Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20150702-v3' into staging

Several s390x patches including:
- missing virtio-1 related code for virtio-ccw
- bugfixes in ipl device, gdb, virtio-ccw
- bugfix in s390-ccw bios + rebuild
- introduce versioned machines for s390-ccw-virtio

# gpg: Signature made Thu Jul  2 15:05:34 2015 BST 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-20150702-v3:
  s390x/migration: Introduce 2.4 machine
  s390x/gdb: synchronize cpu state after modifying acrs
  s390x/ipl: Fix boot if no bootindex was specified
  virtio-ccw: migrate ->revision
  s390x/virtio-ccw: support virtio-1 set_vq format
  s390x/virtio-ccw: add virtio set-revision call
  s390x/css: Add a callback for when subchannel gets disabled
  s390-ccw.img: update
  s390-ccw.img: Consume service interrupts
  css: mss/mcss-e vs. migration
  virtio-ccw: complete handling of guest-initiated resets
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/s390x/css.c

@@ -588,6 +588,7 @@ int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
 {
     SCSW *s = &sch->curr_status.scsw;
     PMCW *p = &sch->curr_status.pmcw;
+    uint16_t oldflags;
     int ret;
     SCHIB schib;
 
@@ -610,6 +611,7 @@ int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
     copy_schib_from_guest(&schib, orig_schib);
     /* Only update the program-modifiable fields. */
     p->intparm = schib.pmcw.intparm;
+    oldflags = p->flags;
     p->flags &= ~(PMCW_FLAGS_MASK_ISC | PMCW_FLAGS_MASK_ENA |
                   PMCW_FLAGS_MASK_LM | PMCW_FLAGS_MASK_MME |
                   PMCW_FLAGS_MASK_MP);
@@ -625,6 +627,12 @@ int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
             (PMCW_CHARS_MASK_MBFC | PMCW_CHARS_MASK_CSENSE);
     sch->curr_status.mba = schib.mba;
 
+    /* Has the channel been disabled? */
+    if (sch->disable_cb && (oldflags & PMCW_FLAGS_MASK_ENA) != 0
+        && (p->flags & PMCW_FLAGS_MASK_ENA) == 0) {
+        sch->disable_cb(sch);
+    }
+
     ret = 0;
 
 out:
@@ -1464,6 +1472,21 @@ int subch_device_load(SubchDev *s, QEMUFile *f)
     }
     s->ccw_fmt_1 = qemu_get_byte(f);
     s->ccw_no_data_cnt = qemu_get_byte(f);
+    /*
+     * Hack alert. We don't migrate the channel subsystem status (no
+     * device!), but we need to find out if the guest enabled mss/mcss-e.
+     * If the subchannel is enabled, it certainly was able to access it,
+     * so adjust the max_ssid/max_cssid values for relevant ssid/cssid
+     * values. This is not watertight, but better than nothing.
+     */
+    if (s->curr_status.pmcw.flags & PMCW_FLAGS_MASK_ENA) {
+        if (s->ssid) {
+            channel_subsys->max_ssid = MAX_SSID;
+        }
+        if (s->cssid != channel_subsys->default_cssid) {
+            channel_subsys->max_cssid = MAX_CSSID;
+        }
+    }
     return 0;
 }
 
@@ -1483,6 +1506,10 @@ void css_reset_sch(SubchDev *sch)
 {
     PMCW *p = &sch->curr_status.pmcw;
 
+    if ((p->flags & PMCW_FLAGS_MASK_ENA) != 0 && sch->disable_cb) {
+        sch->disable_cb(sch);
+    }
+
     p->intparm = 0;
     p->flags &= ~(PMCW_FLAGS_MASK_ISC | PMCW_FLAGS_MASK_ENA |
                   PMCW_FLAGS_MASK_LM | PMCW_FLAGS_MASK_MME |

hw/s390x/css.h

@@ -81,6 +81,7 @@ struct SubchDev {
     uint8_t ccw_no_data_cnt;
     /* transport-provided data: */
     int (*ccw_cb) (SubchDev *, CCW1);
+    void (*disable_cb)(SubchDev *);
     SenseId id;
     void *driver_data;
 };

hw/s390x/ipl.c

@@ -218,7 +218,7 @@ static Property s390_ipl_properties[] = {
  * - -1 if no valid boot device was found
  * - ccw id of the boot device otherwise
  */
-static uint32_t s390_update_iplstate(CPUS390XState *env, S390IPLState *ipl)
+static uint64_t s390_update_iplstate(CPUS390XState *env, S390IPLState *ipl)
 {
     DeviceState *dev_st;
 
