, the access policy currently is broken down into two
+categories depending on the Set Feature effects reported by the device. If the
+Set Feature will cause immediate change to the device, the fwctl access policy
+must be FWCTL_RPC_DEBUG_WRITE_FULL. The effects for this level are
+"immediate config change", "immediate data change", "immediate policy change",
+or "immediate log change" for the set effects mask. If the effects are "config
+change with cold reset" or "config change with conventional reset", then the
+fwctl access policy must be FWCTL_RPC_DEBUG_WRITE or higher.
+
+fwctl cxl User API
+==================
+
+.. kernel-doc:: include/uapi/fwctl/cxl.h
+.. kernel-doc:: include/uapi/cxl/features.h
+
+1. Driver info query
+--------------------
+
+First step for the app is to issue the ioctl(FWCTL_CMD_INFO). Successful
+invocation of the ioctl implies the Features capability is operational and
+returns an all zeros 32bit payload. A ``struct fwctl_info`` needs to be filled
+out with the ``fwctl_info.out_device_type`` set to ``FWCTL_DEVICE_TYPE_CXL``.
+The return data should be ``struct fwctl_info_cxl`` that contains a reserved
+32bit field that should be all zeros.
+
+2. Send hardware commands
+-------------------------
+
+Next step is to send the 'Get Supported Features' command to the driver from
+user space via ioctl(FWCTL_RPC). A ``struct fwctl_rpc_cxl`` is pointed to
+by ``fwctl_rpc.in``. ``struct fwctl_rpc_cxl.in_payload`` points to
+the hardware input structure that is defined by the CXL spec. ``fwctl_rpc.out``
+points to the buffer that contains a ``struct fwctl_rpc_cxl_out`` that includes
+the hardware output data inlined as ``fwctl_rpc_cxl_out.payload``. This command
+is called twice. First time to retrieve the number of features supported.
+A second time to retrieve the specific feature details as the output data.
+
+After getting the specific feature details, a Get/Set Feature command can be
+appropriately programmed and sent. For a "Set Feature" command, the retrieved
+feature info contains an effects field that details the resulting
+"Set Feature" command will trigger. That will inform the user whether
+the system is configured to allowed the "Set Feature" command or not.
+
+Code example of a Get Feature
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: c
+
+        static int cxl_fwctl_rpc_get_test_feature(int fd, struct test_feature *feat_ctx,
+                                                  const uint32_t expected_data)
+        {
+                struct cxl_mbox_get_feat_in feat_in __attribute__((aligned(16))) = {0};
+                struct fwctl_rpc_cxl in __attribute__((aligned(16))) = {0};
+                struct fwctl_rpc_cxl_out *out;
+                struct fwctl_rpc rpc = {0};
+                size_t out_size;
+                uint32_t val;
+                void *data;
+                int rc;
+
+                uuid_copy(feat_in.uuid, feat_ctx->uuid);
+                feat_in.count = feat_ctx->get_size;
+
+                out_size = sizeof(*out) + feat_in.count;
+                out = aligned_alloc(16, out_size);
+                if (!out)
+                        return -ENOMEM;
+
+                memset(out, 0, out_size);
+                data = out->payload;
+
+                in.command_id = CXL_FEATURE_ID_GET_FEATURE;
+                in.op_size = sizeof(feat_in);
+                in.in_payload = (uint64_t)(uint64_t *)&feat_in;
+
+                rpc.size = sizeof(rpc);
+                rpc.scope = FWCTL_RPC_CONFIGURATION;
+                rpc.in_len = sizeof(in);
+                rpc.out_len = out_size;
+                rpc.in = (uint64_t)(uint64_t *)&in;
+                rpc.out = (uint64_t)(uint64_t *)out;
+
+                rc = send_command(fd, &rpc, out);
+                if (rc)
+                        goto out;
+
+                val = le32toh(*(__le32 *)data);
+                if (memcmp(&val, &expected_data, sizeof(val)) != 0) {
+                        rc = -ENXIO;
+                        goto out;
+                }
+
+        out:
+                free(out);
+                return rc;
+        }
+
+It is recommended to take a look at CXL CLI test directory
+<https://github.com/pmem/ndctl/tree/main/test/fwctl.c> for a detailed user code
+example on how to exercise this path.
+
+
+fwctl cxl Kernel API
+====================
+
+.. kernel-doc:: drivers/cxl/core/features.c
+.. kernel-doc:: drivers/cxl/features.c
+   :export:
+.. kernel-doc:: include/cxl/features.h
diff --git a/Documentation/userspace-api/fwctl/index.rst b/Documentation/userspace-api/fwctl/index.rst
index 06959fbf1547..d9d40a468a31 100644
--- a/Documentation/userspace-api/fwctl/index.rst
+++ b/Documentation/userspace-api/fwctl/index.rst
@@ -10,3 +10,4 @@ to securely construct and execute RPCs inside device firmware.
    :maxdepth: 1
 
    fwctl
+   fwctl-cxl
diff --git a/MAINTAINERS b/MAINTAINERS
index 877eb301b1e5..5d67225a22bc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5773,6 +5773,7 @@ M:	Dan Williams <dan.j.williams@intel.com>
 L:	linux-cxl@vger.kernel.org
 S:	Maintained
 F:	Documentation/driver-api/cxl
+F:	Documentation/userspace-api/fwctl/fwctl-cxl.rst
 F:	drivers/cxl/
 F:	include/cxl/
 F:	include/uapi/linux/cxl_mem.h
-- 
2.48.1

Re: [PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Dave Jiang]

On 1/31/25 5:42 PM, Dave Jiang wrote:
> Add fwctl support code to allow sending of CXL feature commands from
> userspace through as ioctls via FWCTL. Provide initial setup bits.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Associate FWCTL with the 'cxl_memdev' through the memdev driver. (Dan)
> - I'm leaving Jonathan's tag off to get this looked at again.
> - Hide FWCTL code behind CONFIG_CXL_FWCTL (Dan)
> ---
>  drivers/cxl/Kconfig        | 15 +++++++
>  drivers/cxl/Makefile       |  1 +
>  drivers/cxl/features.c     | 35 ++++++++++++---
>  drivers/cxl/features.h     |  2 +
>  drivers/cxl/fwctl.c        | 88 ++++++++++++++++++++++++++++++++++++++
>  include/cxl/features.h     |  3 ++
>  include/uapi/fwctl/fwctl.h |  1 +
>  tools/testing/cxl/Kbuild   |  1 +
>  8 files changed, 140 insertions(+), 6 deletions(-)
>  create mode 100644 drivers/cxl/fwctl.c
> 
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index 876469e23f7a..34731890bc8e 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -102,6 +102,21 @@ config CXL_MEM
>  
>  	  If unsure say 'm'.
>  
> +config CXL_FWCTL
> +	bool "CXL: Firmware Control support"
> +	depends on CXL_MEM
> +	select FWCTL
> +	help
> +	  Enable support for firmware control of CXL devices. This allows
> +	  a FWCTL char device to be created in order to issue ioctls from
> +	  user space to exercise the CXL Features commands supported by
> +	  a CXL mailbox. There are some Features defined in the CXL spec
> +	  such as memory sparing. However a lof of those features are

s/lof/lot/

> +	  exclusive to the kernel. Most likely the Features maniulated
s/maniulated/manipulated/

