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