@@ -248,7 +248,7 @@ static uint32_t s390_update_iplstate(CPUS390XState *env, S390IPLState *ipl)
 
     return -1;
 out:
-    return ipl->cssid << 24 | ipl->ssid << 16 | ipl->devno;
+    return (uint32_t) (ipl->cssid << 24 | ipl->ssid << 16 | ipl->devno);
 }
 
 int s390_ipl_update_diag308(IplParameterBlock *iplb)

hw/s390x/s390-virtio-ccw.c

@@ -204,9 +204,6 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
     MachineClass *mc = MACHINE_CLASS(oc);
     NMIClass *nc = NMI_CLASS(oc);
 
-    mc->name = "s390-ccw-virtio";
-    mc->alias = "s390-ccw";
-    mc->desc = "VirtIO-ccw based S390 machine";
     mc->init = ccw_init;
     mc->block_default_type = IF_VIRTIO;
     mc->no_cdrom = 1;
@@ -216,7 +213,6 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
     mc->no_sdcard = 1;
     mc->use_sclp = 1;
     mc->max_cpus = 255;
-    mc->is_default = 1;
     nc->nmi_monitor_handler = s390_nmi;
 }
 
@@ -272,6 +268,7 @@ static inline void s390_machine_initfn(Object *obj)
 static const TypeInfo ccw_machine_info = {
     .name          = TYPE_S390_CCW_MACHINE,
     .parent        = TYPE_MACHINE,
+    .abstract      = true,
     .instance_size = sizeof(S390CcwMachineState),
     .instance_init = s390_machine_initfn,
     .class_init    = ccw_machine_class_init,
@@ -281,9 +278,26 @@ static const TypeInfo ccw_machine_info = {
     },
 };
 
+static void ccw_machine_2_4_class_init(ObjectClass *oc, void *data)
+{
+    MachineClass *mc = MACHINE_CLASS(oc);
+
+    mc->name = "s390-ccw-virtio-2.4";
+    mc->alias = "s390-ccw-virtio";
+    mc->desc = "VirtIO-ccw based S390 machine v2.4";
+    mc->is_default = 1;
+}
+
+static const TypeInfo ccw_machine_2_4_info = {
+    .name          = TYPE_S390_CCW_MACHINE "2.4",
+    .parent        = TYPE_S390_CCW_MACHINE,
+    .class_init    = ccw_machine_2_4_class_init,
+};
+
 static void ccw_machine_register_types(void)
 {
     type_register_static(&ccw_machine_info);
+    type_register_static(&ccw_machine_2_4_info);
 }
 
 type_init(ccw_machine_register_types)

hw/s390x/virtio-ccw.c

@@ -21,6 +21,7 @@
 #include "hw/sysbus.h"
 #include "qemu/bitops.h"
 #include "qemu/error-report.h"
+#include "hw/virtio/virtio-access.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/s390x/adapter.h"
 #include "hw/s390x/s390_flic.h"
@@ -237,11 +238,20 @@ VirtualCssBus *virtual_css_bus_init(void)
 }
 
 /* Communication blocks used by several channel commands. */
-typedef struct VqInfoBlock {
+typedef struct VqInfoBlockLegacy {
     uint64_t queue;
     uint32_t align;
     uint16_t index;
     uint16_t num;
+} QEMU_PACKED VqInfoBlockLegacy;
+
+typedef struct VqInfoBlock {
+    uint64_t desc;
+    uint32_t res0;
+    uint16_t index;
+    uint16_t num;
+    uint64_t avail;
+    uint64_t used;
 } QEMU_PACKED VqInfoBlock;
 
 typedef struct VqConfigBlock {
@@ -261,18 +271,27 @@ typedef struct VirtioThinintInfo {
     uint8_t isc;
 } QEMU_PACKED VirtioThinintInfo;
 
