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 "s390-ccw.h"
  12 #include "virtio.h"
  13
  14 struct vring block;
  15
  16 static long kvm_hypercall(unsigned long nr, unsigned long param1,
  17                           unsigned long param2)
  18 {
  19         register ulong r_nr asm("1") = nr;
  20         register ulong r_param1 asm("2") = param1;
  21         register ulong r_param2 asm("3") = param2;
  22         register long retval asm("2");
  23
  24         asm volatile ("diag 2,4,0x500"
  25                       : "=d" (retval)
  26                       : "d" (r_nr), "0" (r_param1), "r"(r_param2)
  27                       : "memory", "cc");
  28
  29         return retval;
  30 }
  31
  32 static void virtio_notify(struct subchannel_id schid)
  33 {
  34     kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32*)&schid, 0);
  35 }
  36
  37 /***********************************************
  38  *             Virtio functions                *
  39  ***********************************************/
  40
  41 static int drain_irqs(struct subchannel_id schid)
  42 {
  43     struct irb irb = {};
  44     int r = 0;
  45
  46     while (1) {
  47         /* FIXME: make use of TPI, for that enable subchannel and isc */
  48         if (tsch(schid, &irb)) {
  49             /* Might want to differentiate error codes later on. */
  50             if (irb.scsw.cstat) {
  51                 r = -EIO;
  52             } else if (irb.scsw.dstat != 0xc) {
  53                 r = -EIO;
  54             }
  55             return r;
  56         }
  57     }
  58 }
  59
  60 static int run_ccw(struct subchannel_id schid, int cmd, void *ptr, int len)
  61 {
  62     struct ccw1 ccw = {};
  63     struct cmd_orb orb = {};
  64     struct schib schib;
  65     int r;
  66
  67     /* start command processing */
  68     stsch_err(schid, &schib);
  69     schib.scsw.ctrl = SCSW_FCTL_START_FUNC;
  70     msch(schid, &schib);
  71
  72     /* start subchannel command */
  73     orb.fmt = 1;
  74     orb.cpa = (u32)(long)&ccw;
  75     orb.lpm = 0x80;
  76
  77     ccw.cmd_code = cmd;
  78     ccw.cda = (long)ptr;
  79     ccw.count = len;
  80
  81     r = ssch(schid, &orb);
  82     /*
  83      * XXX Wait until device is done processing the CCW. For now we can
  84      *     assume that a simple tsch will have finished the CCW processing,
  85      *     but the architecture allows for asynchronous operation
  86      */
  87     drain_irqs(schid);
  88     return r;
  89 }
  90
  91 static void virtio_set_status(struct subchannel_id schid,
  92                               unsigned long dev_addr)
  93 {
  94     unsigned char status = dev_addr;
  95     run_ccw(schid, CCW_CMD_WRITE_STATUS, &status, sizeof(status));
  96 }
  97
  98 static void virtio_reset(struct subchannel_id schid)
  99 {
 100     run_ccw(schid, CCW_CMD_VDEV_RESET, NULL, 0);
 101 }
 102
 103 static void vring_init(struct vring *vr, unsigned int num, void *p,
 104                        unsigned long align)
 105 {
 106     debug_print_addr("init p", p);
 107     vr->num = num;
 108     vr->desc = p;
 109     vr->avail = p + num*sizeof(struct vring_desc);
 110     vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)
 111                 & ~(align - 1));
 112
 113     /* We're running with interrupts off anyways, so don't bother */
 114     vr->used->flags = VRING_USED_F_NO_NOTIFY;
 115
 116     debug_print_addr("init vr", vr);
 117 }
 118
 119 static void vring_notify(struct subchannel_id schid)
 120 {
 121     virtio_notify(schid);
 122 }
 123
 124 static void vring_send_buf(struct vring *vr, void *p, int len, int flags)
 125 {
 126     /* For follow-up chains we need to keep the first entry point */
 127     if (!(flags & VRING_HIDDEN_IS_CHAIN)) {
 128         vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;
 129     }
 130
 131     vr->desc[vr->next_idx].addr = (ulong)p;
 132     vr->desc[vr->next_idx].len = len;
 133     vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;
 134     vr->desc[vr->next_idx].next = vr->next_idx;
 135     vr->desc[vr->next_idx].next++;
 136     vr->next_idx++;
 137
 138     /* Chains only have a single ID */
 139     if (!(flags & VRING_DESC_F_NEXT)) {
 140         vr->avail->idx++;
 141     }
 142
 143     vr->used->idx = vr->next_idx;
 144 }
 145
 146 static u64 get_clock(void)
 147 {
 148     u64 r;
 149
 150     asm volatile("stck %0" : "=Q" (r) : : "cc");
 151     return r;
 152 }
 153
 154 static ulong get_second(void)
 155 {
 156     return (get_clock() >> 12) / 1000000;
 157 }
 158
 159 /*
 160  * Wait for the host to reply.
