Merge tag 'tags/s390-ccw-bios-2018-02-26' into s390-next

Boot menu patches by Collin L. Walling

# gpg: Signature made Mon 26 Feb 2018 11:24:21 AM CET
# gpg:                using RSA key 2ED9D774FE702DB5
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg:                 aka "Thomas Huth <thuth@redhat.com>" [undefined]
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>" [undefined]
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>" [unknown]

* tag 'tags/s390-ccw-bios-2018-02-26':
  pc-bios/s390: Rebuild the s390x firmware images with the boot menu changes
  s390-ccw: interactive boot menu for scsi
  s390-ccw: use zipl values when no boot menu options are present
  s390-ccw: set cp_receive mask only when needed and consume pending service irqs
  s390-ccw: read user input for boot index via the SCLP console
  s390-ccw: print zipl boot menu
  s390-ccw: read stage2 boot loader data to find menu
  s390-ccw: set up interactive boot menu parameters
  s390-ccw: parse and set boot menu options
  s390-ccw: move auxiliary IPL data to separate location
  s390-ccw: update libc
  s390-ccw: refactor IPL structs
  s390-ccw: refactor eckd_block_num to use CHS
  s390-ccw: refactor boot map table code

15 files changed, 757 insertions, 126 deletions

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index 0d06fc12b63..798e99aadfa 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -23,6 +23,9 @@
 #include "hw/s390x/ebcdic.h"
 #include "ipl.h"
 #include "qemu/error-report.h"
+#include "qemu/config-file.h"
+#include "qemu/cutils.h"
+#include "qemu/option.h"
 
 #define KERN_IMAGE_START                0x010000UL
 #define KERN_PARM_AREA                  0x010480UL
@@ -219,6 +222,61 @@ static Property s390_ipl_properties[] = {
     DEFINE_PROP_END_OF_LIST(),
 };
 
+static void s390_ipl_set_boot_menu(S390IPLState *ipl)
+{
+    QemuOptsList *plist = qemu_find_opts("boot-opts");
+    QemuOpts *opts = QTAILQ_FIRST(&plist->head);
+    uint8_t *flags = &ipl->qipl.qipl_flags;
+    uint32_t *timeout = &ipl->qipl.boot_menu_timeout;
+    const char *tmp;
+    unsigned long splash_time = 0;
+
+    if (!get_boot_device(0)) {
+        if (boot_menu) {
+            error_report("boot menu requires a bootindex to be specified for "
+                         "the IPL device.");
+        }
+        return;
+    }
+
+    switch (ipl->iplb.pbt) {
+    case S390_IPL_TYPE_CCW:
+        /* In the absence of -boot menu, use zipl parameters */
+        if (!qemu_opt_get(opts, "menu")) {
+            *flags |= QIPL_FLAG_BM_OPTS_ZIPL;
+            return;
+        }
+        break;
+    case S390_IPL_TYPE_QEMU_SCSI:
+        break;
+    default:
+        error_report("boot menu is not supported for this device type.");
+        return;
+    }
+
+    if (!boot_menu) {
+        return;
+    }
+
+    *flags |= QIPL_FLAG_BM_OPTS_CMD;
+
+    tmp = qemu_opt_get(opts, "splash-time");
+
+    if (tmp && qemu_strtoul(tmp, NULL, 10, &splash_time)) {
+        error_report("splash-time is invalid, forcing it to 0.");
+        *timeout = 0;
+        return;
+    }
+
+    if (splash_time > 0xffffffff) {
+        error_report("splash-time is too large, forcing it to max value.");
+        *timeout = 0xffffffff;
+        return;
+    }
+
+    *timeout = cpu_to_be32(splash_time);
+}
+
 static bool s390_gen_initial_iplb(S390IPLState *ipl)
 {
     DeviceState *dev_st;
@@ -399,6 +457,21 @@ void s390_reipl_request(void)
     qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
 }
 
+static void s390_ipl_prepare_qipl(S390CPU *cpu)
+{
+    S390IPLState *ipl = get_ipl_device();
+    uint8_t *addr;
+    uint64_t len = 4096;
+
+    addr = cpu_physical_memory_map(cpu->env.psa, &len, 1);
+    if (!addr || len < QIPL_ADDRESS + sizeof(QemuIplParameters)) {
+        error_report("Cannot set QEMU IPL parameters");
+        return;
+    }
+    memcpy(addr + QIPL_ADDRESS, &ipl->qipl, sizeof(QemuIplParameters));
+    cpu_physical_memory_unmap(addr, len, 1, len);
+}
+
 void s390_ipl_prepare_cpu(S390CPU *cpu)
 {
     S390IPLState *ipl = get_ipl_device();
@@ -418,8 +491,10 @@ void s390_ipl_prepare_cpu(S390CPU *cpu)
             error_report_err(err);
             vm_stop(RUN_STATE_INTERNAL_ERROR);
         }
-        ipl->iplb.ccw.netboot_start_addr = cpu_to_be64(ipl->start_addr);
+        ipl->qipl.netboot_start_addr = cpu_to_be64(ipl->start_addr);
     }
+    s390_ipl_set_boot_menu(ipl);
+    s390_ipl_prepare_qipl(cpu);
 }
 
 static void s390_ipl_reset(DeviceState *dev)
diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index 8a705e0428a..0570d0ad755 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -16,8 +16,7 @@
 #include "cpu.h"
 
 struct IplBlockCcw {
-    uint64_t netboot_start_addr;
-    uint8_t  reserved0[77];
+    uint8_t  reserved0[85];
     uint8_t  ssid;
     uint16_t devno;
     uint8_t  vm_flags;
@@ -90,6 +89,33 @@ void s390_ipl_prepare_cpu(S390CPU *cpu);
 IplParameterBlock *s390_ipl_get_iplb(void);
 void s390_reipl_request(void);
 
