[ 031/100] iwlwifi: always copy first 16 bytes of commands

[Greg Kroah-Hartman]

3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@xxxxxxxxx>

commit 8a964f44e01ad3bbc208c3e80d931ba91b9ea786 upstream.

The FH hardware will always write back to the scratch field
in commands, even host commands not just TX commands, which
can overwrite parts of the command. This is problematic if
the command is re-used (with IWL_HCMD_DFL_NOCOPY) and can
cause calibration issues.

Address this problem by always putting at least the first
16 bytes into the buffer we also use for the command header
and therefore make the DMA engine write back into this.

For commands that are smaller than 16 bytes also always map
enough memory for the DMA engine to write back to.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/wireless/iwlwifi/iwl-devtrace.h  |   10 +--
 drivers/net/wireless/iwlwifi/pcie/internal.h |    9 +++
 drivers/net/wireless/iwlwifi/pcie/tx.c       |   75 ++++++++++++++++++++-------
 3 files changed, 71 insertions(+), 23 deletions(-)

--- a/drivers/net/wireless/iwlwifi/iwl-devtrace.h
+++ b/drivers/net/wireless/iwlwifi/iwl-devtrace.h
@@ -349,25 +349,23 @@ TRACE_EVENT(iwlwifi_dev_rx_data,
 TRACE_EVENT(iwlwifi_dev_hcmd,
 	TP_PROTO(const struct device *dev,
 		 struct iwl_host_cmd *cmd, u16 total_size,
-		 const void *hdr, size_t hdr_len),
-	TP_ARGS(dev, cmd, total_size, hdr, hdr_len),
+		 struct iwl_cmd_header *hdr),
+	TP_ARGS(dev, cmd, total_size, hdr),
 	TP_STRUCT__entry(
 		DEV_ENTRY
 		__dynamic_array(u8, hcmd, total_size)
 		__field(u32, flags)
 	),
 	TP_fast_assign(
-		int i, offset = hdr_len;
+		int i, offset = sizeof(*hdr);
 
 		DEV_ASSIGN;
 		__entry->flags = cmd->flags;
-		memcpy(__get_dynamic_array(hcmd), hdr, hdr_len);
+		memcpy(__get_dynamic_array(hcmd), hdr, sizeof(*hdr));
 
 		for (i = 0; i < IWL_MAX_CMD_TFDS; i++) {
 			if (!cmd->len[i])
 				continue;
-			if (!(cmd->dataflags[i] & IWL_HCMD_DFL_NOCOPY))
-				continue;
 			memcpy((u8 *)__get_dynamic_array(hcmd) + offset,
 			       cmd->data[i], cmd->len[i]);
 			offset += cmd->len[i];
--- a/drivers/net/wireless/iwlwifi/pcie/internal.h
+++ b/drivers/net/wireless/iwlwifi/pcie/internal.h
@@ -182,6 +182,15 @@ struct iwl_queue {
 #define TFD_TX_CMD_SLOTS 256
 #define TFD_CMD_SLOTS 32
 
+/*
+ * The FH will write back to the first TB only, so we need
+ * to copy some data into the buffer regardless of whether
+ * it should be mapped or not. This indicates how much to
+ * copy, even for HCMDs it must be big enough to fit the
+ * DRAM scratch from the TX cmd, at least 16 bytes.
+ */
+#define IWL_HCMD_MIN_COPY_SIZE	16
+
 struct iwl_pcie_txq_entry {
 	struct iwl_device_cmd *cmd;
 	struct iwl_device_cmd *copy_cmd;
--- a/drivers/net/wireless/iwlwifi/pcie/tx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/tx.c
@@ -1131,10 +1131,12 @@ static int iwl_pcie_enqueue_hcmd(struct
 	void *dup_buf = NULL;
 	dma_addr_t phys_addr;
 	int idx;
-	u16 copy_size, cmd_size;
+	u16 copy_size, cmd_size, dma_size;
 	bool had_nocopy = false;
 	int i;
 	u32 cmd_pos;
+	const u8 *cmddata[IWL_MAX_CMD_TFDS];
+	u16 cmdlen[IWL_MAX_CMD_TFDS];
 
 	copy_size = sizeof(out_cmd->hdr);
 	cmd_size = sizeof(out_cmd->hdr);
@@ -1143,8 +1145,23 @@ static int iwl_pcie_enqueue_hcmd(struct
 	BUILD_BUG_ON(IWL_MAX_CMD_TFDS > IWL_NUM_OF_TBS - 1);
 
 	for (i = 0; i < IWL_MAX_CMD_TFDS; i++) {
+		cmddata[i] = cmd->data[i];
+		cmdlen[i] = cmd->len[i];
+
 		if (!cmd->len[i])
 			continue;
+
+		/* need at least IWL_HCMD_MIN_COPY_SIZE copied */
+		if (copy_size < IWL_HCMD_MIN_COPY_SIZE) {
+			int copy = IWL_HCMD_MIN_COPY_SIZE - copy_size;
+
+			if (copy > cmdlen[i])
+				copy = cmdlen[i];
+			cmdlen[i] -= copy;
+			cmddata[i] += copy;
+			copy_size += copy;
+		}
+
 		if (cmd->dataflags[i] & IWL_HCMD_DFL_NOCOPY) {
 			had_nocopy = true;
 			if (WARN_ON(cmd->dataflags[i] & IWL_HCMD_DFL_DUP)) {
@@ -1164,7 +1181,7 @@ static int iwl_pcie_enqueue_hcmd(struct
 				goto free_dup_buf;
 			}
 
