xen-platform: allow its creation with XEN_EMULATE mode

The only thing we need to fix to make this build is the PIO hack which
sets the BIOS memory areas to R/W v.s. R/O. Theoretically we could hook
that up to the PAM registers on the emulated PIIX, but in practice
nobody cares, so just leave it doing nothing.

Now it builds without actual Xen, move it to CONFIG_XEN_BUS to include it
in the KVM-only builds.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

2 files changed, 30 insertions, 14 deletions

diff --git a/hw/i386/xen/meson.build b/hw/i386/xen/meson.build
index be84130300..2e64a34e16 100644
--- a/hw/i386/xen/meson.build
+++ b/hw/i386/xen/meson.build
@@ -2,6 +2,9 @@ i386_ss.add(when: 'CONFIG_XEN', if_true: files(
   'xen-hvm.c',
   'xen-mapcache.c',
   'xen_apic.c',
-  'xen_platform.c',
   'xen_pvdevice.c',
 ))
+
+i386_ss.add(when: 'CONFIG_XEN_BUS', if_true: files(
+  'xen_platform.c',
+))
diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
index 8a61697053..539f7da374 100644
--- a/hw/i386/xen/xen_platform.c
+++ b/hw/i386/xen/xen_platform.c
@@ -27,9 +27,9 @@
 #include "qapi/error.h"
 #include "hw/ide/pci.h"
 #include "hw/pci/pci.h"
-#include "hw/xen/xen_common.h"
 #include "migration/vmstate.h"
-#include "hw/xen/xen-legacy-backend.h"
+#include "hw/xen/xen.h"
+#include "net/net.h"
 #include "trace.h"
 #include "sysemu/xen.h"
 #include "sysemu/block-backend.h"
@@ -37,6 +37,11 @@
 #include "qemu/module.h"
 #include "qom/object.h"
 
+#ifdef CONFIG_XEN
+#include "hw/xen/xen_common.h"
+#include "hw/xen/xen-legacy-backend.h"
+#endif
+
 //#define DEBUG_PLATFORM
 
 #ifdef DEBUG_PLATFORM
@@ -279,18 +284,26 @@ static void platform_fixed_ioport_writeb(void *opaque, uint32_t addr, uint32_t v
     PCIXenPlatformState *s = opaque;
 
     switch (addr) {
-    case 0: /* Platform flags */ {
-        hvmmem_type_t mem_type = (val & PFFLAG_ROM_LOCK) ?
-            HVMMEM_ram_ro : HVMMEM_ram_rw;
-        if (xen_set_mem_type(xen_domid, mem_type, 0xc0, 0x40)) {
-            DPRINTF("unable to change ro/rw state of ROM memory area!\n");
-        } else {
+    case 0: /* Platform flags */
+        if (xen_mode == XEN_EMULATE) {
+            /* XX: Use i440gx/q35 PAM setup to do this? */
             s->flags = val & PFFLAG_ROM_LOCK;
-            DPRINTF("changed ro/rw state of ROM memory area. now is %s state.\n",
-                    (mem_type == HVMMEM_ram_ro ? "ro":"rw"));
+#ifdef CONFIG_XEN
+        } else {
+            hvmmem_type_t mem_type = (val & PFFLAG_ROM_LOCK) ?
+                HVMMEM_ram_ro : HVMMEM_ram_rw;
+
+            if (xen_set_mem_type(xen_domid, mem_type, 0xc0, 0x40)) {
+                DPRINTF("unable to change ro/rw state of ROM memory area!\n");
+            } else {
+                s->flags = val & PFFLAG_ROM_LOCK;
+                DPRINTF("changed ro/rw state of ROM memory area. now is %s state.\n",
+                        (mem_type == HVMMEM_ram_ro ? "ro" : "rw"));
+            }
+#endif
         }
         break;
-    }
+
     case 2:
         log_writeb(s, val);
         break;
@@ -508,8 +521,8 @@ static void xen_platform_realize(PCIDevice *dev, Error **errp)
     uint8_t *pci_conf;
 
     /* Device will crash on reset if xen is not initialized */
-    if (!xen_enabled()) {
-        error_setg(errp, "xen-platform device requires the Xen accelerator");
+    if (xen_mode == XEN_DISABLED) {
+        error_setg(errp, "xen-platform device requires a Xen guest");
         return;
     }