+#define QIPL_ADDRESS  0xcc
+
+/* Boot Menu flags */
+#define QIPL_FLAG_BM_OPTS_CMD   0x80
+#define QIPL_FLAG_BM_OPTS_ZIPL  0x40
+
+/*
+ * The QEMU IPL Parameters will be stored at absolute address
+ * 204 (0xcc) which means it is 32-bit word aligned but not
+ * double-word aligned.
+ * Placement of data fields in this area must account for
+ * their alignment needs. E.g., netboot_start_address must
+ * have an offset of 4 + n * 8 bytes within the struct in order
+ * to keep it double-word aligned.
+ * The total size of the struct must never exceed 28 bytes.
+ * This definition must be kept in sync with the defininition
+ * in pc-bios/s390-ccw/iplb.h.
+ */
+struct QemuIplParameters {
+    uint8_t  qipl_flags;
+    uint8_t  reserved1[3];
+    uint64_t netboot_start_addr;
+    uint32_t boot_menu_timeout;
+    uint8_t  reserved2[12];
+} QEMU_PACKED;
+typedef struct QemuIplParameters QemuIplParameters;
+
 #define TYPE_S390_IPL "s390-ipl"
 #define S390_IPL(obj) OBJECT_CHECK(S390IPLState, (obj), TYPE_S390_IPL)
 
@@ -105,6 +131,7 @@ struct S390IPLState {
     bool iplb_valid;
     bool reipl_requested;
     bool netboot;
+    QemuIplParameters qipl;
 
     /*< public >*/
     char *kernel;
diff --git a/pc-bios/s390-ccw.img b/pc-bios/s390-ccw.img
index 97155d2638e..fbd76bb55ed 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 6d0c2ee6910..1712c2d95da 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -9,7 +9,7 @@ $(call set-vpath, $(SRC_PATH)/pc-bios/s390-ccw)
 
 .PHONY : all clean build-all
 
-OBJECTS = start.o main.o bootmap.o sclp.o virtio.o virtio-scsi.o virtio-blkdev.o
+OBJECTS = start.o main.o bootmap.o sclp.o virtio.o virtio-scsi.o virtio-blkdev.o libc.o menu.o
 QEMU_CFLAGS := $(filter -W%, $(QEMU_CFLAGS))
 QEMU_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -msoft-float
 QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 67a6123ed4e..29bfd8c875d 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -83,6 +83,10 @@ static void jump_to_IPL_code(uint64_t address)
 
 static unsigned char _bprs[8*1024]; /* guessed "max" ECKD sector size */
 static const int max_bprs_entries = sizeof(_bprs) / sizeof(ExtEckdBlockPtr);
+static uint8_t _s2[MAX_SECTOR_SIZE * 3] __attribute__((__aligned__(PAGE_SIZE)));
+static void *s2_prev_blk = _s2;
+static void *s2_cur_blk = _s2 + MAX_SECTOR_SIZE;
+static void *s2_next_blk = _s2 + MAX_SECTOR_SIZE * 2;
 
 static inline void verify_boot_info(BootInfo *bip)
 {
@@ -95,32 +99,32 @@ static inline void verify_boot_info(BootInfo *bip)
                "Bad block size in zIPL section of the 1st record.");
 }
 
-static block_number_t eckd_block_num(BootMapPointer *p)
+static block_number_t eckd_block_num(EckdCHS *chs)
 {
     const uint64_t sectors = virtio_get_sectors();
     const uint64_t heads = virtio_get_heads();
-    const uint64_t cylinder = p->eckd.cylinder
-                            + ((p->eckd.head & 0xfff0) << 12);
-    const uint64_t head = p->eckd.head & 0x000f;
+    const uint64_t cylinder = chs->cylinder
+                            + ((chs->head & 0xfff0) << 12);
+    const uint64_t head = chs->head & 0x000f;
     const block_number_t block = sectors * heads * cylinder
                                + sectors * head
-                               + p->eckd.sector
+                               + chs->sector
                                - 1; /* block nr starts with zero */
     return block;
 }
 
 static bool eckd_valid_address(BootMapPointer *p)
 {
-    const uint64_t head = p->eckd.head & 0x000f;
+    const uint64_t head = p->eckd.chs.head & 0x000f;
 
     if (head >= virtio_get_heads()
-        ||  p->eckd.sector > virtio_get_sectors()
-        ||  p->eckd.sector <= 0) {
+        ||  p->eckd.chs.sector > virtio_get_sectors()
+        ||  p->eckd.chs.sector <= 0) {
         return false;
     }
 
     if (!virtio_guessed_disk_nature() &&
-        eckd_block_num(p) >= virtio_get_blocks()) {
+        eckd_block_num(&p->eckd.chs) >= virtio_get_blocks()) {
         return false;
     }
 
@@ -140,7 +144,7 @@ static block_number_t load_eckd_segments(block_number_t blk, uint64_t *address)
     do {
         more_data = false;
         for (j = 0;; j++) {
-            block_nr = eckd_block_num((void *)&(bprs[j].xeckd));
+            block_nr = eckd_block_num(&bprs[j].xeckd.bptr.chs);
             if (is_null_block_number(block_nr)) { /* end of chunk */
                 break;
             }
@@ -182,31 +186,105 @@ static block_number_t load_eckd_segments(block_number_t blk, uint64_t *address)
     return block_nr;
 }
 
