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virtio: Don't expose legacy net features when VIRTIO_NET_NO_LEGACY defined.

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In particular, the virtio header always has the u16 num_buffers field.
We define a new 'struct virtio_net_hdr_v1' 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.

Transitional devices (which can't define VIRTIO_NET_NO_LEGACY) will
have to keep using struct virtio_net_hdr_mrg_rxbuf, which has the same
byte layout as struct virtio_net_hdr_v1.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2015-02-13 17:13:44 +10:30
parent 1e1c17a7a2
commit ed9ecb0415
1 changed files with 30 additions and 2 deletions
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32
include/uapi/linux/virtio_net.h
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@ -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 +101,30 @@ 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.
*
* This is bitwise-equivalent to the legacy struct virtio_net_hdr_mrg_rxbuf.
*/
struct virtio_net_hdr_v1 {
#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 */
/*
* Control virtqueue data structures