wonder why checkpatch did not catch these but caught others

> +	  by CXL_FWCTL will be vendor defined Features.
> +
> +	  If unsure say 'n'.
> +
>  config CXL_PORT
>  	default CXL_BUS
>  	tristate
> diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
> index 12fbc35081bb..cd28fb3bf855 100644
> --- a/drivers/cxl/Makefile
> +++ b/drivers/cxl/Makefile
> @@ -18,4 +18,5 @@ cxl_port-y := port.o
>  cxl_acpi-y := acpi.o
>  cxl_pmem-y := pmem.o security.o
>  cxl_mem-y := mem.o features.o
> +cxl_mem-$(CONFIG_CXL_FWCTL) += fwctl.o
>  cxl_pci-y := pci.o
> diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
> index 82598a409acc..2dcfefdfa6b3 100644
> --- a/drivers/cxl/features.c
> +++ b/drivers/cxl/features.c
> @@ -1,8 +1,11 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
> +#include <linux/pci.h>
>  #include <linux/device.h>
> +#include <linux/module.h>
>  #include <cxl/mailbox.h>
>  #include <cxl/features.h>
> +

stray blank line, will remove

DJ

>  #include "cxl.h"
>  #include "cxlmem.h"
>  #include "features.h"
> @@ -168,11 +171,31 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd,
>  	cxlfs->cap = CXL_FEATURES_RW;
>  }
>  
> +/* The __weak symbol gets replaced by FWCTL allocation function in fwctl.c */
> +struct cxl_features_state * __weak devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
> +{
> +	struct device *dev = &cxlmd->dev;
> +	struct cxl_features_state *cxlfs =
> +		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +
> +	if (!cxlfs)
> +		return ERR_PTR(-ENOMEM);
> +
> +	cxlfs->cxlmd = cxlmd;
> +
> +	return cxlfs;
> +}
> +
> +/* The __weak symbol gets replaced by FWCTL free function in fwctl.c */
> +void __weak devm_cxlfs_free(struct cxl_memdev *cxlmd)
> +{
> +	devm_kfree(&cxlmd->dev, cxlmd->cxlfs);
> +	cxlmd->cxlfs = NULL;
> +}
> +
>  static void cxl_cxlfs_free(struct cxl_features_state *cxlfs)
>  {
> -	struct device *dev = &cxlfs->cxlmd->dev;
> -
> -	devm_kfree(dev, cxlfs);
> +	devm_cxlfs_free(cxlfs->cxlmd);
>  }
>  
>  DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
> @@ -185,15 +208,13 @@ DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
>   */
>  int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>  {
> -	struct device *dev = &cxlmd->dev;
>  	int rc;
>  
>  	struct cxl_features_state *cxlfs __free(free_cxlfs) =
> -		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +		devm_cxlfs_allocate(cxlmd);
>  	if (!cxlfs)
>  		return -ENOMEM;
>  
> -	cxlfs->cxlmd = cxlmd;
>  	enumerate_feature_cmds(cxlmd, cxlfs);
>  	rc = get_supported_features(cxlmd, cxlfs);
>  	if (rc)
> @@ -204,3 +225,5 @@ int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>  	return 0;
>  }
>  EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");
> +
> +MODULE_IMPORT_NS("CXL");
> diff --git a/drivers/cxl/features.h b/drivers/cxl/features.h
> index 8706f944b476..e487c24ff06f 100644
> --- a/drivers/cxl/features.h
> +++ b/drivers/cxl/features.h
> @@ -5,6 +5,8 @@
>  
>  struct cxl_feat_entry;
>  
> +struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd);
> +void devm_cxlfs_free(struct cxl_memdev *cxlmd);
>  int devm_cxl_add_features(struct cxl_memdev *cxlmd);
>  bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);
>  
> diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
> new file mode 100644
> index 000000000000..d8fd68ac8982
> --- /dev/null
> +++ b/drivers/cxl/fwctl.c
> @@ -0,0 +1,88 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2025 Intel Corporation. All rights reserved. */
> +#include <linux/fwctl.h>
> +#include <linux/device.h>
> +#include <cxl/features.h>
> +#include "cxlmem.h"
> +#include "features.h"
> +
> +static int cxlctl_open_uctx(struct fwctl_uctx *uctx)
> +{
> +	return 0;
> +}
> +
> +static void cxlctl_close_uctx(struct fwctl_uctx *uctx)
> +{
> +}
> +
> +static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
> +{
> +	/* Place holder */
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
> +			   void *rpc_in, size_t in_len, size_t *out_len)
> +{
> +	/* Place holder */
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static const struct fwctl_ops cxlctl_ops = {
> +	.device_type = FWCTL_DEVICE_TYPE_CXL,
> +	.uctx_size = sizeof(struct fwctl_uctx),
> +	.open_uctx = cxlctl_open_uctx,
> +	.close_uctx = cxlctl_close_uctx,
> +	.info = cxlctl_info,
> +	.fw_rpc = cxlctl_fw_rpc,
> +};
> +
> +static void remove_cxlfs(void *_cxlfs)
> +{
> +	struct cxl_features_state *cxlfs = _cxlfs;
> +	struct cxl_memdev *cxlmd = cxlfs->cxlmd;
> +	struct fwctl_device *fwctl = &cxlfs->fwctl;
> +
> +	cxlmd->cxlfs = NULL;
> +	fwctl_unregister(fwctl);
> +	fwctl_put(fwctl);
> +}
> +
> +DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) fwctl_put(&_T->fwctl))
> +
> +static struct cxl_features_state *
> +__devm_cxl_cfs_allocate(struct cxl_memdev *cxlmd, const struct fwctl_ops *ops)
> +{
> +	struct device *dev = &cxlmd->dev;
> +	int rc;
> +
> +	struct cxl_features_state *cxlfs __free(free_cxlfs) =
> +		fwctl_alloc_device(dev, ops, struct cxl_features_state, fwctl);
> +	if (!cxlfs)
> +		return ERR_PTR(-ENOMEM);
> +
> +	cxlfs->cxlmd = cxlmd;
> +	rc = fwctl_register(&cxlfs->fwctl);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = devm_add_action_or_reset(dev, remove_cxlfs, cxlfs);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	return no_free_ptr(cxlfs);
> +}
> +
> +struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
> +{
> +	return __devm_cxl_cfs_allocate(cxlmd, &cxlctl_ops);
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxlfs_allocate, "CXL");
> +
> +void devm_cxlfs_free(struct cxl_memdev *cxlmd)
> +{
> +	devm_release_action(&cxlmd->dev, remove_cxlfs, cxlmd);
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxlfs_free, "CXL");
> +
> +MODULE_IMPORT_NS("FWCTL");
> diff --git a/include/cxl/features.h b/include/cxl/features.h
> index 7ae84696d6dd..7c43ac021a8c 100644
> --- a/include/cxl/features.h
> +++ b/include/cxl/features.h
> @@ -4,6 +4,7 @@
>  #define __CXL_FEATURES_H__
>  
>  #include <linux/uuid.h>
> +#include <linux/fwctl.h>
>  
>  /* Feature UUIDs used by the kernel */
>  #define CXL_FEAT_PATROL_SCRUB_UUID						\
> @@ -57,6 +58,7 @@ enum cxl_features_capability {
>  
>  /**
>   * struct cxl_features_state - The Features state for the device
> + * @fwctl: FWCTL device
>   * @cxlmd: Pointer to cxl mem device
>   * @cap: Feature commands capability
>   * @num_features: total Features supported by the device
> @@ -64,6 +66,7 @@ enum cxl_features_capability {
>   * @entries: Feature detail entries fetched from the device
>   */
>  struct cxl_features_state {
> +	struct fwctl_device fwctl;
>  	struct cxl_memdev *cxlmd;
>  	enum cxl_features_capability cap;
>  	int num_features;
> diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h
> index f9b27fb5c161..4e4d30104667 100644
> --- a/include/uapi/fwctl/fwctl.h
> +++ b/include/uapi/fwctl/fwctl.h
> @@ -43,6 +43,7 @@ enum {
>  enum fwctl_device_type {
>  	FWCTL_DEVICE_TYPE_ERROR = 0,
>  	FWCTL_DEVICE_TYPE_MLX5 = 1,
> +	FWCTL_DEVICE_TYPE_CXL = 2,
>  };
>  
>  /**
> diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
> index 6b0a992af4a7..6396d1296cef 100644
> --- a/tools/testing/cxl/Kbuild
> +++ b/tools/testing/cxl/Kbuild
> @@ -47,6 +47,7 @@ cxl_port-y += cxl_port_test.o
>  obj-m += cxl_mem.o
>  
>  cxl_mem-y := $(CXL_SRC)/mem.o $(CXL_SRC)/features.o
> +cxl_mem-$(CONFIG_CXL_FWCTL) += $(CXL_SRC)/fwctl.o
>  cxl_mem-y += config_check.o
>  cxl_mem-y += cxl_mem_test.o
>  

