40ea3ee2ce
Heng Qi says: ==================== virtio-net: support multi buffer xdp Changes since PATCH v4: - Make netdev_warn() in [PATCH 2/10] independent from [PATCH 3/10]. Changes since PATCH v3: - Separate fix patch [2/10] for MTU calculation of single buffer xdp. Note that this patch needs to be backported to the stable branch. Changes since PATCH v2: - Even if single buffer xdp has a hole mechanism, there will be no problem (limiting mtu and turning off GUEST GSO), so there is no need to backport "[PATCH 1/9]"; - Modify calculation of MTU for single buffer xdp in virtnet_xdp_set(); - Make truesize in mergeable mode return to literal meaning; - Add some comments for legibility; Changes since RFC: - Using headroom instead of vi->xdp_enabled to avoid re-reading in add_recvbuf_mergeable(); - Disable GRO_HW and keep linearization for single buffer xdp; - Renamed to virtnet_build_xdp_buff_mrg(); - pr_debug() to netdev_dbg(); - Adjusted the order of the patch series. Currently, virtio net only supports xdp for single-buffer packets or linearized multi-buffer packets. This patchset supports xdp for multi-buffer packets, then larger MTU can be used if xdp sets the xdp.frags. This does not affect single buffer handling. In order to build multi-buffer xdp neatly, we integrated the code into virtnet_build_xdp_buff_mrg() for xdp. The first buffer is used for prepared xdp buff, and the rest of the buffers are added to its skb_shared_info structure. This structure can also be conveniently converted during XDP_PASS to get the corresponding skb. Since virtio net uses comp pages, and bpf_xdp_frags_increase_tail() is based on the assumption of the page pool, (rxq->frag_size - skb_frag_size(frag) - skb_frag_off(frag)) is negative in most cases. So we didn't set xdp_rxq->frag_size in virtnet_open() to disable the tail increase. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.