-static void run_eckd_boot_script(block_number_t mbr_block_nr)
+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++) {
+        if (magic_match(s2_cur_blk + i, ZIPL_MAGIC_EBCDIC)) {
+            *offset = i;
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static int eckd_get_boot_menu_index(block_number_t s1b_block_nr)
+{
+    block_number_t cur_block_nr;
+    block_number_t prev_block_nr = 0;
+    block_number_t next_block_nr = 0;
+    EckdStage1b *s1b = (void *)sec;
+    int banner_offset;
+    int i;
+
+    /* Get Stage1b data */
+    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
+    read_block(s1b_block_nr, s1b, "Cannot read stage1b boot loader");
+
+    memset(_s2, FREE_SPACE_FILLER, sizeof(_s2));
+
+    /* Get Stage2 data */
+    for (i = 0; i < STAGE2_BLK_CNT_MAX; i++) {
+        cur_block_nr = eckd_block_num(&s1b->seek[i].chs);
+
+        if (!cur_block_nr) {
+            break;
+        }
+
+        read_block(cur_block_nr, s2_cur_blk, "Cannot read stage2 boot loader");
+
+        if (find_zipl_boot_menu_banner(&banner_offset)) {
+            /*
+             * Load the adjacent blocks to account for the
+             * possibility of menu data spanning multiple blocks.
+             */
+            if (prev_block_nr) {
+                read_block(prev_block_nr, s2_prev_blk,
+                           "Cannot read stage2 boot loader");
+            }
+
+            if (i + 1 < STAGE2_BLK_CNT_MAX) {
+                next_block_nr = eckd_block_num(&s1b->seek[i + 1].chs);
+            }
+
+            if (next_block_nr) {
+                read_block(next_block_nr, s2_next_blk,
+                           "Cannot read stage2 boot loader");
+            }
+
+            return menu_get_zipl_boot_index(s2_cur_blk + banner_offset);
+        }
+
+        prev_block_nr = cur_block_nr;
+    }
+
+    sclp_print("No zipl boot menu data found. Booting default entry.");
+    return 0;
+}
+
+static void run_eckd_boot_script(block_number_t bmt_block_nr,
+                                 block_number_t s1b_block_nr)
 {
     int i;
     unsigned int loadparm = get_loadparm_index();
     block_number_t block_nr;
     uint64_t address;
-    ScsiMbr *bte = (void *)sec; /* Eckd bootmap table entry */
+    BootMapTable *bmt = (void *)sec;
     BootMapScript *bms = (void *)sec;
 
+    if (menu_is_enabled_zipl()) {
+        loadparm = eckd_get_boot_menu_index(s1b_block_nr);
+    }
+
     debug_print_int("loadparm", loadparm);
-    IPL_assert(loadparm < 31, "loadparm value greater than"
+    IPL_assert(loadparm <= MAX_TABLE_ENTRIES, "loadparm value greater than"
                " maximum number of boot entries allowed");
 
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(mbr_block_nr, sec, "Cannot read MBR");
+    read_block(bmt_block_nr, sec, "Cannot read Boot Map Table");
 
-    block_nr = eckd_block_num((void *)&(bte->blockptr[loadparm]));
-    IPL_assert(block_nr != -1, "No Boot Map");
+    block_nr = eckd_block_num(&bmt->entry[loadparm].xeckd.bptr.chs);
+    IPL_assert(block_nr != -1, "Cannot find Boot Map Table Entry");
 
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(block_nr, sec, "Cannot read Boot Map Script");
 
     for (i = 0; bms->entry[i].type == BOOT_SCRIPT_LOAD; i++) {
         address = bms->entry[i].address.load_address;
-        block_nr = eckd_block_num(&(bms->entry[i].blkptr));
+        block_nr = eckd_block_num(&bms->entry[i].blkptr.xeckd.bptr.chs);
 
         do {
             block_nr = load_eckd_segments(block_nr, &address);
@@ -221,9 +299,9 @@ static void run_eckd_boot_script(block_number_t mbr_block_nr)
 static void ipl_eckd_cdl(void)
 {
     XEckdMbr *mbr;
-    Ipl2 *ipl2 = (void *)sec;
+    EckdCdlIpl2 *ipl2 = (void *)sec;
     IplVolumeLabel *vlbl = (void *)sec;
-    block_number_t block_nr;
+    block_number_t bmt_block_nr, s1b_block_nr;
 
     /* we have just read the block #0 and recognized it as "IPL1" */
     sclp_print("CDL\n");
@@ -231,15 +309,18 @@ static void ipl_eckd_cdl(void)
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(1, ipl2, "Cannot read IPL2 record at block 1");
 
-    mbr = &ipl2->u.x.mbr;
+    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.");
 
-    /* save pointer to Boot Script */
-    block_nr = eckd_block_num((void *)&(mbr->blockptr));
+    /* save pointer to Boot Map Table */
+    bmt_block_nr = eckd_block_num(&mbr->blockptr.xeckd.bptr.chs);
+
+    /* save pointer to Stage1b Data */
+    s1b_block_nr = eckd_block_num(&ipl2->stage1.seek[0].chs);
 
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(2, vlbl, "Cannot read Volume Label at block 2");
@@ -249,7 +330,7 @@ static void ipl_eckd_cdl(void)
                "Invalid magic of volser block");
     print_volser(vlbl->f.volser);
 
-    run_eckd_boot_script(block_nr);
+    run_eckd_boot_script(bmt_block_nr, s1b_block_nr);
     /* no return */
 }
 
@@ -280,8 +361,8 @@ static void print_eckd_ldl_msg(ECKD_IPL_mode_t mode)
 
 static void ipl_eckd_ldl(ECKD_IPL_mode_t mode)
 {
-    block_number_t block_nr;
-    BootInfo *bip = (void *)(sec + 0x70); /* BootInfo is MBR for LDL */
+    block_number_t bmt_block_nr, s1b_block_nr;
+    EckdLdlIpl1 *ipl1 = (void *)sec;
 
     if (mode != ECKD_LDL_UNLABELED) {
         print_eckd_ldl_msg(mode);
@@ -292,15 +373,20 @@ static void ipl_eckd_ldl(ECKD_IPL_mode_t mode)
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(0, sec, "Cannot read block 0 to grab boot info.");
     if (mode == ECKD_LDL_UNLABELED) {
-        if (!magic_match(bip->magic, ZIPL_MAGIC)) {
+        if (!magic_match(ipl1->bip.magic, ZIPL_MAGIC)) {
             return; /* not applicable layout */
         }
         sclp_print("unlabeled LDL.\n");
     }
-    verify_boot_info(bip);
+    verify_boot_info(&ipl1->bip);
 
-    block_nr = eckd_block_num((void *)&(bip->bp.ipl.bm_ptr.eckd.bptr));
-    run_eckd_boot_script(block_nr);
+    /* save pointer to Boot Map Table */
+    bmt_block_nr = eckd_block_num(&ipl1->bip.bp.ipl.bm_ptr.eckd.bptr.chs);
+
+    /* save pointer to Stage1b Data */
+    s1b_block_nr = eckd_block_num(&ipl1->stage1.seek[0].chs);
+
+    run_eckd_boot_script(bmt_block_nr, s1b_block_nr);
     /* no return */
 }
 
