Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20160324' into staging

Support for booting from virtio-scsi devices in the s390-ccw bios.

# gpg: Signature made Thu 24 Mar 2016 08:14:21 GMT using RSA key ID C6F02FAF
# gpg: Good signature from "Cornelia Huck <huckc@linux.vnet.ibm.com>"
# gpg:                 aka "Cornelia Huck <cornelia.huck@de.ibm.com>"

* remotes/cohuck/tags/s390x-20160324:
  s390-ccw.img: rebuild image
  pc-bios/s390-ccw: disambiguation of "No zIPL magic" message
  pc-bios/s390-ccw: enhance bootmap detection
  pc-bios/s390-ccw: enable virtio-scsi
  pc-bios/s390-ccw: add virtio-scsi implementation
  pc-bios/s390-ccw: add scsi definitions
  pc-bios/s390-ccw: add simplified virtio call
  pc-bios/s390-ccw: make provisions for different backends
  pc-bios/s390-ccw: add vdev object to store all device details
  pc-bios/s390-ccw: update virtio implementation to allow up to 3 vrings
  pc-bios/s390-ccw: qemuize types
  pc-bios/s390-ccw: add utility functions and "export" some others
  pc-bios/s390-ccw: virtio_panic -> panic
  pc-bios/s390-ccw: add more disk layout checks

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

11 files changed, 1220 insertions, 294 deletions

diff --git a/pc-bios/s390-ccw.img b/pc-bios/s390-ccw.img
index bd8f21050f..d3978ba050 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 11c5dd4799..4208cb4295 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-ascii.o virtio.o
+OBJECTS = start.o main.o bootmap.o sclp-ascii.o virtio.o virtio-scsi.o
 CFLAGS += -fPIE -fno-stack-protector -ffreestanding -march=z900
 CFLAGS += -fno-delete-null-pointer-checks -msoft-float
 LDFLAGS += -Wl,-pie -nostdlib
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 492530275d..611102e3ef 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -72,7 +72,7 @@ static void jump_to_IPL_code(uint64_t address)
     asm volatile("lghi 1,1\n\t"
                  "diag 1,1,0x308\n\t"
                  : : : "1", "memory");
-    virtio_panic("\n! IPL returns !\n");
+    panic("\n! IPL returns !\n");
 }
 
 /***********************************************************************
@@ -84,7 +84,7 @@ static const int max_bprs_entries = sizeof(_bprs) / sizeof(ExtEckdBlockPtr);
 
 static inline void verify_boot_info(BootInfo *bip)
 {
-    IPL_assert(magic_match(bip->magic, ZIPL_MAGIC), "No zIPL magic");
+    IPL_assert(magic_match(bip->magic, ZIPL_MAGIC), "No zIPL sig in BootInfo");
     IPL_assert(bip->version == BOOT_INFO_VERSION, "Wrong zIPL version");
     IPL_assert(bip->bp_type == BOOT_INFO_BP_TYPE_IPL, "DASD is not for IPL");
     IPL_assert(bip->dev_type == BOOT_INFO_DEV_TYPE_ECKD, "DASD is not ECKD");
@@ -315,6 +315,40 @@ static void print_eckd_msg(void)
     sclp_print(msg);
 }
 
+static void ipl_eckd(void)
+{
+    ScsiMbr *mbr = (void *)sec;
+    LDL_VTOC *vlbl = (void *)sec;
+
+    print_eckd_msg();
+
+    /* Grab the MBR again */
+    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
+    read_block(0, mbr, "Cannot read block 0 on DASD");
+
+    if (magic_match(mbr->magic, IPL1_MAGIC)) {
+        ipl_eckd_cdl(); /* no return */
+    }
+
+    /* LDL/CMS? */
+    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
+    read_block(2, vlbl, "Cannot read block 2");
+
+    if (magic_match(vlbl->magic, CMS1_MAGIC)) {
+        ipl_eckd_ldl(ECKD_CMS); /* no return */
+    }
+    if (magic_match(vlbl->magic, LNX1_MAGIC)) {
+        ipl_eckd_ldl(ECKD_LDL); /* no return */
+    }
+
+    ipl_eckd_ldl(ECKD_LDL_UNLABELED); /* it still may return */
+    /*
+     * Ok, it is not a LDL by any means.
+     * It still might be a CDL with zero record keys for IPL1 and IPL2
+     */
+    ipl_eckd_cdl();
+}
+
 /***********************************************************************
  * IPL a SCSI disk
  */
@@ -382,7 +416,7 @@ static void zipl_run(ScsiBlockPtr *pte)
     read_block(pte->blockno, tmp_sec, "Cannot read header");
     header = (ComponentHeader *)tmp_sec;
 
-    IPL_assert(magic_match(tmp_sec, ZIPL_MAGIC), "No zIPL magic");
+    IPL_assert(magic_match(tmp_sec, ZIPL_MAGIC), "No zIPL magic in header");
     IPL_assert(header->type == ZIPL_COMP_HEADER_IPL, "Bad header type");
 
     dputs("start loading images\n");
@@ -412,16 +446,26 @@ static void ipl_scsi(void)
     const int pte_len = sizeof(ScsiBlockPtr);
     ScsiBlockPtr *prog_table_entry;
 
-    /* The 0-th block (MBR) was already read into sec[] */
+    /* Grab the MBR */
+    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
+    read_block(0, mbr, "Cannot read block 0");
+
+    if (!magic_match(mbr->magic, ZIPL_MAGIC)) {
+        return;
+    }
 
     sclp_print("Using SCSI scheme.\n");
+    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.blockno);
+    IPL_assert(mbr->blockptr.blockno, "No Program Table");
 
     /* Parse the program table */
     read_block(mbr->blockptr.blockno, sec,
                "Error reading Program Table");
 
-    IPL_assert(magic_match(sec, ZIPL_MAGIC), "No zIPL magic");
+    IPL_assert(magic_match(sec, ZIPL_MAGIC), "No zIPL magic in PT");
 
     ns_end = sec + virtio_get_block_size();
     for (ns = (sec + pte_len); (ns + pte_len) < ns_end; ns += pte_len) {
@@ -613,7 +657,7 @@ static IsoBcSection *find_iso_bc_entry(void)
 
     if (!is_iso_bc_valid(e)) {
         /* The validation entry is mandatory */
-        virtio_panic("No valid boot catalog found!\n");
+        panic("No valid boot catalog found!\n");
         return NULL;
     }
 
@@ -629,7 +673,7 @@ static IsoBcSection *find_iso_bc_entry(void)
         }
     }
 
-    virtio_panic("No suitable boot entry found on ISO-9660 media!\n");
+    panic("No suitable boot entry found on ISO-9660 media!\n");
 
     return NULL;
 }
@@ -645,57 +689,58 @@ static void ipl_iso_el_torito(void)
 }
 
 /***********************************************************************
- * IPL starts here
+ * Bus specific IPL sequences
  */
 
-void zipl_load(void)
+static void zipl_load_vblk(void)
 {
-    ScsiMbr *mbr = (void *)sec;
-    LDL_VTOC *vlbl = (void *)sec;
-
-    /* Grab the MBR */
-    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(0, mbr, "Cannot read block 0");
-
-    dputs("checking magic\n");
-
-    if (magic_match(mbr->magic, ZIPL_MAGIC)) {
-        ipl_scsi(); /* no return */
-    }
-
-    /* Check if we can boot as ISO media */
     if (virtio_guessed_disk_nature()) {
         virtio_assume_iso9660();
     }
     ipl_iso_el_torito();
 
-    /* We have failed to follow the SCSI scheme, so */
     if (virtio_guessed_disk_nature()) {
         sclp_print("Using guessed DASD geometry.\n");
         virtio_assume_eckd();
     }
-    print_eckd_msg();
-    if (magic_match(mbr->magic, IPL1_MAGIC)) {
-        ipl_eckd_cdl(); /* no return */
+    ipl_eckd();
+}
+
+static void zipl_load_vscsi(void)
+{
+    if (virtio_get_block_size() == VIRTIO_ISO_BLOCK_SIZE) {
+        /* Is it an ISO image in non-CD drive? */
+        ipl_iso_el_torito();
     }
 
-    /* LDL/CMS? */
-    memset(sec, FREE_SPACE_FILLER, sizeof(sec));
-    read_block(2, vlbl, "Cannot read block 2");
+    sclp_print("Using guessed DASD geometry.\n");
+    virtio_assume_eckd();
+    ipl_eckd();
+}
 
-    if (magic_match(vlbl->magic, CMS1_MAGIC)) {
-        ipl_eckd_ldl(ECKD_CMS); /* no return */
-    }
-    if (magic_match(vlbl->magic, LNX1_MAGIC)) {
-        ipl_eckd_ldl(ECKD_LDL); /* no return */
+/***********************************************************************
+ * IPL starts here
+ */
+
+void zipl_load(void)
+{
+    if (virtio_get_device()->is_cdrom) {
+        ipl_iso_el_torito();
+        panic("\n! Cannot IPL this ISO image !\n");
     }
 
