Merge remote-tracking branch 'remotes/huth-gitlab/tags/pull-request-2020-10-06' into staging

* Don't stop at the first unbootable device, continue scanning
* Fix corner cases in booting from ECKD
* s390x-ccw bios cleanup part 2​

# gpg: Signature made Tue 06 Oct 2020 19:17:46 BST
# gpg:                using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg:                issuer "thuth@redhat.com"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg:                 aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3  EAB9 2ED9 D774 FE70 2DB5

* remotes/huth-gitlab/tags/pull-request-2020-10-06:
  tests/qtest/cdrom: Add more s390x-related boot tests
  pc-bios/s390: Update the s390-ccw bios binaries
  pc-bios: s390x: Go into disabled wait when encountering a PGM exception
  pc-bios: s390x: Use reset PSW if avaliable
  pc-bios: s390x: Save PSW rework
  pc-bios: s390x: Fix bootmap.c zipl component entry data handling
  pc-bios/s390-ccw: break loop if a null block number is reached
  pc-bios/s390-ccw: fix off-by-one error
  pc-bios/s390-ccw/main: Remove superfluous call to enable_subchannel()
  pc-bios/s390-ccw: Allow booting in case the first virtio-blk disk is bad
  pc-bios/s390-ccw: Scan through all devices if no boot device specified
  pc-bios/s390-ccw: Do not bail out early if not finding a SCSI disk
  pc-bios/s390-ccw: Move the inner logic of find_subch() to a separate function
  pc-bios/s390-ccw: Introduce ENODEV define and remove guards of others
  pc-bios/s390-ccw: Move ipl-related code from main() into a separate function
  pc-bios/s390-ccw/Makefile: Compile with -std=gnu99, -fwrapv and -fno-common

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

13 files changed, 218 insertions, 123 deletions

diff --git a/pc-bios/s390-ccw.img b/pc-bios/s390-ccw.img
index 3074686a8c..5b57ea2837 100644
--- a/pc-bios/s390-ccw.img
+++ b/pc-bios/s390-ccw.img
diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index 3eb785048a..29fd9019b8 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -30,10 +30,11 @@ OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.o \
 	  virtio.o virtio-scsi.o virtio-blkdev.o libc.o cio.o dasd-ipl.o
 
 QEMU_CFLAGS := -Wall $(filter -W%, $(QEMU_CFLAGS))
-QEMU_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -msoft-float
-QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing
-QEMU_CFLAGS += -fno-asynchronous-unwind-tables
+QEMU_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -fno-common -fPIE
+QEMU_CFLAGS += -fwrapv -fno-strict-aliasing -fno-asynchronous-unwind-tables
 QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-stack-protector)
+QEMU_CFLAGS += -msoft-float -march=z900
+QEMU_CFLAGS += -std=gnu99
 LDFLAGS += -Wl,-pie -nostdlib
 
 build-all: s390-ccw.img s390-netboot.img
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 97205674e5..44df7d16af 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -10,6 +10,7 @@
 
 #include "libc.h"
 #include "s390-ccw.h"
+#include "s390-arch.h"
 #include "bootmap.h"
 #include "virtio.h"
 #include "bswap.h"
@@ -163,7 +164,7 @@ static bool find_zipl_boot_menu_banner(int *offset)
     int i;
 
     /* Menu banner starts with "zIPL" */
-    for (i = 0; i < virtio_get_block_size() - 4; i++) {
+    for (i = 0; i <= virtio_get_block_size() - 4; i++) {
         if (magic_match(s2_cur_blk + i, ZIPL_MAGIC_EBCDIC)) {
             *offset = i;
             return true;
@@ -192,7 +193,7 @@ static int eckd_get_boot_menu_index(block_number_t s1b_block_nr)
     for (i = 0; i < STAGE2_BLK_CNT_MAX; i++) {
         cur_block_nr = eckd_block_num(&s1b->seek[i].chs);
 
-        if (!cur_block_nr) {
+        if (!cur_block_nr || is_null_block_number(cur_block_nr)) {
             break;
         }
 
@@ -272,7 +273,8 @@ static void run_eckd_boot_script(block_number_t bmt_block_nr,
 
