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virtio.c (9160B)

      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 #include "helper.h"
     18 #include "s390-time.h"
     19 
     20 #define VRING_WAIT_REPLY_TIMEOUT 30
     21 
     22 static VRing block[VIRTIO_MAX_VQS];
     23 static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
     24                      __attribute__((__aligned__(PAGE_SIZE)));
     25 
     26 static VDev vdev = {
     27     .nr_vqs = 1,
     28     .vrings = block,
     29     .cmd_vr_idx = 0,
     30     .ring_area = ring_area,
     31     .wait_reply_timeout = VRING_WAIT_REPLY_TIMEOUT,
     32     .schid = { .one = 1 },
     33     .scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE,
     34     .blk_factor = 1,
     35 };
     36 
     37 VDev *virtio_get_device(void)
     38 {
     39     return &vdev;
     40 }
     41 
     42 VirtioDevType virtio_get_device_type(void)
     43 {
     44     return vdev.senseid.cu_model;
     45 }
     46 
     47 /* virtio spec v1.0 para 4.3.3.2 */
     48 static long kvm_hypercall(unsigned long nr, unsigned long param1,
     49                           unsigned long param2, unsigned long param3)
     50 {
     51     register ulong r_nr asm("1") = nr;
     52     register ulong r_param1 asm("2") = param1;
     53     register ulong r_param2 asm("3") = param2;
     54     register ulong r_param3 asm("4") = param3;
     55     register long retval asm("2");
     56 
     57     asm volatile ("diag %%r2,%%r4,0x500"
     58                   : "=d" (retval)
     59                   : "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
     60                   : "memory", "cc");
     61 
     62     return retval;
     63 }
     64 
     65 static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
     66 {
     67     return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid,
     68                          vq_idx, cookie);
     69 }
     70 
     71 /***********************************************
     72  *             Virtio functions                *
     73  ***********************************************/
     74 
     75 int drain_irqs(SubChannelId schid)
     76 {
     77     Irb irb = {};
     78     int r = 0;
     79 
     80     while (1) {
     81         /* FIXME: make use of TPI, for that enable subchannel and isc */
     82         if (tsch(schid, &irb)) {
     83             /* Might want to differentiate error codes later on. */
     84             if (irb.scsw.cstat) {
     85                 r = -EIO;
     86             } else if (irb.scsw.dstat != 0xc) {
     87                 r = -EIO;
     88             }
     89             return r;
     90         }
     91     }
     92 }
     93 
     94 static int run_ccw(VDev *vdev, int cmd, void *ptr, int len, bool sli)
     95 {
     96     Ccw1 ccw = {};
     97 
     98     ccw.cmd_code = cmd;
     99     ccw.cda = (long)ptr;
    100     ccw.count = len;
    101 
    102     if (sli) {
    103         ccw.flags |= CCW_FLAG_SLI;
    104     }
    105 
    106     return do_cio(vdev->schid, vdev->senseid.cu_type, ptr2u32(&ccw), CCW_FMT1);
    107 }
    108 
    109 static void vring_init(VRing *vr, VqInfo *info)
    110 {
    111     void *p = (void *) info->queue;
    112 
    113     debug_print_addr("init p", p);
    114     vr->id = info->index;
    115     vr->num = info->num;
    116     vr->desc = p;
    117     vr->avail = p + info->num * sizeof(VRingDesc);
    118     vr->used = (void *)(((unsigned long)&vr->avail->ring[info->num]
    119                + info->align - 1) & ~(info->align - 1));
    120 
    121     /* Zero out all relevant field */
    122     vr->avail->flags = 0;
    123     vr->avail->idx = 0;
    124 
    125     /* We're running with interrupts off anyways, so don't bother */
    126     vr->used->flags = VRING_USED_F_NO_NOTIFY;
    127     vr->used->idx = 0;
    128     vr->used_idx = 0;
    129     vr->next_idx = 0;
    130     vr->cookie = 0;
    131 
    132     debug_print_addr("init vr", vr);
    133 }
    134 
    135 bool vring_notify(VRing *vr)
    136 {
    137     vr->cookie = virtio_notify(vr->schid, vr->id, vr->cookie);
    138     return vr->cookie >= 0;
    139 }
    140 
    141 void vring_send_buf(VRing *vr, void *p, int len, int flags)
    142 {
    143     /* For follow-up chains we need to keep the first entry point */
    144     if (!(flags & VRING_HIDDEN_IS_CHAIN)) {
    145         vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;
    146     }
    147 
    148     vr->desc[vr->next_idx].addr = (ulong)p;
    149     vr->desc[vr->next_idx].len = len;
    150     vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;
    151     vr->desc[vr->next_idx].next = vr->next_idx;
    152     vr->desc[vr->next_idx].next++;
    153     vr->next_idx++;
    154 
    155     /* Chains only have a single ID */
    156     if (!(flags & VRING_DESC_F_NEXT)) {
    157         vr->avail->idx++;
    158     }
    159 }
    160 
    161 int vr_poll(VRing *vr)
    162 {
    163     if (vr->used->idx == vr->used_idx) {
    164         vring_notify(vr);
    165         yield();
    166         return 0;
    167     }
    168 
    169     vr->used_idx = vr->used->idx;
    170     vr->next_idx = 0;
    171     vr->desc[0].len = 0;
    172     vr->desc[0].flags = 0;
    173     return 1; /* vr has been updated */
    174 }
    175 
    176 /*
    177  * Wait for the host to reply.
    178  *
    179  * timeout is in seconds if > 0.
    180  *
    181  * Returns 0 on success, 1 on timeout.
