Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 298 insertions, 0 deletions

diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
new file mode 100644
index 000000000..5d2b7ba94
--- /dev/null
+++ b/pc-bios/s390-ccw/main.c
@@ -0,0 +1,298 @@
+/*
+ * S390 virtio-ccw loading program
+ *
+ * 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 "libc.h"
+#include "helper.h"
+#include "s390-arch.h"
+#include "s390-ccw.h"
+#include "cio.h"
+#include "virtio.h"
+#include "dasd-ipl.h"
+
+char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
+static SubChannelId blk_schid = { .one = 1 };
+static char loadparm_str[LOADPARM_LEN + 1];
+QemuIplParameters qipl;
+IplParameterBlock iplb __attribute__((__aligned__(PAGE_SIZE)));
+static bool have_iplb;
+static uint16_t cutype;
+LowCore *lowcore; /* Yes, this *is* a pointer to address 0 */
+
+#define LOADPARM_PROMPT "PROMPT  "
+#define LOADPARM_EMPTY  "        "
+#define BOOT_MENU_FLAG_MASK (QIPL_FLAG_BM_OPTS_CMD | QIPL_FLAG_BM_OPTS_ZIPL)
+
+/*
+ * Principles of Operations (SA22-7832-09) chapter 17 requires that
+ * a subsystem-identification is at 184-187 and bytes 188-191 are zero
+ * after list-directed-IPL and ccw-IPL.
+ */
+void write_subsystem_identification(void)
+{
+    lowcore->subchannel_id = blk_schid.sch_id;
+    lowcore->subchannel_nr = blk_schid.sch_no;
+    lowcore->io_int_parm = 0;
+}
+
+void write_iplb_location(void)
+{
+    if (cutype == CU_TYPE_VIRTIO && virtio_get_device_type() != VIRTIO_ID_NET) {
+        lowcore->ptr_iplb = ptr2u32(&iplb);
+    }
+}
+
+unsigned int get_loadparm_index(void)
+{
+    return atoui(loadparm_str);
+}
+
+static int is_dev_possibly_bootable(int dev_no, int sch_no)
+{
+    bool is_virtio;
+    Schib schib;
+    int r;
+
+    blk_schid.sch_no = sch_no;
+    r = stsch_err(blk_schid, &schib);
+    if (r == 3 || r == -EIO) {
+        return -ENODEV;
+    }
+    if (!schib.pmcw.dnv) {
+        return false;
+    }
+
+    enable_subchannel(blk_schid);
+    cutype = cu_type(blk_schid);
+
+    /*
+     * Note: we always have to run virtio_is_supported() here to make
+     * sure that the vdev.senseid data gets pre-initialized correctly
+     */
+    is_virtio = virtio_is_supported(blk_schid);
+
+    /* No specific devno given, just return whether the device is possibly bootable */
+    if (dev_no < 0) {
+        switch (cutype) {
+        case CU_TYPE_VIRTIO:
+            if (is_virtio) {
+                /*
+                 * Skip net devices since no IPLB is created and therefore
+                 * no network bootloader has been loaded
+                 */
+                if (virtio_get_device_type() != VIRTIO_ID_NET) {
+                    return true;
+                }
+            }
+            return false;
+        case CU_TYPE_DASD_3990:
+        case CU_TYPE_DASD_2107:
+            return true;
+        default:
+            return false;
+        }
+    }
+
+    /* Caller asked for a specific devno */
+    if (schib.pmcw.dev == dev_no) {
+        return true;
+    }
+
+    return false;
+}
+
+/*
+ * Find the subchannel connected to the given device (dev_no) and fill in the
+ * subchannel information block (schib) with the connected subchannel's info.
+ * NOTE: The global variable blk_schid is updated to contain the subchannel
+ * information.
+ *
+ * If the caller gives dev_no=-1 then the user did not specify a boot device.
+ * In this case we'll just use the first potentially bootable device we find.
+ */
+static bool find_subch(int dev_no)
+{
+    int i, r;
+
+    for (i = 0; i < 0x10000; i++) {
+        r = is_dev_possibly_bootable(dev_no, i);
+        if (r < 0) {
+            break;
+        }
+        if (r == true) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static void menu_setup(void)
+{
+    if (memcmp(loadparm_str, LOADPARM_PROMPT, LOADPARM_LEN) == 0) {
+        menu_set_parms(QIPL_FLAG_BM_OPTS_CMD, 0);
+        return;
+    }
+
+    /* If loadparm was set to any other value, then do not enable menu */
+    if (memcmp(loadparm_str, LOADPARM_EMPTY, LOADPARM_LEN) != 0) {
+        return;
+    }
+
+    switch (iplb.pbt) {
+    case S390_IPL_TYPE_CCW:
+    case S390_IPL_TYPE_QEMU_SCSI:
+        menu_set_parms(qipl.qipl_flags & BOOT_MENU_FLAG_MASK,
+                       qipl.boot_menu_timeout);
+        return;
+    }
+}
+
+/*
+ * Initialize the channel I/O subsystem so we can talk to our ipl/boot device.