 161  *
 162  * timeout is in seconds if > 0.
 163  *
 164  * Returns 0 on success, 1 on timeout.
 165  */
 166 static int vring_wait_reply(struct vring *vr, int timeout)
 167 {
 168     ulong target_second = get_second() + timeout;
 169     struct subchannel_id schid = vr->schid;
 170     int r = 0;
 171
 172     while (vr->used->idx == vr->next_idx) {
 173         vring_notify(schid);
 174         if (timeout && (get_second() >= target_second)) {
 175             r = 1;
 176             break;
 177         }
 178         yield();
 179     }
 180
 181     vr->next_idx = 0;
 182     vr->desc[0].len = 0;
 183     vr->desc[0].flags = 0;
 184
 185     return r;
 186 }
 187
 188 /***********************************************
 189  *               Virtio block                  *
 190  ***********************************************/
 191
 192 static int virtio_read_many(ulong sector, void *load_addr, int sec_num)
 193 {
 194     struct virtio_blk_outhdr out_hdr;
 195     u8 status;
 196
 197     /* Tell the host we want to read */
 198     out_hdr.type = VIRTIO_BLK_T_IN;
 199     out_hdr.ioprio = 99;
 200     out_hdr.sector = sector;
 201
 202     vring_send_buf(&block, &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);
 203
 204     /* This is where we want to receive data */
 205     vring_send_buf(&block, load_addr, SECTOR_SIZE * sec_num,
 206                    VRING_DESC_F_WRITE | VRING_HIDDEN_IS_CHAIN |
 207                    VRING_DESC_F_NEXT);
 208
 209     /* status field */
 210     vring_send_buf(&block, &status, sizeof(u8), VRING_DESC_F_WRITE |
 211                    VRING_HIDDEN_IS_CHAIN);
 212
 213     /* Now we can tell the host to read */
 214     vring_wait_reply(&block, 0);
 215
 216     drain_irqs(block.schid);
 217
 218     return status;
 219 }
 220
 221 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
 222                                  ulong subchan_id, void *load_addr)
 223 {
 224     u8 status;
 225     int sec = rec_list1;
 226     int sec_num = (((rec_list2 >> 32)+ 1) & 0xffff);
 227     int sec_len = rec_list2 >> 48;
 228     ulong addr = (ulong)load_addr;
 229
 230     if (sec_len != SECTOR_SIZE) {
 231         return -1;
 232     }
 233
 234     sclp_print(".");
 235     status = virtio_read_many(sec, (void*)addr, sec_num);
 236     if (status) {
 237         virtio_panic("I/O Error");
 238     }
 239     addr += sec_num * SECTOR_SIZE;
 240
 241     return addr;
 242 }
 243
 244 int virtio_read(ulong sector, void *load_addr)
 245 {
 246     return virtio_read_many(sector, load_addr, 1);
 247 }
 248
 249 void virtio_setup_block(struct subchannel_id schid)
 250 {
 251     struct vq_info_block info;
 252
 253     virtio_reset(schid);
 254
 255     /* XXX need to fetch the 128 from host */
 256     vring_init(&block, 128, (void*)(100 * 1024 * 1024),
 257                KVM_S390_VIRTIO_RING_ALIGN);
 258
 259     info.queue = (100ULL * 1024ULL* 1024ULL);
 260     info.align = KVM_S390_VIRTIO_RING_ALIGN;
 261     info.index = 0;
 262     info.num = 128;
 263     block.schid = schid;
 264
 265     run_ccw(schid, CCW_CMD_SET_VQ, &info, sizeof(info));
 266     virtio_set_status(schid, VIRTIO_CONFIG_S_DRIVER_OK);
 267 }
 268
 269 bool virtio_is_blk(struct subchannel_id schid)
 270 {
 271     int r;
 272     struct senseid senseid = {};
 273
 274     /* run sense id command */
 275     r = run_ccw(schid, CCW_CMD_SENSE_ID, &senseid, sizeof(senseid));
 276     if (r) {
 277         return false;
 278     }
 279     if ((senseid.cu_type != 0x3832) || (senseid.cu_model != VIRTIO_ID_BLOCK)) {
 280         return false;
 281     }
 282
 283     return true;
 284 }
 285