@@ -325,7 +411,7 @@ static void print_eckd_msg(void)
 
 static void ipl_eckd(void)
 {
-    ScsiMbr *mbr = (void *)sec;
+    XEckdMbr *mbr = (void *)sec;
     LDL_VTOC *vlbl = (void *)sec;
 
     print_eckd_msg();
@@ -449,10 +535,8 @@ static void zipl_run(ScsiBlockPtr *pte)
 static void ipl_scsi(void)
 {
     ScsiMbr *mbr = (void *)sec;
-    uint8_t *ns, *ns_end;
     int program_table_entries = 0;
-    const int pte_len = sizeof(ScsiBlockPtr);
-    ScsiBlockPtr *prog_table_entry = NULL;
+    BootMapTable *prog_table = (void *)sec;
     unsigned int loadparm = get_loadparm_index();
 
     /* Grab the MBR */
@@ -467,34 +551,32 @@ static void ipl_scsi(void)
     debug_print_int("MBR Version", mbr->version_id);
     IPL_check(mbr->version_id == 1,
               "Unknown MBR layout version, assuming version 1");
-    debug_print_int("program table", mbr->blockptr[0].blockno);
-    IPL_assert(mbr->blockptr[0].blockno, "No Program Table");
+    debug_print_int("program table", mbr->pt.blockno);
+    IPL_assert(mbr->pt.blockno, "No Program Table");
 
     /* Parse the program table */
-    read_block(mbr->blockptr[0].blockno, sec,
-               "Error reading Program Table");
-
+    read_block(mbr->pt.blockno, sec, "Error reading Program Table");
     IPL_assert(magic_match(sec, ZIPL_MAGIC), "No zIPL magic in PT");
 
-    debug_print_int("loadparm index", loadparm);
-    ns_end = sec + virtio_get_block_size();
-    for (ns = (sec + pte_len); (ns + pte_len) < ns_end; ns += pte_len) {
-        prog_table_entry = (ScsiBlockPtr *)ns;
-        if (!prog_table_entry->blockno) {
+    while (program_table_entries <= MAX_TABLE_ENTRIES) {
+        if (!prog_table->entry[program_table_entries].scsi.blockno) {
             break;
         }
-
         program_table_entries++;
-        if (program_table_entries == loadparm + 1) {
-            break; /* selected entry found */
-        }
     }
 
     debug_print_int("program table entries", program_table_entries);
-
     IPL_assert(program_table_entries != 0, "Empty Program Table");
 
-    zipl_run(prog_table_entry); /* no return */
+    if (menu_is_enabled_enum()) {
+        loadparm = menu_get_enum_boot_index(program_table_entries);
+    }
+
+    debug_print_int("loadparm", loadparm);
+    IPL_assert(loadparm <= MAX_TABLE_ENTRIES, "loadparm value greater than"
+               " maximum number of boot entries allowed");
+
+    zipl_run(&prog_table->entry[loadparm].scsi); /* no return */
 }
 
 /***********************************************************************
@@ -512,7 +594,7 @@ static bool is_iso_bc_entry_compatible(IsoBcSection *s)
                     "Failed to read image sector 0");
 
     /* Checking bytes 8 - 32 for S390 Linux magic */
-    return !_memcmp(magic_sec + 8, linux_s390_magic, 24);
+    return !memcmp(magic_sec + 8, linux_s390_magic, 24);
 }
 
 /* Location of the current sector of the directory */
@@ -641,7 +723,7 @@ static uint32_t find_iso_bc(void)
         if (vd->type == VOL_DESC_TYPE_BOOT) {
             IsoVdElTorito *et = &vd->vd.boot;
 
-            if (!_memcmp(&et->el_torito[0], el_torito_magic, 32)) {
+            if (!memcmp(&et->el_torito[0], el_torito_magic, 32)) {
                 return bswap32(et->bc_offset);
             }
         }
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index cf99a4c7285..c636626f1a0 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -32,10 +32,14 @@ typedef struct FbaBlockPtr {
     uint16_t blockct;
 } __attribute__ ((packed)) FbaBlockPtr;
 
-typedef struct EckdBlockPtr {
-    uint16_t cylinder; /* cylinder/head/sector is an address of the block */
+typedef struct EckdCHS {
+    uint16_t cylinder;
     uint16_t head;
     uint8_t sector;
+} __attribute__ ((packed)) EckdCHS;
+
+typedef struct EckdBlockPtr {
+    EckdCHS chs; /* cylinder/head/sector is an address of the block */
     uint16_t size;
     uint8_t count; /* (size_in_blocks-1);
                     * it's 0 for TablePtr, ScriptPtr, and SectionPtr */
@@ -53,6 +57,15 @@ typedef union BootMapPointer {
     ExtEckdBlockPtr xeckd;
 } __attribute__ ((packed)) BootMapPointer;
 
+#define MAX_TABLE_ENTRIES  30
+
+/* aka Program Table */
+typedef struct BootMapTable {
+    uint8_t magic[4];
+    uint8_t reserved[12];
+    BootMapPointer entry[];
+} __attribute__ ((packed)) BootMapTable;
+
 typedef struct ComponentEntry {
     ScsiBlockPtr data;
     uint8_t pad[7];
@@ -70,10 +83,11 @@ typedef struct ScsiMbr {
     uint8_t magic[4];
     uint32_t version_id;
     uint8_t reserved[8];
-    ScsiBlockPtr blockptr[];
+    ScsiBlockPtr pt;   /* block pointer to program table */
 } __attribute__ ((packed)) ScsiMbr;
 
 #define ZIPL_MAGIC              "zIPL"
+#define ZIPL_MAGIC_EBCDIC       "\xa9\xc9\xd7\xd3"
 #define IPL1_MAGIC "\xc9\xd7\xd3\xf1" /* == "IPL1" in EBCDIC */
 #define IPL2_MAGIC "\xc9\xd7\xd3\xf2" /* == "IPL2" in EBCDIC */
 #define VOL1_MAGIC "\xe5\xd6\xd3\xf1" /* == "VOL1" in EBCDIC */
@@ -226,22 +240,45 @@ typedef struct BootInfo {          /* @ 0x70, record #0    */
     } bp;
 } __attribute__ ((packed)) BootInfo; /* see also XEckdMbr   */
 