     IPL_assert(bms->entry[i].type == BOOT_SCRIPT_EXEC,
                "Unknown script entry type");
-    jump_to_IPL_code(bms->entry[i].address.load_address); /* no return */
+    write_reset_psw(bms->entry[i].address.load_address); /* no return */
+    jump_to_IPL_code(0); /* no return */
 }
 
 static void ipl_eckd_cdl(void)
@@ -289,11 +291,18 @@ static void ipl_eckd_cdl(void)
     read_block(1, ipl2, "Cannot read IPL2 record at block 1");
 
     mbr = &ipl2->mbr;
-    IPL_assert(magic_match(mbr, ZIPL_MAGIC), "No zIPL section in IPL2 record.");
-    IPL_assert(block_size_ok(mbr->blockptr.xeckd.bptr.size),
-               "Bad block size in zIPL section of IPL2 record.");
-    IPL_assert(mbr->dev_type == DEV_TYPE_ECKD,
-               "Non-ECKD device type in zIPL section of IPL2 record.");
+    if (!magic_match(mbr, ZIPL_MAGIC)) {
+        sclp_print("No zIPL section in IPL2 record.\n");
+        return;
+    }
+    if (!block_size_ok(mbr->blockptr.xeckd.bptr.size)) {
+        sclp_print("Bad block size in zIPL section of IPL2 record.\n");
+        return;
+    }
+    if (!mbr->dev_type == DEV_TYPE_ECKD) {
+        sclp_print("Non-ECKD device type in zIPL section of IPL2 record.\n");
+        return;
+    }
 
     /* save pointer to Boot Map Table */
     bmt_block_nr = eckd_block_num(&mbr->blockptr.xeckd.bptr.chs);
@@ -303,10 +312,14 @@ static void ipl_eckd_cdl(void)
 
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(2, vlbl, "Cannot read Volume Label at block 2");
-    IPL_assert(magic_match(vlbl->key, VOL1_MAGIC),
-               "Invalid magic of volume label block");
-    IPL_assert(magic_match(vlbl->f.key, VOL1_MAGIC),
-               "Invalid magic of volser block");
+    if (!magic_match(vlbl->key, VOL1_MAGIC)) {
+        sclp_print("Invalid magic of volume label block.\n");
+        return;
+    }
+    if (!magic_match(vlbl->f.key, VOL1_MAGIC)) {
+        sclp_print("Invalid magic of volser block.\n");
+        return;
+    }
     print_volser(vlbl->f.volser);
 
     run_eckd_boot_script(bmt_block_nr, s1b_block_nr);
@@ -398,7 +411,8 @@ static void ipl_eckd(void)
     read_block(0, mbr, "Cannot read block 0 on DASD");
 
     if (magic_match(mbr->magic, IPL1_MAGIC)) {
-        ipl_eckd_cdl(); /* no return */
+        ipl_eckd_cdl();         /* only returns in case of error */
+        return;
     }
 
     /* LDL/CMS? */
@@ -436,7 +450,7 @@ static void zipl_load_segment(ComponentEntry *entry)
     char *blk_no = &err_msg[30]; /* where to print blockno in (those ZZs) */
 
     blockno = entry->data.blockno;
-    address = entry->load_address;
+    address = entry->compdat.load_addr;
 
     debug_print_int("loading segment at block", blockno);
     debug_print_int("addr", address);
@@ -514,7 +528,8 @@ static void zipl_run(ScsiBlockPtr *pte)
     IPL_assert(entry->component_type == ZIPL_COMP_ENTRY_EXEC, "No EXEC entry");
 
     /* should not return */
-    jump_to_IPL_code(entry->load_address);
+    write_reset_psw(entry->compdat.load_psw);
+    jump_to_IPL_code(0);
 }
 
 static void ipl_scsi(void)
@@ -825,5 +840,5 @@ void zipl_load(void)
         panic("\n! Unknown IPL device type !\n");
     }
 
-    panic("\n* this can never happen *\n");
+    sclp_print("zIPL load failed.\n");
 }
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index 12a0166aae..3946aa3f8d 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -64,11 +64,16 @@ typedef struct BootMapTable {
     BootMapPointer entry[];
 } __attribute__ ((packed)) BootMapTable;
 
+typedef union ComponentEntryData {
+    uint64_t load_psw;
+    uint64_t load_addr;
+} ComponentEntryData;
+
 typedef struct ComponentEntry {
     ScsiBlockPtr data;
     uint8_t pad[7];
     uint8_t component_type;
-    uint64_t load_address;
+    ComponentEntryData compdat;
 } __attribute((packed)) ComponentEntry;
 
 typedef struct ComponentHeader {
diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
index 767012bf0c..fbae45b03c 100644
--- a/pc-bios/s390-ccw/jump2ipl.c
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -12,21 +12,24 @@
 
 #define KERN_IMAGE_START 0x010000UL
 #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64)
+#define RESET_PSW ((uint64_t)&jump_to_IPL_addr | RESET_PSW_MASK)
 
