1/* SPDX-License-Identifier: (GPL-2.0 OR MIT)
2 * Google virtual Ethernet (gve) driver
3 *
4 * Copyright (C) 2015-2019 Google, Inc.
5 */
6
7/* GVE Transmit Descriptor formats */
8
9#ifndef _GVE_DESC_H_
10#define _GVE_DESC_H_
11
12#include <linux/build_bug.h>
13
14/* A note on seg_addrs
15 *
16 * Base addresses encoded in seg_addr are not assumed to be physical
17 * addresses. The ring format assumes these come from some linear address
18 * space. This could be physical memory, kernel virtual memory, user virtual
19 * memory.
20 * If raw dma addressing is not supported then gVNIC uses lists of registered
21 * pages. Each queue is assumed to be associated with a single such linear
22 * address space to ensure a consistent meaning for seg_addrs posted to its
23 * rings.
24 */
25
26struct gve_tx_pkt_desc {
27 u8 type_flags; /* desc type is lower 4 bits, flags upper */
28 u8 l4_csum_offset; /* relative offset of L4 csum word */
29 u8 l4_hdr_offset; /* Offset of start of L4 headers in packet */
30 u8 desc_cnt; /* Total descriptors for this packet */
31 __be16 len; /* Total length of this packet (in bytes) */
32 __be16 seg_len; /* Length of this descriptor's segment */
33 __be64 seg_addr; /* Base address (see note) of this segment */
34} __packed;
35
36struct gve_tx_mtd_desc {
37 u8 type_flags; /* type is lower 4 bits, subtype upper */
38 u8 path_state; /* state is lower 4 bits, hash type upper */
39 __be16 reserved0;
40 __be32 path_hash;
41 __be64 reserved1;
42} __packed;
43
44struct gve_tx_seg_desc {
45 u8 type_flags; /* type is lower 4 bits, flags upper */
46 u8 l3_offset; /* TSO: 2 byte units to start of IPH */
47 __be16 reserved;
48 __be16 mss; /* TSO MSS */
49 __be16 seg_len;
50 __be64 seg_addr;
51} __packed;
52
53/* GVE Transmit Descriptor Types */
54#define GVE_TXD_STD (0x0 << 4) /* Std with Host Address */
55#define GVE_TXD_TSO (0x1 << 4) /* TSO with Host Address */
56#define GVE_TXD_SEG (0x2 << 4) /* Seg with Host Address */
57#define GVE_TXD_MTD (0x3 << 4) /* Metadata */
58
59/* GVE Transmit Descriptor Flags for Std Pkts */
60#define GVE_TXF_L4CSUM BIT(0) /* Need csum offload */
61#define GVE_TXF_TSTAMP BIT(2) /* Timestamp required */
62
63/* GVE Transmit Descriptor Flags for TSO Segs */
64#define GVE_TXSF_IPV6 BIT(1) /* IPv6 TSO */
65
66/* GVE Transmit Descriptor Options for MTD Segs */
67#define GVE_MTD_SUBTYPE_PATH 0
68
69#define GVE_MTD_PATH_STATE_DEFAULT 0
70#define GVE_MTD_PATH_STATE_TIMEOUT 1
71#define GVE_MTD_PATH_STATE_CONGESTION 2
72#define GVE_MTD_PATH_STATE_RETRANSMIT 3
73
74#define GVE_MTD_PATH_HASH_NONE (0x0 << 4)
75#define GVE_MTD_PATH_HASH_L4 (0x1 << 4)
76
77/* GVE Receive Packet Descriptor */
78/* The start of an ethernet packet comes 2 bytes into the rx buffer.
79 * gVNIC adds this padding so that both the DMA and the L3/4 protocol header
80 * access is aligned.
81 */
82#define GVE_RX_PAD 2
83
84struct gve_rx_desc {
85 u8 padding[48];
86 __be32 rss_hash; /* Receive-side scaling hash (Toeplitz for gVNIC) */
87 __be16 mss;
88 __be16 reserved; /* Reserved to zero */
89 u8 hdr_len; /* Header length (L2-L4) including padding */
90 u8 hdr_off; /* 64-byte-scaled offset into RX_DATA entry */
91 __sum16 csum; /* 1's-complement partial checksum of L3+ bytes */
92 __be16 len; /* Length of the received packet */
93 __be16 flags_seq; /* Flags [15:3] and sequence number [2:0] (1-7) */
94} __packed;
95static_assert(sizeof(struct gve_rx_desc) == 64);
96
97/* If the device supports raw dma addressing then the addr in data slot is
98 * the dma address of the buffer.
99 * If the device only supports registered segments then the addr is a byte
100 * offset into the registered segment (an ordered list of pages) where the
101 * buffer is.
102 */
103union gve_rx_data_slot {
104 __be64 qpl_offset;
105 __be64 addr;
106};
107
108/* GVE Receive Packet Descriptor Seq No */
109#define GVE_SEQNO(x) (be16_to_cpu(x) & 0x7)
110
111/* GVE Receive Packet Descriptor Flags */
112#define GVE_RXFLG(x) cpu_to_be16(1 << (3 + (x)))
113#define GVE_RXF_FRAG GVE_RXFLG(3) /* IP Fragment */
114#define GVE_RXF_IPV4 GVE_RXFLG(4) /* IPv4 */
115#define GVE_RXF_IPV6 GVE_RXFLG(5) /* IPv6 */
116#define GVE_RXF_TCP GVE_RXFLG(6) /* TCP Packet */
117#define GVE_RXF_UDP GVE_RXFLG(7) /* UDP Packet */
118#define GVE_RXF_ERR GVE_RXFLG(8) /* Packet Error Detected */
119#define GVE_RXF_PKT_CONT GVE_RXFLG(10) /* Multi Fragment RX packet */
120
121/* GVE IRQ */
122#define GVE_IRQ_ACK BIT(31)
123#define GVE_IRQ_MASK BIT(30)
124#define GVE_IRQ_EVENT BIT(29)
125
126static inline bool gve_needs_rss(__be16 flag)
127{
128 if (flag & GVE_RXF_FRAG)
129 return false;
130 if (flag & (GVE_RXF_IPV4 | GVE_RXF_IPV6))
131 return true;
132 return false;
133}
134
135static inline u8 gve_next_seqno(u8 seq)
136{
137 return (seq + 1) == 8 ? 1 : seq + 1;
138}
139#endif /* _GVE_DESC_H_ */
140

source code of linux/drivers/net/ethernet/google/gve/gve_desc.h