-typedef struct Ipl1 {
-    unsigned char key[4]; /* == "IPL1" */
-    unsigned char data[24];
-} __attribute__((packed)) Ipl1;
-
-typedef struct Ipl2 {
-    unsigned char key[4]; /* == "IPL2" */
-    union {
-        unsigned char data[144];
-        struct {
-            unsigned char reserved1[92-4];
-            XEckdMbr mbr;
-            unsigned char reserved2[144-(92-4)-sizeof(XEckdMbr)];
-        } x;
-    } u;
-} __attribute__((packed)) Ipl2;
+/*
+ * Structs for IPL
+ */
+#define STAGE2_BLK_CNT_MAX  24 /* Stage 1b can load up to 24 blocks */
+
+typedef struct EckdCdlIpl1 {
+    uint8_t key[4]; /* == "IPL1" */
+    uint8_t data[24];
+} __attribute__((packed)) EckdCdlIpl1;
+
+typedef struct EckdSeekArg {
+    uint16_t pad;
+    EckdCHS chs;
+    uint8_t pad2;
+} __attribute__ ((packed)) EckdSeekArg;
+
+typedef struct EckdStage1b {
+    uint8_t reserved[32 * STAGE2_BLK_CNT_MAX];
+    struct EckdSeekArg seek[STAGE2_BLK_CNT_MAX];
+    uint8_t unused[64];
+} __attribute__ ((packed)) EckdStage1b;
+
+typedef struct EckdStage1 {
+    uint8_t reserved[72];
+    struct EckdSeekArg seek[2];
+} __attribute__ ((packed)) EckdStage1;
+
+typedef struct EckdCdlIpl2 {
+    uint8_t key[4]; /* == "IPL2" */
+    struct EckdStage1 stage1;
+    XEckdMbr mbr;
+    uint8_t reserved[24];
+} __attribute__((packed)) EckdCdlIpl2;
+
+typedef struct EckdLdlIpl1 {
+    uint8_t reserved[24];
+    struct EckdStage1 stage1;
+    BootInfo bip; /* BootInfo is MBR for LDL */
+} __attribute__((packed)) EckdLdlIpl1;
 
 typedef struct IplVolumeLabel {
     unsigned char key[4]; /* == "VOL1" */
@@ -310,20 +347,6 @@ static inline bool magic_match(const void *data, const void *magic)
     return *((uint32_t *)data) == *((uint32_t *)magic);
 }
 
-static inline int _memcmp(const void *s1, const void *s2, size_t n)
-{
-    int i;
-    const uint8_t *p1 = s1, *p2 = s2;
-
-    for (i = 0; i < n; i++) {
-        if (p1[i] != p2[i]) {
-            return p1[i] > p2[i] ? 1 : -1;
-        }
-    }
-
-    return 0;
-}
-
 static inline uint32_t iso_733_to_u32(uint64_t x)
 {
     return (uint32_t)x;
@@ -416,7 +439,7 @@ const uint8_t vol_desc_magic[] = "CD001";
 
 static inline bool is_iso_vd_valid(IsoVolDesc *vd)
 {
-    return !_memcmp(&vd->ident[0], vol_desc_magic, 5) &&
+    return !memcmp(&vd->ident[0], vol_desc_magic, 5) &&
            vd->version == 0x1 &&
            vd->type <= VOL_DESC_TYPE_PARTITION;
 }
diff --git a/pc-bios/s390-ccw/iplb.h b/pc-bios/s390-ccw/iplb.h
index 890aed9ecee..7dfce4fbcf7 100644
--- a/pc-bios/s390-ccw/iplb.h
+++ b/pc-bios/s390-ccw/iplb.h
@@ -13,8 +13,7 @@
 #define IPLB_H
 
 struct IplBlockCcw {
-    uint64_t netboot_start_addr;
-    uint8_t  reserved0[77];
+    uint8_t  reserved0[85];
     uint8_t  ssid;
     uint16_t devno;
     uint8_t  vm_flags;
@@ -73,6 +72,27 @@ typedef struct IplParameterBlock IplParameterBlock;
 
 extern IplParameterBlock iplb __attribute__((__aligned__(PAGE_SIZE)));
 
