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From 4949ead0219a44a8419ac6726f219aafd0f91137 Mon Sep 17 00:00:00 2001
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From: Cornelia Huck <cohuck@redhat.com>
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Date: Wed, 17 Apr 2019 13:57:40 +0100
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Subject: [PATCH 23/24] s390x: refactor reset/reipl handling
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RH-Author: Cornelia Huck <cohuck@redhat.com>
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Message-id: <20190417135741.25297-24-cohuck@redhat.com>
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Patchwork-id: 85802
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O-Subject: [RHEL-8.1.0 qemu-kvm PATCH v2 23/24] s390x: refactor reset/reipl handling
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Bugzilla: 1699070
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RH-Acked-by: David Hildenbrand <david@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Jens Freimann <jfreimann@redhat.com>
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From: David Hildenbrand <david@redhat.com>
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Calling pause_all_vcpus()/resume_all_vcpus() from a VCPU thread might
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not be the best idea. As pause_all_vcpus() temporarily drops the qemu
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mutex, two parallel calls to pause_all_vcpus() can be active at a time,
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resulting in a deadlock. (either by two VCPUs or by the main thread and a
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VCPU)
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Let's handle it via the main loop instead, as suggested by Paolo. If we
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would have two parallel reset requests by two different VCPUs at the
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same time, the last one would win.
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We use the existing ipl device to handle it. The nice side effect is
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that we can get rid of reipl_requested.
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This change implies that all reset handling now goes via the common
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path, so "no-reboot" handling is now active for all kinds of reboots.
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Let's execute any CPU initialization code on the target CPU using
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run_on_cpu.
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Signed-off-by: David Hildenbrand <david@redhat.com>
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Message-Id: <20180424101859.10239-1-david@redhat.com>
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Acked-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Cornelia Huck <cohuck@redhat.com>
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(cherry picked from commit a30fb811cbe940020a498d2cdac9326cac38b4d9)
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Signed-off-by: Cornelia Huck <cohuck@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/s390x/ipl.c                     | 43 +++++++++++++++++++++++----
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 hw/s390x/ipl.h                     | 16 ++++++++--
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 hw/s390x/s390-virtio-ccw.c         | 51 ++++++++++++++++++++++++++-----
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 include/hw/s390x/s390-virtio-ccw.h |  2 --
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 target/s390x/cpu.h                 | 26 ++++++++++++++++
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 target/s390x/diag.c                | 61 +++-----------------------------------
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 target/s390x/internal.h            |  6 ----
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 target/s390x/kvm.c                 |  2 +-
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 8 files changed, 127 insertions(+), 80 deletions(-)
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diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
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index 10038ec..ee6701e 100644
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--- a/hw/s390x/ipl.c
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+++ b/hw/s390x/ipl.c
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@@ -26,6 +26,7 @@
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 #include "qemu/config-file.h"
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 #include "qemu/cutils.h"
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 #include "qemu/option.h"
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+#include "exec/exec-all.h"
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 #define KERN_IMAGE_START                0x010000UL
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 #define LINUX_MAGIC_ADDR                0x010008UL
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@@ -511,12 +512,20 @@ IplParameterBlock *s390_ipl_get_iplb(void)
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     return &ipl->iplb;
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 }
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-void s390_reipl_request(void)
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+void s390_ipl_reset_request(CPUState *cs, enum s390_reset reset_type)
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 {
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     S390IPLState *ipl = get_ipl_device();
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-    ipl->reipl_requested = true;
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-    if (ipl->iplb_valid &&
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+    if (reset_type == S390_RESET_EXTERNAL || reset_type == S390_RESET_REIPL) {
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+        /* use CPU 0 for full resets */
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+        ipl->reset_cpu_index = 0;
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+    } else {
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+        ipl->reset_cpu_index = cs->cpu_index;
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+    }
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+    ipl->reset_type = reset_type;
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+
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+    if (reset_type == S390_RESET_REIPL &&
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+        ipl->iplb_valid &&
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         !ipl->netboot &&
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         ipl->iplb.pbt == S390_IPL_TYPE_CCW &&
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         is_virtio_scsi_device(&ipl->iplb)) {
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@@ -533,6 +542,31 @@ void s390_reipl_request(void)
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         }
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     }
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     qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
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+    /* as this is triggered by a CPU, make sure to exit the loop */
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+    if (tcg_enabled()) {
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+        cpu_loop_exit(cs);
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+    }
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+}
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+
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+void s390_ipl_get_reset_request(CPUState **cs, enum s390_reset *reset_type)
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+{
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+    S390IPLState *ipl = get_ipl_device();