-    ipl_eckd_ldl(ECKD_LDL_UNLABELED); /* it still may return */
-    /*
-     * Ok, it is not a LDL by any means.
-     * It still might be a CDL with zero record keys for IPL1 and IPL2
-     */
-    ipl_eckd_cdl();
+    ipl_scsi();
+
+    switch (virtio_get_device_type()) {
+    case VIRTIO_ID_BLOCK:
+        zipl_load_vblk();
+        break;
+    case VIRTIO_ID_SCSI:
+        zipl_load_vscsi();
+        break;
+    default:
+        panic("\n! Unknown IPL device type !\n");
+    }
 
-    virtio_panic("\n* this can never happen *\n");
+    panic("\n* this can never happen *\n");
 }
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index f98765b841..bea168714b 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -264,15 +264,6 @@ typedef enum {
 
 /* utility code below */
 
-static inline void IPL_assert(bool term, const char *message)
-{
-    if (!term) {
-        sclp_print("\n! ");
-        sclp_print(message);
-        virtio_panic(" !\n"); /* no return */
-    }
-}
-
 static const unsigned char ebc2asc[256] =
       /* 0123456789abcdef0123456789abcdef */
         "................................" /* 1F */
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index d5fe4cea1d..1c9e0791ab 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -12,9 +12,8 @@
 #include "virtio.h"
 
 char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
-char ring_area[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
 uint64_t boot_value;
-static struct subchannel_id blk_schid = { .one = 1 };
+static SubChannelId blk_schid = { .one = 1 };
 
 /*
  * Priniciples of Operations (SA22-7832-09) chapter 17 requires that
@@ -23,7 +22,7 @@ static struct subchannel_id blk_schid = { .one = 1 };
  */
 void write_subsystem_identification(void)
 {
-    struct subchannel_id *schid = (struct subchannel_id *) 184;
+    SubChannelId *schid = (SubChannelId *) 184;
     uint32_t *zeroes = (uint32_t *) 188;
 
     *schid = blk_schid;
@@ -31,14 +30,14 @@ void write_subsystem_identification(void)
 }
 
 
-void virtio_panic(const char *string)
+void panic(const char *string)
 {
     sclp_print(string);
     disabled_wait();
     while (1) { }
 }
 
-static bool find_dev(struct schib *schib, int dev_no)
+static bool find_dev(Schib *schib, int dev_no)
 {
     int i, r;
 
@@ -51,7 +50,7 @@ static bool find_dev(struct schib *schib, int dev_no)
         if (!schib->pmcw.dnv) {
             continue;
         }
-        if (!virtio_is_blk(blk_schid)) {
+        if (!virtio_is_supported(blk_schid)) {
             continue;
         }
         if ((dev_no < 0) || (schib->pmcw.dev == dev_no)) {
@@ -64,7 +63,7 @@ static bool find_dev(struct schib *schib, int dev_no)
 
 static void virtio_setup(uint64_t dev_info)
 {
-    struct schib schib;
+    Schib schib;
     int ssid;
     bool found = false;
     uint16_t dev_no;
@@ -92,15 +91,11 @@ static void virtio_setup(uint64_t dev_info)
         }
     }
 
-    if (!found) {
-        virtio_panic("No virtio-blk device found!\n");
-    }
+    IPL_assert(found, "No virtio device found");
 
-    virtio_setup_block(blk_schid);
+    virtio_setup_device(blk_schid);
 
-    if (!virtio_ipl_disk_is_valid()) {
-        virtio_panic("No valid hard disk detected.\n");
-    }
+    IPL_assert(virtio_ipl_disk_is_valid(), "No valid IPL device detected");
 }
 
 int main(void)
@@ -111,6 +106,6 @@ int main(void)
 
     zipl_load(); /* no return */
 
-    virtio_panic("Failed to load OS from hard disk\n");
+    panic("Failed to load OS from hard disk\n");
     return 0; /* make compiler happy */
 }
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 5484c2a45c..616d96738d 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -45,15 +45,22 @@ typedef unsigned long long __u64;
 
 #include "cio.h"
 
+typedef struct irb Irb;
+typedef struct ccw1 Ccw1;
+typedef struct cmd_orb CmdOrb;
+typedef struct schib Schib;
+typedef struct chsc_area_sda ChscAreaSda;
+typedef struct senseid SenseId;
+typedef struct subchannel_id SubChannelId;
+
 /* start.s */
 void disabled_wait(void);
 void consume_sclp_int(void);
 
 /* main.c */
-void virtio_panic(const char *string);
+void panic(const char *string);
 void write_subsystem_identification(void);
 extern char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
-extern char ring_area[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
 extern uint64_t boot_value;
 
 /* sclp-ascii.c */
@@ -63,10 +70,11 @@ void sclp_setup(void);
 /* virtio.c */
 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
                                  ulong subchan_id, void *load_addr);
-bool virtio_is_blk(struct subchannel_id schid);
-void virtio_setup_block(struct subchannel_id schid);
+bool virtio_is_supported(SubChannelId schid);
+void virtio_setup_device(SubChannelId schid);
 int virtio_read(ulong sector, void *load_addr);
 int enable_mss_facility(void);
+ulong get_second(void);
 
 /* bootmap.c */
 void zipl_load(void);
@@ -143,4 +151,42 @@ static inline void yield(void)
 
