[PATCH v3 3/4] cxl/uapi: Tag commands from cxl_query_cmd()

[Ira Weiny <ira.weiny@intel.com>]

It was pointed out that commands not supported by the device or excluded
by the kernel were being returned in cxl_query_cmd().[1]

While libcxl correctly handles failing commands, it is more efficient to
not issue an invalid command in the first place.  This can't be done
without additional information being returned from cxl_query_cmd().  In
addition, information about the availability of commands can be useful
for debugging.

Add flags to struct cxl_command_info which reflect if a command is
enabled and/or exclusive to the kernel.

[1] https://lore.kernel.org/all/63b4ec4e37cc1_5178e2941d@dwillia2-xfh.jf.intel.com.notmuch/

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes for v3:
	Dan
		Pass enabled/exclusive flags to user space rather than
		masking those commands.
---
 drivers/cxl/core/mbox.c      | 9 +++++++--
 include/uapi/linux/cxl_mem.h | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index b03fba212799..6ab4613f3cf9 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -445,9 +445,14 @@ int cxl_query_cmd(struct cxl_memdev *cxlmd,
 	 * structures.
 	 */
 	cxl_for_each_cmd(cmd) {
-		const struct cxl_command_info *info = &cmd->info;
+		struct cxl_command_info info = cmd->info;
 
-		if (copy_to_user(&q->commands[j++], info, sizeof(*info)))
+		if (test_bit(info.id, cxlmd->cxlds->enabled_cmds))
+			info.flags |= CXL_MEM_COMMAND_FLAG_ENABLED;
+		if (test_bit(info.id, cxlmd->cxlds->exclusive_cmds))
+			info.flags |= CXL_MEM_COMMAND_FLAG_EXCLUSIVE;
+
+		if (copy_to_user(&q->commands[j++], &info, sizeof(info)))
 			return -EFAULT;
 
 		if (j == n_commands)
diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
index 459a3f7f764b..4aee64b7cc1a 100644
--- a/include/uapi/linux/cxl_mem.h
+++ b/include/uapi/linux/cxl_mem.h
@@ -91,7 +91,9 @@ struct cxl_command_info {
 	__u32 id;
 
 	__u32 flags;
-#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(0, 0)
+#define CXL_MEM_COMMAND_FLAG_MASK		GENMASK(1, 0)
+#define CXL_MEM_COMMAND_FLAG_ENABLED		BIT(0)
+#define CXL_MEM_COMMAND_FLAG_EXCLUSIVE		BIT(1)
 
 	__u32 size_in;
 	__u32 size_out;

-- 
2.39.1