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+
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+    *cs = qemu_get_cpu(ipl->reset_cpu_index);
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+    if (!*cs) {
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+        /* use any CPU */
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+        *cs = first_cpu;
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+    }
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+    *reset_type = ipl->reset_type;
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+}
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+
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+void s390_ipl_clear_reset_request(void)
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+{
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+    S390IPLState *ipl = get_ipl_device();
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+
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+    ipl->reset_type = S390_RESET_EXTERNAL;
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+    /* use CPU 0 for full resets */
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+    ipl->reset_cpu_index = 0;
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 }
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 static void s390_ipl_prepare_qipl(S390CPU *cpu)
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@@ -579,11 +613,10 @@ static void s390_ipl_reset(DeviceState *dev)
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 {
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     S390IPLState *ipl = S390_IPL(dev);
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-    if (!ipl->reipl_requested) {
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+    if (ipl->reset_type != S390_RESET_REIPL) {
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         ipl->iplb_valid = false;
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         memset(&ipl->iplb, 0, sizeof(IplParameterBlock));
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     }
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-    ipl->reipl_requested = false;
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 }
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 static void s390_ipl_class_init(ObjectClass *klass, void *data)
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diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
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index 0570d0a..4e87b89 100644
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--- a/hw/s390x/ipl.h
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+++ b/hw/s390x/ipl.h
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@@ -87,7 +87,17 @@ int s390_ipl_set_loadparm(uint8_t *loadparm);
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 void s390_ipl_update_diag308(IplParameterBlock *iplb);
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 void s390_ipl_prepare_cpu(S390CPU *cpu);
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 IplParameterBlock *s390_ipl_get_iplb(void);
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-void s390_reipl_request(void);
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+
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+enum s390_reset {
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+    /* default is a reset not triggered by a CPU e.g. issued by QMP */
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+    S390_RESET_EXTERNAL = 0,
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+    S390_RESET_REIPL,
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+    S390_RESET_MODIFIED_CLEAR,
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+    S390_RESET_LOAD_NORMAL,
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+};
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+void s390_ipl_reset_request(CPUState *cs, enum s390_reset reset_type);
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+void s390_ipl_get_reset_request(CPUState **cs, enum s390_reset *reset_type);
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+void s390_ipl_clear_reset_request(void);
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 #define QIPL_ADDRESS  0xcc
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@@ -129,9 +139,11 @@ struct S390IPLState {
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     bool enforce_bios;
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     IplParameterBlock iplb;
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     bool iplb_valid;
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-    bool reipl_requested;
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     bool netboot;
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     QemuIplParameters qipl;
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+    /* reset related properties don't have to be migrated or reset */
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+    enum s390_reset reset_type;
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+    int reset_cpu_index;
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     /*< public >*/
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     char *kernel;
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diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
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index 8f93edc..ba90e4f 100644
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--- a/hw/s390x/s390-virtio-ccw.c
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+++ b/hw/s390x/s390-virtio-ccw.c
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@@ -95,7 +95,7 @@ static const char *const reset_dev_types[] = {
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     "diag288",
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 };
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-void subsystem_reset(void)
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+static void subsystem_reset(void)
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 {
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     DeviceState *dev;
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     int i;
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@@ -317,17 +317,54 @@ static void s390_cpu_plug(HotplugHandler *hotplug_dev,
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     }
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 }
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+static inline void s390_do_cpu_ipl(CPUState *cs, run_on_cpu_data arg)
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+{
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+    S390CPU *cpu = S390_CPU(cs);
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+
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+    s390_ipl_prepare_cpu(cpu);
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+    s390_cpu_set_state(S390_CPU_STATE_OPERATING, cpu);
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+}
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+
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 static void s390_machine_reset(void)
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 {
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-    S390CPU *ipl_cpu = S390_CPU(qemu_get_cpu(0));
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+    enum s390_reset reset_type;
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+    CPUState *cs, *t;
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+    /* get the reset parameters, reset them once done */
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+    s390_ipl_get_reset_request(&cs, &reset_type);
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+
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+    /* all CPUs are paused and synchronized at this point */
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     s390_cmma_reset();
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-    qemu_devices_reset();
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-    s390_crypto_reset();
