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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jesper Dangaard Brouer <brouer@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 105/267] ixgbe: Fix XDP redirect on archs with PAGE_SIZE above 4K
Date:   Fri, 19 Jun 2020 16:31:30 +0200
Message-Id: <20200619141653.896871181@linuxfoundation.org>
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References: <20200619141648.840376470@linuxfoundation.org>
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From: Jesper Dangaard Brouer <brouer@redhat.com>

[ Upstream commit 88eb0ee17b2ece64fcf6689a4557a5c2e7a89c4b ]

The ixgbe driver have another memory model when compiled on archs with
PAGE_SIZE above 4096 bytes. In this mode it doesn't split the page in
two halves, but instead increment rx_buffer->page_offset by truesize of
packet (which include headroom and tailroom for skb_shared_info).

This is done correctly in ixgbe_build_skb(), but in ixgbe_rx_buffer_flip
which is currently only called on XDP_TX and XDP_REDIRECT, it forgets
to add the tailroom for skb_shared_info. This breaks XDP_REDIRECT, for
veth and cpumap.  Fix by adding size of skb_shared_info tailroom.

Maintainers notice: This fix have been queued to Jeff.

Fixes: 6453073987ba ("ixgbe: add initial support for xdp redirect")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Link: https://lore.kernel.org/bpf/158945344946.97035.17031588499266605743.stgit@firesoul
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 8177276500f5..7d723b70fcf6 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -2258,7 +2258,8 @@ static void ixgbe_rx_buffer_flip(struct ixgbe_ring *rx_ring,
 	rx_buffer->page_offset ^= truesize;
 #else
 	unsigned int truesize = ring_uses_build_skb(rx_ring) ?
-				SKB_DATA_ALIGN(IXGBE_SKB_PAD + size) :
+				SKB_DATA_ALIGN(IXGBE_SKB_PAD + size) +
+				SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) :
 				SKB_DATA_ALIGN(size);
 
 	rx_buffer->page_offset += truesize;
-- 
2.25.1