diff --git a/hw/s390x/3270-ccw.c b/hw/s390x/3270-ccw.c
index 3af13ea027..2c8d16ccf7 100644
--- a/hw/s390x/3270-ccw.c
+++ b/hw/s390x/3270-ccw.c
@@ -98,13 +98,10 @@ static void emulated_ccw_3270_realize(DeviceState *ds, Error **errp)
     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_GET_CLASS(dev);
     CcwDevice *cdev = CCW_DEVICE(ds);
     CCWDeviceClass *cdk = CCW_DEVICE_GET_CLASS(cdev);
-    DeviceState *parent = DEVICE(cdev);
-    BusState *qbus = qdev_get_parent_bus(parent);
-    VirtualCssBus *cbus = VIRTUAL_CSS_BUS(qbus);
     SubchDev *sch;
     Error *err = NULL;
 
-    sch = css_create_sch(cdev->devno, cbus->squash_mcss, errp);
+    sch = css_create_sch(cdev->devno, errp);
     if (!sch) {
         return;
     }
diff --git a/hw/s390x/css-bridge.c b/hw/s390x/css-bridge.c
index a02d708239..1bd6c8b458 100644
--- a/hw/s390x/css-bridge.c
+++ b/hw/s390x/css-bridge.c
@@ -106,7 +106,6 @@ VirtualCssBus *virtual_css_bus_init(void)
     /* Create bus on bridge device */
     bus = qbus_create(TYPE_VIRTUAL_CSS_BUS, dev, "virtual-css");
     cbus = VIRTUAL_CSS_BUS(bus);
-    cbus->squash_mcss = s390_get_squash_mcss();
 
     /* Enable hotplugging */
     qbus_set_hotplug_handler(bus, dev, &error_abort);
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 5424ea4562..5a9fe45ce8 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -2359,15 +2359,13 @@ const PropertyInfo css_devid_ro_propinfo = {
     .get = get_css_devid,
 };
 
-SubchDev *css_create_sch(CssDevId bus_id, bool squash_mcss, Error **errp)
+SubchDev *css_create_sch(CssDevId bus_id, Error **errp)
 {
     uint16_t schid = 0;
     SubchDev *sch;
 
     if (bus_id.valid) {
-        if (squash_mcss) {
-            bus_id.cssid = channel_subsys.default_cssid;
-        } else if (!channel_subsys.css[bus_id.cssid]) {
+        if (!channel_subsys.css[bus_id.cssid]) {
             css_create_css_image(bus_id.cssid, false);
         }
 
diff --git a/hw/s390x/s390-ccw.c b/hw/s390x/s390-ccw.c
index 214c940593..cad91ee626 100644
--- a/hw/s390x/s390-ccw.c
+++ b/hw/s390x/s390-ccw.c
@@ -67,8 +67,6 @@ static void s390_ccw_realize(S390CCWDevice *cdev, char *sysfsdev, Error **errp)
     CcwDevice *ccw_dev = CCW_DEVICE(cdev);
     CCWDeviceClass *ck = CCW_DEVICE_GET_CLASS(ccw_dev);
     DeviceState *parent = DEVICE(ccw_dev);
-    BusState *qbus = qdev_get_parent_bus(parent);
-    VirtualCssBus *cbus = VIRTUAL_CSS_BUS(qbus);
     SubchDev *sch;
     int ret;
     Error *err = NULL;
@@ -78,7 +76,7 @@ static void s390_ccw_realize(S390CCWDevice *cdev, char *sysfsdev, Error **errp)
         goto out_err_propagate;
     }
 