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-    /* all cpus are stopped - configure and start the ipl cpu only */
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-    s390_ipl_prepare_cpu(ipl_cpu);
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-    s390_cpu_set_state(S390_CPU_STATE_OPERATING, ipl_cpu);
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+    switch (reset_type) {
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+    case S390_RESET_EXTERNAL:
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+    case S390_RESET_REIPL:
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+        qemu_devices_reset();
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+        s390_crypto_reset();
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+
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+        /* configure and start the ipl CPU only */
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+        run_on_cpu(cs, s390_do_cpu_ipl, RUN_ON_CPU_NULL);
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+        break;
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+    case S390_RESET_MODIFIED_CLEAR:
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+        CPU_FOREACH(t) {
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+            run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
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+        }
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+        subsystem_reset();
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+        s390_crypto_reset();
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+        run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
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+        break;
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+    case S390_RESET_LOAD_NORMAL:
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+        CPU_FOREACH(t) {
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+            run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL);
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+        }
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+        subsystem_reset();
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+        run_on_cpu(cs, s390_do_cpu_initial_reset, RUN_ON_CPU_NULL);
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+        run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
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+        break;
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+    default:
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+        g_assert_not_reached();
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+    }
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+    s390_ipl_clear_reset_request();
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 }
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 static void s390_machine_device_plug(HotplugHandler *hotplug_dev,
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diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
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index ac896e3..ab88d49 100644
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--- a/include/hw/s390x/s390-virtio-ccw.h
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+++ b/include/hw/s390x/s390-virtio-ccw.h
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@@ -53,6 +53,4 @@ bool cpu_model_allowed(void);
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  */
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 bool css_migration_enabled(void);
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-void subsystem_reset(void);
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-
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 #endif
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diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
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index 6500f42..21b2f21 100644
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--- a/target/s390x/cpu.h
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+++ b/target/s390x/cpu.h
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@@ -687,6 +687,32 @@ static inline uint64_t s390_build_validity_mcic(void)
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     return mcic;
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 }
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+static inline void s390_do_cpu_full_reset(CPUState *cs, run_on_cpu_data arg)
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+{
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+    cpu_reset(cs);
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+}
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+
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+static inline void s390_do_cpu_reset(CPUState *cs, run_on_cpu_data arg)
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+{
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+    S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
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+
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+    scc->cpu_reset(cs);
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+}
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+
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+static inline void s390_do_cpu_initial_reset(CPUState *cs, run_on_cpu_data arg)
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+{
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+    S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
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+
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+    scc->initial_cpu_reset(cs);
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+}
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+
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+static inline void s390_do_cpu_load_normal(CPUState *cs, run_on_cpu_data arg)
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+{
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+    S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
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+
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+    scc->load_normal(cs);
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+}
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+
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 /* cpu.c */
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 void s390_crypto_reset(void);
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diff --git a/target/s390x/diag.c b/target/s390x/diag.c
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index 50b58df..b5d5f8e 100644
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--- a/target/s390x/diag.c
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+++ b/target/s390x/diag.c
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@@ -22,51 +22,6 @@
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 #include "hw/s390x/ipl.h"
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 #include "hw/s390x/s390-virtio-ccw.h"
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-static int modified_clear_reset(S390CPU *cpu)
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-{
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-    S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
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-    CPUState *t;
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-
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-    pause_all_vcpus();
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-    cpu_synchronize_all_states();
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-    CPU_FOREACH(t) {
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-        run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
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-    }
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-    s390_cmma_reset();
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-    subsystem_reset();
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-    s390_crypto_reset();