    182  */
    183 int vring_wait_reply(void)
    184 {
    185     ulong target_second = get_time_seconds() + vdev.wait_reply_timeout;
    186 
    187     /* Wait for any queue to be updated by the host */
    188     do {
    189         int i, r = 0;
    190 
    191         for (i = 0; i < vdev.nr_vqs; i++) {
    192             r += vr_poll(&vdev.vrings[i]);
    193         }
    194         yield();
    195         if (r) {
    196             return 0;
    197         }
    198     } while (!vdev.wait_reply_timeout || (get_time_seconds() < target_second));
    199 
    200     return 1;
    201 }
    202 
    203 int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
    204 {
    205     VRing *vr = &vdev->vrings[vqid];
    206     int i = 0;
    207 
    208     do {
    209         vring_send_buf(vr, cmd[i].data, cmd[i].size,
    210                        cmd[i].flags | (i ? VRING_HIDDEN_IS_CHAIN : 0));
    211     } while (cmd[i++].flags & VRING_DESC_F_NEXT);
    212 
    213     vring_wait_reply();
    214     if (drain_irqs(vr->schid)) {
    215         return -1;
    216     }
    217     return 0;
    218 }
    219 
    220 void virtio_setup_ccw(VDev *vdev)
    221 {
    222     int i, rc, cfg_size = 0;
    223     uint8_t status;
    224     struct VirtioFeatureDesc {
    225         uint32_t features;
    226         uint8_t index;
    227     } __attribute__((packed)) feats;
    228 
    229     IPL_assert(virtio_is_supported(vdev->schid), "PE");
    230     /* device ID has been established now */
    231 
    232     vdev->config.blk.blk_size = 0; /* mark "illegal" - setup started... */
    233     vdev->guessed_disk_nature = VIRTIO_GDN_NONE;
    234 
    235     run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0, false);
    236 
    237     status = VIRTIO_CONFIG_S_ACKNOWLEDGE;
    238     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
    239     IPL_assert(rc == 0, "Could not write ACKNOWLEDGE status to host");
    240 
    241     switch (vdev->senseid.cu_model) {
    242     case VIRTIO_ID_NET:
    243         vdev->nr_vqs = 2;
    244         vdev->cmd_vr_idx = 0;
    245         cfg_size = sizeof(vdev->config.net);
    246         break;
    247     case VIRTIO_ID_BLOCK:
    248         vdev->nr_vqs = 1;
    249         vdev->cmd_vr_idx = 0;
    250         cfg_size = sizeof(vdev->config.blk);
    251         break;
    252     case VIRTIO_ID_SCSI:
    253         vdev->nr_vqs = 3;
    254         vdev->cmd_vr_idx = VR_REQUEST;
    255         cfg_size = sizeof(vdev->config.scsi);
    256         break;
    257     default:
    258         panic("Unsupported virtio device\n");
    259     }
    260 
    261     status |= VIRTIO_CONFIG_S_DRIVER;
    262     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
    263     IPL_assert(rc == 0, "Could not write DRIVER status to host");
    264 
    265     /* Feature negotiation */
    266     for (i = 0; i < ARRAY_SIZE(vdev->guest_features); i++) {
    267         feats.features = 0;
    268         feats.index = i;
    269         rc = run_ccw(vdev, CCW_CMD_READ_FEAT, &feats, sizeof(feats), false);
    270         IPL_assert(rc == 0, "Could not get features bits");
    271         vdev->guest_features[i] &= bswap32(feats.features);
    272         feats.features = bswap32(vdev->guest_features[i]);
    273         rc = run_ccw(vdev, CCW_CMD_WRITE_FEAT, &feats, sizeof(feats), false);
    274         IPL_assert(rc == 0, "Could not set features bits");
    275     }
    276 
    277     rc = run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size, false);
    278     IPL_assert(rc == 0, "Could not get virtio device configuration");
    279 
    280     for (i = 0; i < vdev->nr_vqs; i++) {
    281         VqInfo info = {
    282             .queue = (unsigned long long) ring_area + (i * VIRTIO_RING_SIZE),
    283             .align = KVM_S390_VIRTIO_RING_ALIGN,
    284             .index = i,
    285             .num = 0,
    286         };
    287         VqConfig config = {
    288             .index = i,
    289             .num = 0,
    290         };
    291 
    292         rc = run_ccw(vdev, CCW_CMD_READ_VQ_CONF, &config, sizeof(config), false);
    293         IPL_assert(rc == 0, "Could not get virtio device VQ configuration");
    294         info.num = config.num;
    295         vring_init(&vdev->vrings[i], &info);
    296         vdev->vrings[i].schid = vdev->schid;
    297         IPL_assert(
    298             run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info), false) == 0,
    299             "Cannot set VQ info");
    300     }
    301 
    302     status |= VIRTIO_CONFIG_S_DRIVER_OK;
    303     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
    304     IPL_assert(rc == 0, "Could not write DRIVER_OK status to host");
    305 }
    306 
    307 bool virtio_is_supported(SubChannelId schid)
    308 {
    309     vdev.schid = schid;
    310     memset(&vdev.senseid, 0, sizeof(vdev.senseid));
    311 
    312     /*
    313      * Run sense id command.
    314      * The size of the senseid data differs between devices (notably,
    315      * between virtio devices and dasds), so specify the largest possible
    316      * size and suppress the incorrect length indication for smaller sizes.
    317      */
    318     if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid),
    319                 true)) {
    320         return false;
    321     }
    322     if (vdev.senseid.cu_type == 0x3832) {
    323         switch (vdev.senseid.cu_model) {
    324         case VIRTIO_ID_BLOCK:
    325         case VIRTIO_ID_SCSI:
    326         case VIRTIO_ID_NET:
    327             return true;
    328         }
    329     }
    330     return false;
    331 }