[PATCH v8 bpf-next 12/14] bpf: introduce multibuff support to bpf_prog_test_run_xdp()

[Lorenzo Bianconi]

Introduce the capability to allocate a xdp multi-buff in
bpf_prog_test_run_xdp routine. This is a preliminary patch to introduce
the selftests for new xdp multi-buff ebpf helpers

Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
---
 net/bpf/test_run.c | 52 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 44 insertions(+), 8 deletions(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 1acd94377822..bb953b2e6501 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -692,23 +692,22 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const 
union bpf_attr *kattr,
 {
        u32 tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
        u32 headroom = XDP_PACKET_HEADROOM;
-       u32 size = kattr->test.data_size_in;
+       struct xdp_shared_info *xdp_sinfo;
        u32 repeat = kattr->test.repeat;
        struct netdev_rx_queue *rxqueue;
        struct xdp_buff xdp = {};
+       u32 max_data_sz, size;
        u32 retval, duration;
-       u32 max_data_sz;
+       int i, ret;
        void *data;
-       int ret;
 
        if (kattr->test.ctx_in || kattr->test.ctx_out)
                return -EINVAL;
 
-       /* XDP have extra tailroom as (most) drivers use full page */
        max_data_sz = 4096 - headroom - tailroom;
+       size = min_t(u32, kattr->test.data_size_in, max_data_sz);
 
-       data = bpf_test_init(kattr, kattr->test.data_size_in,
-                            max_data_sz, headroom, tailroom);
+       data = bpf_test_init(kattr, size, max_data_sz, headroom, tailroom);
        if (IS_ERR(data))
                return PTR_ERR(data);
 
@@ -717,16 +716,53 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const 
union bpf_attr *kattr,
                      &rxqueue->xdp_rxq);
        xdp_prepare_buff(&xdp, data, headroom, size, true);
 
+       xdp_sinfo = xdp_get_shared_info_from_buff(&xdp);
+       if (unlikely(kattr->test.data_size_in > size)) {
+               void __user *data_in = u64_to_user_ptr(kattr->test.data_in);
+
+               while (size < kattr->test.data_size_in) {
+                       struct page *page;
+                       skb_frag_t *frag;
+                       int data_len;
+
+                       page = alloc_page(GFP_KERNEL);
+                       if (!page) {
+                               ret = -ENOMEM;
+                               goto out;
+                       }
+
+                       frag = &xdp_sinfo->frags[xdp_sinfo->nr_frags++];
+                       xdp_set_frag_page(frag, page);
+
+                       data_len = min_t(int, kattr->test.data_size_in - size,
+                                        PAGE_SIZE);
+                       xdp_set_frag_size(frag, data_len);
+
+                       if (copy_from_user(page_address(page), data_in + size,
+                                          data_len)) {
+                               ret = -EFAULT;
+                               goto out;
+                       }
+                       xdp_sinfo->data_length += data_len;
+                       size += data_len;
+               }
+               xdp.mb = 1;
+       }
+
        bpf_prog_change_xdp(NULL, prog);
        ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
        if (ret)
                goto out;
-       if (xdp.data != data + headroom || xdp.data_end != xdp.data + size)
-               size = xdp.data_end - xdp.data;
+
+       size = xdp.data_end - xdp.data + xdp_sinfo->data_length;
        ret = bpf_test_finish(kattr, uattr, xdp.data, size, retval, duration);
+
 out:
        bpf_prog_change_xdp(prog, NULL);
+       for (i = 0; i < xdp_sinfo->nr_frags; i++)
+               __free_page(xdp_get_frag_page(&xdp_sinfo->frags[i]));
        kfree(data);
+
        return ret;
 }
 
-- 
2.30.2