[PATCH v2 3/3] accel: Add xen CpusAccel using dummy-cpus

[Jason Andryuk <jandryuk@gmail.com>]

Xen was broken by commit 1583a3898853 ("cpus: extract out qtest-specific
code to accel/qtest").  Xen relied on qemu_init_vcpu() calling
qemu_dummy_start_vcpu() in the default case, but that was replaced by
g_assert_not_reached().

Add a minimal "CpusAccel" for Xen using the dummy-cpus implementation
used by qtest.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
---
 accel/meson.build   | 1 +
 accel/xen/xen-all.c | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/accel/meson.build b/accel/meson.build
index 9a417396bd..b26cca227a 100644
--- a/accel/meson.build
+++ b/accel/meson.build
@@ -12,3 +12,4 @@ dummy_ss.add(files(
 ))
 
 specific_ss.add_all(when: ['CONFIG_SOFTMMU', 'CONFIG_POSIX'], if_true: dummy_ss)
+specific_ss.add_all(when: ['CONFIG_XEN'], if_true: dummy_ss)
diff --git a/accel/xen/xen-all.c b/accel/xen/xen-all.c
index 60b971d0a8..878a4089d9 100644
--- a/accel/xen/xen-all.c
+++ b/accel/xen/xen-all.c
@@ -16,6 +16,7 @@
 #include "hw/xen/xen_pt.h"
 #include "chardev/char.h"
 #include "sysemu/accel.h"
+#include "sysemu/cpus.h"
 #include "sysemu/xen.h"
 #include "sysemu/runstate.h"
 #include "migration/misc.h"
@@ -153,6 +154,10 @@ static void xen_setup_post(MachineState *ms, AccelState *accel)
     }
 }
 
+const CpusAccel xen_cpus = {
+    .create_vcpu_thread = dummy_start_vcpu_thread,
+};
+
 static int xen_init(MachineState *ms)
 {
     MachineClass *mc = MACHINE_GET_CLASS(ms);
@@ -180,6 +185,9 @@ static int xen_init(MachineState *ms)
      * opt out of system RAM being allocated by generic code
      */
     mc->default_ram_id = NULL;
+
+    cpus_register_accel(&xen_cpus);
+
     return 0;
 }
 
-- 
2.25.1