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Subject[PATCH 5.3 187/193] gve: Fixes DMA synchronization.
Date
From: Yangchun Fu <yangchun@google.com>

[ Upstream commit 9cfeeb576d49a7b5e643b8066ba64a55e8417c5d ]

Synces the DMA buffer properly in order for CPU and device to see
the most up-to-data data.

Signed-off-by: Yangchun Fu <yangchun@google.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/google/gve/gve_rx.c | 2 ++
drivers/net/ethernet/google/gve/gve_tx.c | 24 ++++++++++++++++++++++--
2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_rx.c b/drivers/net/ethernet/google/gve/gve_rx.c
index 59564ac99d2a6..edec61dfc8687 100644
--- a/drivers/net/ethernet/google/gve/gve_rx.c
+++ b/drivers/net/ethernet/google/gve/gve_rx.c
@@ -289,6 +289,8 @@ static bool gve_rx(struct gve_rx_ring *rx, struct gve_rx_desc *rx_desc,

len = be16_to_cpu(rx_desc->len) - GVE_RX_PAD;
page_info = &rx->data.page_info[idx];
+ dma_sync_single_for_cpu(&priv->pdev->dev, rx->data.qpl->page_buses[idx],
+ PAGE_SIZE, DMA_FROM_DEVICE);

/* gvnic can only receive into registered segments. If the buffer
* can't be recycled, our only choice is to copy the data out of
diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c
index 778b87b5a06c2..0a9a7ee2a8668 100644
--- a/drivers/net/ethernet/google/gve/gve_tx.c
+++ b/drivers/net/ethernet/google/gve/gve_tx.c
@@ -390,7 +390,21 @@ static void gve_tx_fill_seg_desc(union gve_tx_desc *seg_desc,
seg_desc->seg.seg_addr = cpu_to_be64(addr);
}

-static int gve_tx_add_skb(struct gve_tx_ring *tx, struct sk_buff *skb)
+static void gve_dma_sync_for_device(struct device *dev, dma_addr_t *page_buses,
+ u64 iov_offset, u64 iov_len)
+{
+ dma_addr_t dma;
+ u64 addr;
+
+ for (addr = iov_offset; addr < iov_offset + iov_len;
+ addr += PAGE_SIZE) {
+ dma = page_buses[addr / PAGE_SIZE];
+ dma_sync_single_for_device(dev, dma, PAGE_SIZE, DMA_TO_DEVICE);
+ }
+}
+
+static int gve_tx_add_skb(struct gve_tx_ring *tx, struct sk_buff *skb,
+ struct device *dev)
{
int pad_bytes, hlen, hdr_nfrags, payload_nfrags, l4_hdr_offset;
union gve_tx_desc *pkt_desc, *seg_desc;
@@ -432,6 +446,9 @@ static int gve_tx_add_skb(struct gve_tx_ring *tx, struct sk_buff *skb)
skb_copy_bits(skb, 0,
tx->tx_fifo.base + info->iov[hdr_nfrags - 1].iov_offset,
hlen);
+ gve_dma_sync_for_device(dev, tx->tx_fifo.qpl->page_buses,
+ info->iov[hdr_nfrags - 1].iov_offset,
+ info->iov[hdr_nfrags - 1].iov_len);
copy_offset = hlen;

for (i = payload_iov; i < payload_nfrags + payload_iov; i++) {
@@ -445,6 +462,9 @@ static int gve_tx_add_skb(struct gve_tx_ring *tx, struct sk_buff *skb)
skb_copy_bits(skb, copy_offset,
tx->tx_fifo.base + info->iov[i].iov_offset,
info->iov[i].iov_len);
+ gve_dma_sync_for_device(dev, tx->tx_fifo.qpl->page_buses,
+ info->iov[i].iov_offset,
+ info->iov[i].iov_len);
copy_offset += info->iov[i].iov_len;
}

@@ -473,7 +493,7 @@ netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev)
gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
return NETDEV_TX_BUSY;
}
- nsegs = gve_tx_add_skb(tx, skb);
+ nsegs = gve_tx_add_skb(tx, skb, &priv->pdev->dev);

netdev_tx_sent_queue(tx->netdev_txq, skb->len);
skb_tx_timestamp(skb);
--
2.20.1


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