-			dup_buf = kmemdup(cmd->data[i], cmd->len[i],
+			dup_buf = kmemdup(cmddata[i], cmdlen[i],
 					  GFP_ATOMIC);
 			if (!dup_buf)
 				return -ENOMEM;
@@ -1174,7 +1191,7 @@ static int iwl_pcie_enqueue_hcmd(struct
 				idx = -EINVAL;
 				goto free_dup_buf;
 			}
-			copy_size += cmd->len[i];
+			copy_size += cmdlen[i];
 		}
 		cmd_size += cmd->len[i];
 	}
@@ -1221,14 +1238,31 @@ static int iwl_pcie_enqueue_hcmd(struct
 
 	/* and copy the data that needs to be copied */
 	cmd_pos = offsetof(struct iwl_device_cmd, payload);
+	copy_size = sizeof(out_cmd->hdr);
 	for (i = 0; i < IWL_MAX_CMD_TFDS; i++) {
-		if (!cmd->len[i])
+		int copy = 0;
+
+		if (!cmd->len)
 			continue;
-		if (cmd->dataflags[i] & (IWL_HCMD_DFL_NOCOPY |
-					 IWL_HCMD_DFL_DUP))
-			break;
-		memcpy((u8 *)out_cmd + cmd_pos, cmd->data[i], cmd->len[i]);
-		cmd_pos += cmd->len[i];
+
+		/* need at least IWL_HCMD_MIN_COPY_SIZE copied */
+		if (copy_size < IWL_HCMD_MIN_COPY_SIZE) {
+			copy = IWL_HCMD_MIN_COPY_SIZE - copy_size;
+
+			if (copy > cmd->len[i])
+				copy = cmd->len[i];
+		}
+
+		/* copy everything if not nocopy/dup */
+		if (!(cmd->dataflags[i] & (IWL_HCMD_DFL_NOCOPY |
+					   IWL_HCMD_DFL_DUP)))
+			copy = cmd->len[i];
+
+		if (copy) {
+			memcpy((u8 *)out_cmd + cmd_pos, cmd->data[i], copy);
+			cmd_pos += copy;
+			copy_size += copy;
+		}
 	}
 
 	WARN_ON_ONCE(txq->entries[idx].copy_cmd);
@@ -1254,7 +1288,14 @@ static int iwl_pcie_enqueue_hcmd(struct
 		     out_cmd->hdr.cmd, le16_to_cpu(out_cmd->hdr.sequence),
 		     cmd_size, q->write_ptr, idx, trans_pcie->cmd_queue);
 
-	phys_addr = dma_map_single(trans->dev, &out_cmd->hdr, copy_size,
+	/*
+	 * If the entire command is smaller than IWL_HCMD_MIN_COPY_SIZE, we must
+	 * still map at least that many bytes for the hardware to write back to.
+	 * We have enough space, so that's not a problem.
+	 */
+	dma_size = max_t(u16, copy_size, IWL_HCMD_MIN_COPY_SIZE);
+
+	phys_addr = dma_map_single(trans->dev, &out_cmd->hdr, dma_size,
 				   DMA_BIDIRECTIONAL);
 	if (unlikely(dma_mapping_error(trans->dev, phys_addr))) {
 		idx = -ENOMEM;
@@ -1262,14 +1303,15 @@ static int iwl_pcie_enqueue_hcmd(struct
 	}
 
 	dma_unmap_addr_set(out_meta, mapping, phys_addr);
-	dma_unmap_len_set(out_meta, len, copy_size);
+	dma_unmap_len_set(out_meta, len, dma_size);
 
 	iwl_pcie_txq_build_tfd(trans, txq, phys_addr, copy_size, 1);
 
+	/* map the remaining (adjusted) nocopy/dup fragments */
 	for (i = 0; i < IWL_MAX_CMD_TFDS; i++) {
-		const void *data = cmd->data[i];
+		const void *data = cmddata[i];
 
-		if (!cmd->len[i])
+		if (!cmdlen[i])
 			continue;
 		if (!(cmd->dataflags[i] & (IWL_HCMD_DFL_NOCOPY |
 					   IWL_HCMD_DFL_DUP)))
@@ -1277,7 +1319,7 @@ static int iwl_pcie_enqueue_hcmd(struct
 		if (cmd->dataflags[i] & IWL_HCMD_DFL_DUP)
 			data = dup_buf;
 		phys_addr = dma_map_single(trans->dev, (void *)data,
-					   cmd->len[i], DMA_BIDIRECTIONAL);
+					   cmdlen[i], DMA_BIDIRECTIONAL);
 		if (dma_mapping_error(trans->dev, phys_addr)) {
 			iwl_pcie_tfd_unmap(trans, out_meta,
 					   &txq->tfds[q->write_ptr],
@@ -1286,7 +1328,7 @@ static int iwl_pcie_enqueue_hcmd(struct
 			goto out;
 		}
 
-		iwl_pcie_txq_build_tfd(trans, txq, phys_addr, cmd->len[i], 0);
+		iwl_pcie_txq_build_tfd(trans, txq, phys_addr, cmdlen[i], 0);
 	}
 
 	out_meta->flags = cmd->flags;
@@ -1296,8 +1338,7 @@ static int iwl_pcie_enqueue_hcmd(struct
 
 	txq->need_update = 1;
 
-	trace_iwlwifi_dev_hcmd(trans->dev, cmd, cmd_size,
-			       &out_cmd->hdr, copy_size);
+	trace_iwlwifi_dev_hcmd(trans->dev, cmd, cmd_size, &out_cmd->hdr);
 
 	/* start timer if queue currently empty */
 	if (q->read_ptr == q->write_ptr && trans_pcie->wd_timeout)


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