Re: [PATCH v2 02/16] cxl: Enumerate feature commands

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:41:55 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add feature commands enumeration code in order to detect and enumerate
> the 3 feature related commands "get supported features", "get feature",
> and "set feature". The enumeration will help determine whether the driver
> can issue any of the 3 commands to the device.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Setup allocation of cxlfs and move enumeration of commands to
>   the setup function.
> - Introduce features_capability enum. (Dan)
> - Name the setup function devm_cxl_add_features(). (Dan)
> - Drop 'cxl_mem_command' support. (Dan)
> - Move feature support to mem probe. (Dan)
> - Remove comma at last entry of data structs. (Jonathan)
Got carried away on this one.   Only drop them for termination
entries.  So MAX or NULL or similar.

> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index bdb8f060f2c1..25fb7bd770b3 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -69,6 +69,29 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
>  	CXL_CMD(GET_TIMESTAMP, 0, 0x8, 0),
>  };
>  
> +static u16 cxl_feature_commands[] = {
> +	CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
> +	CXL_MBOX_OP_GET_FEATURE,
> +	CXL_MBOX_OP_SET_FEATURE

This one does want a trailing comma. Might be more feature commands in future.

> +};

> diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
> new file mode 100644
> index 000000000000..13b0b29ee102
> --- /dev/null
> +++ b/drivers/cxl/features.c
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
> +#include <linux/device.h>
> +#include <cxl/mailbox.h>
> +#include <cxl/features.h>
> +#include "cxl.h"
> +#include "cxlmem.h"
> +#include "features.h"
> +
> +static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
> +{
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
> +	struct cxl_features_state *cxlfs = cxlds->cxlmd->cxlfs;
Going in circles?
	cxlmd->cxlfs;


> +	int fid;
> +
> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
> +		return;
> +
> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_FEATURE);
> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
> +		return;
> +
> +	cxlfs->cap = CXL_FEATURES_RO;
> +
> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_SET_FEATURE);
> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
> +		return;
> +
> +	cxlfs->cap = CXL_FEATURES_RW;
> +}
> +
> +/**
> + * devm_cxl_add_features() - Allocate and initialize features context
> + * @cxlmd: CXL memory device
> + *
> + * Return 0 on success or -errno on failure.
> + */
> +int devm_cxl_add_features(struct cxl_memdev *cxlmd)
> +{
> +	struct cxl_features_state *cxlfs;
> +	struct device *dev = &cxlmd->dev;
> +
> +	cxlfs = devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +	if (!cxlfs)
> +		return -ENOMEM;
> +
> +	cxlmd->cxlfs = cxlfs;

So I was curious about this one and why we leave the pointer
hanging in the remove path + whether the two way pointer nest
is needed.

That gets dealt with in patch 8.

I'd be tempted to drag the bones of dev_cxlfs_allocate() to this
patch so that you can do that cleanup now and avoid some of the churn
of the later patches.

As for the two way pointer nest. I'm not sure it is needed.
Seems like most if not all places we use cxlmd->cxlfs have
just gotten it in the caller from cxlfs->cxlmd.
e.g. cxl_cxlfs_free() in patch 8. For here we could
just pass it into enumerate_feature_cmds.

Maybe Shiju's set needs it. I haven't checked.




> +	cxlfs->cxlmd = cxlmd;
> +	enumerate_feature_cmds(cxlmd);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");

> diff --git a/include/cxl/features.h b/include/cxl/features.h
> new file mode 100644
> index 000000000000..eadf0d56553f
> --- /dev/null
> +++ b/include/cxl/features.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Copyright(c) 2024-2025 Intel Corporation. */
> +#ifndef __CXL_FEATURES_H__
> +#define __CXL_FEATURES_H__
> +
> +struct cxl_mailbox;
> +
> +/* Index IDs for CXL mailbox Feature commands */
> +enum feature_cmds {
> +	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
> +	CXL_FEATURE_ID_GET_FEATURE,
> +	CXL_FEATURE_ID_SET_FEATURE,
> +	CXL_FEATURE_ID_MAX
> +};
> +
> +/* Feature commands capability supported by a device */
> +enum cxl_features_capability {
> +	CXL_FEATURES_NONE = 0,
> +	CXL_FEATURES_RO,
> +	CXL_FEATURES_RW

Trivial but this one should have a trailing comma.  Maybe
we'll have a write only one!  Anyhow, it's not a terminating
entry so we shouldn't assume nothing comes after it.

> +};
> +
> +/**
> + * struct cxl_features_state - The Features state for the device
> + * @cxlmd: Pointer to cxl mem device
> + * @cap: Feature commands capability
> + * @num_features: total Features supported by the device
> + */
> +struct cxl_features_state {
> +	struct cxl_memdev *cxlmd;
> +	enum cxl_features_capability cap;
> +	int num_features;
> +};
> +
> +#endif

Re: [PATCH v2 03/16] cxl: Add Get Supported Features command for kernel usage

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:41:56 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> CXL spec r3.2 8.2.9.6.1 Get Supported Features (Opcode 0500h)
> The command retrieve the list of supported device-specific features
> (identified by UUID) and general information about each Feature.
> 
> The driver will retrieve the feature entries in order to make checks and
> provide information for the Get Feature and Set Feature command. One of
> the main piece of information retrieved are the effects a Set Feature
> command would have for a particular feature.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Move to memdev driver and drop features driver support. (Dan)
> - Use features_capability to check what's supported. (Dan)
> - Drop cxl_get_supported_feature_entry() as no usage (Dan, Jonathan)
> - Drop Shiju sign off tags per requested. (Shiju)
> - Rename EXTEND bit(9) to VALID. (Jonathan)
I've read this code too many times :(

Anyhow some feedback on stuff I think belongs in patch 2 and
use of struct_size() to make the sizing calcs more obvious that
I'd missed until now.

> +static int get_supported_features(struct cxl_memdev *cxlmd,
> +				  struct cxl_features_state *cxlfs)
> +{
> +	int remain_feats, max_size, max_feats, start, rc, hdr_size;
> +	struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
> +	int feat_size = sizeof(struct cxl_feat_entry);
> +	struct cxl_mbox_get_sup_feats_in mbox_in;
> +	struct cxl_feat_entry *entry;
> +	struct cxl_mbox_cmd mbox_cmd;
> +	int count;
> +
> +	if (cxlfs->cap < CXL_FEATURES_RO)
> +		return -EOPNOTSUPP;
> +
> +	count = cxl_get_supported_features_count(cxl_mbox);
> +	if (count == 0)
> +		return 0;

Not sure this should return 0.  That will leave the cxlfs
in place.  + your outermost call in the mem driver prints
a message saying nothing found only if an error is returned.

