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Subject[RFC PATCH v10 16/16]An example how to alloc user buffer based on napi_gro_frags() interface.
Date
From: Xin Xiaohui <xiaohui.xin@intel.com>

This example is made on ixgbe driver which using napi_gro_frags().
It can get buffers from guest side directly using netdev_alloc_page()
and release guest buffers using netdev_free_page().

---
drivers/net/ixgbe/ixgbe_main.c | 25 +++++++++++++++++++++----
1 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index 905d6d2..0977f2f 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -691,7 +691,14 @@ static inline void ixgbe_release_rx_desc(struct ixgbe_hw *hw,
static bool is_rx_buffer_mapped_as_page(struct ixgbe_rx_buffer *bi,
struct net_device *dev)
{
- return true;
+ return dev_is_mpassthru(dev);
+}
+
+static u32 get_page_skb_offset(struct net_device *dev)
+{
+ if (!dev_is_mpassthru(dev))
+ return 0;
+ return dev->mp_port->vnet_hlen;
}

/**
@@ -764,7 +771,8 @@ static void ixgbe_alloc_rx_buffers(struct ixgbe_adapter *adapter,
adapter->alloc_rx_page_failed++;
goto no_buffers;
}
- bi->page_skb_offset = 0;
+ bi->page_skb_offset =
+ get_page_skb_offset(adapter->netdev);
bi->dma = pci_map_page(pdev, bi->page_skb,
bi->page_skb_offset,
(PAGE_SIZE / 2),
@@ -899,8 +907,10 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
len = le16_to_cpu(rx_desc->wb.upper.length);
}

- if (is_no_buffer(rx_buffer_info))
+ if (is_no_buffer(rx_buffer_info)) {
+ printk("no buffers\n");
break;
+ }

cleaned = true;

@@ -959,6 +969,12 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
rx_buffer_info->page_skb,
rx_buffer_info->page_skb_offset,
len);
+ if (dev_is_mpassthru(netdev) &&
+ netdev->mp_port->hash)
+ skb_shinfo(skb)->destructor_arg =
+ netdev->mp_port->hash(netdev,
+ rx_buffer_info->page_skb);
+
rx_buffer_info->page_skb = NULL;
skb->len += len;
skb->data_len += len;
@@ -976,7 +992,8 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
upper_len);

if ((rx_ring->rx_buf_len > (PAGE_SIZE / 2)) ||
- (page_count(rx_buffer_info->page) != 1))
+ (page_count(rx_buffer_info->page) != 1) ||
+ dev_is_mpassthru(netdev))
rx_buffer_info->page = NULL;
else
get_page(rx_buffer_info->page);
--
1.5.4.4


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