 #define MAX_SECTOR_SIZE 4096
 
+static inline void sleep(unsigned int seconds)
+{
+    ulong target = get_second() + seconds;
+
+    while (get_second() < target) {
+        yield();
+    }
+}
+
+static inline void *memcpy(void *s1, const void *s2, size_t n)
+{
+    uint8_t *p1 = s1;
+    const uint8_t *p2 = s2;
+
+    while (n--) {
+        p1[n] = p2[n];
+    }
+    return s1;
+}
+
+static inline void IPL_assert(bool term, const char *message)
+{
+    if (!term) {
+        sclp_print("\n! ");
+        sclp_print(message);
+        panic(" !\n"); /* no return */
+    }
+}
+
+static inline void IPL_check(bool term, const char *message)
+{
+    if (!term) {
+        sclp_print("\n! WARNING: ");
+        sclp_print(message);
+        sclp_print(" !\n");
+    }
+}
+
 #endif /* S390_CCW_H */
diff --git a/pc-bios/s390-ccw/scsi.h b/pc-bios/s390-ccw/scsi.h
new file mode 100644
index 0000000000..fc830f7e52
--- /dev/null
+++ b/pc-bios/s390-ccw/scsi.h
@@ -0,0 +1,184 @@
+/*
+ * SCSI definitions for s390 machine loader for qemu
+ *
+ * Copyright 2015 IBM Corp.
+ * Author: Eugene "jno" Dvurechenski <jno@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.
+ */
+
+#ifndef SCSI_H
+#define SCSI_H
+
+#include "s390-ccw.h"
+
+#define SCSI_DEFAULT_CDB_SIZE                   32
+#define SCSI_DEFAULT_SENSE_SIZE                 96
+
+#define CDB_STATUS_GOOD                         0
+#define CDB_STATUS_CHECK_CONDITION              0x02U
+#define CDB_STATUS_VALID(status)    (((status) & ~0x3eU) == 0)
+
+#define SCSI_SENSE_CODE_MASK                    0x7fU
+#define SCSI_SENSE_KEY_MASK                     0x0fU
+#define SCSI_SENSE_KEY_NO_SENSE                 0
+#define SCSI_SENSE_KEY_UNIT_ATTENTION           6
+
+union ScsiLun {
+    uint64_t v64;        /* numeric shortcut                             */
+    uint8_t  v8[8];      /* generic 8 bytes representation               */
+    uint16_t v16[4];     /* 4-level big-endian LUN as specified by SAM-2 */
+};
+typedef union ScsiLun ScsiLun;
+
+struct ScsiSense70 {
+    uint8_t b0;         /* b0 & 7f = resp code (0x70 or 0x71)   */
+    uint8_t b1, b2;     /* b2 & 0f = sense key                  */
+    uint8_t u1[1 * 4 + 1 + 1 * 4];   /* b7 = N - 7                  */
+    uint8_t additional_sense_code;              /* b12          */
+    uint8_t additional_sense_code_qualifier;    /* b13          */
+    uint8_t u2[1 + 3 + 0];           /* up to N (<=252) bytes       */
+} __attribute__((packed));
+typedef struct ScsiSense70 ScsiSense70;
+
+/* don't confuse with virtio-scsi response/status fields! */
+
+static inline uint8_t scsi_sense_response(const void *p)
+{
+    return ((const ScsiSense70 *)p)->b0 & SCSI_SENSE_CODE_MASK;
+}
+
+static inline uint8_t scsi_sense_key(const void *p)
+{
+    return ((const ScsiSense70 *)p)->b2 & SCSI_SENSE_KEY_MASK;
+}
+
+#define SCSI_INQ_RDT_CDROM                      0x05
+
+struct ScsiInquiryStd {
+    uint8_t peripheral_qdt; /* b0, use (b0 & 0x1f) to get SCSI_INQ_RDT  */
+    uint8_t b1;             /* Removable Media Bit = b1 & 0x80          */
+    uint8_t spc_version;    /* b2                                       */
+    uint8_t b3;             /* b3 & 0x0f == resp_data_fmt == 2, must!   */
+    uint8_t u1[1 + 1 + 1 + 1 + 8];  /* b4..b15 unused, b4 = (N - 1)     */
+    char prod_id[16];       /* "QEMU CD-ROM" is here                    */
+    uint8_t u2[4            /* b32..b35 unused, mandatory               */
+              + 8 + 12 + 1 + 1 + 8 * 2 + 22  /* b36..95 unused, optional*/
+              + 0];          /* b96..bN unused, vendor specific          */
+    /* byte N                                                           */
+}  __attribute__((packed));
+typedef struct ScsiInquiryStd ScsiInquiryStd;
+
+struct ScsiCdbInquiry {
+    uint8_t command;     /* b0, == 0x12         */
+    uint8_t b1;          /* b1, |= 0x01 (evpd)  */
+    uint8_t b2;          /* b2; if evpd==1      */
+    uint16_t alloc_len;  /* b3, b4              */
+    uint8_t control;     /* b5                  */
+}  __attribute__((packed));
+typedef struct ScsiCdbInquiry ScsiCdbInquiry;
+
+struct ScsiCdbRead10 {
+    uint8_t command;    /* =0x28    */
+    uint8_t b1;
+    uint32_t lba;
+    uint8_t b6;
+    uint16_t xfer_length;
+    uint8_t control;
+}  __attribute__((packed));
+typedef struct ScsiCdbRead10 ScsiCdbRead10;
+
+struct ScsiCdbTestUnitReady {
+    uint8_t command;    /* =0x00    */
+    uint8_t b1_b4[4];
+    uint8_t control;
+} __attribute__((packed));
+typedef struct ScsiCdbTestUnitReady ScsiCdbTestUnitReady;
+
+struct ScsiCdbReportLuns {
+    uint8_t command;        /* =0xa0        */
+    uint8_t b1;
+    uint8_t select_report;  /* =0x02, "all" */
+    uint8_t b3_b5[3];
+    uint32_t alloc_len;
+    uint8_t b10;
+    uint8_t control;
+} __attribute__((packed));
+typedef struct ScsiCdbReportLuns ScsiCdbReportLuns;
+
+struct ScsiLunReport {
+    uint32_t lun_list_len;
+    uint32_t b4_b7;
+    ScsiLun lun[1];   /* space for at least 1 lun must be allocated */
+} __attribute__((packed));
+typedef struct ScsiLunReport ScsiLunReport;
+
+struct ScsiCdbReadCapacity16 {
+    uint8_t command;        /* =0x9e = "service action in 16"       */
+    uint8_t service_action; /* 5 bits, =0x10 = "read capacity 16"   */
+    uint64_t b2_b9;
+    uint32_t alloc_len;
+    uint8_t b14;
+    uint8_t control;
+} __attribute__((packed));
+typedef struct ScsiCdbReadCapacity16 ScsiCdbReadCapacity16;
+
+struct ScsiReadCapacity16Data {
+    uint64_t ret_lba;             /* get it, 0..7     */
+    uint32_t lb_len;              /* bytes, 8..11     */
+    uint8_t u1[2 + 1 * 2 + 16];   /* b12..b31, unused */
+} __attribute__((packed));
+typedef struct ScsiReadCapacity16Data ScsiReadCapacity16Data;
+
+static inline ScsiLun make_lun(uint16_t channel, uint16_t target, uint32_t lun)
+{
+    ScsiLun r = { .v64 = 0 };
+
+    /* See QEMU code to choose the way to handle LUNs.
+     *
+     * So, a valid LUN must have (always channel #0):
+     *  lun[0] == 1
+     *  lun[1] - target, any value
+     *  lun[2] == 0 or (LUN, MSB, 0x40 set, 0x80 clear)
+     *  lun[3] - LUN, LSB, any value
+     */
+    r.v8[0] = 1;
+    r.v8[1] = target & 0xffU;
+    r.v8[2] = (lun >> 8) & 0x3fU;
+    if (r.v8[2]) {
+        r.v8[2] |= 0x40;
+    }
+    r.v8[3] = lun & 0xffU;
+
+    return r;
+}
+
+static inline const char *scsi_cdb_status_msg(uint8_t status)
+{
+    static char err_msg[] = "STATUS=XX";
+    uint8_t v = status & 0x3eU;
+
+    fill_hex_val(err_msg + 7, &v, 1);
+    return err_msg;
+}
+
+static inline const char *scsi_cdb_asc_msg(const void *s)
+{
+    static char err_msg[] = "RSPN=XX KEY=XX CODE=XX QLFR=XX";
+    const ScsiSense70 *p = s;
+    uint8_t sr = scsi_sense_response(s);
+    uint8_t sk = scsi_sense_key(s);
+    uint8_t ac = p->additional_sense_code;
+    uint8_t cq = p->additional_sense_code_qualifier;
+
+    fill_hex_val(err_msg + 5, &sr, 1);
+    fill_hex_val(err_msg + 12, &sk, 1);
+    fill_hex_val(err_msg + 20, &ac, 1);
+    fill_hex_val(err_msg + 28, &cq, 1);
+
+    return err_msg;
+}
+
+#endif /* SCSI_H */
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
new file mode 100644
index 0000000000..3bb48e917e
--- /dev/null
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -0,0 +1,342 @@
+/*
+ * Virtio-SCSI implementation for s390 machine loader for qemu
+ *
+ * Copyright 2015 IBM Corp.
+ * Author: Eugene "jno" Dvurechenski <jno@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 "s390-ccw.h"
+#include "virtio.h"
+#include "scsi.h"
+#include "virtio-scsi.h"
+
+static ScsiDevice default_scsi_device;
+static VirtioScsiCmdReq req;
+static VirtioScsiCmdResp resp;
+
+static uint8_t scsi_inquiry_std_response[256];
+
+static inline void vs_assert(bool term, const char **msgs)
+{
+    if (!term) {
+        int i = 0;
+
+        sclp_print("\n! ");
+        while (msgs[i]) {
+            sclp_print(msgs[i++]);
+        }
+        panic(" !\n");
+    }
+}
+
+static void virtio_scsi_verify_response(VirtioScsiCmdResp *resp,
+                                        const char *title)
+{
+    const char *mr[] = {
+        title, ": response ", virtio_scsi_response_msg(resp), 0
+    };
+    const char *ms[] = {
+        title,
+        CDB_STATUS_VALID(resp->status) ? ": " : ": invalid ",
+        scsi_cdb_status_msg(resp->status),
+        resp->status == CDB_STATUS_CHECK_CONDITION ? " " : 0,
+        resp->sense_len ? scsi_cdb_asc_msg(resp->sense)
+                        : "no sense data",
+        scsi_sense_response(resp->sense)  == 0x70 ? ", sure" : "?",
+        0
+    };
+
+    vs_assert(resp->response == VIRTIO_SCSI_S_OK, mr);
+    vs_assert(resp->status == CDB_STATUS_GOOD, ms);
+}
+
+static void prepare_request(VDev *vdev, const void *cdb, int cdb_size,
+                            void *data, uint32_t data_size)
+{
+    const ScsiDevice *sdev = vdev->scsi_device;
+
+    memset(&req, 0, sizeof(req));
+    req.lun = make_lun(sdev->channel, sdev->target, sdev->lun);
+    memcpy(&req.cdb, cdb, cdb_size);
+
+    memset(&resp, 0, sizeof(resp));
+    resp.status = 0xff;     /* set invalid  */
+    resp.response = 0xff;   /*              */
+
+    if (data && data_size) {
+        memset(data, 0, data_size);
+    }
+}
+
+static inline void vs_io_assert(bool term, const char *msg)
+{
+    if (!term) {
+        virtio_scsi_verify_response(&resp, msg);
+    }
+}
+
+static void vs_run(const char *title, VirtioCmd *cmd, VDev *vdev,
+                   const void *cdb, int cdb_size,
+                   void *data, uint32_t data_size)
+{
+    prepare_request(vdev, cdb, cdb_size, data, data_size);
+    vs_io_assert(virtio_run(vdev, VR_REQUEST, cmd) == 0, title);
+}
+
+/* SCSI protocol implementation routines */
+
+static bool scsi_inquiry(VDev *vdev, void *data, uint32_t data_size)
+{
+    ScsiCdbInquiry cdb = {
+        .command = 0x12,
+        .alloc_len = data_size < 65535 ? data_size : 65535,
+    };
