gve_desc.h

  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_ */