+typedef struct VirtioRevInfo {
+    uint16_t revision;
+    uint16_t length;
+    uint8_t data[0];
+} QEMU_PACKED VirtioRevInfo;
+
 /* Specify where the virtqueues for the subchannel are in guest memory. */
-static int virtio_ccw_set_vqs(SubchDev *sch, uint64_t addr, uint32_t align,
-                              uint16_t index, uint16_t num)
+static int virtio_ccw_set_vqs(SubchDev *sch, VqInfoBlock *info,
+                              VqInfoBlockLegacy *linfo)
 {
     VirtIODevice *vdev = virtio_ccw_get_vdev(sch);
+    uint16_t index = info ? info->index : linfo->index;
+    uint16_t num = info ? info->num : linfo->num;
+    uint64_t desc = info ? info->desc : linfo->queue;
 
     if (index >= VIRTIO_CCW_QUEUE_MAX) {
         return -EINVAL;
     }
 
     /* Current code in virtio.c relies on 4K alignment. */
-    if (addr && (align != 4096)) {
+    if (linfo && desc && (linfo->align != 4096)) {
         return -EINVAL;
     }
 
@@ -280,8 +299,12 @@ static int virtio_ccw_set_vqs(SubchDev *sch, uint64_t addr, uint32_t align,
         return -EINVAL;
     }
 
-    virtio_queue_set_addr(vdev, index, addr);
-    if (!addr) {
+    if (info) {
+        virtio_queue_set_rings(vdev, index, desc, info->avail, info->used);
+    } else {
+        virtio_queue_set_addr(vdev, index, desc);
+    }
+    if (!desc) {
         virtio_queue_set_vector(vdev, index, VIRTIO_NO_VECTOR);
     } else {
         /* Fail if we don't have a big enough queue. */
@@ -296,10 +319,98 @@ static int virtio_ccw_set_vqs(SubchDev *sch, uint64_t addr, uint32_t align,
     return 0;
 }
 
