From 42557dab78edc8235aba5b441f2eb35f725a0ede Mon Sep 17 00:00:00 2001

From: Lijun Pan <ljp@linux.ibm.com>

Date: Fri, 12 Feb 2021 20:48:40 -0600

Subject: [PATCH] ibmvnic: add memory barrier to protect long term buffer

References: bsc#1184114 ltc#192237 bsc#1182485 ltc#191591

Patch-mainline: v5.12-rc1

Git-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@linux.ibm.com>

Acked-by: Thomas Falcon <tlfalcon@linux.ibm.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 drivers/net/ethernet/ibm/ibmvnic.c | 5 +++++

 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c

index 621be6d2da97..f6402a20ba32 100644

--- a/drivers/net/ethernet/ibm/ibmvnic.c

+++ b/drivers/net/ethernet/ibm/ibmvnic.c

@@ -1700,6 +1700,9 @@ 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;

@@ -2539,6 +2542,8 @@ 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);

-- 

2.26.2