diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 838e838bad..8cba755c9b 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2843,6 +2843,56 @@ qemuDomainChrDefDropDefaultPath(virDomainChrDefPtr chr,
 }
 
 
+static int
+qemuDomainShmemDefPostParse(virDomainShmemDefPtr shm)
+{
+    /* This was the default since the introduction of this device. */
+    if (shm->model != VIR_DOMAIN_SHMEM_MODEL_IVSHMEM_DOORBELL && !shm->size)
+        shm->size = 4 << 20;
+
+    /* Nothing more to check/change for IVSHMEM */
+    if (shm->model == VIR_DOMAIN_SHMEM_MODEL_IVSHMEM)
+        return 0;
+
+    if (!shm->server.enabled) {
+        if (shm->model == VIR_DOMAIN_SHMEM_MODEL_IVSHMEM_DOORBELL) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shmem model '%s' is supported "
+                             "only with server option enabled"),
+                           virDomainShmemModelTypeToString(shm->model));
+            return -1;
+        }
+
+        if (shm->msi.enabled) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shmem model '%s' doesn't support "
+                             "msi"),
+                           virDomainShmemModelTypeToString(shm->model));
+        }
+    } else {
+        if (shm->model == VIR_DOMAIN_SHMEM_MODEL_IVSHMEM_PLAIN) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shmem model '%s' is supported "
+                             "only with server option disabled"),
+                           virDomainShmemModelTypeToString(shm->model));
+            return -1;
+        }
+
+        if (shm->size) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("shmem model '%s' does not support size setting"),
+                           virDomainShmemModelTypeToString(shm->model));
+            return -1;
+        }
+        shm->msi.enabled = true;
+        if (!shm->msi.ioeventfd)
+            shm->msi.ioeventfd = VIR_TRISTATE_SWITCH_ON;
+    }
+
+    return 0;
+}
+
+
 static int
 qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
                              const virDomainDef *def,
@@ -3047,6 +3097,10 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
         }
     }
 
+    if (dev->type == VIR_DOMAIN_DEVICE_SHMEM &&
+        qemuDomainShmemDefPostParse(dev->data.shmem) < 0)
+        goto cleanup;
+
     ret = 0;
 
  cleanup:
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-shmem.args b/tests/qemuxml2argvdata/qemuxml2argv-shmem.args
index 99fac119b0..bdf660a3c4 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-shmem.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-shmem.args
@@ -17,7 +17,7 @@ QEMU_AUDIO_DRV=none \
 -no-acpi \
 -boot c \
 -usb \
--device ivshmem,id=shmem0,shm=shmem0,bus=pci.0,addr=0x3 \
+-device ivshmem,id=shmem0,size=4m,shm=shmem0,bus=pci.0,addr=0x3 \
 -device ivshmem,id=shmem1,size=128m,shm=shmem1,bus=pci.0,addr=0x5 \
 -device ivshmem,id=shmem2,size=256m,shm=shmem2,bus=pci.0,addr=0x4 \
 -device ivshmem,id=shmem3,size=512m,chardev=charshmem3,bus=pci.0,addr=0x6 \
diff --git a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem-plain-doorbell.xml b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem-plain-doorbell.xml
index ab9c69bfcc..7872e1c8a1 100644
--- a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem-plain-doorbell.xml
+++ b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem-plain-doorbell.xml
@@ -23,6 +23,7 @@
     <memballoon model='none'/>
     <shmem name='shmem0'>
       <model type='ivshmem-plain'/>
+      <size unit='M'>4</size>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </shmem>
     <shmem name='shmem1'>
@@ -38,11 +39,13 @@
     <shmem name='shmem3'>
       <model type='ivshmem-doorbell'/>
       <server/>
+      <msi ioeventfd='on'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
     </shmem>
     <shmem name='shmem4'>
       <model type='ivshmem-doorbell'/>
       <server path='/tmp/shmem4-sock'/>
+      <msi ioeventfd='on'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
     </shmem>
     <shmem name='shmem5'>
@@ -54,7 +57,7 @@
     <shmem name='shmem6'>
       <model type='ivshmem-doorbell'/>
       <server path='/tmp/shmem6-sock'/>
-      <msi vectors='16'/>
+      <msi vectors='16' ioeventfd='on'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>
     </shmem>
     <shmem name='shmem7'>
diff --git a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
index 5602913648..04b463a278 100644
--- a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
+++ b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
@@ -23,6 +23,7 @@
     <memballoon model='none'/>
     <shmem name='shmem0'>
       <model type='ivshmem'/>
+      <size unit='M'>4</size>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </shmem>
     <shmem name='shmem1'>