-static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
+static void virtio_ccw_reset_virtio(VirtioCcwDevice *dev, VirtIODevice *vdev)
+{
+    virtio_ccw_stop_ioeventfd(dev);
+    virtio_reset(vdev);
+    if (dev->indicators) {
+        release_indicator(&dev->routes.adapter, dev->indicators);
+        dev->indicators = NULL;
+    }
+    if (dev->indicators2) {
+        release_indicator(&dev->routes.adapter, dev->indicators2);
+        dev->indicators2 = NULL;
+    }
+    if (dev->summary_indicator) {
+        release_indicator(&dev->routes.adapter, dev->summary_indicator);
+        dev->summary_indicator = NULL;
+    }
+    dev->sch->thinint_active = false;
+}
+
+static int virtio_ccw_handle_set_vq(SubchDev *sch, CCW1 ccw, bool check_len,
+                                    bool is_legacy)
 {
     int ret;
     VqInfoBlock info;
+    VqInfoBlockLegacy linfo;
+    size_t info_len = is_legacy ? sizeof(linfo) : sizeof(info);
+
+    if (check_len) {
+        if (ccw.count != info_len) {
+            return -EINVAL;
+        }
+    } else if (ccw.count < info_len) {
+        /* Can't execute command. */
+        return -EINVAL;
+    }
+    if (!ccw.cda) {
+        return -EFAULT;
+    }
+    if (is_legacy) {
+        linfo.queue = address_space_ldq_be(&address_space_memory, ccw.cda,
+                                           MEMTXATTRS_UNSPECIFIED, NULL);
+        linfo.align = address_space_ldl_be(&address_space_memory,
+                                           ccw.cda + sizeof(linfo.queue),
+                                           MEMTXATTRS_UNSPECIFIED,
+                                           NULL);
+        linfo.index = address_space_lduw_be(&address_space_memory,
+                                            ccw.cda + sizeof(linfo.queue)
+                                            + sizeof(linfo.align),
+                                            MEMTXATTRS_UNSPECIFIED,
+                                            NULL);
+        linfo.num = address_space_lduw_be(&address_space_memory,
+                                          ccw.cda + sizeof(linfo.queue)
+                                          + sizeof(linfo.align)
+                                          + sizeof(linfo.index),
+                                          MEMTXATTRS_UNSPECIFIED,
+                                          NULL);
+        ret = virtio_ccw_set_vqs(sch, NULL, &linfo);
+    } else {
+        info.desc = address_space_ldq_be(&address_space_memory, ccw.cda,
+                                           MEMTXATTRS_UNSPECIFIED, NULL);
+        info.index = address_space_lduw_be(&address_space_memory,
+                                           ccw.cda + sizeof(info.desc)
+                                           + sizeof(info.res0),
+                                           MEMTXATTRS_UNSPECIFIED, NULL);
+        info.num = address_space_lduw_be(&address_space_memory,
+                                         ccw.cda + sizeof(info.desc)
+                                         + sizeof(info.res0)
+                                         + sizeof(info.index),
+                                         MEMTXATTRS_UNSPECIFIED, NULL);
+        info.avail = address_space_ldq_be(&address_space_memory,
+                                          ccw.cda + sizeof(info.desc)
+                                          + sizeof(info.res0)
+                                          + sizeof(info.index)
+                                          + sizeof(info.num),
+                                          MEMTXATTRS_UNSPECIFIED, NULL);
+        info.used = address_space_ldq_be(&address_space_memory,
+                                         ccw.cda + sizeof(info.desc)
+                                         + sizeof(info.res0)
+                                         + sizeof(info.index)
+                                         + sizeof(info.num)
+                                         + sizeof(info.avail),
+                                         MEMTXATTRS_UNSPECIFIED, NULL);
+        ret = virtio_ccw_set_vqs(sch, &info, NULL);
+    }
+    sch->curr_status.scsw.count = 0;
+    return ret;
+}
+
+static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
+{
+    int ret;
+    VirtioRevInfo revinfo;
     uint8_t status;
     VirtioFeatDesc features;
     void *config;
@@ -323,44 +434,10 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
     /* Look at the command. */
     switch (ccw.cmd_code) {
     case CCW_CMD_SET_VQ:
-        if (check_len) {
-            if (ccw.count != sizeof(info)) {
-                ret = -EINVAL;
-                break;
-            }
-        } else if (ccw.count < sizeof(info)) {
-            /* Can't execute command. */
-            ret = -EINVAL;
-            break;
-        }
-        if (!ccw.cda) {
-            ret = -EFAULT;
-        } else {
-            info.queue = address_space_ldq(&address_space_memory, ccw.cda,
-                                           MEMTXATTRS_UNSPECIFIED, NULL);
-            info.align = address_space_ldl(&address_space_memory,
-                                           ccw.cda + sizeof(info.queue),
-                                           MEMTXATTRS_UNSPECIFIED,
-                                           NULL);
-            info.index = address_space_lduw(&address_space_memory,
-                                            ccw.cda + sizeof(info.queue)
-                                            + sizeof(info.align),
-                                            MEMTXATTRS_UNSPECIFIED,
-                                            NULL);
-            info.num = address_space_lduw(&address_space_memory,
-                                          ccw.cda + sizeof(info.queue)
-                                          + sizeof(info.align)
-                                          + sizeof(info.index),
-                                          MEMTXATTRS_UNSPECIFIED,
-                                          NULL);
-            ret = virtio_ccw_set_vqs(sch, info.queue, info.align, info.index,
-                                     info.num);
-            sch->curr_status.scsw.count = 0;
-        }
+        ret = virtio_ccw_handle_set_vq(sch, ccw, check_len, dev->revision < 1);
         break;
     case CCW_CMD_VDEV_RESET:
-        virtio_ccw_stop_ioeventfd(dev);
-        virtio_reset(vdev);
+        virtio_ccw_reset_virtio(dev, vdev);
         ret = 0;
         break;
     case CCW_CMD_READ_FEAT:
@@ -383,7 +460,16 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
                                                 MEMTXATTRS_UNSPECIFIED,
                                                 NULL);
             if (features.index == 0) {
-                features.features = vdev->host_features;
+                features.features = (uint32_t)vdev->host_features;
+            } else if (features.index == 1) {
+                features.features = (uint32_t)(vdev->host_features >> 32);
+                /*
+                 * Don't offer version 1 to the guest if it did not
+                 * negotiate at least revision 1.
+                 */
+                if (dev->revision <= 0) {
+                    features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32));
+                }
             } else {
                 /* Return zeroes if the guest supports more feature bits. */
                 features.features = 0;
@@ -419,7 +505,20 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
                                                      MEMTXATTRS_UNSPECIFIED,
                                                      NULL);
             if (features.index == 0) {
-                virtio_set_features(vdev, features.features);
+                virtio_set_features(vdev,
+                                    (vdev->guest_features & 0xffffffff00000000ULL) |
+                                    features.features);
+            } else if (features.index == 1) {
+                /*
+                 * The guest should not set version 1 if it didn't
+                 * negotiate a revision >= 1.
+                 */
+                if (dev->revision <= 0) {
+                    features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32));
+                }
+                virtio_set_features(vdev,
+                                    (vdev->guest_features & 0x00000000ffffffffULL) |
+                                    ((uint64_t)features.features << 32));
             } else {
                 /*
                  * If the guest supports more feature bits, assert that it
@@ -500,7 +599,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             }
             if (virtio_set_status(vdev, status) == 0) {
                 if (vdev->status == 0) {
-                    virtio_reset(vdev);
+                    virtio_ccw_reset_virtio(dev, vdev);
                 }
                 if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
                     virtio_ccw_start_ioeventfd(dev);
@@ -640,6 +739,40 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             }
         }
         break;
+    case CCW_CMD_SET_VIRTIO_REV:
+        len = sizeof(revinfo);
+        if (ccw.count < len) {
+            ret = -EINVAL;
+            break;
+        }
+        if (!ccw.cda) {
+            ret = -EFAULT;
+            break;
+        }
+        revinfo.revision =
+            address_space_lduw_be(&address_space_memory, ccw.cda,
+                                  MEMTXATTRS_UNSPECIFIED, NULL);
+        revinfo.length =
+            address_space_lduw_be(&address_space_memory,
+                                  ccw.cda + sizeof(revinfo.revision),
+                                  MEMTXATTRS_UNSPECIFIED, NULL);
+        if (ccw.count < len + revinfo.length ||
+            (check_len && ccw.count > len + revinfo.length)) {
+            ret = -EINVAL;
+            break;
+        }
+        /*
+         * Once we start to support revisions with additional data, we'll
+         * need to fetch it here. Nothing to do for now, though.
+         */
+        if (dev->revision >= 0 ||
+            revinfo.revision > virtio_ccw_rev_max(vdev)) {
+            ret = -ENOSYS;
+            break;
+        }
+        ret = 0;
+        dev->revision = revinfo.revision;
+        break;
     default:
         ret = -ENOSYS;
         break;
@@ -647,6 +780,13 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
     return ret;
 }
 
