[PATCH v1 02/23] pc/q35: Apply PCI bus BSEL property for Xen PCI device hotplug

[Joel Upham]

On Q35 we still need to assign BSEL property to bus(es) for PCI device
add/hotplug to work.
Extend acpi_set_pci_info() function to support Q35 as well. This patch adds new 
(trivial)
function find_q35() which returns root PCIBus object on Q35, in a way
similar to what find_i440fx does.

Signed-off-by: Alexey Gerasimenko <x1917x@xxxxxxxxx>
Signed-off-by: Joel Upham <jupham125@gmail.com>
---
 hw/acpi/pcihp.c      | 4 +++-
 hw/pci-host/q35.c    | 9 +++++++++
 include/hw/i386/pc.h | 3 +++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index cdd6f775a1..f4e39d7a9c 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -40,6 +40,7 @@
 #include "qapi/error.h"
 #include "qom/qom-qobject.h"
 #include "trace.h"
+#include "sysemu/xen.h"
 
 #define ACPI_PCIHP_SIZE 0x0018
 #define PCI_UP_BASE 0x0000
@@ -84,7 +85,8 @@ static void *acpi_set_bsel(PCIBus *bus, void *opaque)
     bool is_bridge = IS_PCI_BRIDGE(br);
 
     /* hotplugged bridges can't be described in ACPI ignore them */
-    if (qbus_is_hotpluggable(BUS(bus))) {
+    /* Xen requires hotplugging to the root device, even on the Q35 chipset */
+    if (qbus_is_hotpluggable(BUS(bus)) || xen_enabled()) {
         if (!is_bridge || (!br->hotplugged && info->has_bridge_hotplug)) {
             bus_bsel = g_malloc(sizeof *bus_bsel);
 
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index fd18920e7f..fe5fc0f47c 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -259,6 +259,15 @@ static void q35_host_initfn(Object *obj)
                              qdev_prop_allow_set_link_before_realize, 0);
 }
 
+PCIBus *find_q35(void)
+{
+    PCIHostState *s = OBJECT_CHECK(PCIHostState,
+                                   object_resolve_path("/machine/q35", NULL),
+                                   TYPE_PCI_HOST_BRIDGE);
+    return s ? s->bus : NULL;
+}
+
+
 static const TypeInfo q35_host_info = {
     .name       = TYPE_Q35_HOST_DEVICE,
     .parent     = TYPE_PCIE_HOST_BRIDGE,
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index c661e9cc80..550f8fa221 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -196,6 +196,9 @@ void pc_madt_cpu_entry(int uid, const CPUArchIdList 
*apic_ids,
 /* sgx.c */
 void pc_machine_init_sgx_epc(PCMachineState *pcms);
 
+/* q35.c */
+PCIBus *find_q35(void);
+
 extern GlobalProperty pc_compat_8_0[];
 extern const size_t pc_compat_8_0_len;
 
-- 
2.34.1