+#define QIPL_ADDRESS  0xcc
+
+/* Boot Menu flags */
+#define QIPL_FLAG_BM_OPTS_CMD   0x80
+#define QIPL_FLAG_BM_OPTS_ZIPL  0x40
+
+/*
+ * This definition must be kept in sync with the defininition
+ * in hw/s390x/ipl.h
+ */
+struct QemuIplParameters {
+    uint8_t  qipl_flags;
+    uint8_t  reserved1[3];
+    uint64_t netboot_start_addr;
+    uint32_t boot_menu_timeout;
+    uint8_t  reserved2[12];
+} __attribute__ ((packed));
+typedef struct QemuIplParameters QemuIplParameters;
+
+extern QemuIplParameters qipl;
+
 #define S390_IPL_TYPE_FCP 0x00
 #define S390_IPL_TYPE_CCW 0x02
 #define S390_IPL_TYPE_QEMU_SCSI 0xff
diff --git a/pc-bios/s390-ccw/libc.c b/pc-bios/s390-ccw/libc.c
new file mode 100644
index 00000000000..38ea77d7aad
--- /dev/null
+++ b/pc-bios/s390-ccw/libc.c
@@ -0,0 +1,88 @@
+/*
+ * libc-style definitions and functions
+ *
+ * Copyright 2018 IBM Corp.
+ * Author(s): Collin L. Walling <walling@linux.vnet.ibm.com>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include "libc.h"
+#include "s390-ccw.h"
+
+/**
+ * atoui:
+ * @str: the string to be converted.
+ *
+ * Given a string @str, convert it to an integer. Leading spaces are
+ * ignored. Any other non-numerical value will terminate the conversion
+ * and return 0. This function only handles numbers between 0 and
+ * UINT64_MAX inclusive.
+ *
+ * Returns: an integer converted from the string @str, or the number 0
+ * if an error occurred.
+ */
+uint64_t atoui(const char *str)
+{
+    int val = 0;
+
+    if (!str || !str[0]) {
+        return 0;
+    }
+
+    while (*str == ' ') {
+        str++;
+    }
+
+    while (*str) {
+        if (!isdigit(*str)) {
+            break;
+        }
+        val = val * 10 + *str - '0';
+        str++;
+    }
+
+    return val;
+}
+
+/**
+ * uitoa:
+ * @num: an integer (base 10) to be converted.
+ * @str: a pointer to a string to store the conversion.
+ * @len: the length of the passed string.
+ *
+ * Given an integer @num, convert it to a string. The string @str must be
+ * allocated beforehand. The resulting string will be null terminated and
+ * returned. This function only handles numbers between 0 and UINT64_MAX
+ * inclusive.
+ *
+ * Returns: the string @str of the converted integer @num
+ */
+char *uitoa(uint64_t num, char *str, size_t len)
+{
+    size_t num_idx = 1; /* account for NUL */
+    uint64_t tmp = num;
+
+    IPL_assert(str != NULL, "uitoa: no space allocated to store string");
+
+    /* Count indices of num */
+    while ((tmp /= 10) != 0) {
+        num_idx++;
+    }
+
+    /* Check if we have enough space for num and NUL */
+    IPL_assert(len > num_idx, "uitoa: array too small for conversion");
+
+    str[num_idx--] = '\0';
+
+    /* Convert int to string */
+    while (num_idx >= 0) {
+        str[num_idx--] = num % 10 + '0';
+        num /= 10;
+    }
+
+    return str;
+}
diff --git a/pc-bios/s390-ccw/libc.h b/pc-bios/s390-ccw/libc.h
index 0142ea8e7bc..63ece70c6b1 100644
--- a/pc-bios/s390-ccw/libc.h
+++ b/pc-bios/s390-ccw/libc.h
@@ -1,6 +1,8 @@
 /*
  * libc-style definitions and functions
  *
+ * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
+ *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
  * Free Software Foundation; either version 2 of the License, or (at your
@@ -19,7 +21,7 @@ typedef unsigned long long uint64_t;
 
 static inline void *memset(void *s, int c, size_t n)
 {
-    int i;
+    size_t i;
     unsigned char *p = s;
 
     for (i = 0; i < n; i++) {
@@ -33,7 +35,7 @@ static inline void *memcpy(void *s1, const void *s2, size_t n)
 {
     uint8_t *dest = s1;
     const uint8_t *src = s2;
-    int i;
+    size_t i;
 
     for (i = 0; i < n; i++) {
         dest[i] = src[i];
@@ -42,4 +44,35 @@ static inline void *memcpy(void *s1, const void *s2, size_t n)
     return s1;
 }
 
+static inline int memcmp(const void *s1, const void *s2, size_t n)
+{
+    size_t i;
+    const uint8_t *p1 = s1, *p2 = s2;
+
+    for (i = 0; i < n; i++) {
+        if (p1[i] != p2[i]) {
+            return p1[i] > p2[i] ? 1 : -1;
+        }
+    }
+
+    return 0;
+}
+
+static inline size_t strlen(const char *str)
+{
+    size_t i;
+    for (i = 0; *str; i++) {
+        str++;
+    }
+    return i;
+}
+
+static inline int isdigit(int c)
+{
+    return (c >= '0') && (c <= '9');
+}
+
+uint64_t atoui(const char *str);
+char *uitoa(uint64_t num, char *str, size_t len);
+
 #endif
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index 401e9dbb5fe..9d9f8cf4d34 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -16,6 +16,11 @@ char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
 static SubChannelId blk_schid = { .one = 1 };
 IplParameterBlock iplb __attribute__((__aligned__(PAGE_SIZE)));
 static char loadparm[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+QemuIplParameters qipl;
+
+#define LOADPARM_PROMPT "PROMPT  "
+#define LOADPARM_EMPTY  "........"
+#define BOOT_MENU_FLAG_MASK (QIPL_FLAG_BM_OPTS_CMD | QIPL_FLAG_BM_OPTS_ZIPL)
 
 /*
  * Priniciples of Operations (SA22-7832-09) chapter 17 requires that
@@ -40,22 +45,7 @@ void panic(const char *string)
 
 unsigned int get_loadparm_index(void)
 {
-    const char *lp = loadparm;
-    int i;
-    unsigned int idx = 0;
-
-    for (i = 0; i < 8; i++) {
-        char c = lp[i];
-
-        if (c < '0' || c > '9') {
-            break;
-        }
-
-        idx *= 10;
-        idx += c - '0';
-    }
-
-    return idx;
+    return atoui(loadparm);
 }
 
 static bool find_dev(Schib *schib, int dev_no)
@@ -88,6 +78,27 @@ static bool find_dev(Schib *schib, int dev_no)
     return false;
 }
 
+static void menu_setup(void)
+{
+    if (memcmp(loadparm, LOADPARM_PROMPT, 8) == 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, LOADPARM_EMPTY, 8) != 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;
+    }
+}
+
 static void virtio_setup(void)
 {
     Schib schib;
@@ -96,6 +107,7 @@ static void virtio_setup(void)
     uint16_t dev_no;
     char ldp[] = "LOADPARM=[________]\n";
     VDev *vdev = virtio_get_device();
+    QemuIplParameters *early_qipl = (QemuIplParameters *)QIPL_ADDRESS;
 
     /*
      * We unconditionally enable mss support. In every sane configuration,
@@ -108,6 +120,8 @@ static void virtio_setup(void)
     memcpy(ldp + 10, loadparm, 8);
     sclp_print(ldp);
 