+    VirtioCmd inquiry[] = {
+        { &req, sizeof(req), VRING_DESC_F_NEXT },
+        { &resp, sizeof(resp), VRING_DESC_F_WRITE | VRING_DESC_F_NEXT },
+        { data, data_size, VRING_DESC_F_WRITE },
+    };
+
+    vs_run("inquiry", inquiry, vdev, &cdb, sizeof(cdb), data, data_size);
+
+    return virtio_scsi_response_ok(&resp);
+}
+
+static bool scsi_test_unit_ready(VDev *vdev)
+{
+    ScsiCdbTestUnitReady cdb = {
+        .command = 0x00,
+    };
+    VirtioCmd test_unit_ready[] = {
+        { &req, sizeof(req), VRING_DESC_F_NEXT },
+        { &resp, sizeof(resp), VRING_DESC_F_WRITE },
+    };
+
+    prepare_request(vdev, &cdb, sizeof(cdb), 0, 0);
+    virtio_run(vdev, VR_REQUEST, test_unit_ready); /* ignore errors here */
+
+    return virtio_scsi_response_ok(&resp);
+}
+
+static bool scsi_report_luns(VDev *vdev, void *data, uint32_t data_size)
+{
+    ScsiCdbReportLuns cdb = {
+        .command = 0xa0,
+        .select_report = 0x02, /* REPORT ALL */
+        .alloc_len = data_size,
+    };
+    VirtioCmd report_luns[] = {
+        { &req, sizeof(req), VRING_DESC_F_NEXT },
+        { &resp, sizeof(resp), VRING_DESC_F_WRITE | VRING_DESC_F_NEXT },
+        { data, data_size, VRING_DESC_F_WRITE },
+    };
+
+    vs_run("report luns", report_luns,
+           vdev, &cdb, sizeof(cdb), data, data_size);
+
+    return virtio_scsi_response_ok(&resp);
+}
+
+static bool scsi_read_10(VDev *vdev,
+                         ulong sector, int sectors, void *data)
+{
+    int f = vdev->blk_factor;
+    unsigned int data_size = sectors * virtio_get_block_size() * f;
+    ScsiCdbRead10 cdb = {
+        .command = 0x28,
+        .lba = sector * f,
+        .xfer_length = sectors * f,
+    };
+    VirtioCmd read_10[] = {
+        { &req, sizeof(req), VRING_DESC_F_NEXT },
+        { &resp, sizeof(resp), VRING_DESC_F_WRITE | VRING_DESC_F_NEXT },
+        { data, data_size * f, VRING_DESC_F_WRITE },
+    };
+
+    debug_print_int("read_10  sector", sector);
+    debug_print_int("read_10 sectors", sectors);
+
+    vs_run("read(10)", read_10, vdev, &cdb, sizeof(cdb), data, data_size);
+
+    return virtio_scsi_response_ok(&resp);
+}
+
+static bool scsi_read_capacity(VDev *vdev,
+                               void *data, uint32_t data_size)
+{
+    ScsiCdbReadCapacity16 cdb = {
+        .command = 0x9e, /* SERVICE_ACTION_IN_16 */
+        .service_action = 0x10, /* SA_READ_CAPACITY */
+        .alloc_len = data_size,
+    };
+    VirtioCmd read_capacity_16[] = {
+        { &req, sizeof(req), VRING_DESC_F_NEXT },
+        { &resp, sizeof(resp), VRING_DESC_F_WRITE | VRING_DESC_F_NEXT },
+        { data, data_size, VRING_DESC_F_WRITE },
+    };
+
+    vs_run("read capacity", read_capacity_16,
+           vdev, &cdb, sizeof(cdb), data, data_size);
+
+    return virtio_scsi_response_ok(&resp);
+}
+
+/* virtio-scsi routines */
+
+static void virtio_scsi_locate_device(VDev *vdev)
+{
+    const uint16_t channel = 0; /* again, it's what QEMU does */
+    uint16_t target;
+    static uint8_t data[16 + 8 * 63];
+    ScsiLunReport *r = (void *) data;
+    ScsiDevice *sdev = vdev->scsi_device;
+    int i, luns;
+
+    /* QEMU has hardcoded channel #0 in many places.
+     * If this hardcoded value is ever changed, we'll need to add code for
+     * vdev->config.scsi.max_channel != 0 here.
+     */
+    debug_print_int("config.scsi.max_channel", vdev->config.scsi.max_channel);
+    debug_print_int("config.scsi.max_target ", vdev->config.scsi.max_target);
+    debug_print_int("config.scsi.max_lun    ", vdev->config.scsi.max_lun);
+
+    for (target = 0; target <= vdev->config.scsi.max_target; target++) {
+        sdev->channel = channel;
+        sdev->target = target; /* sdev->lun will be 0 here */
+        if (!scsi_report_luns(vdev, data, sizeof(data))) {
+            if (resp.response == VIRTIO_SCSI_S_BAD_TARGET) {
+                continue;
+            }
+            print_int("target", target);
+            virtio_scsi_verify_response(&resp, "SCSI cannot report LUNs");
+        }
+        if (r->lun_list_len == 0) {
+            print_int("no LUNs for target", target);
+            continue;
+        }
+        luns = r->lun_list_len / 8;
+        debug_print_int("LUNs reported", luns);
+        if (luns == 1) {
+            /* There is no ",lun=#" arg for -device or ",lun=0" given.
+             * Hence, the only LUN reported.
+             * Usually, it's 0.
+             */
+            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 */
+        }
+        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 */
+            }
+        }
+    }
+    panic("\n! Cannot locate virtio-scsi device !\n");
+}
+
+int virtio_scsi_read_many(VDev *vdev,
+                          ulong sector, void *load_addr, int sec_num)
+{
+    if (!scsi_read_10(vdev, sector, sec_num, load_addr)) {
+        virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
+    }
+
+    return 0;
+}
+
+static bool virtio_scsi_inquiry_response_is_cdrom(void *data)
+{
+    const ScsiInquiryStd *response = data;
+    const int resp_data_fmt = response->b3 & 0x0f;
+    int i;
+
+    IPL_check(resp_data_fmt == 2, "Wrong INQUIRY response format");
+    if (resp_data_fmt != 2) {
+        return false; /* cannot decode */
+    }
+
+    if ((response->peripheral_qdt & 0x1f) == SCSI_INQ_RDT_CDROM) {
+        return true;
+    }
+
+    for (i = 0; i < sizeof(response->prod_id); i++) {
+        if (response->prod_id[i] != QEMU_CDROM_SIGNATURE[i]) {
+            return false;
+        }
+    }
+    return true;
+}
+
+static void scsi_parse_capacity_report(void *data,
+                                       uint64_t *last_lba, uint32_t *lb_len)
+{
+    ScsiReadCapacity16Data *p = data;
+
+    if (last_lba) {
+        *last_lba = p->ret_lba;
+    }
+
+    if (lb_len) {
+        *lb_len = p->lb_len;
+    }
+}
+
+void virtio_scsi_setup(VDev *vdev)
+{
+    int retry_test_unit_ready = 3;
+    uint8_t data[256];
+    uint32_t data_size = sizeof(data);
+
+    vdev->scsi_device = &default_scsi_device;
+    virtio_scsi_locate_device(vdev);
+
+    /* We have to "ping" the device before it becomes readable */
+    while (!scsi_test_unit_ready(vdev)) {
+
+        if (!virtio_scsi_response_ok(&resp)) {
+            uint8_t code = resp.sense[0] & SCSI_SENSE_CODE_MASK;
+            uint8_t sense_key = resp.sense[2] & SCSI_SENSE_KEY_MASK;
+
+            IPL_assert(resp.sense_len != 0, "virtio-scsi:setup: no SENSE data");
+
+            IPL_assert(retry_test_unit_ready && code == 0x70 &&
+                       sense_key == SCSI_SENSE_KEY_UNIT_ATTENTION,
+                       "virtio-scsi:setup: cannot retry");
+
+            /* retry on CHECK_CONDITION/UNIT_ATTENTION as it
+             * may not designate a real error, but it may be
+             * a result of device reset, etc.
+             */
+            retry_test_unit_ready--;
+            sleep(1);
+            continue;
+        }
+
+        virtio_scsi_verify_response(&resp, "virtio-scsi:setup");
+    }
+
+    /* read and cache SCSI INQUIRY response */
+    if (!scsi_inquiry(vdev, scsi_inquiry_std_response,
+                      sizeof(scsi_inquiry_std_response))) {
+        virtio_scsi_verify_response(&resp, "virtio-scsi:setup:inquiry");
+    }
+
+    if (virtio_scsi_inquiry_response_is_cdrom(scsi_inquiry_std_response)) {
+        sclp_print("SCSI CD-ROM detected.\n");
+        vdev->is_cdrom = true;
+        vdev->scsi_block_size = VIRTIO_ISO_BLOCK_SIZE;
+    }
+
+    if (!scsi_read_capacity(vdev, data, data_size)) {
+        virtio_scsi_verify_response(&resp, "virtio-scsi:setup:read_capacity");
+    }
+    scsi_parse_capacity_report(data, &vdev->scsi_last_block,
+                               (uint32_t *) &vdev->scsi_block_size);
+}
diff --git a/pc-bios/s390-ccw/virtio-scsi.h b/pc-bios/s390-ccw/virtio-scsi.h
new file mode 100644
index 0000000000..f50b38b18b
--- /dev/null
+++ b/pc-bios/s390-ccw/virtio-scsi.h
@@ -0,0 +1,72 @@
+/*
+ * Virtio-SCSI definitions for s390 machine loader for qemu
+ *
+ * Copyright 2015 IBM Corp.
+ * Author: Eugene "jno" Dvurechenski <jno@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.
+ */
+
+#ifndef VIRTIO_SCSI_H
+#define VIRTIO_SCSI_H
+
+#include "s390-ccw.h"
+#include "virtio.h"
+#include "scsi.h"
+
+#define VIRTIO_SCSI_CDB_SIZE   SCSI_DEFAULT_CDB_SIZE
+#define VIRTIO_SCSI_SENSE_SIZE SCSI_DEFAULT_SENSE_SIZE
+
+/* command-specific response values */
+#define VIRTIO_SCSI_S_OK                     0x00
+#define VIRTIO_SCSI_S_BAD_TARGET             0x03
+
+#define QEMU_CDROM_SIGNATURE "QEMU CD-ROM     "
+
+enum virtio_scsi_vq_id {
+    VR_CONTROL  = 0,
+    VR_EVENT    = 1,
+    VR_REQUEST  = 2,
+};
+
+struct VirtioScsiCmdReq {
+    ScsiLun lun;
+    uint64_t id;
+    uint8_t task_attr;   /* = 0 = VIRTIO_SCSI_S_SIMPLE */
+    uint8_t prio;
+    uint8_t crn;         /* = 0 */
+    uint8_t cdb[VIRTIO_SCSI_CDB_SIZE];
+} __attribute__((packed));
+typedef struct VirtioScsiCmdReq VirtioScsiCmdReq;
+
+struct VirtioScsiCmdResp {
+        uint32_t sense_len;
+        uint32_t residual;
+        uint16_t status_qualifier;
+        uint8_t status;      /* first check for .response    */
+        uint8_t response;    /* then for .status             */
+        uint8_t sense[VIRTIO_SCSI_SENSE_SIZE];
+} __attribute__((packed));
+typedef struct VirtioScsiCmdResp VirtioScsiCmdResp;
+
+static inline const char *virtio_scsi_response_msg(const VirtioScsiCmdResp *r)
+{
+    static char err_msg[] = "VS RESP=XX";
+    uint8_t v = r->response;
+
+    fill_hex_val(err_msg + 8, &v, 1);
+    return err_msg;
+}
+
+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_read_many(VDev *vdev,
+                          ulong sector, void *load_addr, int sec_num);
+
+#endif /* VIRTIO_SCSI_H */
diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
index 87aed38a95..1d34e8c1aa 100644
--- a/pc-bios/s390-ccw/virtio.c
+++ b/pc-bios/s390-ccw/virtio.c
@@ -10,39 +10,68 @@
 