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-    scc->load_normal(CPU(cpu));
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-    cpu_synchronize_all_post_reset();
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-    resume_all_vcpus();
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-    return 0;
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-}
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-
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-static inline void s390_do_cpu_reset(CPUState *cs, run_on_cpu_data arg)
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-{
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-    S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
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-
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-    scc->cpu_reset(cs);
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-}
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-
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-static int load_normal_reset(S390CPU *cpu)
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-{
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-    S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
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-    CPUState *t;
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-
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-    pause_all_vcpus();
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-    cpu_synchronize_all_states();
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-    CPU_FOREACH(t) {
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-        run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL);
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-    }
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-    s390_cmma_reset();
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-    subsystem_reset();
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-    scc->initial_cpu_reset(CPU(cpu));
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-    scc->load_normal(CPU(cpu));
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-    cpu_synchronize_all_post_reset();
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-    resume_all_vcpus();
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-    return 0;
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-}
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-
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 int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3)
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 {
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     uint64_t func = env->regs[r1];
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@@ -101,6 +56,7 @@ int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3)
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 void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
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 {
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+    CPUState *cs = CPU(s390_env_get_cpu(env));
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     uint64_t addr =  env->regs[r1];
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     uint64_t subcode = env->regs[r3];
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     IplParameterBlock *iplb;
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@@ -117,22 +73,13 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
b38b0f
 
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     switch (subcode) {
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     case 0:
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-        modified_clear_reset(s390_env_get_cpu(env));
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-        if (tcg_enabled()) {
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-            cpu_loop_exit(CPU(s390_env_get_cpu(env)));
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-        }
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+        s390_ipl_reset_request(cs, S390_RESET_MODIFIED_CLEAR);
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         break;
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     case 1:
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-        load_normal_reset(s390_env_get_cpu(env));
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-        if (tcg_enabled()) {
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-            cpu_loop_exit(CPU(s390_env_get_cpu(env)));
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-        }
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+        s390_ipl_reset_request(cs, S390_RESET_LOAD_NORMAL);
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         break;
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     case 3:
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-        s390_reipl_request();
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-        if (tcg_enabled()) {
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-            cpu_loop_exit(CPU(s390_env_get_cpu(env)));
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-        }
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+        s390_ipl_reset_request(cs, S390_RESET_REIPL);
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         break;
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     case 5:
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         if ((r1 & 1) || (addr & 0x0fffULL)) {
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diff --git a/target/s390x/internal.h b/target/s390x/internal.h
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index 61a509d..f2a771e 100644
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--- a/target/s390x/internal.h
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+++ b/target/s390x/internal.h
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@@ -258,12 +258,6 @@ static inline hwaddr decode_basedisp_s(CPUS390XState *env, uint32_t ipb,
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 /* Base/displacement are at the same locations. */
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 #define decode_basedisp_rs decode_basedisp_s
b38b0f
 
b38b0f
-static inline void s390_do_cpu_full_reset(CPUState *cs, run_on_cpu_data arg)
b38b0f
-{
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-    cpu_reset(cs);
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-}
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-
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-
b38b0f
 /* arch_dump.c */
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 int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
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                               int cpuid, void *opaque);
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diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
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index 1cf117b..114502d 100644
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--- a/target/s390x/kvm.c
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+++ b/target/s390x/kvm.c
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@@ -1826,7 +1826,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
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             ret = handle_intercept(cpu);
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             break;
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         case KVM_EXIT_S390_RESET:
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-            s390_reipl_request();
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+            s390_ipl_reset_request(cs, S390_RESET_REIPL);
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             break;
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         case KVM_EXIT_S390_TSCH:
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             ret = handle_tsch(cpu);
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-- 
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1.8.3.1
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