Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753618AbbBHK7Q (ORCPT ); Sun, 8 Feb 2015 05:59:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49933 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751836AbbBHK7O (ORCPT ); Sun, 8 Feb 2015 05:59:14 -0500 Date: Sun, 8 Feb 2015 11:59:08 +0100 From: "Michael S. Tsirkin" To: Rusty Russell Cc: lkml , "netdev@vger.kernel.org" Subject: Re: [PATCH 3/5] virtio: Don't expose legacy net features when VIRTIO_NET_NO_LEGACY defined. Message-ID: <20150208105908.GI3185@redhat.com> References: <1423199216-2094-1-git-send-email-rusty@rustcorp.com.au> <1423199216-2094-4-git-send-email-rusty@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1423199216-2094-4-git-send-email-rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4107 Lines: 97 On Fri, Feb 06, 2015 at 03:36:54PM +1030, Rusty Russell wrote: > In particular, the virtio header always has the u16 num_buffers field. > We define a new 'struct virtio_net_modern_hdr' for this (rather than > simply calling it 'struct virtio_net_hdr', to avoid nasty type errors > if some parts of a project define VIRTIO_NET_NO_LEGACY and some don't. > > Signed-off-by: Rusty Russell > --- > include/uapi/linux/virtio_net.h | 30 ++++++++++++++++++++++++++++-- > 1 file changed, 28 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > index b5f1677b291c..32754f3000e8 100644 > --- a/include/uapi/linux/virtio_net.h > +++ b/include/uapi/linux/virtio_net.h > @@ -35,7 +35,6 @@ > #define VIRTIO_NET_F_CSUM 0 /* Host handles pkts w/ partial csum */ > #define VIRTIO_NET_F_GUEST_CSUM 1 /* Guest handles pkts w/ partial csum */ > #define VIRTIO_NET_F_MAC 5 /* Host has given MAC address. */ > -#define VIRTIO_NET_F_GSO 6 /* Host handles pkts w/ any GSO type */ > #define VIRTIO_NET_F_GUEST_TSO4 7 /* Guest can handle TSOv4 in. */ > #define VIRTIO_NET_F_GUEST_TSO6 8 /* Guest can handle TSOv6 in. */ > #define VIRTIO_NET_F_GUEST_ECN 9 /* Guest can handle TSO[6] w/ ECN in. */ > @@ -56,6 +55,10 @@ > * Steering */ > #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */ > > +#ifndef VIRTIO_NET_NO_LEGACY > +#define VIRTIO_NET_F_GSO 6 /* Host handles pkts w/ any GSO type */ > +#endif /* VIRTIO_NET_NO_LEGACY */ > + > #define VIRTIO_NET_S_LINK_UP 1 /* Link is up */ > #define VIRTIO_NET_S_ANNOUNCE 2 /* Announcement is needed */ > > @@ -71,8 +74,9 @@ struct virtio_net_config { > __u16 max_virtqueue_pairs; > } __attribute__((packed)); > > +#ifndef VIRTIO_NET_NO_LEGACY > /* This header comes first in the scatter-gather list. > - * If VIRTIO_F_ANY_LAYOUT is not negotiated, it must > + * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated, it must > * be the first element of the scatter-gather list. If you don't > * specify GSO or CSUM features, you can simply ignore the header. */ > struct virtio_net_hdr { > @@ -97,6 +101,28 @@ struct virtio_net_hdr_mrg_rxbuf { > struct virtio_net_hdr hdr; > __virtio16 num_buffers; /* Number of merged rx buffers */ > }; > +#else /* ... VIRTIO_NET_NO_LEGACY */ > +/* > + * This header comes first in the scatter-gather list. If you don't > + * specify GSO or CSUM features, you can simply ignore the header. > + */ > +struct virtio_net_modern_hdr { > +#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 /* Use csum_start, csum_offset */ > +#define VIRTIO_NET_HDR_F_DATA_VALID 2 /* Csum is valid */ > + __u8 flags; > +#define VIRTIO_NET_HDR_GSO_NONE 0 /* Not a GSO frame */ > +#define VIRTIO_NET_HDR_GSO_TCPV4 1 /* GSO frame, IPv4 TCP (TSO) */ > +#define VIRTIO_NET_HDR_GSO_UDP 3 /* GSO frame, IPv4 UDP (UFO) */ > +#define VIRTIO_NET_HDR_GSO_TCPV6 4 /* GSO frame, IPv6 TCP */ > +#define VIRTIO_NET_HDR_GSO_ECN 0x80 /* TCP has ECN set */ > + __u8 gso_type; > + __virtio16 hdr_len; /* Ethernet + IP + tcp/udp hdrs */ > + __virtio16 gso_size; /* Bytes to append to hdr_len per frame */ > + __virtio16 csum_start; /* Position to start checksumming from */ > + __virtio16 csum_offset; /* Offset after that to place checksum */ > + __virtio16 num_buffers; /* Number of merged rx buffers */ > +}; > +#endif /* ...VIRTIO_NET_NO_LEGACY */ This kind of masks the fact that it's the same as virtio_net_hdr_mrg_rxbuf. So it's forcing people to duplicate code for transitional devices. How about struct virtio_net_modern_hdr { struct virtio_net_hdr_mrg_rxbuf hdr; } This will also make it look nicer when we start adding stuff in the header, the main header is separated in a struct by its own, so it's easy to apply operations such as sizeof. > /* > * Control virtqueue data structures > -- > 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/