+static void virtio_sch_disable_cb(SubchDev *sch)
+{
+    VirtioCcwDevice *dev = sch->driver_data;
+
+    dev->revision = -1;
+}
+
 static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
 {
     unsigned int cssid = 0;
@@ -766,12 +906,15 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
     css_sch_build_virtual_schib(sch, 0, VIRTIO_CCW_CHPID_TYPE);
 
     sch->ccw_cb = virtio_ccw_cb;
+    sch->disable_cb = virtio_sch_disable_cb;
 
     /* Build senseid data. */
     memset(&sch->id, 0, sizeof(SenseId));
     sch->id.reserved = 0xff;
     sch->id.cu_type = VIRTIO_CCW_CU_TYPE;
 
+    dev->revision = -1;
+
     if (k->realize) {
         k->realize(dev, &err);
     }
@@ -1081,21 +1224,8 @@ static void virtio_ccw_reset(DeviceState *d)
     VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
     VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
 
-    virtio_ccw_stop_ioeventfd(dev);
-    virtio_reset(vdev);
+    virtio_ccw_reset_virtio(dev, vdev);
     css_reset_sch(dev->sch);
-    if (dev->indicators) {
-        release_indicator(&dev->routes.adapter, dev->indicators);
-        dev->indicators = NULL;
-    }
-    if (dev->indicators2) {
-        release_indicator(&dev->routes.adapter, dev->indicators2);
-        dev->indicators2 = NULL;
-    }
-    if (dev->summary_indicator) {
-        release_indicator(&dev->routes.adapter, dev->summary_indicator);
-        dev->summary_indicator = NULL;
-    }
 }
 
