pc-bios/s390-ccw/virtio.c

   1 /*
   2  * Virtio driver bits
   3  *
   4  * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or (at
   7  * your option) any later version. See the COPYING file in the top-level
   8  * directory.
   9  */
  10
  11 #include "libc.h"
  12 #include "s390-ccw.h"
  13 #include "cio.h"
  14 #include "virtio.h"
  15 #include "virtio-scsi.h"
  16 #include "bswap.h"
  17
  18 #define VRING_WAIT_REPLY_TIMEOUT 30
  19
  20 static VRing block[VIRTIO_MAX_VQS];
  21 static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
  22                      __attribute__((__aligned__(PAGE_SIZE)));
  23
  24 static VDev vdev = {
  25     .nr_vqs = 1,
  26     .vrings = block,
  27     .cmd_vr_idx = 0,
  28     .ring_area = ring_area,
  29     .wait_reply_timeout = VRING_WAIT_REPLY_TIMEOUT,
  30     .schid = { .one = 1 },
  31     .scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE,
  32     .blk_factor = 1,
  33 };
  34
  35 VDev *virtio_get_device(void)
  36 {
  37     return &vdev;
  38 }
  39
  40 VirtioDevType virtio_get_device_type(void)
  41 {
  42     return vdev.senseid.cu_model;
  43 }
  44
  45 /* virtio spec v1.0 para 4.3.3.2 */
  46 static long kvm_hypercall(unsigned long nr, unsigned long param1,
  47                           unsigned long param2, unsigned long param3)
  48 {
  49     register ulong r_nr asm("1") = nr;
  50     register ulong r_param1 asm("2") = param1;
  51     register ulong r_param2 asm("3") = param2;
  52     register ulong r_param3 asm("4") = param3;
  53     register long retval asm("2");
  54
  55     asm volatile ("diag 2,4,0x500"
  56                   : "=d" (retval)
  57                   : "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
  58                   : "memory", "cc");
  59
  60     return retval;
  61 }
  62
  63 static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
  64 {
  65     return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid,
  66                          vq_idx, cookie);
  67 }
  68
  69 /***********************************************
  70  *             Virtio functions                *
  71  ***********************************************/
  72
  73 int drain_irqs(SubChannelId schid)
  74 {
  75     Irb irb = {};
  76     int r = 0;
  77
  78     while (1) {
  79         /* FIXME: make use of TPI, for that enable subchannel and isc */
  80         if (tsch(schid, &irb)) {
  81             /* Might want to differentiate error codes later on. */
  82             if (irb.scsw.cstat) {
  83                 r = -EIO;
  84             } else if (irb.scsw.dstat != 0xc) {
  85                 r = -EIO;
  86             }
  87             return r;
  88         }
  89     }
  90 }
  91
  92 static int run_ccw(VDev *vdev, int cmd, void *ptr, int len)
  93 {
  94     Ccw1 ccw = {};
  95     CmdOrb orb = {};
  96     int r;
  97
  98     enable_subchannel(vdev->schid);
  99
 100     /* start subchannel command */
 101     orb.fmt = 1;
 102     orb.cpa = (u32)(long)&ccw;
 103     orb.lpm = 0x80;
 104
 105     ccw.cmd_code = cmd;
 106     ccw.cda = (long)ptr;
 107     ccw.count = len;
 108
 109     r = ssch(vdev->schid, &orb);
 110     /*
 111      * XXX Wait until device is done processing the CCW. For now we can
 112      *     assume that a simple tsch will have finished the CCW processing,
 113      *     but the architecture allows for asynchronous operation
 114      */
 115     if (!r) {
 116         r = drain_irqs(vdev->schid);
 117     }
 118     return r;