-typedef struct ResetInfo {
-    uint64_t ipl_psw;
-    uint32_t ipl_continue;
-} ResetInfo;
+static uint64_t *reset_psw = 0, save_psw, ipl_continue;
 
-static ResetInfo save;
+void write_reset_psw(uint64_t psw)
+{
+    *reset_psw = psw;
+}
 
-static void jump_to_IPL_2(void)
+static void jump_to_IPL_addr(void)
 {
-    ResetInfo *current = 0;
+    __attribute__((noreturn)) void (*ipl)(void) = (void *)ipl_continue;
 
-    void (*ipl)(void) = (void *) (uint64_t) current->ipl_continue;
-    *current = save;
-    ipl(); /* should not return */
+    /* Restore reset PSW */
+    write_reset_psw(save_psw);
+
+    ipl();
+    /* should not return */
 }
 
 void jump_to_IPL_code(uint64_t address)
@@ -46,15 +49,12 @@ void jump_to_IPL_code(uint64_t address)
      * content of non-BIOS memory after we loaded the guest, so we
      * save the original content and restore it in jump_to_IPL_2.
      */
-    ResetInfo *current = 0;
-
-    save = *current;
-
-    current->ipl_psw = (uint64_t) &jump_to_IPL_2;
-    current->ipl_psw |= RESET_PSW_MASK;
-    current->ipl_continue = address & PSW_MASK_SHORT_ADDR;
-
-    debug_print_int("set IPL addr to", current->ipl_continue);
+    if (address) {
+        save_psw = *reset_psw;
+        write_reset_psw(RESET_PSW);
+        ipl_continue = address;
+    }
+    debug_print_int("set IPL addr to", address ?: *reset_psw & PSW_MASK_SHORT_ADDR);
 
     /* Ensure the guest output starts fresh */
     sclp_print("\n");
@@ -84,7 +84,12 @@ void jump_to_low_kernel(void)
 
     /* Trying to get PSW at zero address */
     if (*((uint64_t *)0) & RESET_PSW_MASK) {
-        jump_to_IPL_code((*((uint64_t *)0)) & PSW_MASK_SHORT_ADDR);
+        /*
+         * Surely nobody will try running directly from lowcore, so
+         * let's use 0 as an indication that we want to load the reset
+         * psw at 0x0 and not jump to the entry.
+         */
+        jump_to_IPL_code(0);
     }
 
     /* No other option left, so use the Linux kernel start address */
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index 146a50760b..43c792cf95 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -51,6 +51,60 @@ 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.
@@ -62,53 +116,14 @@ unsigned int get_loadparm_index(void)
  */
 static bool find_subch(int dev_no)
 {
-    Schib schib;
     int i, r;
-    bool is_virtio;
 
     for (i = 0; i < 0x10000; i++) {
-        blk_schid.sch_no = i;
-        r = stsch_err(blk_schid, &schib);
-        if ((r == 3) || (r == -EIO)) {
+        r = is_dev_possibly_bootable(dev_no, i);
+        if (r < 0) {
             break;
         }
-        if (!schib.pmcw.dnv) {
-            continue;
-        }
-
-        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 1st possibly bootable device */
-        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;
-                    }
-                }
-                continue;
-            case CU_TYPE_DASD_3990:
-            case CU_TYPE_DASD_2107:
-                return true;
-            default:
-                continue;
-            }
-        }
-
-        /* Caller asked for a specific devno */
-        if (schib.pmcw.dev == dev_no) {
+        if (r == true) {
             return true;
         }
     }
@@ -167,20 +182,8 @@ static void boot_setup(void)
 static void find_boot_device(void)
 {
     VDev *vdev = virtio_get_device();
-    int ssid;
     bool found;
 
-    if (!have_iplb) {
-        for (ssid = 0; ssid < 0x3; ssid++) {
-            blk_schid.ssid = ssid;
-            found = find_subch(-1);
-            if (found) {
-                return;
-            }
-        }
-        panic("Could not find a suitable boot device (none specified)\n");
-    }
-
     switch (iplb.pbt) {
     case S390_IPL_TYPE_CCW:
         debug_print_int("device no. ", iplb.ccw.devno);
@@ -203,7 +206,7 @@ static void find_boot_device(void)
     IPL_assert(found, "Boot device not found\n");
 }
 
-static void virtio_setup(void)
+static int virtio_setup(void)
 {
     VDev *vdev = virtio_get_device();
     QemuIplParameters *early_qipl = (QemuIplParameters *)QIPL_ADDRESS;
@@ -218,31 +221,68 @@ static void virtio_setup(void)
         sclp_print("Network boot device detected\n");
         vdev->netboot_start_addr = qipl.netboot_start_addr;
     } else {
-        virtio_blk_setup_device(blk_schid);
+        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;
 }
 