-    sch = css_create_sch(ccw_dev->devno, cbus->squash_mcss, &err);
+    sch = css_create_sch(ccw_dev->devno, &err);
     if (!sch) {
         goto out_mdevid_free;
     }
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index d366909474..f0f7fdcadd 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -282,19 +282,8 @@ static void ccw_init(MachineState *machine)
     virtio_ccw_register_hcalls();
 
     s390_enable_css_support(s390_cpu_addr2state(0));
-    /*
-     * Non mcss-e enabled guests only see the devices from the default
-     * css, which is determined by the value of the squash_mcss property.
-     */
-    if (css_bus->squash_mcss) {
-        ret = css_create_css_image(0, true);
-    } else {
-        ret = css_create_css_image(VIRTUAL_CSSID, true);
-    }
-    if (qemu_opt_get(qemu_get_machine_opts(), "s390-squash-mcss")) {
-        warn_report("The machine property 's390-squash-mcss' is deprecated"
-                    " (obsoleted by lifting the cssid restrictions).");
-    }
+
+    ret = css_create_css_image(VIRTUAL_CSSID, true);
 
     assert(ret == 0);
     if (css_migration_enabled()) {
@@ -575,21 +564,6 @@ static void machine_set_loadparm(Object *obj, const char *val, Error **errp)
         ms->loadparm[i] = ' '; /* pad right with spaces */
     }
 }
-static inline bool machine_get_squash_mcss(Object *obj, Error **errp)
-{
-    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
-
-    return ms->s390_squash_mcss;
-}
-
-static inline void machine_set_squash_mcss(Object *obj, bool value,
-                                           Error **errp)
-{
-    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
-
-    ms->s390_squash_mcss = value;
-}
-
 static inline void s390_machine_initfn(Object *obj)
 {
     object_property_add_bool(obj, "aes-key-wrap",
@@ -614,13 +588,6 @@ static inline void s390_machine_initfn(Object *obj)
             " to upper case) to pass to machine loader, boot manager,"
             " and guest kernel",
             NULL);
-    object_property_add_bool(obj, "s390-squash-mcss",
-                             machine_get_squash_mcss,
-                             machine_set_squash_mcss, NULL);
-    object_property_set_description(obj, "s390-squash-mcss", "(deprecated) "
-            "enable/disable squashing subchannels into the default css",
-            NULL);
-    object_property_set_bool(obj, false, "s390-squash-mcss", NULL);
 }
 
 static const TypeInfo ccw_machine_info = {
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 7ddb378d52..2713b7feaa 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -694,13 +694,10 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
     VirtIOCCWDeviceClass *k = VIRTIO_CCW_DEVICE_GET_CLASS(dev);
     CcwDevice *ccw_dev = CCW_DEVICE(dev);
     CCWDeviceClass *ck = CCW_DEVICE_GET_CLASS(ccw_dev);
-    DeviceState *parent = DEVICE(ccw_dev);
-    BusState *qbus = qdev_get_parent_bus(parent);
-    VirtualCssBus *cbus = VIRTUAL_CSS_BUS(qbus);
     SubchDev *sch;
     Error *err = NULL;
 
-    sch = css_create_sch(ccw_dev->devno, cbus->squash_mcss, errp);
+    sch = css_create_sch(ccw_dev->devno, errp);
     if (!sch) {
         return;
     }
diff --git a/include/hw/s390x/css-bridge.h b/include/hw/s390x/css-bridge.h
index cf0860432a..5a0203be5f 100644
--- a/include/hw/s390x/css-bridge.h
+++ b/include/hw/s390x/css-bridge.h
@@ -28,7 +28,6 @@ typedef struct VirtualCssBridge {
 /* virtual css bus type */
 typedef struct VirtualCssBus {
     BusState parent_obj;
-    bool squash_mcss;
 } VirtualCssBus;
 
 #define TYPE_VIRTUAL_CSS_BUS "virtual-css-bus"
diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
index 35facb47d2..9da5912921 100644
--- a/include/hw/s390x/css.h
+++ b/include/hw/s390x/css.h
@@ -266,11 +266,8 @@ extern const PropertyInfo css_devid_ro_propinfo;
 /**
  * Create a subchannel for the given bus id.
  *
- * If @p bus_id is valid, and @p squash_mcss is true, verify that it is
- * not already in use in the default css, and find a free devno from the
- * default css image for it.
- * If @p bus_id is valid, and @p squash_mcss is false, verify that it is
- * not already in use, and find a free devno for it.
+ * If @p bus_id is valid, verify that it is not already in use, and find a
+ * free devno for it.
  * If @p bus_id is not valid find a free subchannel id and device number
  * across all subchannel sets and all css images starting from the default
  * css image.
@@ -282,7 +279,7 @@ extern const PropertyInfo css_devid_ro_propinfo;
  * The caller becomes owner of the returned subchannel structure and
  * is responsible for unregistering and freeing it.
  */
-SubchDev *css_create_sch(CssDevId bus_id, bool squash_mcss, Error **errp);
+SubchDev *css_create_sch(CssDevId bus_id, Error **errp);
 
