cxl/mem: Add a "RAW" send command

The CXL memory device send interface will have a number of supported commands. The raw command is not such a command. Raw commands allow userspace to send a specified opcode to the underlying hardware and bypass all driver checks on the command. The primary use for this command is to [begrudgingly] allow undocumented vendor specific hardware commands. While not the main motivation, it also allows prototyping new hardware commands without a driver patch and rebuild. While this all sounds very powerful it comes with a couple of caveats: 1. Bug reports using raw commands will not get the same level of attention as bug reports using supported commands (via taint). 2. Supported commands will be rejected by the RAW command. With this comes new debugfs knob to allow full access to your toes with your weapon of choice.

Ben Widawsky committed 5 years ago

Commit 13237181 parent 583fa5e3 files · +161 −1Browse files

Showing the changes to include/uapi (1 of 3 files). Show all

Unified · Split

include/uapi/linux/cxl_mem.h+11−1

@@ -22,6 +22,7 @@ · 21 unmodified lines
22	22	#define CXL_CMDS \
23	23	___C(INVALID, "Invalid Command"), \
24	24	___C(IDENTIFY, "Identify Command"), \
	25	+ ___C(RAW, "Raw device command"), \
25	26	___C(MAX, "invalid / last command")
26	27
27	28	#define ___C(a, b) CXL_MEM_COMMAND_ID_##a
@@ -115,6 +116,9 @@ struct cxl_mem_query_commands { · 87 unmodified lines
115	116	* @id: The command to send to the memory device. This must be one of the
116	117	* commands returned by the query command.
117	118	* @flags: Flags for the command (input).
	119	+ * @raw: Special fields for raw commands
	120	+ * @raw.opcode: Opcode passed to hardware when using the RAW command.
	121	+ * @raw.rsvd: Must be zero.
118	122	* @rsvd: Must be zero.
119	123	* @retval: Return value from the memory device (output).
120	124	* @in: Parameters associated with input payload.
@@ -137,7 +141,13 @@ struct cxl_mem_query_commands { · 16 unmodified lines
137	141	struct cxl_send_command {
138	142	__u32 id;
139	143	__u32 flags;
140		− __u32 rsvd;
	144	+ union {
	145	+ struct {
	146	+ __u16 opcode;
	147	+ __u16 rsvd;
	148	+ } raw;
	149	+ __u32 rsvd;
	150	+ };
141	151	__u32 retval;
142	152
143	153	struct {