+    memcpy(&qipl, early_qipl, sizeof(QemuIplParameters));
+
     if (store_iplb(&iplb)) {
         switch (iplb.pbt) {
         case S390_IPL_TYPE_CCW:
@@ -128,6 +142,7 @@ static void virtio_setup(void)
         default:
             panic("List-directed IPL not supported yet!\n");
         }
+        menu_setup();
     } else {
         for (ssid = 0; ssid < 0x3; ssid++) {
             blk_schid.ssid = ssid;
@@ -142,7 +157,7 @@ static void virtio_setup(void)
 
     if (virtio_get_device_type() == VIRTIO_ID_NET) {
         sclp_print("Network boot device detected\n");
-        vdev->netboot_start_addr = iplb.ccw.netboot_start_addr;
+        vdev->netboot_start_addr = qipl.netboot_start_addr;
     } else {
         virtio_blk_setup_device(blk_schid);
 
diff --git a/pc-bios/s390-ccw/menu.c b/pc-bios/s390-ccw/menu.c
new file mode 100644
index 00000000000..96eec81e842
--- /dev/null
+++ b/pc-bios/s390-ccw/menu.c
@@ -0,0 +1,249 @@
+/*
+ * QEMU S390 Interactive Boot Menu
+ *
+ * Copyright 2018 IBM Corp.
+ * Author: Collin L. Walling <walling@linux.vnet.ibm.com>
+ *
+ * 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 "s390-ccw.h"
+#include "sclp.h"
+
+#define KEYCODE_NO_INP '\0'
+#define KEYCODE_ESCAPE '\033'
+#define KEYCODE_BACKSP '\177'
+#define KEYCODE_ENTER  '\r'
+
+/* Offsets from zipl fields to zipl banner start */
+#define ZIPL_TIMEOUT_OFFSET 138
+#define ZIPL_FLAG_OFFSET    140
+
+#define TOD_CLOCK_MILLISECOND   0x3e8000
+
+#define LOW_CORE_EXTERNAL_INT_ADDR   0x86
+#define CLOCK_COMPARATOR_INT         0X1004
+
+static uint8_t flag;
+static uint64_t timeout;
+
+static inline void enable_clock_int(void)
+{
+    uint64_t tmp = 0;
+
+    asm volatile(
+        "stctg      0,0,%0\n"
+        "oi         6+%0, 0x8\n"
+        "lctlg      0,0,%0"
+        : : "Q" (tmp) : "memory"
+    );
+}
+
+static inline void disable_clock_int(void)
+{
+    uint64_t tmp = 0;
+
+    asm volatile(
+        "stctg      0,0,%0\n"
+        "ni         6+%0, 0xf7\n"
+        "lctlg      0,0,%0"
+        : : "Q" (tmp) : "memory"
+    );
+}
+
+static inline void set_clock_comparator(uint64_t time)
+{
+    asm volatile("sckc %0" : : "Q" (time));
+}
+
+static inline bool check_clock_int(void)
+{
+    uint16_t *code = (uint16_t *)LOW_CORE_EXTERNAL_INT_ADDR;
+
+    consume_sclp_int();
+
+    return *code == CLOCK_COMPARATOR_INT;
+}
+
+static int read_prompt(char *buf, size_t len)
+{
+    char inp[2] = {};
+    uint8_t idx = 0;
+    uint64_t time;
+
+    if (timeout) {
+        time = get_clock() + timeout * TOD_CLOCK_MILLISECOND;
+        set_clock_comparator(time);
+        enable_clock_int();
+        timeout = 0;
+    }
+
+    while (!check_clock_int()) {
+
+        sclp_read(inp, 1); /* Process only one character at a time */
+
+        switch (inp[0]) {
+        case KEYCODE_NO_INP:
+        case KEYCODE_ESCAPE:
+            continue;
+        case KEYCODE_BACKSP:
+            if (idx > 0) {
+                buf[--idx] = 0;
+                sclp_print("\b \b");
+            }
+            continue;
+        case KEYCODE_ENTER:
+            disable_clock_int();
+            return idx;
+        default:
+            /* Echo input and add to buffer */
+            if (idx < len) {
+                buf[idx++] = inp[0];
+                sclp_print(inp);
+            }
+        }
+    }
+
+    disable_clock_int();
+    *buf = 0;
+
+    return 0;
+}
+
+static int get_index(void)
+{
+    char buf[11];
+    int len;
+    int i;
+
+    memset(buf, 0, sizeof(buf));
+
+    sclp_set_write_mask(SCLP_EVENT_MASK_MSG_ASCII, SCLP_EVENT_MASK_MSG_ASCII);
+
+    len = read_prompt(buf, sizeof(buf) - 1);
+
+    sclp_set_write_mask(0, SCLP_EVENT_MASK_MSG_ASCII);
+
+    /* If no input, boot default */
+    if (len == 0) {
+        return 0;
+    }
+
+    /* Check for erroneous input */
+    for (i = 0; i < len; i++) {
+        if (!isdigit(buf[i])) {
+            return -1;
+        }
+    }
+
+    return atoui(buf);
+}
+
+static void boot_menu_prompt(bool retry)
+{
+    char tmp[11];
+
+    if (retry) {
+        sclp_print("\nError: undefined configuration"
+                   "\nPlease choose:\n");
+    } else if (timeout > 0) {
+        sclp_print("Please choose (default will boot in ");
+        sclp_print(uitoa(timeout / 1000, tmp, sizeof(tmp)));
+        sclp_print(" seconds):\n");
+    } else {
+        sclp_print("Please choose:\n");
+    }
+}
+
+static int get_boot_index(int entries)
+{
+    int boot_index;
+    bool retry = false;
+    char tmp[5];
+
+    do {
+        boot_menu_prompt(retry);
+        boot_index = get_index();
+        retry = true;
+    } while (boot_index < 0 || boot_index >= entries);
+
+    sclp_print("\nBooting entry #");
+    sclp_print(uitoa(boot_index, tmp, sizeof(tmp)));
+
+    return boot_index;
+}
+
+static void zipl_println(const char *data, size_t len)
+{
+    char buf[len + 2];
+
+    ebcdic_to_ascii(data, buf, len);
+    buf[len] = '\n';
+    buf[len + 1] = '\0';
+
+    sclp_print(buf);
+}
+
+int menu_get_zipl_boot_index(const char *menu_data)
+{
+    size_t len;
+    int entries;
+    uint16_t zipl_flag = *(uint16_t *)(menu_data - ZIPL_FLAG_OFFSET);
+    uint16_t zipl_timeout = *(uint16_t *)(menu_data - ZIPL_TIMEOUT_OFFSET);
+
+    if (flag == QIPL_FLAG_BM_OPTS_ZIPL) {
+        if (!zipl_flag) {
+            return 0; /* Boot default */
+        }
+        /* zipl stores timeout as seconds */
+        timeout = zipl_timeout * 1000;
+    }
+
+    /* Print and count all menu items, including the banner */
+    for (entries = 0; *menu_data; entries++) {
+        len = strlen(menu_data);
+        zipl_println(menu_data, len);
+        menu_data += len + 1;
+
+        if (entries < 2) {
+            sclp_print("\n");
+        }
+    }
+
+    sclp_print("\n");
+    return get_boot_index(entries - 1); /* subtract 1 to exclude banner */
+}
+
+
+int menu_get_enum_boot_index(int entries)
+{
+    char tmp[4];
+
+    sclp_print("s390x Enumerated Boot Menu.\n\n");
+
+    sclp_print(uitoa(entries, tmp, sizeof(tmp)));
+    sclp_print(" entries detected. Select from boot index 0 to ");
+    sclp_print(uitoa(entries - 1, tmp, sizeof(tmp)));
+    sclp_print(".\n\n");
+
+    return get_boot_index(entries);
+}
+
+void menu_set_parms(uint8_t boot_menu_flag, uint32_t boot_menu_timeout)
+{
+    flag = boot_menu_flag;
+    timeout = boot_menu_timeout;
+}
+
+bool menu_is_enabled_zipl(void)
+{
+    return flag & (QIPL_FLAG_BM_OPTS_CMD | QIPL_FLAG_BM_OPTS_ZIPL);
+}
+
+bool menu_is_enabled_enum(void)
+{
+    return flag & QIPL_FLAG_BM_OPTS_CMD;
+}
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 25d4d213eab..fd18da22c6a 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -69,8 +69,10 @@ unsigned int get_loadparm_index(void);
 