> +	if (count < 0)
> +		return -ENXIO;
> +
> +	struct cxl_feat_entry *entries __free(kvfree) =
> +		kvmalloc(count * sizeof(*entries), GFP_KERNEL);
> +	if (!entries)
> +		return -ENOMEM;
> +
> +	struct cxl_mbox_get_sup_feats_out *mbox_out __free(kvfree) =
> +		kvmalloc(cxl_mbox->payload_size, GFP_KERNEL);
> +	if (!mbox_out)
> +		return -ENOMEM;
> +
> +	hdr_size = sizeof(*mbox_out);

May seem an odd request but can we make this 
struct_size(mbox_out, ents, 0)
as it seems odd to say how big is this thing we just allocated
and get a smaller size (though correct given the trailing [] array)

> +	max_size = cxl_mbox->payload_size - hdr_size;
> +	/* max feat entries that can fit in mailbox max payload size */
> +	max_feats = max_size / feat_size;
> +	entry = entries;
> +
> +	start = 0;
> +	remain_feats = count;
> +	do {
> +		int retrieved, alloc_size, copy_feats;
> +		int num_entries;
> +
> +		if (remain_feats > max_feats) {
> +			alloc_size = sizeof(*mbox_out) + max_feats * feat_size;

alloc_size = struct_size(mbox_out, ents, max_feats); 

> +			remain_feats = remain_feats - max_feats;
> +			copy_feats = max_feats;
> +		} else {
> +			alloc_size = sizeof(*mbox_out) + remain_feats * feat_size;

alloc_size = struct_size(mbox_out, ents, remain_feats);

> +			copy_feats = remain_feats;
> +			remain_feats = 0;
> +		}
> +
> +		memset(&mbox_in, 0, sizeof(mbox_in));
> +		mbox_in.count = cpu_to_le32(alloc_size);
> +		mbox_in.start_idx = cpu_to_le16(start);
> +		memset(mbox_out, 0, alloc_size);
> +		mbox_cmd = (struct cxl_mbox_cmd) {
> +			.opcode = CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
> +			.size_in = sizeof(mbox_in),
> +			.payload_in = &mbox_in,
> +			.size_out = alloc_size,
> +			.payload_out = mbox_out,
> +			.min_out = hdr_size,
> +		};
> +		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
> +		if (rc < 0)
> +			return rc;
> +
> +		if (mbox_cmd.size_out <= hdr_size)
> +			return -ENXIO;
> +
> +		/*
> +		 * Make sure retrieved out buffer is multiple of feature
> +		 * entries.
> +		 */
> +		retrieved = mbox_cmd.size_out - hdr_size;
> +		if (retrieved % feat_size)
> +			return -ENXIO;
> +
> +		num_entries = le16_to_cpu(mbox_out->num_entries);
> +		/*
> +		 * If the reported output entries * defined entry size !=
> +		 * retrieved output bytes, then the output package is incorrect.
> +		 */
> +		if (num_entries * feat_size != retrieved)
> +			return -ENXIO;
> +
> +		memcpy(entry, mbox_out->ents, retrieved);
> +		entry++;
> +		/*
> +		 * If the number of output entries is less than expected, add the
> +		 * remaining entries to the next batch.
> +		 */
> +		remain_feats += copy_feats - num_entries;
> +		start += num_entries;
> +	} while (remain_feats);
> +
> +	cxlfs->num_features = count;
> +	cxlfs->entries = no_free_ptr(entries);
> +	return devm_add_action_or_reset(&cxlmd->dev, cxl_free_feature_entries,
> +					cxlfs->entries);
> +}
> +
> +static void enumerate_feature_cmds(struct cxl_memdev *cxlmd,
> +				   struct cxl_features_state *cxlfs)
Good.  Suggested this in previous.
>  {
>  	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>  	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
> -	struct cxl_features_state *cxlfs = cxlds->cxlmd->cxlfs;

And you drop the circular line. Push this into patch 2.

>  	int fid;
>  
>  	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
> @@ -31,6 +164,15 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
>  	cxlfs->cap = CXL_FEATURES_RW;
>  }
>  
> +static void cxl_cxlfs_free(struct cxl_features_state *cxlfs)
> +{
> +	struct device *dev = &cxlfs->cxlmd->dev;
> +
> +	devm_kfree(dev, cxlfs);

As below. Let's bring cleanup here if we have to unset cxlmd->cxlfs
later.

> +}
> +
> +DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
> +
>  /**
>   * devm_cxl_add_features() - Allocate and initialize features context
>   * @cxlmd: CXL memory device
> @@ -39,16 +181,21 @@ static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
>   */
>  int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>  {
> -	struct cxl_features_state *cxlfs;
>  	struct device *dev = &cxlmd->dev;
> +	int rc;
>  
> -	cxlfs = devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +	struct cxl_features_state *cxlfs __free(free_cxlfs) =
> +		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);

This line changes 3 times in the series.  Can we drag the
last one here (as per comment on patch 2) by introducing
the new allocate function at this point.

>  	if (!cxlfs)
>  		return -ENOMEM;
>  
> -	cxlmd->cxlfs = cxlfs;
>  	cxlfs->cxlmd = cxlmd;
> -	enumerate_feature_cmds(cxlmd);
> +	enumerate_feature_cmds(cxlmd, cxlfs);
> +	rc = get_supported_features(cxlmd, cxlfs);
> +	if (rc)
> +		return rc;
> +
> +	cxlmd->cxlfs = no_free_ptr(cxlfs);
>  
>  	return 0;
>  }

Re: [PATCH v2 04/16] cxl/test: Add Get Supported Features mailbox command support

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:41:57 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add cxl-test emulation of Get Supported Features mailbox command.
> Currently only adding a test feature with feature identifier of
> all f's for testing.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Acked-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>


> +static int mock_get_supported_features(struct cxl_mockmem_data *mdata,
> +				       struct cxl_mbox_cmd *cmd)
> +{
> +	struct cxl_mbox_get_sup_feats_in *in = cmd->payload_in;
> +	struct cxl_mbox_get_sup_feats_out *out = cmd->payload_out;
> +	struct cxl_feat_entry *feat;
> +	u16 start_idx, count;
> +
> +	if (cmd->size_out < sizeof(*out)) {
> +		cmd->return_code = CXL_MBOX_CMD_RC_PAYLOADLEN;
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Current emulation only supports 1 feature
> +	 */
> +	start_idx = le16_to_cpu(in->start_idx);
> +	if (start_idx != 0) {
> +		cmd->return_code = CXL_MBOX_CMD_RC_INPUT;
> +		return -EINVAL;
> +	}
> +
> +	count = le16_to_cpu(in->count);
> +	if (count < sizeof(*out)) {
> +		cmd->return_code = CXL_MBOX_CMD_RC_PAYLOADLEN;
> +		return -EINVAL;
> +	}
> +
> +	out->supported_feats = cpu_to_le16(1);
> +	cmd->return_code = 0;
> +	if (count < sizeof(*out) + sizeof(*feat)) {

struct_size() probably makes sense here as well.