 #include "s390-ccw.h"
 #include "virtio.h"
+#include "virtio-scsi.h"
 
-static struct vring block;
+#define VRING_WAIT_REPLY_TIMEOUT 3
+
+static VRing block[VIRTIO_MAX_VQS];
+static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
+                     __attribute__((__aligned__(PAGE_SIZE)));
 
 static char chsc_page[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
 
+static VDev vdev = {
+    .nr_vqs = 1,
+    .vrings = block,
+    .cmd_vr_idx = 0,
+    .ring_area = ring_area,
+    .wait_reply_timeout = VRING_WAIT_REPLY_TIMEOUT,
+    .schid = { .one = 1 },
+    .scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE,
+    .blk_factor = 1,
+};
+
+VDev *virtio_get_device(void)
+{
+    return &vdev;
+}
+
+VirtioDevType virtio_get_device_type(void)
+{
+    return vdev.senseid.cu_model;
+}
+
+/* virtio spec v1.0 para 4.3.3.2 */
 static long kvm_hypercall(unsigned long nr, unsigned long param1,
-                          unsigned long param2)
+                          unsigned long param2, unsigned long param3)
 {
     register ulong r_nr asm("1") = nr;
     register ulong r_param1 asm("2") = param1;
     register ulong r_param2 asm("3") = param2;
+    register ulong r_param3 asm("4") = param3;
     register long retval asm("2");
 
     asm volatile ("diag 2,4,0x500"
                   : "=d" (retval)
-                  : "d" (r_nr), "0" (r_param1), "r"(r_param2)
+                  : "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
                   : "memory", "cc");
 
     return retval;
 }
 
-static void virtio_notify(struct subchannel_id schid)
+static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
 {
-    kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid, 0);
+    return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid,
+                         vq_idx, cookie);
 }
 
 /***********************************************
  *             Virtio functions                *
  ***********************************************/
 
-static int drain_irqs(struct subchannel_id schid)
+static int drain_irqs(SubChannelId schid)
 {
-    struct irb irb = {};
+    Irb irb = {};
     int r = 0;
 
     while (1) {
@@ -59,17 +88,17 @@ static int drain_irqs(struct subchannel_id schid)
     }
 }
 
-static int run_ccw(struct subchannel_id schid, int cmd, void *ptr, int len)
+static int run_ccw(VDev *vdev, int cmd, void *ptr, int len)
 {
-    struct ccw1 ccw = {};
-    struct cmd_orb orb = {};
-    struct schib schib;
+    Ccw1 ccw = {};
+    CmdOrb orb = {};
+    Schib schib;
     int r;
 
     /* start command processing */
-    stsch_err(schid, &schib);
+    stsch_err(vdev->schid, &schib);
     schib.scsw.ctrl = SCSW_FCTL_START_FUNC;
-    msch(schid, &schib);
+    msch(vdev->schid, &schib);
 
     /* start subchannel command */
     orb.fmt = 1;
@@ -80,41 +109,29 @@ static int run_ccw(struct subchannel_id schid, int cmd, void *ptr, int len)
     ccw.cda = (long)ptr;
     ccw.count = len;
 
-    r = ssch(schid, &orb);
+    r = ssch(vdev->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
      */
     if (!r) {
-        r = drain_irqs(schid);
+        r = drain_irqs(vdev->schid);
     }
     return r;
 }
 
-static void virtio_set_status(struct subchannel_id schid,
-                              unsigned long dev_addr)
+static void vring_init(VRing *vr, VqInfo *info)
 {
-    unsigned char status = dev_addr;
-    if (run_ccw(schid, CCW_CMD_WRITE_STATUS, &status, sizeof(status))) {
-        virtio_panic("Could not write status to host!\n");
-    }
-}
+    void *p = (void *) info->queue;
 
-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->id = info->index;
+    vr->num = info->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));
+    vr->avail = p + info->num * sizeof(VRingDesc);
+    vr->used = (void *)(((unsigned long)&vr->avail->ring[info->num]
+               + info->align - 1) & ~(info->align - 1));
 
     /* Zero out all relevant field */
     vr->avail->flags = 0;
@@ -125,16 +142,18 @@ static void vring_init(struct vring *vr, unsigned int num, void *p,
     vr->used->idx = 0;
     vr->used_idx = 0;
     vr->next_idx = 0;
+    vr->cookie = 0;
 
     debug_print_addr("init vr", vr);
 }
 
-static void vring_notify(struct subchannel_id schid)
+static bool vring_notify(VRing *vr)
 {
-    virtio_notify(schid);
+    vr->cookie = virtio_notify(vr->schid, vr->id, vr->cookie);
+    return vr->cookie >= 0;
 }
 
-static void vring_send_buf(struct vring *vr, void *p, int len, int flags)
+static void vring_send_buf(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)) {
@@ -162,11 +181,26 @@ static u64 get_clock(void)
     return r;
 }
 
-static ulong get_second(void)
+ulong get_second(void)
 {
     return (get_clock() >> 12) / 1000000;
 }
 
+static int vr_poll(VRing *vr)
+{
+    if (vr->used->idx == vr->used_idx) {
+        vring_notify(vr);
+        yield();
+        return 0;
+    }
+
+    vr->used_idx = vr->used->idx;
+    vr->next_idx = 0;
+    vr->desc[0].len = 0;
+    vr->desc[0].flags = 0;
+    return 1; /* vr has been updated */
+}
+
 /*
  * Wait for the host to reply.
  *
@@ -174,67 +208,92 @@ static ulong get_second(void)
  *
  * Returns 0 on success, 1 on timeout.
  */
-static int vring_wait_reply(struct vring *vr, int timeout)
+static int vring_wait_reply(void)
 {
-    ulong target_second = get_second() + timeout;
-    struct subchannel_id schid = vr->schid;
-    int r = 0;
+    ulong target_second = get_second() + vdev.wait_reply_timeout;
 
