pc: Factor out (un)plug handling of virtio-md-pci devices

Let's factor out (un)plug handling, to be reused from arm/virt code.

Provide stubs for the case that CONFIG_VIRTIO_MD is not selected because
neither virtio-mem nor virtio-pmem is enabled. While this cannot
currently happen for x86, it will be possible for arm/virt.

Message-ID: <20230711153445.514112-3-david@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

MAINTAINERS

@@ -2234,6 +2234,7 @@ M: David Hildenbrand <david@redhat.com>
 S: Supported
 F: hw/virtio/virtio-md-pci.c
 F: include/hw/virtio/virtio-md-pci.h
+F: stubs/virtio-md-pci.c
 
 virtio-mem
 M: David Hildenbrand <david@redhat.com>

hw/i386/pc.c

@@ -88,13 +88,11 @@
 #include "hw/net/ne2000-isa.h"
 #include "standard-headers/asm-x86/bootparam.h"
 #include "hw/virtio/virtio-iommu.h"
-#include "hw/virtio/virtio-pmem-pci.h"
-#include "hw/virtio/virtio-mem-pci.h"
+#include "hw/virtio/virtio-md-pci.h"
 #include "hw/i386/kvm/xen_overlay.h"
 #include "hw/i386/kvm/xen_evtchn.h"
 #include "hw/i386/kvm/xen_gnttab.h"
 #include "hw/i386/kvm/xen_xenstore.h"
-#include "hw/mem/memory-device.h"
 #include "sysemu/replay.h"
 #include "target/i386/cpu.h"
 #include "e820_memory_layout.h"
@@ -1493,78 +1491,15 @@ static void pc_memory_unplug(HotplugHandler *hotplug_dev,
     error_propagate(errp, local_err);
 }
 
-static void pc_virtio_md_pci_pre_plug(HotplugHandler *hotplug_dev,
-                                      DeviceState *dev, Error **errp)
-{
-    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
-    Error *local_err = NULL;
-
-    if (!hotplug_dev2 && dev->hotplugged) {
-        /*
-         * Without a bus hotplug handler, we cannot control the plug/unplug
-         * order. We should never reach this point when hotplugging on x86,
-         * however, better add a safety net.
-         */
-        error_setg(errp, "hotplug of virtio based memory devices not supported"
-                   " on this bus.");
-        return;
-    }
-    /*
-     * First, see if we can plug this memory device at all. If that
-     * succeeds, branch of to the actual hotplug handler.
-     */
-    memory_device_pre_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev), NULL,
-                           &local_err);
-    if (!local_err && hotplug_dev2) {
-        hotplug_handler_pre_plug(hotplug_dev2, dev, &local_err);
-    }
-    error_propagate(errp, local_err);
-}
-
-static void pc_virtio_md_pci_plug(HotplugHandler *hotplug_dev,
-                                  DeviceState *dev, Error **errp)
-{
-    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
-    Error *local_err = NULL;
-
-    /*
-     * Plug the memory device first and then branch off to the actual
-     * hotplug handler. If that one fails, we can easily undo the memory
-     * device bits.
-     */
-    memory_device_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
-    if (hotplug_dev2) {
-        hotplug_handler_plug(hotplug_dev2, dev, &local_err);
-        if (local_err) {
-            memory_device_unplug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
-        }
-    }
-    error_propagate(errp, local_err);
-}
-
-static void pc_virtio_md_pci_unplug_request(HotplugHandler *hotplug_dev,
-                                            DeviceState *dev, Error **errp)
-{
-    /* We don't support hot unplug of virtio based memory devices */
-    error_setg(errp, "virtio based memory devices cannot be unplugged.");
-}
-
-static void pc_virtio_md_pci_unplug(HotplugHandler *hotplug_dev,
-                                    DeviceState *dev, Error **errp)
-{
-    /* We don't support hot unplug of virtio based memory devices */
-}
-
 static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                           DeviceState *dev, Error **errp)
 {
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         pc_memory_pre_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
         x86_cpu_pre_plug(hotplug_dev, dev, errp);
-    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-               object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
-        pc_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
+        virtio_md_pci_pre_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         /* Declare the APIC range as the reserved MSI region */
         char *resv_prop_str = g_strdup_printf("0xfee00000:0xfeefffff:%d",
@@ -1596,9 +1531,8 @@ static void pc_machine_device_plug_cb(HotplugHandler *hotplug_dev,
         pc_memory_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
         x86_cpu_plug(hotplug_dev, dev, errp);
-    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-               object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
-        pc_virtio_md_pci_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
+        virtio_md_pci_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
     }
 }
 
