[Xen-devel] [PATCH net-next RFC 4/5] xen-netback: Change RX path for mapped SKB fragments

[Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>]

RX path need to know if the SKB fragments are stored on pages from another
domain.

Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>
---
 drivers/net/xen-netback/netback.c |   46 +++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 204fa46..0ffa412 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -322,7 +322,9 @@ static struct xenvif_rx_meta *get_next_rx_buffer(struct 
xenvif *vif,
 static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
                                 struct netrx_pending_operations *npo,
                                 struct page *page, unsigned long size,
-                                unsigned long offset, int *head)
+                                unsigned long offset, int *head,
+                                struct xenvif *foreign_vif,
+                                grant_ref_t foreign_gref)
 {
        struct gnttab_copy *copy_gop;
        struct xenvif_rx_meta *meta;
@@ -364,8 +366,15 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, 
struct sk_buff *skb,
                copy_gop->flags = GNTCOPY_dest_gref;
                copy_gop->len = bytes;
 
-               copy_gop->source.domid = DOMID_SELF;
-               copy_gop->source.u.gmfn = virt_to_mfn(page_address(page));
+               if (foreign_vif) {
+                       copy_gop->source.domid = foreign_vif->domid;
+                       copy_gop->source.u.ref = foreign_gref;
+                       copy_gop->flags |= GNTCOPY_source_gref;
+               } else {
+                       copy_gop->source.domid = DOMID_SELF;
+                       copy_gop->source.u.gmfn =
+                               virt_to_mfn(page_address(page));
+               }
                copy_gop->source.offset = offset;
 
                copy_gop->dest.domid = vif->domid;
@@ -426,6 +435,9 @@ static int xenvif_gop_skb(struct sk_buff *skb,
        int old_meta_prod;
        int gso_type;
        int gso_size;
+       struct ubuf_info *ubuf = skb_shinfo(skb)->destructor_arg;
+       grant_ref_t foreign_grefs[MAX_SKB_FRAGS];
+       struct xenvif *foreign_vif = NULL;
 
        old_meta_prod = npo->meta_prod;
 
@@ -466,6 +478,26 @@ static int xenvif_gop_skb(struct sk_buff *skb,
        npo->copy_off = 0;
        npo->copy_gref = req->gref;
 
+       if ((skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) &&
+                (ubuf->callback == &xenvif_zerocopy_callback)) {
+               u16 pending_idx = ubuf->desc;
+               int i = 0;
+               struct pending_tx_info *temp =
+                       container_of(ubuf,
+                               struct pending_tx_info,
+                               callback_struct);
+               foreign_vif =
+                       container_of(temp - pending_idx,
+                               struct xenvif,
+                               pending_tx_info[0]);
+               do {
+                       pending_idx = ubuf->desc;
+                       ubuf = (struct ubuf_info *) ubuf->ctx;
+                       foreign_grefs[i++] =
+                               
foreign_vif->pending_tx_info[pending_idx].req.gref;
+               } while (ubuf);
+       }
+
        data = skb->data;
        while (data < skb_tail_pointer(skb)) {
                unsigned int offset = offset_in_page(data);
@@ -475,7 +507,9 @@ static int xenvif_gop_skb(struct sk_buff *skb,
                        len = skb_tail_pointer(skb) - data;
 
                xenvif_gop_frag_copy(vif, skb, npo,
-                                    virt_to_page(data), len, offset, &head);
+                                    virt_to_page(data), len, offset, &head,
+                                    NULL,
+                                    0);
                data += len;
        }
 
@@ -484,7 +518,9 @@ static int xenvif_gop_skb(struct sk_buff *skb,
                                     skb_frag_page(&skb_shinfo(skb)->frags[i]),
                                     skb_frag_size(&skb_shinfo(skb)->frags[i]),
                                     skb_shinfo(skb)->frags[i].page_offset,
-                                    &head);
+                                    &head,
+                                    foreign_vif,
+                                    foreign_grefs[i]);
        }
 
        return npo->meta_prod - old_meta_prod;

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