Re: [RFC PATCH v2 07/22] pc_piix: handle XEN_EMULATE backend init

[Paul Durrant]

On 09/12/2022 09:55, David Woodhouse wrote:
From: Joao Martins <joao.m.mart...@oracle.com>
And use newly added xen_emulated_machine_init() to iniitalize
the xenstore and the sysdev bus for future emulated devices.

Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
[dwmw2: Move it to xen-legacy-backend.c]
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
---
  hw/i386/pc_piix.c                   |  5 +++++
  hw/xen/xen-legacy-backend.c         | 22 ++++++++++++++++------
  include/hw/xen/xen-legacy-backend.h |  2 ++
  3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 13286d0739..3dcac2f4b6 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -47,6 +47,7 @@
  #include "hw/sysbus.h"
  #include "hw/i2c/smbus_eeprom.h"
  #include "hw/xen/xen-x86.h"
+#include "hw/xen/xen-legacy-backend.h"
  #include "exec/memory.h"
  #include "hw/acpi/acpi.h"
  #include "hw/acpi/piix4.h"
@@ -155,6 +156,10 @@ static void pc_init1(MachineState *machine,
              x86ms->above_4g_mem_size = 0;
              x86ms->below_4g_mem_size = machine->ram_size;
          }
+
+        if (pcms->xen_version && !xen_be_xenstore_open()) {

So, this is a bit subtle... it's only *because* using real Xen results 
in xen_version being 0 that this is sane? Also does this not mean that 
we are now relying on libxenstore? Shouldn't that be called out in the 
config?

+            xen_emulated_machine_init();
+        }
      }
  
      pc_machine_init_sgx_epc(pcms);
diff --git a/hw/xen/xen-legacy-backend.c b/hw/xen/xen-legacy-backend.c
index 694e7bbc54..60a7bc7ab6 100644
--- a/hw/xen/xen-legacy-backend.c
+++ b/hw/xen/xen-legacy-backend.c
@@ -31,6 +31,7 @@
  #include "qapi/error.h"
  #include "hw/xen/xen-legacy-backend.h"
  #include "hw/xen/xen_pvdev.h"
+#include "hw/xen/xen-bus.h"
  #include "monitor/qdev.h"
  
  DeviceState *xen_sysdev;
@@ -294,13 +295,15 @@ static struct XenLegacyDevice *xen_be_get_xendev(const 
char *type, int dom,
      xendev->debug      = debug;
      xendev->local_port = -1;
  
-    xendev->evtchndev = xenevtchn_open(NULL, 0);
-    if (xendev->evtchndev == NULL) {
-        xen_pv_printf(NULL, 0, "can't open evtchn device\n");
-        qdev_unplug(DEVICE(xendev), NULL);
-        return NULL;
+    if (xen_mode != XEN_EMULATE) {
+        xendev->evtchndev = xenevtchn_open(NULL, 0);

Doesn't this need stubbing out so that we can build without libxenevtchn?

  Paul

+        if (xendev->evtchndev == NULL) {
+            xen_pv_printf(NULL, 0, "can't open evtchn device\n");
+            qdev_unplug(DEVICE(xendev), NULL);
+            return NULL;
+        }
+        qemu_set_cloexec(xenevtchn_fd(xendev->evtchndev));
      }
-    qemu_set_cloexec(xenevtchn_fd(xendev->evtchndev));
  
      xen_pv_insert_xendev(xendev);
  
@@ -859,3 +862,10 @@ static void xenbe_register_types(void)
  }
  
  type_init(xenbe_register_types)
+
+void xen_emulated_machine_init(void)
+{
+    xen_bus_init();
+    xen_be_sysdev_init();
+    xen_be_register_common();
+}
diff --git a/include/hw/xen/xen-legacy-backend.h 
b/include/hw/xen/xen-legacy-backend.h
index 0aa171f6c2..aa09015662 100644
--- a/include/hw/xen/xen-legacy-backend.h
+++ b/include/hw/xen/xen-legacy-backend.h
@@ -105,4 +105,6 @@ int xen_config_dev_vfb(int vdev, const char *type);
  int xen_config_dev_vkbd(int vdev);
  int xen_config_dev_console(int vdev);
  
+void xen_emulated_machine_init(void);
+
  #endif /* HW_XEN_LEGACY_BACKEND_H */