@@ -1609,9 +1543,9 @@ static void pc_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
         pc_memory_unplug_request(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
         x86_cpu_unplug_request_cb(hotplug_dev, dev, errp);
-    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-               object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
-        pc_virtio_md_pci_unplug_request(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
+        virtio_md_pci_unplug_request(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev),
+                                     errp);
     } else {
         error_setg(errp, "acpi: device unplug request for not supported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -1625,9 +1559,8 @@ static void pc_machine_device_unplug_cb(HotplugHandler *hotplug_dev,
         pc_memory_unplug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
         x86_cpu_unplug_cb(hotplug_dev, dev, errp);
-    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-               object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
-        pc_virtio_md_pci_unplug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
+        virtio_md_pci_unplug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
     } else {
         error_setg(errp, "acpi: device unplug for not supported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -1639,8 +1572,7 @@ static HotplugHandler *pc_get_hotplug_handler(MachineState *machine,
 {
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
         object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
-        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
-        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
         return HOTPLUG_HANDLER(machine);

hw/virtio/virtio-md-pci.c

@@ -13,6 +13,69 @@
 #include "qemu/osdep.h"
 #include "hw/virtio/virtio-md-pci.h"
 #include "hw/mem/memory-device.h"
+#include "qapi/error.h"
+
+void virtio_md_pci_pre_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    DeviceState *dev = DEVICE(vmd);
+    HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
+    MemoryDeviceState *md = MEMORY_DEVICE(vmd);
+    Error *local_err = NULL;
+
+    if (!bus_handler && dev->hotplugged) {
+        /*
+         * Without a bus hotplug handler, we cannot control the plug/unplug
+         * order. We should never reach this point when hotplugging on x86,
+         * however, better add a safety net.
+         */
+        error_setg(errp, "hotplug of virtio based memory devices not supported"
+                   " on this bus.");
+        return;
+    }
+    /*
+     * First, see if we can plug this memory device at all. If that
+     * succeeds, branch of to the actual hotplug handler.
+     */
+    memory_device_pre_plug(md, ms, NULL, &local_err);
+    if (!local_err && bus_handler) {
+        hotplug_handler_pre_plug(bus_handler, dev, &local_err);
+    }
+    error_propagate(errp, local_err);
+}
+
+void virtio_md_pci_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    DeviceState *dev = DEVICE(vmd);
+    HotplugHandler *bus_handler = qdev_get_bus_hotplug_handler(dev);
+    MemoryDeviceState *md = MEMORY_DEVICE(vmd);
+    Error *local_err = NULL;
+
+    /*
+     * Plug the memory device first and then branch off to the actual
+     * hotplug handler. If that one fails, we can easily undo the memory
+     * device bits.
+     */
+    memory_device_plug(md, ms);
+    if (bus_handler) {
+        hotplug_handler_plug(bus_handler, dev, &local_err);
+        if (local_err) {
+            memory_device_unplug(md, ms);
+        }
+    }
+    error_propagate(errp, local_err);
+}
+
+void virtio_md_pci_unplug_request(VirtIOMDPCI *vmd, MachineState *ms,
+                                  Error **errp)
+{
+    /* We don't support hot unplug of virtio based memory devices */
+    error_setg(errp, "virtio based memory devices cannot be unplugged.");
+}
+
+void virtio_md_pci_unplug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    /* We don't support hot unplug of virtio based memory devices */
+}
 
 static const TypeInfo virtio_md_pci_info = {
     .name = TYPE_VIRTIO_MD_PCI,

include/hw/virtio/virtio-md-pci.h

@@ -32,4 +32,10 @@ struct VirtIOMDPCI {
     VirtIOPCIProxy parent_obj;
 };
 
+void virtio_md_pci_pre_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp);
+void virtio_md_pci_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp);
+void virtio_md_pci_unplug_request(VirtIOMDPCI *vmd, MachineState *ms,
+                                  Error **errp);
+void virtio_md_pci_unplug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp);
+
 #endif

stubs/meson.build

@@ -60,6 +60,7 @@ if have_system
   stub_ss.add(files('semihost.c'))
   stub_ss.add(files('usb-dev-stub.c'))
   stub_ss.add(files('xen-hw-stub.c'))
+  stub_ss.add(files('virtio-md-pci.c'))
 else
   stub_ss.add(files('qdev.c'))
 endif

stubs/virtio-md-pci.c

@@ -0,0 +1,24 @@
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/virtio/virtio-md-pci.h"
+
+void virtio_md_pci_pre_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    error_setg(errp, "virtio based memory devices not supported");
+}
+
+void virtio_md_pci_plug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    error_setg(errp, "virtio based memory devices not supported");
+}
+
+void virtio_md_pci_unplug_request(VirtIOMDPCI *vmd, MachineState *ms,
+                                  Error **errp)
+{
+    error_setg(errp, "virtio based memory devices not supported");
+}
+
+void virtio_md_pci_unplug(VirtIOMDPCI *vmd, MachineState *ms, Error **errp)
+{
+    error_setg(errp, "virtio based memory devices not supported");
+}