-    /* Wait until the used index has moved. */
-    while (vr->used->idx == vr->used_idx) {
-        vring_notify(schid);
-        if (timeout && (get_second() >= target_second)) {
-            r = 1;
-            break;
+    /* Wait for any queue to be updated by the host */
+    do {
+        int i, r = 0;
+
+        for (i = 0; i < vdev.nr_vqs; i++) {
+            r += vr_poll(&vdev.vrings[i]);
         }
         yield();
-    }
+        if (r) {
+            return 0;
+        }
+    } while (!vdev.wait_reply_timeout || (get_second() < target_second));
 
-    vr->used_idx = vr->used->idx;
-    vr->next_idx = 0;
-    vr->desc[0].len = 0;
-    vr->desc[0].flags = 0;
+    return 1;
+}
 
-    return r;
+int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
+{
+    VRing *vr = &vdev->vrings[vqid];
+    int i = 0;
+
+    do {
+        vring_send_buf(vr, cmd[i].data, cmd[i].size,
+                       cmd[i].flags | (i ? VRING_HIDDEN_IS_CHAIN : 0));
+    } while (cmd[i++].flags & VRING_DESC_F_NEXT);
+
+    vring_wait_reply();
+    if (drain_irqs(vr->schid)) {
+        return -1;
+    }
+    return 0;
 }
 
 /***********************************************
  *               Virtio block                  *
  ***********************************************/
 
-int virtio_read_many(ulong sector, void *load_addr, int sec_num)
+static int virtio_blk_read_many(VDev *vdev,
+                                ulong sector, void *load_addr, int sec_num)
 {
-    struct virtio_blk_outhdr out_hdr;
+    VirtioBlkOuthdr out_hdr;
     u8 status;
-    int r;
+    VRing *vr = &vdev->vrings[vdev->cmd_vr_idx];
 
     /* Tell the host we want to read */
     out_hdr.type = VIRTIO_BLK_T_IN;
     out_hdr.ioprio = 99;
     out_hdr.sector = virtio_sector_adjust(sector);
 
-    vring_send_buf(&block, &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);
+    vring_send_buf(vr, &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);
 
     /* This is where we want to receive data */
-    vring_send_buf(&block, load_addr, virtio_get_block_size() * sec_num,
+    vring_send_buf(vr, load_addr, virtio_get_block_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);
+    vring_send_buf(vr, &status, sizeof(u8),
+                   VRING_DESC_F_WRITE | VRING_HIDDEN_IS_CHAIN);
 
     /* Now we can tell the host to read */
-    vring_wait_reply(&block, 0);
+    vring_wait_reply();
 
-    r = drain_irqs(block.schid);
-    if (r) {
+    if (drain_irqs(vr->schid)) {
         /* Well, whatever status is supposed to contain... */
         status = 1;
     }
     return status;
 }
 
+int virtio_read_many(ulong sector, void *load_addr, int sec_num)
+{
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return virtio_blk_read_many(&vdev, sector, load_addr, sec_num);
+    case VIRTIO_ID_SCSI:
+        return virtio_scsi_read_many(&vdev, sector, load_addr, sec_num);
+    }
+    panic("\n! No readable IPL device !\n");
+    return -1;
+}
+
 unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
                                  ulong subchan_id, void *load_addr)
 {
@@ -251,7 +310,7 @@ unsigned long virtio_load_direct(ulong rec_list1, ulong rec_list2,
     sclp_print(".");
     status = virtio_read_many(sec, (void *)addr, sec_num);
     if (status) {
-        virtio_panic("I/O Error");
+        panic("I/O Error");
     }
     addr += sec_num * virtio_get_block_size();
 
@@ -263,78 +322,110 @@ int virtio_read(ulong sector, void *load_addr)
     return virtio_read_many(sector, load_addr, 1);
 }
 
-static VirtioBlkConfig blk_cfg = {};
-static bool guessed_disk_nature;
+/*
+ * Other supported value pairs, if any, would need to be added here.
+ * Note: head count is always 15.
+ */
+static inline u8 virtio_eckd_sectors_for_block_size(int size)
+{
+    switch (size) {
+    case 512:
+        return 49;
+    case 1024:
+        return 33;
+    case 2048:
+        return 21;
+    case 4096:
+        return 12;
+    }
+    return 0;
+}
 
-bool virtio_guessed_disk_nature(void)
+VirtioGDN virtio_guessed_disk_nature(void)
 {
-    return guessed_disk_nature;
+    return vdev.guessed_disk_nature;
 }
 
 void virtio_assume_scsi(void)
 {
-    guessed_disk_nature = true;
-    blk_cfg.blk_size = 512;
-    blk_cfg.physical_block_exp = 0;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        vdev.guessed_disk_nature = VIRTIO_GDN_SCSI;
+        vdev.config.blk.blk_size = VIRTIO_SCSI_BLOCK_SIZE;
+        vdev.config.blk.physical_block_exp = 0;
+        vdev.blk_factor = 1;
+        break;
+    case VIRTIO_ID_SCSI:
+        vdev.scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE;
+        break;
+    }
 }
 
 void virtio_assume_iso9660(void)
 {
-    guessed_disk_nature = true;
-    blk_cfg.blk_size = 2048;
-    blk_cfg.physical_block_exp = 0;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        vdev.guessed_disk_nature = VIRTIO_GDN_SCSI;
+        vdev.config.blk.blk_size = VIRTIO_ISO_BLOCK_SIZE;
+        vdev.config.blk.physical_block_exp = 0;
+        vdev.blk_factor = VIRTIO_ISO_BLOCK_SIZE / VIRTIO_SECTOR_SIZE;
+        break;
+    case VIRTIO_ID_SCSI:
+        vdev.scsi_block_size = VIRTIO_ISO_BLOCK_SIZE;
+        break;
+    }
 }
 
 void virtio_assume_eckd(void)
 {
-    guessed_disk_nature = true;
-    blk_cfg.blk_size = 4096;
-    blk_cfg.physical_block_exp = 0;
-
-    /* this must be here to calculate code segment position */
-    blk_cfg.geometry.heads = 15;
-    blk_cfg.geometry.sectors = 12;
+    vdev.guessed_disk_nature = VIRTIO_GDN_DASD;
+    vdev.blk_factor = 1;
+    vdev.config.blk.physical_block_exp = 0;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        vdev.config.blk.blk_size = 4096;
+        break;
+    case VIRTIO_ID_SCSI:
+        vdev.config.blk.blk_size = vdev.scsi_block_size;
+        break;
+    }
+    vdev.config.blk.geometry.heads = 15;
+    vdev.config.blk.geometry.sectors =
+        virtio_eckd_sectors_for_block_size(vdev.config.blk.blk_size);
 }
 
 bool virtio_disk_is_scsi(void)
 {
-    if (guessed_disk_nature) {
-        return (virtio_get_block_size()  == 512);
+    if (vdev.guessed_disk_nature == VIRTIO_GDN_SCSI) {
+        return true;
     }
-    return (blk_cfg.geometry.heads == 255)
-        && (blk_cfg.geometry.sectors == 63)
-        && (virtio_get_block_size()  == 512);
-}
-
-/*
- * Other supported value pairs, if any, would need to be added here.
- * Note: head count is always 15.
- */
-static inline u8 virtio_eckd_sectors_for_block_size(int size)
-{
-    switch (size) {
-    case 512:
-        return 49;
-    case 1024:
-        return 33;
-    case 2048:
-        return 21;
-    case 4096:
-        return 12;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return (vdev.config.blk.geometry.heads == 255)
+            && (vdev.config.blk.geometry.sectors == 63)
+            && (virtio_get_block_size()  == VIRTIO_SCSI_BLOCK_SIZE);
+    case VIRTIO_ID_SCSI:
+        return true;
     }
-    return 0;
+    return false;
 }
 
 bool virtio_disk_is_eckd(void)
 {
     const int block_size = virtio_get_block_size();
 
