cxl/mbox: Enable cxl_mbox_send_cmd() users to validate output size

Internally cxl_mbox_send_cmd() converts all passed-in parameters to a
'struct cxl_mbox_cmd' instance and sends that to cxlds->mbox_send(). It
then teases the possibilty that the caller can validate the output size.
However, they cannot since the resulting output size is not conveyed to
the called. Fix that by making the caller pass in a constructed 'struct
cxl_mbox_cmd'. This prepares for a future patch to add output size
validation on a per-command basis.

Given the change in signature, also change the name to differentiate it
from the user command submission path that performs more validation
before generating the 'struct cxl_mbox_cmd' instance to execute.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/167030055370.4044561.17788093375112783036.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 52 insertions, 34 deletions

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 35dd889f1d3a..ed451ca60ce5 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -146,13 +146,9 @@ static const char *cxl_mem_opcode_to_name(u16 opcode)
 }
 
 /**
- * cxl_mbox_send_cmd() - Send a mailbox command to a device.
+ * cxl_internal_send_cmd() - Kernel internal interface to send a mailbox command
  * @cxlds: The device data for the operation
- * @opcode: Opcode for the mailbox command.
- * @in: The input payload for the mailbox command.
- * @in_size: The length of the input payload
- * @out: Caller allocated buffer for the output.
- * @out_size: Expected size of output.
+ * @mbox_cmd: initialized command to execute
  *
  * Context: Any context.
  * Return:
@@ -167,40 +163,37 @@ static const char *cxl_mem_opcode_to_name(u16 opcode)
  * error. While this distinction can be useful for commands from userspace, the
  * kernel will only be able to use results when both are successful.
  */
-int cxl_mbox_send_cmd(struct cxl_dev_state *cxlds, u16 opcode, void *in,
-		      size_t in_size, void *out, size_t out_size)
+int cxl_internal_send_cmd(struct cxl_dev_state *cxlds,
+			  struct cxl_mbox_cmd *mbox_cmd)
 {
-	const struct cxl_mem_command *cmd = cxl_mem_find_command(opcode);
-	struct cxl_mbox_cmd mbox_cmd = {
-		.opcode = opcode,
-		.payload_in = in,
-		.size_in = in_size,
-		.size_out = out_size,
-		.payload_out = out,
-	};
+	const struct cxl_mem_command *cmd =
+		cxl_mem_find_command(mbox_cmd->opcode);
+	size_t out_size;
 	int rc;
 
-	if (in_size > cxlds->payload_size || out_size > cxlds->payload_size)
+	if (mbox_cmd->size_in > cxlds->payload_size ||
+	    mbox_cmd->size_out > cxlds->payload_size)
 		return -E2BIG;
 
-	rc = cxlds->mbox_send(cxlds, &mbox_cmd);
+	out_size = mbox_cmd->size_out;
+	rc = cxlds->mbox_send(cxlds, mbox_cmd);
 	if (rc)
 		return rc;
 
-	if (mbox_cmd.return_code != CXL_MBOX_CMD_RC_SUCCESS)
-		return cxl_mbox_cmd_rc2errno(&mbox_cmd);
+	if (mbox_cmd->return_code != CXL_MBOX_CMD_RC_SUCCESS)
+		return cxl_mbox_cmd_rc2errno(mbox_cmd);
 
 	/*
 	 * Variable sized commands can't be validated and so it's up to the
 	 * caller to do that if they wish.
 	 */
 	if (cmd->info.size_out != CXL_VARIABLE_PAYLOAD) {
-		if (mbox_cmd.size_out != out_size)
+		if (mbox_cmd->size_out != out_size)
 			return -EIO;
 	}
 	return 0;
 }
-EXPORT_SYMBOL_NS_GPL(cxl_mbox_send_cmd, CXL);
+EXPORT_SYMBOL_NS_GPL(cxl_internal_send_cmd, CXL);
 
 static bool cxl_mem_raw_command_allowed(u16 opcode)
 {
@@ -567,15 +560,25 @@ static int cxl_xfer_log(struct cxl_dev_state *cxlds, uuid_t *uuid, u32 size, u8
 
 	while (remaining) {
 		u32 xfer_size = min_t(u32, remaining, cxlds->payload_size);
-		struct cxl_mbox_get_log log = {
+		struct cxl_mbox_cmd mbox_cmd;
+		struct cxl_mbox_get_log log;
+		int rc;
+
+		log = (struct cxl_mbox_get_log) {
 			.uuid = *uuid,
 			.offset = cpu_to_le32(offset),
-			.length = cpu_to_le32(xfer_size)
+			.length = cpu_to_le32(xfer_size),
+		};
+
+		mbox_cmd = (struct cxl_mbox_cmd) {
+			.opcode = CXL_MBOX_OP_GET_LOG,
+			.size_in = sizeof(log),
+			.payload_in = &log,
+			.size_out = xfer_size,
+			.payload_out = out,
 		};
-		int rc;
 
-		rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_GET_LOG, &log, sizeof(log),
-				       out, xfer_size);
+		rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
 		if (rc < 0)
 			return rc;
 
@@ -621,19 +624,25 @@ static void cxl_walk_cel(struct cxl_dev_state *cxlds, size_t size, u8 *cel)
 static struct cxl_mbox_get_supported_logs *cxl_get_gsl(struct cxl_dev_state *cxlds)
 {
 	struct cxl_mbox_get_supported_logs *ret;
+	struct cxl_mbox_cmd mbox_cmd;
 	int rc;
 
 	ret = kvmalloc(cxlds->payload_size, GFP_KERNEL);
 	if (!ret)
 		return ERR_PTR(-ENOMEM);
 
-	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_GET_SUPPORTED_LOGS, NULL, 0, ret,
-			       cxlds->payload_size);
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_GET_SUPPORTED_LOGS,
+		.size_out = cxlds->payload_size,
+		.payload_out = ret,
+	};
+	rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
 	if (rc < 0) {
 		kvfree(ret);
 		return ERR_PTR(rc);
 	}
 
+
 	return ret;
 }
 
@@ -735,11 +744,15 @@ EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL);
 static int cxl_mem_get_partition_info(struct cxl_dev_state *cxlds)
 {
 	struct cxl_mbox_get_partition_info pi;
+	struct cxl_mbox_cmd mbox_cmd;
 	int rc;
 
-	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_GET_PARTITION_INFO, NULL, 0,
-			       &pi, sizeof(pi));
-
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_GET_PARTITION_INFO,
+		.size_out = sizeof(pi),
+		.payload_out = &pi,
+	};
+	rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
 	if (rc)
 		return rc;
 
@@ -768,10 +781,15 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
 {
 	/* See CXL 2.0 Table 175 Identify Memory Device Output Payload */
 	struct cxl_mbox_identify id;
+	struct cxl_mbox_cmd mbox_cmd;
 	int rc;
 
-	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_IDENTIFY, NULL, 0, &id,
-			       sizeof(id));
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_IDENTIFY,
+		.size_out = sizeof(id),
+		.payload_out = &id,
+	};
+	rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
 	if (rc < 0)
 		return rc;