This is a note to let you know that I've just added the patch titled ibmvnic: add memory barrier to protect long term buffer to the 5.4-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: ibmvnic-add-memory-barrier-to-protect-long-term-buff.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit a04450263bf9b18d9fa61622ae535b9084b9a285 Author: Lijun Pan <ljp@xxxxxxxxxxxxx> Date: Fri Feb 12 20:48:40 2021 -0600 ibmvnic: add memory barrier to protect long term buffer [ Upstream commit 42557dab78edc8235aba5b441f2eb35f725a0ede ] dma_rmb() barrier is added to load the long term buffer before copying it to socket buffer; and dma_wmb() barrier is added to update the long term buffer before it being accessed by VIOS (virtual i/o server). Fixes: 032c5e82847a ("Driver for IBM System i/p VNIC protocol") Signed-off-by: Lijun Pan <ljp@xxxxxxxxxxxxx> Acked-by: Thomas Falcon <tlfalcon@xxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c index 5b5d488c2f374..901883a44a320 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c @@ -1518,6 +1518,9 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) skb_copy_from_linear_data(skb, dst, skb->len); } + /* post changes to long_term_buff *dst before VIOS accessing it */ + dma_wmb(); + tx_pool->consumer_index = (tx_pool->consumer_index + 1) % tx_pool->num_buffers; @@ -2340,6 +2343,8 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget) offset = be16_to_cpu(next->rx_comp.off_frame_data); flags = next->rx_comp.flags; skb = rx_buff->skb; + /* load long_term_buff before copying to skb */ + dma_rmb(); skb_copy_to_linear_data(skb, rx_buff->data + offset, length);