> +		out->num_entries = 0;
> +		return 0;
> +	}
> +
> +	out->num_entries = cpu_to_le16(1);
> +	feat = out->ents;
> +	fill_feature_vendor_test(feat);
> +
> +	return 0;
> +}
> +
>  static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
>  			      struct cxl_mbox_cmd *cmd)
>  {
> @@ -1422,6 +1487,9 @@ static int cxl_mock_mbox_send(struct cxl_mailbox *cxl_mbox,
>  	case CXL_MBOX_OP_ACTIVATE_FW:
>  		rc = mock_activate_fw(mdata, cmd);
>  		break;
> +	case CXL_MBOX_OP_GET_SUPPORTED_FEATURES:
> +		rc = mock_get_supported_features(mdata, cmd);
> +		break;
>  	default:
>  		break;
>  	}

Re: [PATCH v2 06/16] cxl/mbox: Add SET_FEATURE mailbox command

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:41:59 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> From: Shiju Jose <shiju.jose@huawei.com>
> 
> Add support for SET_FEATURE mailbox command.
> 
> CXL spec r3.2 section 8.2.9.6 describes optional device specific features.
> CXL devices supports features with changeable attributes.
> The settings of a feature can be optionally modified using Set Feature
> command.
> CXL spec r3.2 section 8.2.9.6.3 describes Set Feature command.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Just one tiny thing on a reread.

J
> ---
> v2:
> - Set input as 'struct cxl_mailbox' for cxl_get_feature() (Dan)
> - Set feat_uuid as 'uuid_t *' (Dan)
> - Use uuid_copy() to assign uuid
> - Fix tab alignment. (Jonathan)
> - Update kmalloc() to kzalloc(). (Dan)
> ---
>  drivers/cxl/core/features.c | 81 +++++++++++++++++++++++++++++++++++++
>  include/cxl/features.h      | 33 +++++++++++++++
>  2 files changed, 114 insertions(+)
> 
> diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
> index b01dc5ebb24d..7dd3b64b6976 100644
> --- a/drivers/cxl/core/features.c
> +++ b/drivers/cxl/core/features.c
> @@ -57,3 +57,84 @@ size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
>  	return data_rcvd_size;
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_get_feature, "CXL");
> +
> +/*
> + * FEAT_DATA_MIN_PAYLOAD_SIZE - min extra number of bytes should be
> + * available in the mailbox for storing the actual feature data so that
> + * the feature data transfer would work as expected.
> + */
> +#define FEAT_DATA_MIN_PAYLOAD_SIZE 10
> +int cxl_set_feature(struct cxl_mailbox *cxl_mbox,
> +		    const uuid_t *feat_uuid, u8 feat_version,
> +		    void *feat_data, size_t feat_data_size,
> +		    u32 feat_flag, u16 offset, u16 *return_code)
> +{
> +	struct cxl_memdev_set_feat_pi {
> +		struct cxl_mbox_set_feat_hdr hdr;
> +		u8 feat_data[];
> +	}  __packed;
> +	size_t data_in_size, data_sent_size = 0;
> +	struct cxl_mbox_cmd mbox_cmd;
> +	size_t hdr_size;
> +	int rc = 0;
> +
> +	if (return_code)
> +		*return_code = CXL_MBOX_CMD_RC_INPUT;
> +
> +	struct cxl_memdev_set_feat_pi *pi __free(kfree) =
> +			kzalloc(cxl_mbox->payload_size, GFP_KERNEL);
> +	uuid_copy(&pi->hdr.uuid, feat_uuid);
> +	pi->hdr.version = feat_version;
> +	feat_flag &= ~CXL_SET_FEAT_FLAG_DATA_TRANSFER_MASK;
> +	feat_flag |= CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET;
> +	hdr_size = sizeof(pi->hdr);
> +	/*
> +	 * Check minimum mbox payload size is available for
> +	 * the feature data transfer.
> +	 */
> +	if (hdr_size + FEAT_DATA_MIN_PAYLOAD_SIZE > cxl_mbox->payload_size)
> +		return -ENOMEM;
> +
> +	if ((hdr_size + feat_data_size) <= cxl_mbox->payload_size) {

Trivial: Inconsistent brackets wrt to previous check.  I'd drop them inner
set here as not adding anything.

> +		pi->hdr.flags = cpu_to_le32(feat_flag |
> +				       CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER);
> +		data_in_size = feat_data_size;
> +	} else {
> +		pi->hdr.flags = cpu_to_le32(feat_flag |
> +				       CXL_SET_FEAT_FLAG_INITIATE_DATA_TRANSFER);
> +		data_in_size = cxl_mbox->payload_size - hdr_size;
> +	}
> +
> +	do {
> +		pi->hdr.offset = cpu_to_le16(offset + data_sent_size);
> +		memcpy(pi->feat_data, feat_data + data_sent_size, data_in_size);
> +		mbox_cmd = (struct cxl_mbox_cmd) {
> +			.opcode = CXL_MBOX_OP_SET_FEATURE,
> +			.size_in = hdr_size + data_in_size,
> +			.payload_in = pi,
> +		};
> +		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
> +		if (rc < 0) {
> +			if (return_code)
> +				*return_code = mbox_cmd.return_code;
> +			return rc;
> +		}
> +
> +		data_sent_size += data_in_size;
> +		if (data_sent_size >= feat_data_size) {
> +			if (return_code)
> +				*return_code = CXL_MBOX_CMD_RC_SUCCESS;
> +			return 0;
> +		}
> +
> +		if ((feat_data_size - data_sent_size) <= (cxl_mbox->payload_size - hdr_size)) {
> +			data_in_size = feat_data_size - data_sent_size;
> +			pi->hdr.flags = cpu_to_le32(feat_flag |
> +					       CXL_SET_FEAT_FLAG_FINISH_DATA_TRANSFER);
> +		} else {
> +			pi->hdr.flags = cpu_to_le32(feat_flag |
> +					       CXL_SET_FEAT_FLAG_CONTINUE_DATA_TRANSFER);
> +		}
> +	} while (true);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_set_feature, "CXL");

Re: [PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:42:01 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add fwctl support code to allow sending of CXL feature commands from
> userspace through as ioctls via FWCTL. Provide initial setup bits.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Associate FWCTL with the 'cxl_memdev' through the memdev driver. (Dan)
> - I'm leaving Jonathan's tag off to get this looked at again.
Wise move ;)  Comments inline.  Mind you I'm rereading the lot
as been off a few days and this is all gone from my head!



> diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
> index 82598a409acc..2dcfefdfa6b3 100644
> --- a/drivers/cxl/features.c
> +++ b/drivers/cxl/features.c

>  
> +/* The __weak symbol gets replaced by FWCTL allocation function in fwctl.c */
> +struct cxl_features_state * __weak devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
> +{
> +	struct device *dev = &cxlmd->dev;
> +	struct cxl_features_state *cxlfs =
> +		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +
> +	if (!cxlfs)
> +		return ERR_PTR(-ENOMEM);
This is returning an error pointer, but the DEFINE FREE assumes
NULL I think for the failed to allocate case. Or just return NULL
and don't modify that.

> +
> +	cxlfs->cxlmd = cxlmd;
> +
> +	return cxlfs;
> +}
> +
> +/* The __weak symbol gets replaced by FWCTL free function in fwctl.c */
> +void __weak devm_cxlfs_free(struct cxl_memdev *cxlmd)
> +{
> +	devm_kfree(&cxlmd->dev, cxlmd->cxlfs);
> +	cxlmd->cxlfs = NULL;

This missing clear of hanging pointer I mentioned back in earlier patch.

> +}
> +
>  static void cxl_cxlfs_free(struct cxl_features_state *cxlfs)
>  {
> -	struct device *dev = &cxlfs->cxlmd->dev;
> -
> -	devm_kfree(dev, cxlfs);
> +	devm_cxlfs_free(cxlfs->cxlmd);
>  }
>  
>  DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))
> @@ -185,15 +208,13 @@ DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) cxl_cxlfs_free(_T))

As above, needs to be if (!IS_ERR_OR_NULL(_T)) I think.

