Patch "mailbox: ti-msgmgr: Fill non-message tx data fields with 0x0" has been added to the 5.10-stable tree

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This is a note to let you know that I've just added the patch titled

    mailbox: ti-msgmgr: Fill non-message tx data fields with 0x0

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mailbox-ti-msgmgr-fill-non-message-tx-data-fields-wi.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fa372120604ab979ca8e1579a6a76715f8d63feb
Author: Nishanth Menon <nm@xxxxxx>
Date:   Tue Jun 20 20:00:22 2023 -0500

    mailbox: ti-msgmgr: Fill non-message tx data fields with 0x0
    
    [ Upstream commit 1b712f18c461bd75f018033a15cf381e712806b5 ]
    
    Sec proxy/message manager data buffer is 60 bytes with the last of the
    registers indicating transmission completion. This however poses a bit
    of a challenge.
    
    The backing memory for sec_proxy / message manager is regular memory,
    and all sec proxy does is to trigger a burst of all 60 bytes of data
    over to the target thread backing ring accelerator. It doesn't do a
    memory scrub when it moves data out in the burst. When we transmit
    multiple messages, remnants of previous message is also transmitted
    which results in some random data being set in TISCI fields of
    messages that have been expanded forward.
    
    The entire concept of backward compatibility hinges on the fact that
    the unused message fields remain 0x0 allowing for 0x0 value to be
    specially considered when backward compatibility of message extension
    is done.
    
    So, instead of just writing the completion register, we continue
    to fill the message buffer up with 0x0 (note: for partial message
    involving completion, we already do this).
    
    This allows us to scale and introduce ABI changes back also work with
    other boot stages that may have left data in the internal memory.
    
    While at this, be consistent and explicit with the data_reg pointer
    increment.
    
    Fixes: aace66b170ce ("mailbox: Introduce TI message manager driver")
    Signed-off-by: Nishanth Menon <nm@xxxxxx>
    Signed-off-by: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mailbox/ti-msgmgr.c b/drivers/mailbox/ti-msgmgr.c
index 0130628f4d9db..535fe73ce3109 100644
--- a/drivers/mailbox/ti-msgmgr.c
+++ b/drivers/mailbox/ti-msgmgr.c
@@ -385,14 +385,20 @@ static int ti_msgmgr_send_data(struct mbox_chan *chan, void *data)
 		/* Ensure all unused data is 0 */
 		data_trail &= 0xFFFFFFFF >> (8 * (sizeof(u32) - trail_bytes));
 		writel(data_trail, data_reg);
-		data_reg++;
+		data_reg += sizeof(u32);
 	}
+
 	/*
 	 * 'data_reg' indicates next register to write. If we did not already
 	 * write on tx complete reg(last reg), we must do so for transmit
+	 * In addition, we also need to make sure all intermediate data
+	 * registers(if any required), are reset to 0 for TISCI backward
+	 * compatibility to be maintained.
 	 */
-	if (data_reg <= qinst->queue_buff_end)
-		writel(0, qinst->queue_buff_end);
+	while (data_reg <= qinst->queue_buff_end) {
+		writel(0, data_reg);
+		data_reg += sizeof(u32);
+	}
 
 	return 0;
 }



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