xref: /openbmc/qemu/pc-bios/s390-ccw/virtio-net.c (revision aecdfcc3)
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 #include "helper.h"
24 
25 #ifndef DEBUG_VIRTIO_NET
26 #define DEBUG_VIRTIO_NET 0
27 #endif
28 
29 #define VIRTIO_NET_F_MAC_BIT  (1 << 5)
30 
31 #define VQ_RX 0         /* Receive queue */
32 #define VQ_TX 1         /* Transmit queue */
33 
34 struct VirtioNetHdr {
35     uint8_t flags;
36     uint8_t gso_type;
37     uint16_t hdr_len;
38     uint16_t gso_size;
39     uint16_t csum_start;
40     uint16_t csum_offset;
41     /*uint16_t num_buffers;*/ /* Only with VIRTIO_NET_F_MRG_RXBUF or VIRTIO1 */
42 };
43 typedef struct VirtioNetHdr VirtioNetHdr;
44 
45 static uint16_t rx_last_idx;  /* Last index in receive queue "used" ring */
46 
virtio_net_init(void * mac_addr)47 int virtio_net_init(void *mac_addr)
48 {
49     VDev *vdev = virtio_get_device();
50     VRing *rxvq = &vdev->vrings[VQ_RX];
51     void *buf;
52     int i;
53 
54     vdev->guest_features[0] = VIRTIO_NET_F_MAC_BIT;
55     virtio_setup_ccw(vdev);
56 
57     IPL_assert(vdev->guest_features[0] & VIRTIO_NET_F_MAC_BIT,
58                "virtio-net device does not support the MAC address feature");
59     memcpy(mac_addr, vdev->config.net.mac, ETH_ALEN);
60 
61     for (i = 0; i < 64; i++) {
62         buf = malloc(ETH_MTU_SIZE + sizeof(VirtioNetHdr));
63         IPL_assert(buf != NULL, "Can not allocate memory for receive buffers");
64         vring_send_buf(rxvq, buf, ETH_MTU_SIZE + sizeof(VirtioNetHdr),
65                        VRING_DESC_F_WRITE);
66     }
67     vring_notify(rxvq);
68 
69     return 0;
70 }
71 
send(int fd,const void * buf,int len,int flags)72 int send(int fd, const void *buf, int len, int flags)
73 {
74     VirtioNetHdr tx_hdr;
75     VDev *vdev = virtio_get_device();
76     VRing *txvq = &vdev->vrings[VQ_TX];
77 
78     /* Set up header - we do not use anything special, so simply clear it */
79     memset(&tx_hdr, 0, sizeof(tx_hdr));
80 
81     vring_send_buf(txvq, &tx_hdr, sizeof(tx_hdr), VRING_DESC_F_NEXT);
82     vring_send_buf(txvq, (void *)buf, len, VRING_HIDDEN_IS_CHAIN);
83     while (!vr_poll(txvq)) {
84         yield();
85     }
86     if (drain_irqs(txvq->schid)) {
87         puts("send: drain irqs failed");
88         return -1;
89     }
90 
91     return len;
92 }
93 
recv(int fd,void * buf,int maxlen,int flags)94 int recv(int fd, void *buf, int maxlen, int flags)
95 {
96     VDev *vdev = virtio_get_device();
97     VRing *rxvq = &vdev->vrings[VQ_RX];
98     int len, id;
99     uint8_t *pkt;
100 
101     if (rx_last_idx == rxvq->used->idx) {
102         return 0;
103     }
104 
105     len = rxvq->used->ring[rx_last_idx % rxvq->num].len - sizeof(VirtioNetHdr);
106     if (len > maxlen) {
107         puts("virtio-net: Receive buffer too small");
108         len = maxlen;
109     }
110     id = rxvq->used->ring[rx_last_idx % rxvq->num].id % rxvq->num;
111     pkt = (uint8_t *)(rxvq->desc[id].addr + sizeof(VirtioNetHdr));
112 
113 #if DEBUG_VIRTIO_NET   /* Dump packet */
114     int i;
115     printf("\nbuf %p: len=%i\n", (void *)rxvq->desc[id].addr, len);
116     for (i = 0; i < 64; i++) {
117         printf(" %02x", pkt[i]);
118         if ((i % 16) == 15) {
119             printf("\n");
120         }
121     }
122     printf("\n");
123 #endif
124 
125     /* Copy data to destination buffer */
126     memcpy(buf, pkt, len);
127 
128     /* Mark buffer as available to the host again */
129     rxvq->avail->ring[rxvq->avail->idx % rxvq->num] = id;
130     rxvq->avail->idx = rxvq->avail->idx + 1;
131     vring_notify(rxvq);
132 
133     /* Move index to next entry */
134     rx_last_idx = rx_last_idx + 1;
135 
136     return len;
137 }
138