-int main(void)
+static void ipl_boot_device(void)
 {
-    sclp_setup();
-    css_setup();
-    boot_setup();
-    find_boot_device();
-    enable_subchannel(blk_schid);
-
     switch (cutype) {
     case CU_TYPE_DASD_3990:
     case CU_TYPE_DASD_2107:
         dasd_ipl(blk_schid, cutype); /* no return */
         break;
     case CU_TYPE_VIRTIO:
-        virtio_setup();
-        zipl_load(); /* no return */
+        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("");
+        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");
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 36b884cced..6cd92669e9 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -27,12 +27,10 @@ typedef unsigned long long __u64;
 #define false 0
 #define PAGE_SIZE 4096
 
-#ifndef EIO
 #define EIO     1
-#endif
-#ifndef EBUSY
 #define EBUSY   2
-#endif
+#define ENODEV  3
+
 #ifndef NULL
 #define NULL    0
 #endif
@@ -71,13 +69,14 @@ int sclp_read(char *str, size_t count);
 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
                                  ulong subchan_id, void *load_addr);
 bool virtio_is_supported(SubChannelId schid);
-void virtio_blk_setup_device(SubChannelId schid);
+int virtio_blk_setup_device(SubChannelId schid);
 int virtio_read(ulong sector, void *load_addr);
 
 /* bootmap.c */
 void zipl_load(void);
 
 /* jump2ipl.c */
+void write_reset_psw(uint64_t psw);
 void jump_to_IPL_code(uint64_t address);
 void jump_to_low_kernel(void);
 
diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S
index ce519300a1..4d5ad21653 100644
--- a/pc-bios/s390-ccw/start.S
+++ b/pc-bios/s390-ccw/start.S
@@ -34,7 +34,10 @@ remainder:
 	larl	%r2,memsetxc
 	ex	%r3,0(%r2)
 done:
-	j      main		/* And call C */
+        /* set up a pgm exception disabled wait psw */
+        larl	%r2, disabled_wait_psw
+        mvc	0x01d0(16), 0(%r2)
+        j      main		/* And call C */
 
 memsetxc:
 	xc	0(1,%r1),0(%r1)
diff --git a/pc-bios/s390-ccw/virtio-blkdev.c b/pc-bios/s390-ccw/virtio-blkdev.c
index 11c56261ca..7d35050292 100644
--- a/pc-bios/s390-ccw/virtio-blkdev.c
+++ b/pc-bios/s390-ccw/virtio-blkdev.c
@@ -263,9 +263,10 @@ uint64_t virtio_get_blocks(void)
     return 0;
 }
 
-void virtio_blk_setup_device(SubChannelId schid)
+int virtio_blk_setup_device(SubChannelId schid)
 {
     VDev *vdev = virtio_get_device();
+    int ret = 0;
 
     vdev->schid = schid;
     virtio_setup_ccw(vdev);
@@ -288,9 +289,11 @@ void virtio_blk_setup_device(SubChannelId schid)
             "Config: CDB size mismatch");
 
         sclp_print("Using virtio-scsi.\n");
-        virtio_scsi_setup(vdev);
+        ret = virtio_scsi_setup(vdev);
         break;
     default:
         panic("\n! No IPL device available !\n");
     }
+
+    return ret;
 }
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index eddfb8a7ad..2c8d0f3097 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -194,7 +194,12 @@ static bool scsi_read_capacity(VDev *vdev,
 
 /* virtio-scsi routines */
 
-static void virtio_scsi_locate_device(VDev *vdev)
+/*
+ * Tries to locate a SCSI device and and adds the information for the found
+ * device to the vdev->scsi_device structure.
+ * Returns 0 if SCSI device could be located, or a error code < 0 otherwise
+ */
+static int virtio_scsi_locate_device(VDev *vdev)
 {
     const uint16_t channel = 0; /* again, it's what QEMU does */
     uint16_t target;
@@ -220,7 +225,7 @@ static void virtio_scsi_locate_device(VDev *vdev)
         IPL_check(sdev->channel == 0, "non-zero channel requested");
         IPL_check(sdev->target <= vdev->config.scsi.max_target, "target# high");
         IPL_check(sdev->lun <= vdev->config.scsi.max_lun, "LUN# high");
-        return;
+        return 0;
     }
 
