Archipelago » qemu

/*

 * Virtio driver bits

 *

 * Copyright (c) 2013 Alexander Graf <agraf@suse.de>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or (at

 * your option) any later version. See the COPYING file in the top-level

 * directory.

 */

#include "s390-ccw.h"

#include "virtio.h"

struct vring block;

static long kvm_hypercall(unsigned long nr, unsigned long param1,

                          unsigned long param2)

{

        register ulong r_nr asm("1") = nr;

        register ulong r_param1 asm("2") = param1;

        register ulong r_param2 asm("3") = param2;

        register long retval asm("2");

        asm volatile ("diag 2,4,0x500"

                      : "=d" (retval)

                      : "d" (r_nr), "0" (r_param1), "r"(r_param2)

                      : "memory", "cc");

        return retval;

}

static void virtio_notify(struct subchannel_id schid)

{

    kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32*)&schid, 0);

}

/***********************************************

 *             Virtio functions                *

 ***********************************************/

static int drain_irqs(struct subchannel_id schid)

{

    struct irb irb = {};

    int r = 0;

    while (1) {

        /* FIXME: make use of TPI, for that enable subchannel and isc */

        if (tsch(schid, &irb)) {

            /* Might want to differentiate error codes later on. */

            if (irb.scsw.cstat) {

                r = -EIO;

            } else if (irb.scsw.dstat != 0xc) {

                r = -EIO;

            }

            return r;

        }

    }

}

static int run_ccw(struct subchannel_id schid, int cmd, void *ptr, int len)

{

    struct ccw1 ccw = {};

    struct cmd_orb orb = {};

    struct schib schib;

    int r;

    /* start command processing */

    stsch_err(schid, &schib);

    schib.scsw.ctrl = SCSW_FCTL_START_FUNC;

    msch(schid, &schib);

    /* start subchannel command */

    orb.fmt = 1;

    orb.cpa = (u32)(long)&ccw;

    orb.lpm = 0x80;

    ccw.cmd_code = cmd;

    ccw.cda = (long)ptr;

    ccw.count = len;

    r = ssch(schid, &orb);

    /*

     * XXX Wait until device is done processing the CCW. For now we can

     *     assume that a simple tsch will have finished the CCW processing,

     *     but the architecture allows for asynchronous operation

     */

    drain_irqs(schid);

    return r;

}

static void virtio_set_status(struct subchannel_id schid,

                              unsigned long dev_addr)

{

    unsigned char status = dev_addr;

    run_ccw(schid, CCW_CMD_WRITE_STATUS, &status, sizeof(status));

}

static void virtio_reset(struct subchannel_id schid)

{

    run_ccw(schid, CCW_CMD_VDEV_RESET, NULL, 0);

}

static void vring_init(struct vring *vr, unsigned int num, void *p,

                       unsigned long align)

{

    debug_print_addr("init p", p);

    vr->num = num;

    vr->desc = p;

    vr->avail = p + num*sizeof(struct vring_desc);

    vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)

                & ~(align - 1));

    /* We're running with interrupts off anyways, so don't bother */

    vr->used->flags = VRING_USED_F_NO_NOTIFY;

    debug_print_addr("init vr", vr);

}

static void vring_notify(struct subchannel_id schid)

{

    virtio_notify(schid);

}

static void vring_send_buf(struct vring *vr, void *p, int len, int flags)

{

    /* For follow-up chains we need to keep the first entry point */

    if (!(flags & VRING_HIDDEN_IS_CHAIN)) {

        vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;

    }

    vr->desc[vr->next_idx].addr = (ulong)p;

    vr->desc[vr->next_idx].len = len;

    vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;

    vr->desc[vr->next_idx].next = vr->next_idx;

    vr->desc[vr->next_idx].next++;

    vr->next_idx++;

    /* Chains only have a single ID */

    if (!(flags & VRING_DESC_F_NEXT)) {

        vr->avail->idx++;

    }

    vr->used->idx = vr->next_idx;

}

static u64 get_clock(void)

{

    u64 r;

    asm volatile("stck %0" : "=Q" (r) : : "cc");

    return r;

}

static ulong get_second(void)

{

    return (get_clock() >> 12) / 1000000;

}

/*

 * Wait for the host to reply.

 *

 * timeout is in seconds if > 0.

 *

 * Returns 0 on success, 1 on timeout.

 */

static int vring_wait_reply(struct vring *vr, int timeout)

{

    ulong target_second = get_second() + timeout;

    struct subchannel_id schid = vr->schid;

    int r = 0;

    while (vr->used->idx == vr->next_idx) {

        vring_notify(schid);

        if (timeout && (get_second() >= target_second)) {

            r = 1;

            break;

        }

        yield();

    }

    vr->next_idx = 0;

    vr->desc[0].len = 0;

    vr->desc[0].flags = 0;

    return r;

}

/***********************************************

 *               Virtio block                  *

 ***********************************************/

static int virtio_read_many(ulong sector, void *load_addr, int sec_num)

{

    struct virtio_blk_outhdr out_hdr;

    u8 status;

    /* Tell the host we want to read */

    out_hdr.type = VIRTIO_BLK_T_IN;

    out_hdr.ioprio = 99;

    out_hdr.sector = sector;

    vring_send_buf(&block, &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);

    /* This is where we want to receive data */

    vring_send_buf(&block, load_addr, SECTOR_SIZE * sec_num,

                   VRING_DESC_F_WRITE | VRING_HIDDEN_IS_CHAIN |

                   VRING_DESC_F_NEXT);

    /* status field */

    vring_send_buf(&block, &status, sizeof(u8), VRING_DESC_F_WRITE |

                   VRING_HIDDEN_IS_CHAIN);

    /* Now we can tell the host to read */

    vring_wait_reply(&block, 0);

    drain_irqs(block.schid);

    return status;

}

unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,

                                 ulong subchan_id, void *load_addr)

{

    u8 status;

    int sec = rec_list1;

    int sec_num = (((rec_list2 >> 32)+ 1) & 0xffff);

    int sec_len = rec_list2 >> 48;

    ulong addr = (ulong)load_addr;

    if (sec_len != SECTOR_SIZE) {

        return -1;

    }

    sclp_print(".");

    status = virtio_read_many(sec, (void*)addr, sec_num);

    if (status) {

        virtio_panic("I/O Error");

    }

    addr += sec_num * SECTOR_SIZE;

    return addr;

}

int virtio_read(ulong sector, void *load_addr)

{

    return virtio_read_many(sector, load_addr, 1);

}

void virtio_setup_block(struct subchannel_id schid)

{

    struct vq_info_block info;

    virtio_reset(schid);

    /* XXX need to fetch the 128 from host */

    vring_init(&block, 128, (void*)(100 * 1024 * 1024),

               KVM_S390_VIRTIO_RING_ALIGN);

    info.queue = (100ULL * 1024ULL* 1024ULL);

    info.align = KVM_S390_VIRTIO_RING_ALIGN;

    info.index = 0;

    info.num = 128;

    block.schid = schid;

    run_ccw(schid, CCW_CMD_SET_VQ, &info, sizeof(info));

    virtio_set_status(schid, VIRTIO_CONFIG_S_DRIVER_OK);

}

bool virtio_is_blk(struct subchannel_id schid)

{

    int r;

    struct senseid senseid = {};

    /* run sense id command */

    r = run_ccw(schid, CCW_CMD_SENSE_ID, &senseid, sizeof(senseid));

    if (r) {

        return false;

    }

    if ((senseid.cu_type != 0x3832) || (senseid.cu_model != VIRTIO_ID_BLOCK)) {

        return false;

    }

    return true;

}