>   */
>  int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>  {
> -	struct device *dev = &cxlmd->dev;
>  	int rc;
>  
>  	struct cxl_features_state *cxlfs __free(free_cxlfs) =
> -		devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
> +		devm_cxlfs_allocate(cxlmd);

As per early comments. I'd drag this much earlier in the series
though make only add the __weak markings and comments in this
patch.  That will reduce churn.

>  	if (!cxlfs)
>  		return -ENOMEM;
>  
> -	cxlfs->cxlmd = cxlmd;
>  	enumerate_feature_cmds(cxlmd, cxlfs);
>  	rc = get_supported_features(cxlmd, cxlfs);
>  	if (rc)
> @@ -204,3 +225,5 @@ int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>  	return 0;
>  }
>  EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");
> +
> +MODULE_IMPORT_NS("CXL");

> diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
> new file mode 100644
> index 000000000000..d8fd68ac8982
> --- /dev/null
> +++ b/drivers/cxl/fwctl.c
> @@ -0,0 +1,88 @@

> +static void remove_cxlfs(void *_cxlfs)
> +{
> +	struct cxl_features_state *cxlfs = _cxlfs;
> +	struct cxl_memdev *cxlmd = cxlfs->cxlmd;
> +	struct fwctl_device *fwctl = &cxlfs->fwctl;
> +
> +	cxlmd->cxlfs = NULL;

This is a little nasty.  Originally set in enumerate commands, so not
obvious it should be unwound down in here. Perhaps a comment is
enough.

> +	fwctl_unregister(fwctl);
> +	fwctl_put(fwctl);
> +}
> +
> +DEFINE_FREE(free_cxlfs, struct cxl_features_state *, if (_T) fwctl_put(&_T->fwctl))
> +
> +static struct cxl_features_state *
> +__devm_cxl_cfs_allocate(struct cxl_memdev *cxlmd, const struct fwctl_ops *ops)
> +{
> +	struct device *dev = &cxlmd->dev;
> +	int rc;
> +
> +	struct cxl_features_state *cxlfs __free(free_cxlfs) =
> +		fwctl_alloc_device(dev, ops, struct cxl_features_state, fwctl);
> +	if (!cxlfs)
> +		return ERR_PTR(-ENOMEM);

As above, the caller of this is used with __free that is assuming NULL
for failed.

> +
> +	cxlfs->cxlmd = cxlmd;
> +	rc = fwctl_register(&cxlfs->fwctl);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	rc = devm_add_action_or_reset(dev, remove_cxlfs, cxlfs);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	return no_free_ptr(cxlfs);
> +}

This use of weak functions is a bit too clever for me to be entirely happy but it
seems right so fair enough.

> +
> +struct cxl_features_state *devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
> +{
> +	return __devm_cxl_cfs_allocate(cxlmd, &cxlctl_ops);
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxlfs_allocate, "CXL");
> +
> +void devm_cxlfs_free(struct cxl_memdev *cxlmd)
> +{
> +	devm_release_action(&cxlmd->dev, remove_cxlfs, cxlmd);
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxlfs_free, "CXL");
> +
> +MODULE_IMPORT_NS("FWCTL");

Re: [PATCH v2 09/16] cxl: Add support for FWCTL get driver information callback

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:42:02 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add definition for fwctl_ops->info() to return driver information. The
> function will return a data structure with a reserved u32. This is setup
> for future usages.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

> diff --git a/include/uapi/fwctl/cxl.h b/include/uapi/fwctl/cxl.h
> new file mode 100644
> index 000000000000..4e766ffb1388
> --- /dev/null
> +++ b/include/uapi/fwctl/cxl.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Copyright (c) 2024, Intel Corporation
> + *
> + * These are definitions for the mailbox command interface of CXL subsystem.
> + */
> +#ifndef _UAPI_FWCTL_CXL_H_
> +#define _UAPI_FWCTL_CXL_H_
> +
> +#include <linux/types.h>
> +
> +/**
> + * struct fwctl_info_cxl - ioctl(FWCTL_INFO) out_device_data
> + * @reserved: Place older for future usages
holder.  Freudian slip?
 :)
> + */
> +struct fwctl_info_cxl {
> +	__u32 reserved;
> +};
> +#endif

Re: [PATCH v2 11/16] cxl: Add support for fwctl RPC command to enable CXL feature commands

[Jonathan Cameron]

On Fri, 31 Jan 2025 17:42:04 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> fwctl provides a fwctl_ops->fw_rpc() callback in order to issue ioctls
> to a device. The cxl fwctl driver will start by supporting the CXL
> feature commands: Get Supported Features, Get Feature, and Set Feature.
> 
> The fw_rpc() callback provides 'enum fwctl_rpc_scope' parameter where
> it indicates the security scope of the call. The Get Supported Features
> and Get Feature calls can be executed with the scope of
> FWCTL_RPC_CONFIGRATION. The Set Feature call is gated by the effects
> of the feature reported by Get Supported Features call for the specific
> feature.
> 
> Only "get supported features" is supported in this patch. Additional
> commands will be added in follow on patches. "Get supported features"
> will filter the features that are exclusive to the kernel and only
> report out features that are not kernel only.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v2:
> - Return -EINVAL for get_support_feature_info() instead of -ENOENT. (Dan)
> - Set set_feat_size to 0 for kernel exclusive features.
> - Just don't bother checking the valid (9) bit. (Dan)
> - Reject if the reserved bits are set. (Dan)

A few minor things inline.  Main ones are things that should
be in earlier patches to reduce noise in this one.

Jonathan


> diff --git a/drivers/cxl/fwctl.c b/drivers/cxl/fwctl.c
> index b7984c98645c..93c6174ded20 100644
> --- a/drivers/cxl/fwctl.c
> +++ b/drivers/cxl/fwctl.c
> @@ -35,11 +35,209 @@ static void *cxlctl_info(struct fwctl_uctx *uctx, size_t *length)
>  	return info;
>  }

> +
> +static void *cxlctl_get_supported_features(struct cxl_features_state *cxlfs,
> +					   const struct fwctl_rpc_cxl *rpc_in,
> +					   size_t *out_len)
> +{
> +	struct cxl_mbox_get_sup_feats_out *feat_out;
> +	struct cxl_mbox_get_sup_feats_in feat_in;
> +	struct cxl_feat_entry *pos;
> +	int requested, copied;
> +	size_t out_size;
> +	u32 count;
> +	u16 start;
> +
> +	if (rpc_in->op_size != sizeof(feat_in))
> +		return ERR_PTR(-EINVAL);
> +
> +	if (copy_from_user(&feat_in, u64_to_user_ptr(rpc_in->in_payload),
> +			   rpc_in->op_size))
> +		return ERR_PTR(-EFAULT);
> +
> +	count = le32_to_cpu(feat_in.count);
> +	start = le16_to_cpu(feat_in.start_idx);
> +	requested = count / sizeof(*pos);
> +
> +	/*
> +	 * Make sure that the total requested number of entries is not greater
> +	 * than the total number of supported features allowed for userspace.
> +	 */
> +	if (start >= cxlfs->num_user_features)
> +		return ERR_PTR(-EINVAL);
> +
> +	requested = min_t(int, requested, cxlfs->num_user_features - start);
> +
> +	out_size = sizeof(struct fwctl_rpc_cxl_out) + sizeof(*feat_out) +
> +		   requested * sizeof(*pos);
Pity we don't have a pointer to rpc_out until next line, otherwise
could do
	out_size = struct_size(rpc_out, payload,
			       struct_size(feat_out, ents, requested));

Maybe still worth
	out_size = sizeof(struct fwctl_rpc_cxl_out) +
		struct_size(feat_out, ents, requested);
Whilst pos is the right type, it isn't anything in particular in
some code paths so this just seems odd.
 