 /** Turn on css migration */
 void css_register_vmstate(void);
diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index ab88d49d10..e9c4f4182b 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -29,7 +29,6 @@ typedef struct S390CcwMachineState {
     bool aes_key_wrap;
     bool dea_key_wrap;
     uint8_t loadparm[8];
-    bool s390_squash_mcss;
 } S390CcwMachineState;
 
 typedef struct S390CcwMachineClass {
diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index df319cfd82..67b721156f 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -111,14 +111,6 @@ The ``-nodefconfig`` argument is a synonym for ``-no-user-config``.
 The @option{--balloon virtio} argument has been superseded by
 @option{--device virtio-balloon}.
 
-@subsection -machine s390-squash-mcss=on|off (since 2.12.0)
-
-The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
-cssid to be chosen freely. Instead of squashing subchannels into the
-default channel subsystem image for guests that do not support multiple
-channel subsystems, all devices can be put into the default channel
-subsystem image.
-
 @subsection -fsdev handle (since 2.12.0)
 
 The ``handle'' fsdev backend does not support symlinks and causes the 9p
diff --git a/qemu-options.hx b/qemu-options.hx
index ea4edb4938..4efdedfdbb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -43,7 +43,6 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
     "                nvdimm=on|off controls NVDIMM support (default=off)\n"
     "                enforce-config-section=on|off enforce configuration section migration (default=off)\n"
-    "                s390-squash-mcss=on|off (deprecated) controls support for squashing into default css (default=off)\n"
     "                memory-encryption=@var{} memory encryption object to use (default=none)\n",
     QEMU_ARCH_ALL)
 STEXI
@@ -96,15 +95,6 @@ controls whether DEA wrapping keys will be created to allow
 execution of DEA cryptographic functions.  The default is on.
 @item nvdimm=on|off
 Enables or disables NVDIMM support. The default is off.
-@item s390-squash-mcss=on|off
-Enables or disables squashing subchannels into the default css.
-The default is off.
-NOTE: This property is deprecated and will be removed in future releases.
-The ``s390-squash-mcss=on`` property has been obsoleted by allowing the
-cssid to be chosen freely. Instead of squashing subchannels into the
-default channel subsystem image for guests that do not support multiple
-channel subsystems, all devices can be put into the default channel
-subsystem image.
 @item enforce-config-section=on|off
 If @option{enforce-config-section} is set to @var{on}, force migration
 code to send configuration section even if the machine-type sets the
diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
index 271c5ce652..8ed4823d6e 100644
--- a/target/s390x/cpu.c
+++ b/target/s390x/cpu.c
@@ -421,16 +421,6 @@ void s390_crypto_reset(void)
     }
 }
 
-bool s390_get_squash_mcss(void)
-{
-    if (object_property_get_bool(OBJECT(qdev_get_machine()), "s390-squash-mcss",
-                                 NULL)) {
-        return true;
-    }
-
-    return false;
-}
-
 void s390_enable_css_support(S390CPU *cpu)
 {
     if (kvm_enabled()) {
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 2c3dd2d189..86b66dfeac 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -713,7 +713,6 @@ static inline void s390_do_cpu_load_normal(CPUState *cs, run_on_cpu_data arg)
 
 /* cpu.c */
 void s390_crypto_reset(void);
-bool s390_get_squash_mcss(void);
 int s390_set_memory_limit(uint64_t new_limit, uint64_t *hw_limit);
 void s390_cmma_reset(void);
 void s390_enable_css_support(S390CPU *cpu);