xref: /qemu/pc-bios/s390-ccw/virtio-net.c (revision e70bc57ba0c982944cf5b71f293122dbb2b462f4)
1 /*
2  * Virtio-net driver for the s390-ccw firmware
3  *
4  * Copyright 2017 Thomas Huth, Red Hat Inc.
5  *
6  * This code is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the
8  * Free Software Foundation; either version 2 of the License, or (at your
9  * option) any later version.
10  */
11 
12 #include <stdint.h>
13 #include <stdbool.h>
14 #include <stdio.h>
15 #include <stdlib.h>
16 #include <string.h>
17 #include <unistd.h>
18 #include <sys/socket.h>
19 #include <ethernet.h>
20 #include "s390-ccw.h"
21 #include "virtio.h"
22 #include "s390-time.h"
23 
24 #ifndef DEBUG_VIRTIO_NET
25 #define DEBUG_VIRTIO_NET 0
26 #endif
27 
28 #define VIRTIO_NET_F_MAC_BIT  (1 << 5)
29 
30 #define VQ_RX 0         /* Receive queue */
31 #define VQ_TX 1         /* Transmit queue */
32 
33 struct VirtioNetHdr {
34     uint8_t flags;
35     uint8_t gso_type;
36     uint16_t hdr_len;
37     uint16_t gso_size;
38     uint16_t csum_start;
39     uint16_t csum_offset;
40     /*uint16_t num_buffers;*/ /* Only with VIRTIO_NET_F_MRG_RXBUF or VIRTIO1 */
41 };
42 typedef struct VirtioNetHdr VirtioNetHdr;
43 
44 static uint16_t rx_last_idx;  /* Last index in receive queue "used" ring */
45 
46 int virtio_net_init(void *mac_addr)
47 {
48     VDev *vdev = virtio_get_device();
49     VRing *rxvq = &vdev->vrings[VQ_RX];
50     void *buf;
51     int i;
52 
53     vdev->guest_features[0] = VIRTIO_NET_F_MAC_BIT;
54     virtio_setup_ccw(vdev);
55 
56     IPL_assert(vdev->guest_features[0] & VIRTIO_NET_F_MAC_BIT,
57                "virtio-net device does not support the MAC address feature");
58     memcpy(mac_addr, vdev->config.net.mac, ETH_ALEN);
59 
60     for (i = 0; i < 64; i++) {
61         buf = malloc(ETH_MTU_SIZE + sizeof(VirtioNetHdr));
62         IPL_assert(buf != NULL, "Can not allocate memory for receive buffers");
63         vring_send_buf(rxvq, buf, ETH_MTU_SIZE + sizeof(VirtioNetHdr),
64                        VRING_DESC_F_WRITE);
65     }
66     vring_notify(rxvq);
67 
68     return 0;
69 }
70 
71 int send(int fd, const void *buf, int len, int flags)
72 {
73     VirtioNetHdr tx_hdr;
74     VDev *vdev = virtio_get_device();
75     VRing *txvq = &vdev->vrings[VQ_TX];
76 
77     /* Set up header - we do not use anything special, so simply clear it */
78     memset(&tx_hdr, 0, sizeof(tx_hdr));
79 
80     vring_send_buf(txvq, &tx_hdr, sizeof(tx_hdr), VRING_DESC_F_NEXT);
81     vring_send_buf(txvq, (void *)buf, len, VRING_HIDDEN_IS_CHAIN);
82     while (!vr_poll(txvq)) {
83         yield();
84     }
85     if (drain_irqs(txvq->schid)) {
86         puts("send: drain irqs failed");
87         return -1;
88     }
89 
90     return len;
91 }
92 
93 int recv(int fd, void *buf, int maxlen, int flags)
94 {
95     VDev *vdev = virtio_get_device();
96     VRing *rxvq = &vdev->vrings[VQ_RX];
97     int len, id;
98     uint8_t *pkt;
99 
100     if (rx_last_idx == rxvq->used->idx) {
101         return 0;
102     }
103 
104     len = rxvq->used->ring[rx_last_idx % rxvq->num].len - sizeof(VirtioNetHdr);
105     if (len > maxlen) {
106         puts("virtio-net: Receive buffer too small");
107         len = maxlen;
108     }
109     id = rxvq->used->ring[rx_last_idx % rxvq->num].id % rxvq->num;
110     pkt = (uint8_t *)(rxvq->desc[id].addr + sizeof(VirtioNetHdr));
111 
112 #if DEBUG_VIRTIO_NET   /* Dump packet */
113     int i;
114     printf("\nbuf %p: len=%i\n", (void *)rxvq->desc[id].addr, len);
115     for (i = 0; i < 64; i++) {
116         printf(" %02x", pkt[i]);
117         if ((i % 16) == 15) {
118             printf("\n");
119         }
120     }
121     printf("\n");
122 #endif
123 
124     /* Copy data to destination buffer */
125     memcpy(buf, pkt, len);
126 
127     /* Mark buffer as available to the host again */
128     rxvq->avail->ring[rxvq->avail->idx % rxvq->num] = id;
129     rxvq->avail->idx = rxvq->avail->idx + 1;
130     vring_notify(rxvq);
131 
132     /* Move index to next entry */
133     rx_last_idx = rx_last_idx + 1;
134 
135     return len;
136 }
137