xen: fixup RAM memory region initialization

Since bd457782b3b0 ("x86/pc: use memdev for RAM") Xen
machine fails to start with:
   qemu-system-i386: xen: failed to populate ram at 0

The reason is that xen_ram_alloc() which is called by
memory_region_init_ram(), compares memory region with
statically allocated 'global' ram_memory memory region
that it uses for RAM, and does nothing in case it matches.

While it's possible feed machine->ram to xen_ram_alloc()
in the same manner to keep that hack working, I'd prefer
not to keep that circular dependency and try to untangle that.

However it doesn't look trivial to fix, so as temporary
fixup opt out Xen machine from memdev based RAM allocation,
and let xen_ram_alloc() do its trick for now.

Reported-by: Anthony PERARD <[email protected]>
Signed-off-by: Igor Mammedov <[email protected]>
Message-Id: <20200402145418[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

diff --git a/hw/xen/xen-common.c b/hw/xen/xen-common.c
index 15650d7f6a8609a7d1b4095d5685a08d3603950b..a15070f7f6c908a387d644ab8ca2bb11de638266 100644 (file)
--- a/hw/xen/xen-common.c
+++ b/hw/xen/xen-common.c
@@ -19,6 +19,7 @@
 #include "sysemu/runstate.h"
 #include "migration/misc.h"
 #include "migration/global_state.h"
+#include "hw/boards.h"
 
 //#define DEBUG_XEN
 
@@ -151,6 +152,8 @@ static void xen_setup_post(MachineState *ms, AccelState *accel)
 
 static int xen_init(MachineState *ms)
 {
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+
     xen_xc = xc_interface_open(0, 0, 0);
     if (xen_xc == NULL) {
         xen_pv_printf(NULL, 0, "can't open xen interface\n");
@@ -170,6 +173,10 @@ static int xen_init(MachineState *ms)
         return -1;
     }
     qemu_add_vm_change_state_handler(xen_change_state_handler, NULL);
+    /*
+     * opt out of system RAM being allocated by generic code
+     */
+    mc->default_ram_id = NULL;
     return 0;
 }