qemu: probe for -chardev 'fd' parameter for FD passing

QEMU >= 2.12 will support passing of pre-opened file descriptors for
socket based character devices.

Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/qemu/qemu_capabilities.c

@@ -493,6 +493,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
 
               /* 305 */
               "vhost-vsock",
+              "chardev-fd-pass",
     );
 
 
@@ -2570,6 +2571,7 @@ static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
     { "chardev", "reconnect", QEMU_CAPS_CHARDEV_RECONNECT },
     { "sandbox", "enable", QEMU_CAPS_SECCOMP_SANDBOX },
     { "sandbox", "elevateprivileges", QEMU_CAPS_SECCOMP_BLACKLIST },
+    { "chardev", "fd", QEMU_CAPS_CHARDEV_FD_PASS },
 };
 
 static int

src/qemu/qemu_capabilities.h

@@ -477,6 +477,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */
 
     /* 305 */
     QEMU_CAPS_DEVICE_VHOST_VSOCK, /* -device vhost-vsock-* */
+    QEMU_CAPS_CHARDEV_FD_PASS, /* Passing pre-opened FDs for chardevs */
 
     QEMU_CAPS_LAST /* this must always be the last item */
 } virQEMUCapsFlags;

tests/qemucapabilitiesdata/caps_2.12.0.aarch64.xml

@@ -167,6 +167,7 @@
   <flag name='hda-output'/>
   <flag name='blockdev-del'/>
   <flag name='vhost-vsock'/>
+  <flag name='chardev-fd-pass'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>343099</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.ppc64.xml

@@ -164,6 +164,7 @@
   <flag name='hda-output'/>
   <flag name='blockdev-del'/>
   <flag name='vhost-vsock'/>
+  <flag name='chardev-fd-pass'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>419968</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.s390x.xml

@@ -131,6 +131,7 @@
   <flag name='screendump_device'/>
   <flag name='blockdev-del'/>
   <flag name='vhost-vsock'/>
+  <flag name='chardev-fd-pass'/>
   <version>2012000</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>371055</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.x86_64.xml

@@ -206,6 +206,7 @@
   <flag name='blockdev-del'/>
   <flag name='vmgenid'/>
   <flag name='vhost-vsock'/>
+  <flag name='chardev-fd-pass'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>390813</microcodeVersion>