     for (target = 0; target <= vdev->config.scsi.max_target; target++) {
@@ -247,18 +252,20 @@ static void virtio_scsi_locate_device(VDev *vdev)
              */
             sdev->lun = r->lun[0].v16[0]; /* it's returned this way */
             debug_print_int("Have to use LUN", sdev->lun);
-            return; /* we have to use this device */
+            return 0; /* we have to use this device */
         }
         for (i = 0; i < luns; i++) {
             if (r->lun[i].v64) {
                 /* Look for non-zero LUN - we have where to choose from */
                 sdev->lun = r->lun[i].v16[0];
                 debug_print_int("Will use LUN", sdev->lun);
-                return; /* we have found a device */
+                return 0; /* we have found a device */
             }
         }
     }
-    panic("\n! Cannot locate virtio-scsi device !\n");
+
+    sclp_print("Warning: Could not locate a usable virtio-scsi device\n");
+    return -ENODEV;
 }
 
 int virtio_scsi_read_many(VDev *vdev,
@@ -322,17 +329,20 @@ static void scsi_parse_capacity_report(void *data,
     }
 }
 
-void virtio_scsi_setup(VDev *vdev)
+int virtio_scsi_setup(VDev *vdev)
 {
     int retry_test_unit_ready = 3;
     uint8_t data[256];
     uint32_t data_size = sizeof(data);
     ScsiInquiryEvpdPages *evpd = &scsi_inquiry_evpd_pages_response;
     ScsiInquiryEvpdBl *evpd_bl = &scsi_inquiry_evpd_bl_response;
-    int i;
+    int i, ret;
 
     vdev->scsi_device = &default_scsi_device;
-    virtio_scsi_locate_device(vdev);
+    ret = virtio_scsi_locate_device(vdev);
+    if (ret < 0) {
+        return ret;
+    }
 
     /* We have to "ping" the device before it becomes readable */
     while (!scsi_test_unit_ready(vdev)) {
@@ -417,4 +427,6 @@ void virtio_scsi_setup(VDev *vdev)
     }
     scsi_parse_capacity_report(data, &vdev->scsi_last_block,
                                (uint32_t *) &vdev->scsi_block_size);
+
+    return 0;
 }
diff --git a/pc-bios/s390-ccw/virtio-scsi.h b/pc-bios/s390-ccw/virtio-scsi.h
index 4c4f4bbc31..4b14c2c2f9 100644
--- a/pc-bios/s390-ccw/virtio-scsi.h
+++ b/pc-bios/s390-ccw/virtio-scsi.h
@@ -67,7 +67,7 @@ static inline bool virtio_scsi_response_ok(const VirtioScsiCmdResp *r)
         return r->response == VIRTIO_SCSI_S_OK && r->status == CDB_STATUS_GOOD;
 }
 
-void virtio_scsi_setup(VDev *vdev);
+int virtio_scsi_setup(VDev *vdev);
 int virtio_scsi_read_many(VDev *vdev,
                           ulong sector, void *load_addr, int sec_num);
 
diff --git a/pc-bios/s390-netboot.img b/pc-bios/s390-netboot.img
index d9c319604b..3dfce693f5 100644
--- a/pc-bios/s390-netboot.img
+++ b/pc-bios/s390-netboot.img
diff --git a/tests/qtest/cdrom-test.c b/tests/qtest/cdrom-test.c
index e9afab693c..eef242dc80 100644
--- a/tests/qtest/cdrom-test.c
+++ b/tests/qtest/cdrom-test.c
@@ -163,6 +163,18 @@ static void add_s390x_tests(void)
     qtest_add_data_func("cdrom/boot/virtio-scsi",
                         "-device virtio-scsi -device scsi-cd,drive=cdr "
                         "-blockdev file,node-name=cdr,filename=", test_cdboot);
+    qtest_add_data_func("cdrom/boot/with-bootindex",
+                        "-device virtio-serial -device virtio-scsi "
+                        "-device virtio-blk,drive=d1 "
+                        "-drive driver=null-co,read-zeroes=on,if=none,id=d1 "
+                        "-device virtio-blk,drive=d2,bootindex=1 "
+                        "-drive if=none,id=d2,media=cdrom,file=", test_cdboot);
+    qtest_add_data_func("cdrom/boot/without-bootindex",
+                        "-device virtio-scsi -device virtio-serial "
+                        "-device x-terminal3270 -device virtio-blk,drive=d1 "
+                        "-drive driver=null-co,read-zeroes=on,if=none,id=d1 "
+                        "-device virtio-blk,drive=d2 "
+                        "-drive if=none,id=d2,media=cdrom,file=", test_cdboot);
 }
 
 int main(int argc, char **argv)