-    if (guessed_disk_nature) {
-        return (block_size  == 4096);
+    if (vdev.guessed_disk_nature == VIRTIO_GDN_DASD) {
+        return true;
     }
-    return (blk_cfg.geometry.heads == 15)
-        && (blk_cfg.geometry.sectors ==
-            virtio_eckd_sectors_for_block_size(block_size));
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return (vdev.config.blk.geometry.heads == 15)
+            && (vdev.config.blk.geometry.sectors ==
+                virtio_eckd_sectors_for_block_size(block_size));
+    case VIRTIO_ID_SCSI:
+        return false;
+    }
+    return false;
 }
 
 bool virtio_ipl_disk_is_valid(void)
@@ -344,34 +435,80 @@ bool virtio_ipl_disk_is_valid(void)
 
 int virtio_get_block_size(void)
 {
-    return blk_cfg.blk_size << blk_cfg.physical_block_exp;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return vdev.config.blk.blk_size << vdev.config.blk.physical_block_exp;
+    case VIRTIO_ID_SCSI:
+        return vdev.scsi_block_size;
+    }
+    return 0;
 }
 
 uint8_t virtio_get_heads(void)
 {
-    return blk_cfg.geometry.heads;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return vdev.config.blk.geometry.heads;
+    case VIRTIO_ID_SCSI:
+        return vdev.guessed_disk_nature == VIRTIO_GDN_DASD
+               ? vdev.config.blk.geometry.heads : 255;
+    }
+    return 0;
 }
 
 uint8_t virtio_get_sectors(void)
 {
-    return blk_cfg.geometry.sectors;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return vdev.config.blk.geometry.sectors;
+    case VIRTIO_ID_SCSI:
+        return vdev.guessed_disk_nature == VIRTIO_GDN_DASD
+               ? vdev.config.blk.geometry.sectors : 63;
+    }
+    return 0;
 }
 
 uint64_t virtio_get_blocks(void)
 {
-    return blk_cfg.capacity /
-           (virtio_get_block_size() / VIRTIO_SECTOR_SIZE);
+    const uint64_t factor = virtio_get_block_size() / VIRTIO_SECTOR_SIZE;
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        return vdev.config.blk.capacity / factor;
+    case VIRTIO_ID_SCSI:
+        return vdev.scsi_last_block / factor;
+    }
+    return 0;
 }
 
-void virtio_setup_block(struct subchannel_id schid)
+static void virtio_setup_ccw(VDev *vdev)
 {
-    struct vq_info_block info;
-    struct vq_config_block config = {};
-
-    blk_cfg.blk_size = 0; /* mark "illegal" - setup started... */
-    guessed_disk_nature = false;
-
-    virtio_reset(schid);
+    int i, cfg_size = 0;
+    unsigned char status = VIRTIO_CONFIG_S_DRIVER_OK;
+
+    IPL_assert(virtio_is_supported(vdev->schid), "PE");
+    /* device ID has been established now */
+
+    vdev->config.blk.blk_size = 0; /* mark "illegal" - setup started... */
+    vdev->guessed_disk_nature = VIRTIO_GDN_NONE;
+
+    run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0);
+
+    switch (vdev->senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        vdev->nr_vqs = 1;
+        vdev->cmd_vr_idx = 0;
+        cfg_size = sizeof(vdev->config.blk);
+        break;
+    case VIRTIO_ID_SCSI:
+        vdev->nr_vqs = 3;
+        vdev->cmd_vr_idx = VR_REQUEST;
+        cfg_size = sizeof(vdev->config.scsi);
+        break;
+    default:
+        panic("Unsupported virtio device\n");
+    }
+    IPL_assert(run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size) == 0,
+               "Could not get block device configuration");
 
     /*
      * Skipping CCW_CMD_READ_FEAT. We're not doing anything fancy, and
@@ -379,54 +516,84 @@ void virtio_setup_block(struct subchannel_id schid)
      * expect it.
      */
 
-    config.index = 0;
-    if (run_ccw(schid, CCW_CMD_READ_VQ_CONF, &config, sizeof(config))) {
-        virtio_panic("Could not get block device VQ configuration\n");
-    }
-    if (run_ccw(schid, CCW_CMD_READ_CONF, &blk_cfg, sizeof(blk_cfg))) {
-        virtio_panic("Could not get block device configuration\n");
-    }
-    vring_init(&block, config.num, ring_area,
-               KVM_S390_VIRTIO_RING_ALIGN);
-
-    info.queue = (unsigned long long) ring_area;
-    info.align = KVM_S390_VIRTIO_RING_ALIGN;
-    info.index = 0;
-    info.num = config.num;
-    block.schid = schid;
-
-    if (!run_ccw(schid, CCW_CMD_SET_VQ, &info, sizeof(info))) {
-        virtio_set_status(schid, VIRTIO_CONFIG_S_DRIVER_OK);
+    for (i = 0; i < vdev->nr_vqs; i++) {
+        VqInfo info = {
+            .queue = (unsigned long long) ring_area + (i * VIRTIO_RING_SIZE),
+            .align = KVM_S390_VIRTIO_RING_ALIGN,
+            .index = i,
+            .num = 0,
+        };
+        VqConfig config = {
+            .index = i,
+            .num = 0,
+        };
+
+        IPL_assert(
+            run_ccw(vdev, CCW_CMD_READ_VQ_CONF, &config, sizeof(config)) == 0,
+            "Could not get block device VQ configuration");
+        info.num = config.num;
+        vring_init(&vdev->vrings[i], &info);
+        vdev->vrings[i].schid = vdev->schid;
+        IPL_assert(run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info)) == 0,
+                   "Cannot set VQ info");
     }
+    IPL_assert(
+        run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status)) == 0,
+        "Could not write status to host");
+}
 
-    if (!virtio_ipl_disk_is_valid()) {
-        /* make sure all getters but blocksize return 0 for invalid IPL disk */
-        memset(&blk_cfg, 0, sizeof(blk_cfg));
-        virtio_assume_scsi();
+void virtio_setup_device(SubChannelId schid)
+{
+    vdev.schid = schid;
+    virtio_setup_ccw(&vdev);
+
+    switch (vdev.senseid.cu_model) {
+    case VIRTIO_ID_BLOCK:
+        sclp_print("Using virtio-blk.\n");
+        if (!virtio_ipl_disk_is_valid()) {
+            /* make sure all getters but blocksize return 0 for
+             * invalid IPL disk
+             */
+            memset(&vdev.config.blk, 0, sizeof(vdev.config.blk));
+            virtio_assume_scsi();
+        }
+        break;
+    case VIRTIO_ID_SCSI:
+        IPL_assert(vdev.config.scsi.sense_size == VIRTIO_SCSI_SENSE_SIZE,
+            "Config: sense size mismatch");
+        IPL_assert(vdev.config.scsi.cdb_size == VIRTIO_SCSI_CDB_SIZE,
+            "Config: CDB size mismatch");
+
+        sclp_print("Using virtio-scsi.\n");
+        virtio_scsi_setup(&vdev);
+        break;
+    default:
+        panic("\n! No IPL device available !\n");
     }
 }
 
-bool virtio_is_blk(struct subchannel_id schid)
+bool virtio_is_supported(SubChannelId schid)
 {
-    int r;
-    struct senseid senseid = {};
-
+    vdev.schid = schid;
+    memset(&vdev.senseid, 0, sizeof(vdev.senseid));
     /* run sense id command */
-    r = run_ccw(schid, CCW_CMD_SENSE_ID, &senseid, sizeof(senseid));
-    if (r) {
+    if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid))) {
         return false;
     }
-    if ((senseid.cu_type != 0x3832) || (senseid.cu_model != VIRTIO_ID_BLOCK)) {
-        return false;
+    if (vdev.senseid.cu_type == 0x3832) {
+        switch (vdev.senseid.cu_model) {
+        case VIRTIO_ID_BLOCK:
+        case VIRTIO_ID_SCSI:
+            return true;
+        }
     }
-
-    return true;
+    return false;
 }
 
 int enable_mss_facility(void)
 {
     int ret;
-    struct chsc_area_sda *sda_area = (struct chsc_area_sda *) chsc_page;
+    ChscAreaSda *sda_area = (ChscAreaSda *) chsc_page;
 
     memset(sda_area, 0, PAGE_SIZE);
     sda_area->request.length = 0x0400;
diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h
index afa01a885b..3c6e91510e 100644
--- a/pc-bios/s390-ccw/virtio.h
+++ b/pc-bios/s390-ccw/virtio.h
@@ -23,49 +23,58 @@
 /* We've given up on this device. */
 #define VIRTIO_CONFIG_S_FAILED          0x80
 
-enum virtio_dev_type {
+enum VirtioDevType {
     VIRTIO_ID_NET = 1,
     VIRTIO_ID_BLOCK = 2,
     VIRTIO_ID_CONSOLE = 3,
     VIRTIO_ID_BALLOON = 5,
+    VIRTIO_ID_SCSI = 8,
 };
-
-struct virtio_dev_header {
-    enum virtio_dev_type type : 8;
-    u8  num_vq;
-    u8  feature_len;
-    u8  config_len;
-    u8  status;
-    u8  vqconfig[];
+typedef enum VirtioDevType VirtioDevType;
+
+struct VirtioDevHeader {
+    VirtioDevType type:8;
+    uint8_t num_vq;
+    uint8_t feature_len;
+    uint8_t config_len;
+    uint8_t status;
+    uint8_t vqconfig[];
 } __attribute__((packed));
+typedef struct VirtioDevHeader VirtioDevHeader;
 
