S390: ccw firmware: Add virtio device drivers

In order to boot, we need to be able to access a virtio-blk device through
the CCW bus. Implement support for this.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 274 insertions, 0 deletions

diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
new file mode 100644
index 0000000000..79e2941618
--- /dev/null
+++ b/pc-bios/s390-ccw/virtio.c
@@ -0,0 +1,274 @@
+/*
+ * 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 void drain_irqs(struct subchannel_id schid)
+{
+    struct irb irb = {};
+    while (1) {
+        if (tsch(schid, &irb)) {
+            return;
+        }
+    }
+}
+
+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;
+
+    /* 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;
+}
+