 static void virtio_ccw_vmstate_change(DeviceState *d, bool running)
@@ -1342,6 +1472,7 @@ static void virtio_ccw_save_config(DeviceState *d, QEMUFile *f)
     qemu_put_be16(f, vdev->config_vector);
     qemu_put_be64(f, dev->routes.adapter.ind_offset);
     qemu_put_byte(f, dev->thinint_isc);
+    qemu_put_be32(f, dev->revision);
 }
 
 static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f)
@@ -1382,6 +1513,7 @@ static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f)
                                        dev->thinint_isc, true, false,
                                        &dev->routes.adapter.adapter_id);
     }
+    dev->revision = qemu_get_be32(f);
 
     return 0;
 }

hw/s390x/virtio-ccw.h

@@ -41,6 +41,7 @@
 #define CCW_CMD_SET_CONF_IND 0x53
 #define CCW_CMD_READ_VQ_CONF 0x32
 #define CCW_CMD_SET_IND_ADAPTER 0x73
+#define CCW_CMD_SET_VIRTIO_REV 0x83
 
 #define TYPE_VIRTIO_CCW_DEVICE "virtio-ccw-device"
 #define VIRTIO_CCW_DEVICE(obj) \
@@ -86,6 +87,7 @@ struct VirtioCcwDevice {
     DeviceState parent_obj;
     SubchDev *sch;
     char *bus_id;
+    int revision;
     VirtioBusState bus;
     bool ioeventfd_started;
     bool ioeventfd_disabled;
@@ -99,6 +101,12 @@ struct VirtioCcwDevice {
     uint64_t ind_bit;
 };
 
+/* The maximum virtio revision we support. */
+static inline int virtio_ccw_rev_max(VirtIODevice *vdev)
+{
+    return 0;
+}
+
 /* virtual css bus type */
 typedef struct VirtualCssBus {
     BusState parent_obj;

pc-bios/s390-ccw/s390-ccw.h

@@ -47,6 +47,7 @@ typedef unsigned long long __u64;
 
 /* start.s */
 void disabled_wait(void);
+void consume_sclp_int(void);
 
 /* main.c */
 void virtio_panic(const char *string);

pc-bios/s390-ccw/sclp-ascii.c

@@ -24,6 +24,7 @@ static int sclp_service_call(unsigned int command, void *sccb)
                 "       srl     %0,28"
                 : "=&d" (cc) : "d" (command), "a" (__pa(sccb))
                 : "cc", "memory");
+        consume_sclp_int();
         if (cc == 3)
                 return -EIO;
         if (cc == 2)

pc-bios/s390-ccw/start.S

@@ -28,6 +28,38 @@ disabled_wait:
         larl %r1,disabled_wait_psw
         lpswe   0(%r1)
 
+
+/*
+ * void consume_sclp_int(void)
+ *
+ * eats one sclp interrupt
+ */
+        .globl consume_sclp_int
+consume_sclp_int:
+        /* enable service interrupts in cr0 */
+        stctg 0,0,0(15)
+        oi 6(15), 0x2
+        lctlg 0,0,0(15)
+        /* prepare external call handler */
+        larl %r1, external_new_code
+        stg %r1, 0x1b8
+        larl %r1, external_new_mask
+        mvc 0x1b0(8),0(%r1)
+        /* load enabled wait PSW */
+        larl %r1, enabled_wait_psw
+        lpswe 0(%r1)
+
+external_new_code:
+        /* disable service interrupts in cr0 */
+        stctg 0,0,0(15)
+        ni 6(15), 0xfd
+        lctlg 0,0,0(15)
+        br 14
+
         .align  8
 disabled_wait_psw:
         .quad   0x0002000180000000,0x0000000000000000
+enabled_wait_psw:
+        .quad   0x0302000180000000,0x0000000000000000
+external_new_mask:
+        .quad   0x0000000180000000

target-s390x/gdbstub.c

@@ -92,6 +92,7 @@ static int cpu_write_ac_reg(CPUS390XState *env, uint8_t *mem_buf, int n)
     switch (n) {
     case S390_A0_REGNUM ... S390_A15_REGNUM:
         env->aregs[n] = ldl_p(mem_buf);
+        cpu_synchronize_post_init(ENV_GET_CPU(env));
         return 4;
     default:
         return 0;