-struct virtio_vqconfig {
-    u64 token;
-    u64 address;
-    u16 num;
-    u8  pad[6];
+struct VirtioVqConfig {
+    uint64_t token;
+    uint64_t address;
+    uint16_t num;
+    uint8_t pad[6];
 } __attribute__((packed));
+typedef struct VirtioVqConfig VirtioVqConfig;
 
-struct vq_info_block {
-    u64 queue;
-    u32 align;
-    u16 index;
-    u16 num;
+struct VqInfo {
+    uint64_t queue;
+    uint32_t align;
+    uint16_t index;
+    uint16_t num;
 } __attribute__((packed));
+typedef struct VqInfo VqInfo;
 
-struct vq_config_block {
-    u16 index;
-    u16 num;
+struct VqConfig {
+    uint16_t index;
+    uint16_t num;
 } __attribute__((packed));
+typedef struct VqConfig VqConfig;
 
-struct virtio_dev {
-    struct virtio_dev_header *header;
-    struct virtio_vqconfig *vqconfig;
+struct VirtioDev {
+    VirtioDevHeader *header;
+    VirtioVqConfig *vqconfig;
     char *host_features;
     char *guest_features;
     char *config;
 };
+typedef struct VirtioDev VirtioDev;
 
+#define VIRTIO_RING_SIZE            (PAGE_SIZE * 8)
+#define VIRTIO_MAX_VQS              3
 #define KVM_S390_VIRTIO_RING_ALIGN  4096
 
 #define VRING_USED_F_NO_NOTIFY  1
@@ -81,46 +90,53 @@ struct virtio_dev {
 #define VRING_HIDDEN_IS_CHAIN   256
 
 /* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
-struct vring_desc {
+struct VRingDesc {
     /* Address (guest-physical). */
-    u64 addr;
+    uint64_t addr;
     /* Length. */
-    u32 len;
+    uint32_t len;
     /* The flags as indicated above. */
-    u16 flags;
+    uint16_t flags;
     /* We chain unused descriptors via this, too */
-    u16 next;
+    uint16_t next;
 } __attribute__((packed));
+typedef struct VRingDesc VRingDesc;
 
-struct vring_avail {
-    u16 flags;
-    u16 idx;
-    u16 ring[];
+struct VRingAvail {
+    uint16_t flags;
+    uint16_t idx;
+    uint16_t ring[];
 } __attribute__((packed));
+typedef struct VRingAvail VRingAvail;
 
-/* u32 is used here for ids for padding reasons. */
-struct vring_used_elem {
+/* uint32_t is used here for ids for padding reasons. */
+struct VRingUsedElem {
     /* Index of start of used descriptor chain. */
-    u32 id;
+    uint32_t id;
     /* Total length of the descriptor chain which was used (written to) */
-    u32 len;
+    uint32_t len;
 } __attribute__((packed));
+typedef struct VRingUsedElem VRingUsedElem;
 
-struct vring_used {
-    u16 flags;
-    u16 idx;
-    struct vring_used_elem ring[];
+struct VRingUsed {
+    uint16_t flags;
+    uint16_t idx;
+    VRingUsedElem ring[];
 } __attribute__((packed));
+typedef struct VRingUsed VRingUsed;
 
-struct vring {
+struct VRing {
     unsigned int num;
     int next_idx;
     int used_idx;
-    struct vring_desc *desc;
-    struct vring_avail *avail;
-    struct vring_used *used;
-    struct subchannel_id schid;
+    VRingDesc *desc;
+    VRingAvail *avail;
+    VRingUsed *used;
+    SubChannelId schid;
+    long cookie;
+    int id;
 };
+typedef struct VRing VRing;
 
 
 /***********************************************
@@ -152,39 +168,49 @@ struct vring {
 #define VIRTIO_BLK_T_BARRIER    0x80000000
 
 /* This is the first element of the read scatter-gather list. */
-struct virtio_blk_outhdr {
+struct VirtioBlkOuthdr {
         /* VIRTIO_BLK_T* */
-        u32 type;
+        uint32_t type;
         /* io priority. */
-        u32 ioprio;
+        uint32_t ioprio;
         /* Sector (ie. 512 byte offset) */
-        u64 sector;
+        uint64_t sector;
 };
+typedef struct VirtioBlkOuthdr VirtioBlkOuthdr;
 
-typedef struct VirtioBlkConfig {
-    u64 capacity; /* in 512-byte sectors */
-    u32 size_max; /* max segment size (if VIRTIO_BLK_F_SIZE_MAX) */
-    u32 seg_max;  /* max number of segments (if VIRTIO_BLK_F_SEG_MAX) */
+struct VirtioBlkConfig {
+    uint64_t capacity; /* in 512-byte sectors */
+    uint32_t size_max; /* max segment size (if VIRTIO_BLK_F_SIZE_MAX) */
+    uint32_t seg_max;  /* max number of segments (if VIRTIO_BLK_F_SEG_MAX) */
 
-    struct virtio_blk_geometry {
-        u16 cylinders;
-        u8 heads;
-        u8 sectors;
+    struct VirtioBlkGeometry {
+        uint16_t cylinders;
+        uint8_t heads;
+        uint8_t sectors;
     } geometry; /* (if VIRTIO_BLK_F_GEOMETRY) */
 
-    u32 blk_size; /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
+    uint32_t blk_size; /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
 
     /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
-    u8 physical_block_exp; /* exponent for physical block per logical block */
-    u8 alignment_offset;   /* alignment offset in logical blocks */
-    u16 min_io_size;       /* min I/O size without performance penalty
+    uint8_t physical_block_exp; /* exponent for physical blk per logical blk */
+    uint8_t alignment_offset;   /* alignment offset in logical blocks */
+    uint16_t min_io_size;       /* min I/O size without performance penalty
                               in logical blocks */
-    u32 opt_io_size;       /* optimal sustained I/O size in logical blocks */
+    uint32_t opt_io_size;       /* optimal sustained I/O size in logical blks */
+
+    uint8_t wce; /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
+} __attribute__((packed));
+typedef struct VirtioBlkConfig VirtioBlkConfig;
 
-    u8 wce; /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
-} __attribute__((packed)) VirtioBlkConfig;
+enum guessed_disk_nature_type {
+    VIRTIO_GDN_NONE     = 0,
+    VIRTIO_GDN_DASD     = 1,
+    VIRTIO_GDN_CDROM    = 2,
+    VIRTIO_GDN_SCSI     = 3,
+};
+typedef enum guessed_disk_nature_type VirtioGDN;
 
-bool virtio_guessed_disk_nature(void);
+VirtioGDN virtio_guessed_disk_nature(void);
 void virtio_assume_scsi(void);
 void virtio_assume_eckd(void);
 void virtio_assume_iso9660(void);
@@ -199,10 +225,68 @@ extern uint64_t virtio_get_blocks(void);
 extern int virtio_read_many(ulong sector, void *load_addr, int sec_num);
 
 #define VIRTIO_SECTOR_SIZE 512
+#define VIRTIO_ISO_BLOCK_SIZE 2048
+#define VIRTIO_SCSI_BLOCK_SIZE 512
 
 static inline ulong virtio_sector_adjust(ulong sector)
 {
     return sector * (virtio_get_block_size() / VIRTIO_SECTOR_SIZE);
 }
 
+struct VirtioScsiConfig {
+    uint32_t num_queues;
+    uint32_t seg_max;
+    uint32_t max_sectors;
+    uint32_t cmd_per_lun;
+    uint32_t event_info_size;
+    uint32_t sense_size;
+    uint32_t cdb_size;
+    uint16_t max_channel;
+    uint16_t max_target;
+    uint32_t max_lun;
+} __attribute__((packed));
+typedef struct VirtioScsiConfig VirtioScsiConfig;
+
+struct ScsiDevice {
+    uint16_t channel;   /* Always 0 in QEMU     */
+    uint16_t target;    /* will be scanned over */
+    uint32_t lun;       /* will be reported     */
+};
+typedef struct ScsiDevice ScsiDevice;
+
+struct VDev {
+    int nr_vqs;
+    VRing *vrings;
+    int cmd_vr_idx;
+    void *ring_area;
+    long wait_reply_timeout;
+    VirtioGDN guessed_disk_nature;
+    SubChannelId schid;
+    SenseId senseid;
+    union {
+        VirtioBlkConfig blk;
+        VirtioScsiConfig scsi;
+    } config;
+    ScsiDevice *scsi_device;
+    bool is_cdrom;
+    int scsi_block_size;
+    int blk_factor;
+    uint64_t scsi_last_block;
+    uint32_t scsi_dev_cyls;
+    uint8_t scsi_dev_heads;
+};
+typedef struct VDev VDev;
+
+VDev *virtio_get_device(void);
+VirtioDevType virtio_get_device_type(void);
+
+struct VirtioCmd {
+    void *data;
+    int size;
+    int flags;
+};
+typedef struct VirtioCmd VirtioCmd;
+
+int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd);
+
 #endif /* VIRTIO_H */