 /* sclp.c */
 void sclp_print(const char *string);
+void sclp_set_write_mask(uint32_t receive_mask, uint32_t send_mask);
 void sclp_setup(void);
 void sclp_get_loadparm_ascii(char *loadparm);
+int sclp_read(char *str, size_t count);
 
 /* virtio.c */
 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
@@ -79,11 +81,19 @@ bool virtio_is_supported(SubChannelId schid);
 void virtio_blk_setup_device(SubChannelId schid);
 int virtio_read(ulong sector, void *load_addr);
 int enable_mss_facility(void);
+u64 get_clock(void);
 ulong get_second(void);
 
 /* bootmap.c */
 void zipl_load(void);
 
+/* menu.c */
+void menu_set_parms(uint8_t boot_menu_flag, uint32_t boot_menu_timeout);
+int menu_get_zipl_boot_index(const char *menu_data);
+bool menu_is_enabled_zipl(void);
+int menu_get_enum_boot_index(int entries);
+bool menu_is_enabled_enum(void);
+
 static inline void fill_hex(char *out, unsigned char val)
 {
     const char hex[] = "0123456789abcdef";
diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
index 90d1bc31478..3836cb4716b 100644
--- a/pc-bios/s390-ccw/sclp.c
+++ b/pc-bios/s390-ccw/sclp.c
@@ -46,31 +46,21 @@ static int sclp_service_call(unsigned int command, void *sccb)
         return 0;
 }
 
-static void sclp_set_write_mask(void)
+void sclp_set_write_mask(uint32_t receive_mask, uint32_t send_mask)
 {
     WriteEventMask *sccb = (void *)_sccb;
 
     sccb->h.length = sizeof(WriteEventMask);
     sccb->mask_length = sizeof(unsigned int);
-    sccb->receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->cp_receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->send_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->cp_send_mask = SCLP_EVENT_MASK_MSG_ASCII;
+    sccb->cp_receive_mask = receive_mask;
+    sccb->cp_send_mask = send_mask;
 
     sclp_service_call(SCLP_CMD_WRITE_EVENT_MASK, sccb);
 }
 
 void sclp_setup(void)
 {
-    sclp_set_write_mask();
-}
-
-static int _strlen(const char *str)
-{
-    int i;
-    for (i = 0; *str; i++)
-        str++;
-    return i;
+    sclp_set_write_mask(0, SCLP_EVENT_MASK_MSG_ASCII);
 }
 
 long write(int fd, const void *str, size_t len)
@@ -113,7 +103,7 @@ long write(int fd, const void *str, size_t len)
 
 void sclp_print(const char *str)
 {
-    write(1, str, _strlen(str));
+    write(1, str, strlen(str));
 }
 
 void sclp_get_loadparm_ascii(char *loadparm)
@@ -127,3 +117,22 @@ void sclp_get_loadparm_ascii(char *loadparm)
         ebcdic_to_ascii((char *) sccb->loadparm, loadparm, 8);
     }
 }
+
+int sclp_read(char *str, size_t count)
+{
+    ReadEventData *sccb = (void *)_sccb;
+    char *buf = (char *)(&sccb->ebh) + 7;
+
+    /* If count exceeds max buffer size, then restrict it to the max size */
+    if (count > SCCB_SIZE - 8) {
+        count = SCCB_SIZE - 8;
+    }
+
+    sccb->h.length = SCCB_SIZE;
+    sccb->h.function_code = SCLP_UNCONDITIONAL_READ;
+
+    sclp_service_call(SCLP_CMD_READ_EVENT_DATA, sccb);
+    memcpy(str, buf, count);
+
+    return sccb->ebh.length - 7;
+}
diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
index c890a0330b6..817e7f56ea0 100644
--- a/pc-bios/s390-ccw/virtio.c
+++ b/pc-bios/s390-ccw/virtio.c
@@ -176,7 +176,7 @@ void vring_send_buf(VRing *vr, void *p, int len, int flags)
     }
 }
 
-static u64 get_clock(void)
+u64 get_clock(void)
 {
     u64 r;
 
diff --git a/pc-bios/s390-netboot.img b/pc-bios/s390-netboot.img
index 24f40feae6f..9f5926b534c 100755..100644
--- a/pc-bios/s390-netboot.img
+++ b/pc-bios/s390-netboot.img