 119 }
 120
 121 static void vring_init(VRing *vr, VqInfo *info)
 122 {
 123     void *p = (void *) info->queue;
 124
 125     debug_print_addr("init p", p);
 126     vr->id = info->index;
 127     vr->num = info->num;
 128     vr->desc = p;
 129     vr->avail = p + info->num * sizeof(VRingDesc);
 130     vr->used = (void *)(((unsigned long)&vr->avail->ring[info->num]
 131                + info->align - 1) & ~(info->align - 1));
 132
 133     /* Zero out all relevant field */
 134     vr->avail->flags = 0;
 135     vr->avail->idx = 0;
 136
 137     /* We're running with interrupts off anyways, so don't bother */
 138     vr->used->flags = VRING_USED_F_NO_NOTIFY;
 139     vr->used->idx = 0;
 140     vr->used_idx = 0;
 141     vr->next_idx = 0;
 142     vr->cookie = 0;
 143
 144     debug_print_addr("init vr", vr);
 145 }
 146
 147 bool vring_notify(VRing *vr)
 148 {
 149     vr->cookie = virtio_notify(vr->schid, vr->id, vr->cookie);
 150     return vr->cookie >= 0;
 151 }
 152
 153 void vring_send_buf(VRing *vr, void *p, int len, int flags)
 154 {
 155     /* For follow-up chains we need to keep the first entry point */
 156     if (!(flags & VRING_HIDDEN_IS_CHAIN)) {
 157         vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;
 158     }
 159
 160     vr->desc[vr->next_idx].addr = (ulong)p;
 161     vr->desc[vr->next_idx].len = len;
 162     vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;
 163     vr->desc[vr->next_idx].next = vr->next_idx;
 164     vr->desc[vr->next_idx].next++;
 165     vr->next_idx++;
 166
 167     /* Chains only have a single ID */
 168     if (!(flags & VRING_DESC_F_NEXT)) {
 169         vr->avail->idx++;
 170     }
 171 }
 172
 173 u64 get_clock(void)
 174 {
 175     u64 r;
 176
 177     asm volatile("stck %0" : "=Q" (r) : : "cc");
 178     return r;
 179 }
 180
 181 ulong get_second(void)
 182 {
 183     return (get_clock() >> 12) / 1000000;
 184 }
 185
 186 int vr_poll(VRing *vr)
 187 {
 188     if (vr->used->idx == vr->used_idx) {
 189         vring_notify(vr);
 190         yield();
 191         return 0;
 192     }
 193
 194     vr->used_idx = vr->used->idx;
 195     vr->next_idx = 0;
 196     vr->desc[0].len = 0;
 197     vr->desc[0].flags = 0;
 198     return 1; /* vr has been updated */
 199 }
 200
 201 /*
 202  * Wait for the host to reply.
 203  *
 204  * timeout is in seconds if > 0.
 205  *
 206  * Returns 0 on success, 1 on timeout.
 207  */
 208 int vring_wait_reply(void)
 209 {
 210     ulong target_second = get_second() + vdev.wait_reply_timeout;
 211
 212     /* Wait for any queue to be updated by the host */
 213     do {
 214         int i, r = 0;
 215
 216         for (i = 0; i < vdev.nr_vqs; i++) {
 217             r += vr_poll(&vdev.vrings[i]);
 218         }
 219         yield();
 220         if (r) {
 221             return 0;
 222         }
 223     } while (!vdev.wait_reply_timeout || (get_second() < target_second));
 224
 225     return 1;
 226 }
 227
 228 int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
 229 {
 230     VRing *vr = &vdev->vrings[vqid];
 231     int i = 0;
 232
 233     do {
 234         vring_send_buf(vr, cmd[i].data, cmd[i].size,
 235                        cmd[i].flags | (i ? VRING_HIDDEN_IS_CHAIN : 0));
 236     } while (cmd[i++].flags & VRING_DESC_F_NEXT);
 237
 238     vring_wait_reply();
 239     if (drain_irqs(vr->schid)) {
 240         return -1;
 241     }
 242     return 0;
 243 }
 244
 245 void virtio_setup_ccw(VDev *vdev)
 246 {
