[RFC PATCH 16/30] q35/xen: Add Xen platform device support for Q35

[Alexey Gerasimenko <x1917x@gmail.com>]

Current Xen/QEMU method to control Xen Platform device on i440 is a bit
odd -- enabling/disabling Xen platform device actually modifies the QEMU
emulated machine type, namely xenfv <--> pc.

In order to avoid multiplying machine types, use a new way to control Xen
Platform device for QEMU -- "xen-platform-dev" machine property (bool).
To maintain backward compatibility with existing Xen/QEMU setups, this
is only applicable to q35 machine currently. i440 emulation still uses the
old method (i.e. xenfv/pc machine selection) to control Xen Platform
device, this may be changed later to xen-platform-dev property as well.

This way we can use a single machine type (q35) and change just
xen-platform-dev value to on/off to control Xen platform device.

Signed-off-by: Alexey Gerasimenko <x1917x@gmail.com>
---
 hw/core/machine.c   | 21 +++++++++++++++++++++
 hw/i386/pc_q35.c    | 14 ++++++++++++++
 include/hw/boards.h |  1 +
 qemu-options.hx     |  1 +
 4 files changed, 37 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 5e2bbcdace..205e7da3ce 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -290,6 +290,20 @@ static void machine_set_igd_gfx_passthru(Object *obj, bool value, Error **errp)
     ms->igd_gfx_passthru = value;
 }
 
+static bool machine_get_xen_platform_dev(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return ms->xen_platform_dev;
+}
+
+static void machine_set_xen_platform_dev(Object *obj, bool value, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    ms->xen_platform_dev = value;
+}
+
 static char *machine_get_firmware(Object *obj, Error **errp)
 {
     MachineState *ms = MACHINE(obj);
@@ -595,6 +609,13 @@ static void machine_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, "igd-passthru",
         "Set on/off to enable/disable igd passthrou", &error_abort);
 
+    object_class_property_add_bool(oc, "xen-platform-dev",
+        machine_get_xen_platform_dev,
+        machine_set_xen_platform_dev, &error_abort);
+    object_class_property_set_description(oc, "xen-platform-dev",
+        "Set on/off to enable/disable Xen Platform device",
+        &error_abort);
+
     object_class_property_add_str(oc, "firmware",
         machine_get_firmware, machine_set_firmware,
         &error_abort);
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 0db670f6d7..62caf924cf 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -56,6 +56,18 @@
 /* ICH9 AHCI has 6 ports */
 #define MAX_SATA_PORTS     6
 
+static void q35_xen_hvm_init(MachineState *machine)
+{
+    PCMachineState *pcms = PC_MACHINE(machine);
+
+    if (xen_enabled()) {
+        /* check if Xen Platform device is enabled */
+        if (machine->xen_platform_dev) {
+            pci_create_simple(pcms->bus, -1, "xen-platform");
+        }
+    }
+}
+
 /* PC hardware initialisation */
 static void pc_q35_init(MachineState *machine)
 {
@@ -207,6 +219,8 @@ static void pc_q35_init(MachineState *machine)
     if (xen_enabled()) {
         pci_bus_irqs(host_bus, xen_cmn_set_irq, xen_cmn_pci_slot_get_pirq,
                      ich9_lpc, ICH9_XEN_NUM_IRQ_SOURCES);
+
+        q35_xen_hvm_init(machine);
     } else {
         pci_bus_irqs(host_bus, ich9_lpc_set_irq, ich9_lpc_map_irq, ich9_lpc,
                      ICH9_LPC_NB_PIRQS);
diff --git a/include/hw/boards.h b/include/hw/boards.h
index efb0a9edfd..f35fc1cc03 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -238,6 +238,7 @@ struct MachineState {
     bool usb;
     bool usb_disabled;
     bool igd_gfx_passthru;
+    bool xen_platform_dev;
     char *firmware;
     bool iommu;
     bool suppress_vmdesc;
diff --git a/qemu-options.hx b/qemu-options.hx
index 6585058c6c..cee0b92028 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -38,6 +38,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
     "                mem-merge=on|off controls memory merge support (default: on)\n"
     "                igd-passthru=on|off controls IGD GFX passthrough support (default=off)\n"
+    "                xen-platform-dev=on|off controls Xen Platform device (default=off)\n"
     "                aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
     "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
     "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
-- 
2.11.0


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