+ */
+static void css_setup(void)
+{
+    /*
+     * Unconditionally enable mss support. In every sane configuration this
+     * will succeed; and even if it doesn't, stsch_err() can handle it.
+     */
+    enable_mss_facility();
+}
+
+/*
+ * Collect various pieces of information from the hypervisor/hardware that
+ * we'll use to determine exactly how we'll boot.
+ */
+static void boot_setup(void)
+{
+    char lpmsg[] = "LOADPARM=[________]\n";
+
+    sclp_get_loadparm_ascii(loadparm_str);
+    memcpy(lpmsg + 10, loadparm_str, 8);
+    sclp_print(lpmsg);
+
+    /*
+     * Clear out any potential S390EP magic (see jump_to_low_kernel()),
+     * so we don't taint our decision-making process during a reboot.
+     */
+    memset((char *)S390EP, 0, 6);
+
+    have_iplb = store_iplb(&iplb);
+}
+
+static void find_boot_device(void)
+{
+    VDev *vdev = virtio_get_device();
+    bool found;
+
+    switch (iplb.pbt) {
+    case S390_IPL_TYPE_CCW:
+        debug_print_int("device no. ", iplb.ccw.devno);
+        blk_schid.ssid = iplb.ccw.ssid & 0x3;
+        debug_print_int("ssid ", blk_schid.ssid);
+        found = find_subch(iplb.ccw.devno);
+        break;
+    case S390_IPL_TYPE_QEMU_SCSI:
+        vdev->scsi_device_selected = true;
+        vdev->selected_scsi_device.channel = iplb.scsi.channel;
+        vdev->selected_scsi_device.target = iplb.scsi.target;
+        vdev->selected_scsi_device.lun = iplb.scsi.lun;
+        blk_schid.ssid = iplb.scsi.ssid & 0x3;
+        found = find_subch(iplb.scsi.devno);
+        break;
+    default:
+        panic("List-directed IPL not supported yet!\n");
+    }
+
+    IPL_assert(found, "Boot device not found\n");
+}
+
+static int virtio_setup(void)
+{
+    VDev *vdev = virtio_get_device();
+    QemuIplParameters *early_qipl = (QemuIplParameters *)QIPL_ADDRESS;
+
+    memcpy(&qipl, early_qipl, sizeof(QemuIplParameters));
+
+    if (have_iplb) {
+        menu_setup();
+    }
+
+    if (virtio_get_device_type() == VIRTIO_ID_NET) {
+        sclp_print("Network boot device detected\n");
+        vdev->netboot_start_addr = qipl.netboot_start_addr;
+    } else {
+        int ret = virtio_blk_setup_device(blk_schid);
+        if (ret) {
+            return ret;
+        }
+        IPL_assert(virtio_ipl_disk_is_valid(), "No valid IPL device detected");
+    }
+
+    return 0;
+}
+
+static void ipl_boot_device(void)
+{
+    switch (cutype) {
+    case CU_TYPE_DASD_3990:
+    case CU_TYPE_DASD_2107:
+        dasd_ipl(blk_schid, cutype); /* no return */
+        break;
+    case CU_TYPE_VIRTIO:
+        if (virtio_setup() == 0) {
+            zipl_load();             /* Only returns in case of errors */
+        }
+        break;
+    default:
+        print_int("Attempting to boot from unexpected device type", cutype);
+        panic("\nBoot failed.\n");
+    }
+}
+
+/*
+ * No boot device has been specified, so we have to scan through the
+ * channels to find one.
+ */
+static void probe_boot_device(void)
+{
+    int ssid, sch_no, ret;
+
+    for (ssid = 0; ssid < 0x3; ssid++) {
+        blk_schid.ssid = ssid;
+        for (sch_no = 0; sch_no < 0x10000; sch_no++) {
+            ret = is_dev_possibly_bootable(-1, sch_no);
+            if (ret < 0) {
+                break;
+            }
+            if (ret == true) {
+                ipl_boot_device();      /* Only returns if unsuccessful */
+            }
+        }
+    }
+
+    sclp_print("Could not find a suitable boot device (none specified)\n");
+}
+
+int main(void)
+{
+    sclp_setup();
+    css_setup();
+    boot_setup();
+    if (have_iplb) {
+        find_boot_device();
+        ipl_boot_device();
+    } else {
+        probe_boot_device();
+    }
+
+    panic("Failed to load OS from hard disk\n");
+    return 0; /* make compiler happy */
+}