 247     int i, rc, cfg_size = 0;
 248     unsigned char status = VIRTIO_CONFIG_S_DRIVER_OK;
 249     struct VirtioFeatureDesc {
 250         uint32_t features;
 251         uint8_t index;
 252     } __attribute__((packed)) feats;
 253
 254     IPL_assert(virtio_is_supported(vdev->schid), "PE");
 255     /* device ID has been established now */
 256
 257     vdev->config.blk.blk_size = 0; /* mark "illegal" - setup started... */
 258     vdev->guessed_disk_nature = VIRTIO_GDN_NONE;
 259
 260     run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0);
 261
 262     switch (vdev->senseid.cu_model) {
 263     case VIRTIO_ID_NET:
 264         vdev->nr_vqs = 2;
 265         vdev->cmd_vr_idx = 0;
 266         cfg_size = sizeof(vdev->config.net);
 267         break;
 268     case VIRTIO_ID_BLOCK:
 269         vdev->nr_vqs = 1;
 270         vdev->cmd_vr_idx = 0;
 271         cfg_size = sizeof(vdev->config.blk);
 272         break;
 273     case VIRTIO_ID_SCSI:
 274         vdev->nr_vqs = 3;
 275         vdev->cmd_vr_idx = VR_REQUEST;
 276         cfg_size = sizeof(vdev->config.scsi);
 277         break;
 278     default:
 279         panic("Unsupported virtio device\n");
 280     }
 281     IPL_assert(run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size) == 0,
 282                "Could not get block device configuration");
 283
 284     /* Feature negotiation */
 285     for (i = 0; i < ARRAY_SIZE(vdev->guest_features); i++) {
 286         feats.features = 0;
 287         feats.index = i;
 288         rc = run_ccw(vdev, CCW_CMD_READ_FEAT, &feats, sizeof(feats));
 289         IPL_assert(rc == 0, "Could not get features bits");
 290         vdev->guest_features[i] &= bswap32(feats.features);
 291         feats.features = bswap32(vdev->guest_features[i]);
 292         rc = run_ccw(vdev, CCW_CMD_WRITE_FEAT, &feats, sizeof(feats));
 293         IPL_assert(rc == 0, "Could not set features bits");
 294     }
 295
 296     for (i = 0; i < vdev->nr_vqs; i++) {
 297         VqInfo info = {
 298             .queue = (unsigned long long) ring_area + (i * VIRTIO_RING_SIZE),
 299             .align = KVM_S390_VIRTIO_RING_ALIGN,
 300             .index = i,
 301             .num = 0,
 302         };
 303         VqConfig config = {
 304             .index = i,
 305             .num = 0,
 306         };
 307
 308         IPL_assert(
 309             run_ccw(vdev, CCW_CMD_READ_VQ_CONF, &config, sizeof(config)) == 0,
 310             "Could not get block device VQ configuration");
 311         info.num = config.num;
 312         vring_init(&vdev->vrings[i], &info);
 313         vdev->vrings[i].schid = vdev->schid;
 314         IPL_assert(run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info)) == 0,
 315                    "Cannot set VQ info");
 316     }
 317     IPL_assert(
 318         run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status)) == 0,
 319         "Could not write status to host");
 320 }
 321
 322 bool virtio_is_supported(SubChannelId schid)
 323 {
 324     vdev.schid = schid;
 325     memset(&vdev.senseid, 0, sizeof(vdev.senseid));
 326     /* run sense id command */
 327     if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid))) {
 328         return false;
 329     }
 330     if (vdev.senseid.cu_type == 0x3832) {
 331         switch (vdev.senseid.cu_model) {
 332         case VIRTIO_ID_BLOCK:
 333         case VIRTIO_ID_SCSI:
 334         case VIRTIO_ID_NET:
 335             return true;
 336         }
 337     }
 338     return false;
 339 }