> +
> +	struct fwctl_rpc_cxl_out *rpc_out __free(kvfree) =
> +		kvzalloc(out_size, GFP_KERNEL);
> +	if (!rpc_out)
> +		return ERR_PTR(-ENOMEM);
> +
> +	rpc_out->size = sizeof(*feat_out) + requested * sizeof(*pos);

	struct_size for this one.

> +	feat_out = (struct cxl_mbox_get_sup_feats_out *)rpc_out->payload;
> +	if (requested == 0) {
> +		feat_out->num_entries = cpu_to_le16(requested);
> +		feat_out->supported_feats =
> +			cpu_to_le16(cxlfs->num_user_features);
> +		rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
> +		*out_len = out_size;
> +		return no_free_ptr(rpc_out);
> +	}
> +
> +	pos = &feat_out->ents[0];
> +
> +	copied = 0;
> +	for (int i = 0; i < cxlfs->num_features; i++, pos++) {
	for (int i = 0, copied = 0, pos = &feat_out->ents[0],
	     i < cxlfs->num_features; i++, pos++)

perhaps, or maybe keep copied outside given it's not adjusted
in the loops control.
 
> +		memcpy(pos, &cxlfs->entries[i], sizeof(*pos));
> +		/*
> +		 * If the feature is exclusive, set the set_feat_size to 0 to
> +		 * indicate that the feature is not changeable.
> +		 */
> +		if (is_cxl_feature_exclusive(pos))
> +			pos->set_feat_size = 0;
> +
> +		copied++;
Could move copied alongside pos++ in the loop definition and
this check to the start of the loop.

I don't mind on these changes.  That loop will get very
fiddly.


> +		if (copied == requested)
> +			break;
> +	}
> +
> +	feat_out->num_entries = cpu_to_le16(requested);
> +	feat_out->supported_feats = cpu_to_le16(cxlfs->num_features);
> +	rpc_out->retval = CXL_MBOX_CMD_RC_SUCCESS;
> +	*out_len = out_size;
> +
> +	return no_free_ptr(rpc_out);
> +}


> +
>  static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
> -			   void *rpc_in, size_t in_len, size_t *out_len)
> +			   void *in, size_t in_len, size_t *out_len)

Push renames back to where the stub was introduced.
Reduces noise as I doubt anyone minds them!

>  {
> -	/* Place holder */
> -	return ERR_PTR(-EOPNOTSUPP);
> +	struct fwctl_device *fwctl = uctx->fwctl;
> +	struct cxl_features_state *cxlfs = to_cxl_features_state(fwctl);
> +	const struct fwctl_rpc_cxl *rpc_in = in;
> +	u16 opcode;
> +
> +	opcode = cxl_get_feature_command_opcode(rpc_in->command_id);
> +	if (opcode == 0xffff)
> +		return ERR_PTR(-EINVAL);
> +
> +	if (!cxlctl_validate_hw_command(cxlfs, rpc_in, scope, opcode))
> +		return ERR_PTR(-EINVAL);
> +
> +	return cxlctl_handle_commands(cxlfs, rpc_in, out_len, opcode);
>  }
>  
>  static const struct fwctl_ops cxlctl_ops = {
> diff --git a/include/cxl/features.h b/include/cxl/features.h
> index eb13d7ee64f0..f43aa761a7ee 100644
> --- a/include/cxl/features.h
> +++ b/include/cxl/features.h
> @@ -42,14 +42,6 @@
>  
>  struct cxl_mailbox;
>  
> -/* Index IDs for CXL mailbox Feature commands */
> -enum feature_cmds {
> -	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
> -	CXL_FEATURE_ID_GET_FEATURE,
> -	CXL_FEATURE_ID_SET_FEATURE,
> -	CXL_FEATURE_ID_MAX
> -};
> -
>  /* Feature commands capability supported by a device */
>  enum cxl_features_capability {
>  	CXL_FEATURES_NONE = 0,
> @@ -83,5 +75,6 @@ size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
>  int cxl_set_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
>  		    u8 feat_version, void *feat_data, size_t feat_data_size,
>  		    u32 feat_flag, u16 offset, u16 *return_code);
> +bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry);

Why not put it here directly in patch 7?
Isn't it defined in two places after this patch?


>  
>  #endif

Re: [PATCH v2 16/16] fwctl/cxl: Add documentation to FWCTL CXL

[Jonathan Cameron]

One minor comment.  With a sentence added on that (assuming I didn't miss
it somewhere)
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> diff --git a/Documentation/userspace-api/fwctl/fwctl-cxl.rst b/Documentation/userspace-api/fwctl/fwctl-cxl.rst
> new file mode 100644
> index 000000000000..8d9aeb77bc6d
> --- /dev/null
> +++ b/Documentation/userspace-api/fwctl/fwctl-cxl.rst
> @@ -0,0 +1,135 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +================
> +fwctl cxl driver
> +================
> +
> +:Author: Dave Jiang
> +
> +Overview
> +========
> +
> +The CXL spec defines a set of commands that can be issued to the mailbox of a
> +CXL device or switch. It also left room for vendor specific commands to be
> +issued to the mailbox as well. fwctl provides a path to issue a set of allowed
> +mailbox commands from user space to the device moderated by the kernel driver.
> +
> +The following 3 commands will be used to support CXL Features:
> +CXL spec r3.1 8.2.9.6.1 Get Supported Features (Opcode 0500h)
> +CXL spec r3.1 8.2.9.6.2 Get Feature (Opcode 0501h)
> +CXL spec r3.1 8.2.9.6.3 Set Feature (Opcode 0502h)
> +
> +The "Get Supported Features" return data may be filtered by the kernel driver to
> +drop any features that are forbidden by the kernel or being exclusively used by
> +the kernel. The "Get Supported Features" command and the "Get Features" falls
> +under the fwctl policy of FWCTL_RPC_CONFIGURATION.

Document what 'filtered' means given change to zero sized set?

> +
> +For "Set Feature" command, the access policy currently is broken down into two
> +categories depending on the Set Feature effects reported by the device. If the
> +Set Feature will cause immediate change to the device, the fwctl access policy
> +must be FWCTL_RPC_DEBUG_WRITE_FULL. The effects for this level are
> +"immediate config change", "immediate data change", "immediate policy change",
> +or "immediate log change" for the set effects mask. If the effects are "config
> +change with cold reset" or "config change with conventional reset", then the
> +fwctl access policy must be FWCTL_RPC_DEBUG_WRITE or higher.

Re: [PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Jason Gunthorpe]

On Mon, Feb 03, 2025 at 12:42:32PM +0000, Jonathan Cameron wrote:

> > diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
> > index 82598a409acc..2dcfefdfa6b3 100644
> > --- a/drivers/cxl/features.c
> > +++ b/drivers/cxl/features.c
> 
> >  
> > +/* The __weak symbol gets replaced by FWCTL allocation function in fwctl.c */
> > +struct cxl_features_state * __weak devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
> > +{

> This use of weak functions is a bit too clever for me to be entirely happy but it
> seems right so fair enough.

weak functions have become frowned upon lately and I can't clearly see
why you'd want this? Can you do it without it please?

