[libvirt] [PATCH 09/20] qemu: Save various defaults for shmem

[Martin Kletzander]

When we change the device used for the shared memory, it should not
change the settings, so rather save them upfront then having problems
later.

The only thing we are not saving is the role for old ivshmem and that's
because we were not specifying it, which means role=auto and that is
really bad idea to be using (due to various things).  However, we don't
want to change the behaviour, so that's the reason for that.

Details for the defaults of the newer implementation can be found in
qemu's commit 5400c02b90bb:

  http://git.qemu.org/?p=qemu.git;a=commit;h=5400c02b90bb

Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
 src/qemu/qemu_domain.c                            | 33 +++++++++++++++++++++++
 tests/qemuxml2argvdata/qemuxml2argv-shmem.args    |  2 +-
 tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml |  3 ++-
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 3f16dbee2e6a..1fdbdf68fc8b 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2747,6 +2747,39 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
         }
     }

+    if (dev->type == VIR_DOMAIN_DEVICE_SHMEM) {
+        if (!dev->data.shmem->server.enabled) {
+            /* The size is 4M if not specified */
+            if (!dev->data.shmem->size)
+                dev->data.shmem->size = 4 << 20;
+            /* For old ivshmem we shouldn't change the role, the new
+             * ones are peer by default, mostly to safeguard that
+             * there should be no more than one master */
+            if (!dev->data.shmem->role) {
+                if (dev->data.shmem->model == VIR_DOMAIN_SHMEM_MODEL_IVSHMEM)
+                    dev->data.shmem->role = VIR_DOMAIN_SHMEM_ROLE_MASTER;
+                else
+                    dev->data.shmem->role = VIR_DOMAIN_SHMEM_ROLE_PEER;
+            }
+        } else {
+            /* In QEMU, role doesn't make sense for server-side shmem */
+            dev->data.shmem->role = VIR_DOMAIN_SHMEM_ROLE_DEFAULT;
+
+            /* Defaults/Requirements for the newer device that we should save */
+            if (dev->data.shmem->model == VIR_DOMAIN_SHMEM_MODEL_IVSHMEM_DOORBELL) {
+                /* Size does not make much sense when claiming memory from
+                 * the server and so the newer version doesn't support that */
+                dev->data.shmem->size = 0;
+
+                /* Also they can only exist with MSI and ioeventfd is
+                 * enabled unless specifically disabled */
+                dev->data.shmem->msi.enabled = true;
+                if (!dev->data.shmem->msi.ioeventfd)
+                    dev->data.shmem->msi.ioeventfd = VIR_TRISTATE_SWITCH_ON;
+            }
+        }
+    }
+
     ret = 0;

  cleanup:
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-shmem.args b/tests/qemuxml2argvdata/qemuxml2argv-shmem.args
index dc69f4ab50fb..d1624d5c00bd 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,shm=shmem0,id=shmem0,bus=pci.0,addr=0x3 \
+-device ivshmem,size=4m,shm=shmem0,id=shmem0,role=master,bus=pci.0,addr=0x3 \
 -device ivshmem,size=128m,shm=shmem1,id=shmem1,role=peer,bus=pci.0,addr=0x5 \
 -device ivshmem,size=256m,shm=shmem2,id=shmem2,role=master,bus=pci.0,addr=0x4 \
 -device ivshmem,size=512m,chardev=charshmem3,id=shmem3,bus=pci.0,addr=0x6 \
diff --git a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
index 0a1579155170..d594806b9d64 100644
--- a/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
+++ b/tests/qemuxml2xmloutdata/qemuxml2xmlout-shmem.xml
@@ -21,8 +21,9 @@
     <input type='mouse' bus='ps2'/>
     <input type='keyboard' bus='ps2'/>
     <memballoon model='none'/>
-    <shmem name='shmem0'>
+    <shmem name='shmem0' role='master'>
       <model type='ivshmem'/>
+      <size unit='M'>4</size>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </shmem>
     <shmem name='shmem1' role='peer'>
-- 
2.10.0