Jason

Re: [PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Dave Jiang]

On 2/3/25 7:25 AM, Jason Gunthorpe wrote:
> On Mon, Feb 03, 2025 at 12:42:32PM +0000, Jonathan Cameron wrote:
> 
>>> diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
>>> index 82598a409acc..2dcfefdfa6b3 100644
>>> --- a/drivers/cxl/features.c
>>> +++ b/drivers/cxl/features.c
>>
>>>  
>>> +/* The __weak symbol gets replaced by FWCTL allocation function in fwctl.c */
>>> +struct cxl_features_state * __weak devm_cxlfs_allocate(struct cxl_memdev *cxlmd)
>>> +{
> 
>> This use of weak functions is a bit too clever for me to be entirely happy but it
>> seems right so fair enough.
> 
> weak functions have become frowned upon lately and I can't clearly see
> why you'd want this? Can you do it without it please?

The intent is to allow the allocation function to be replaced with the FWCTL version when CONFIG_CXL_FWCTL is set. I'll think about how to do this differently. I was really trying to avoid doing #ifdef in the C file. 
 
> 
> Jason

Re: [PATCH v2 08/16] cxl: Add FWCTL support to the CXL memdev driver

[Jason Gunthorpe]

On Mon, Feb 03, 2025 at 09:22:48AM -0700, Dave Jiang wrote:

> The intent is to allow the allocation function to be replaced with
> the FWCTL version when CONFIG_CXL_FWCTL is set. I'll think about how
> to do this differently. I was really trying to avoid doing #ifdef in
> the C file.

Use an #ifdef (maybe wrapped in an inline function or something), it
is much, much better

Jason

Re: [PATCH v2 02/16] cxl: Enumerate feature commands

[Dave Jiang]

On 2/3/25 5:06 AM, Jonathan Cameron wrote:
> On Fri, 31 Jan 2025 17:41:55 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>> Add feature commands enumeration code in order to detect and enumerate
>> the 3 feature related commands "get supported features", "get feature",
>> and "set feature". The enumeration will help determine whether the driver
>> can issue any of the 3 commands to the device.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>> v2:
>> - Setup allocation of cxlfs and move enumeration of commands to
>>   the setup function.
>> - Introduce features_capability enum. (Dan)
>> - Name the setup function devm_cxl_add_features(). (Dan)
>> - Drop 'cxl_mem_command' support. (Dan)
>> - Move feature support to mem probe. (Dan)
>> - Remove comma at last entry of data structs. (Jonathan)
> Got carried away on this one.   Only drop them for termination
> entries.  So MAX or NULL or similar.
> 
>> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
>> index bdb8f060f2c1..25fb7bd770b3 100644
>> --- a/drivers/cxl/core/mbox.c
>> +++ b/drivers/cxl/core/mbox.c
>> @@ -69,6 +69,29 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
>>  	CXL_CMD(GET_TIMESTAMP, 0, 0x8, 0),
>>  };
>>  
>> +static u16 cxl_feature_commands[] = {
>> +	CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
>> +	CXL_MBOX_OP_GET_FEATURE,
>> +	CXL_MBOX_OP_SET_FEATURE
> 
> This one does want a trailing comma. Might be more feature commands in future.

ok

> 
>> +};
> 
>> diff --git a/drivers/cxl/features.c b/drivers/cxl/features.c
>> new file mode 100644
>> index 000000000000..13b0b29ee102
>> --- /dev/null
>> +++ b/drivers/cxl/features.c
>> @@ -0,0 +1,55 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
>> +#include <linux/device.h>
>> +#include <cxl/mailbox.h>
>> +#include <cxl/features.h>
>> +#include "cxl.h"
>> +#include "cxlmem.h"
>> +#include "features.h"
>> +
>> +static void enumerate_feature_cmds(struct cxl_memdev *cxlmd)
>> +{
>> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>> +	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
>> +	struct cxl_features_state *cxlfs = cxlds->cxlmd->cxlfs;
> Going in circles?
> 	cxlmd->cxlfs;

yeah oops. should be cleaned up with the other changes going on in this patch

> 
> 
>> +	int fid;
>> +
>> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_SUPPORTED_FEATURES);
>> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
>> +		return;
>> +
>> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_GET_FEATURE);
>> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
>> +		return;
>> +
>> +	cxlfs->cap = CXL_FEATURES_RO;
>> +
>> +	fid = cxl_get_feature_command_id(CXL_MBOX_OP_SET_FEATURE);
>> +	if (!test_bit(fid, cxl_mbox->feature_cmds))
>> +		return;
>> +
>> +	cxlfs->cap = CXL_FEATURES_RW;
>> +}
>> +
>> +/**
>> + * devm_cxl_add_features() - Allocate and initialize features context
>> + * @cxlmd: CXL memory device
>> + *
>> + * Return 0 on success or -errno on failure.
>> + */
>> +int devm_cxl_add_features(struct cxl_memdev *cxlmd)
>> +{
>> +	struct cxl_features_state *cxlfs;
>> +	struct device *dev = &cxlmd->dev;
>> +
>> +	cxlfs = devm_kzalloc(dev, sizeof(*cxlfs), GFP_KERNEL);
>> +	if (!cxlfs)
>> +		return -ENOMEM;
>> +
>> +	cxlmd->cxlfs = cxlfs;
> 
> So I was curious about this one and why we leave the pointer
> hanging in the remove path + whether the two way pointer nest
> is needed.
> 
> That gets dealt with in patch 8.
> 
> I'd be tempted to drag the bones of dev_cxlfs_allocate() to this
> patch so that you can do that cleanup now and avoid some of the churn
> of the later patches.

ok I'll do that. 

> 
> As for the two way pointer nest. I'm not sure it is needed.
> Seems like most if not all places we use cxlmd->cxlfs have
> just gotten it in the caller from cxlfs->cxlmd.
> e.g. cxl_cxlfs_free() in patch 8. For here we could
> just pass it into enumerate_feature_cmds.
> 
> Maybe Shiju's set needs it. I haven't checked.

I think he does with calling of cxl_get_supported_feature_entry(). Need a way to go from cxlmd to cxlfs.
> 
> 
> 
> 
>> +	cxlfs->cxlmd = cxlmd;
>> +	enumerate_feature_cmds(cxlmd);
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(devm_cxl_add_features, "CXL");
> 
>> diff --git a/include/cxl/features.h b/include/cxl/features.h
>> new file mode 100644
>> index 000000000000..eadf0d56553f
>> --- /dev/null
>> +++ b/include/cxl/features.h
>> @@ -0,0 +1,35 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/* Copyright(c) 2024-2025 Intel Corporation. */
>> +#ifndef __CXL_FEATURES_H__
>> +#define __CXL_FEATURES_H__
>> +
>> +struct cxl_mailbox;
>> +
>> +/* Index IDs for CXL mailbox Feature commands */
>> +enum feature_cmds {
>> +	CXL_FEATURE_ID_GET_SUPPORTED_FEATURES = 0,
>> +	CXL_FEATURE_ID_GET_FEATURE,
>> +	CXL_FEATURE_ID_SET_FEATURE,
>> +	CXL_FEATURE_ID_MAX
>> +};
>> +
>> +/* Feature commands capability supported by a device */
>> +enum cxl_features_capability {
>> +	CXL_FEATURES_NONE = 0,
>> +	CXL_FEATURES_RO,
>> +	CXL_FEATURES_RW
> 
> Trivial but this one should have a trailing comma.  Maybe
> we'll have a write only one!  Anyhow, it's not a terminating
> entry so we shouldn't assume nothing comes after it.

ok

> 
>> +};
>> +
>> +/**
>> + * struct cxl_features_state - The Features state for the device
>> + * @cxlmd: Pointer to cxl mem device
>> + * @cap: Feature commands capability
>> + * @num_features: total Features supported by the device
>> + */
>> +struct cxl_features_state {
>> +	struct cxl_memdev *cxlmd;
>> +	enum cxl_features_capability cap;
>> +	int num_features;
>> +};
>> +
>> +#endif
>