hw/acpi: refactor acpi hp modules so that targets can just use what they need

Currently various acpi hotplug modules like cpu hotplug, memory hotplug, pci
hotplug, nvdimm hotplug are all pulled in when CONFIG_ACPI_X86 is turned on.
This brings in support for whole lot of subsystems that some targets like
mips does not need. They are added just to satisfy symbol dependencies. This
is ugly and should be avoided. Targets should be able to pull in just what they
need and no more. For example, mips only needs support for PIIX4 and does not
need acpi pci hotplug support or cpu hotplug support or memory hotplug support
etc. This change is an effort to clean this up.
In this change, new config variables are added for various acpi hotplug
subsystems. Targets like mips can only enable PIIX4 support and not the rest
of all the other modules which were being previously pulled in as a part of
CONFIG_ACPI_X86. Function stubs make sure that symbols which piix4 needs but
are not required by mips (for example, symbols specific to pci hotplug etc)
are available to satisfy the dependencies.

Currently, this change only addresses issues with mips malta targets. In future
we might be able to clean up other targets which are similarly pulling in lot
of unnecessary hotplug modules by enabling ACPI_X86.

This change should also address issues such as the following:
https://gitlab.com/qemu-project/qemu/-/issues/221
https://gitlab.com/qemu-project/qemu/-/issues/193

Signed-off-by: Ani Sinha <ani@anisinha.ca>
Message-Id: <20210812071409.492299-1-ani@anisinha.ca>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/hw/acpi/acpi-cpu-hotplug-stub.c b/hw/acpi/acpi-cpu-hotplug-stub.c
new file mode 100644
index 0000000000..3fc4b14c26
--- /dev/null
+++ b/hw/acpi/acpi-cpu-hotplug-stub.c
@@ -0,0 +1,50 @@
+#include "qemu/osdep.h"
+#include "hw/acpi/cpu_hotplug.h"
+#include "migration/vmstate.h"
+
+
+/* Following stubs are all related to ACPI cpu hotplug */
+const VMStateDescription vmstate_cpu_hotplug;
+
+void acpi_switch_to_modern_cphp(AcpiCpuHotplug *gpe_cpu,
+                                CPUHotplugState *cpuhp_state,
+                                uint16_t io_port)
+{
+    return;
+}
+
+void legacy_acpi_cpu_hotplug_init(MemoryRegion *parent, Object *owner,
+                                  AcpiCpuHotplug *gpe_cpu, uint16_t base)
+{
+    return;
+}
+
+void acpi_cpu_ospm_status(CPUHotplugState *cpu_st, ACPIOSTInfoList ***list)
+{
+    return;
+}
+
+void acpi_cpu_plug_cb(HotplugHandler *hotplug_dev,
+                      CPUHotplugState *cpu_st, DeviceState *dev, Error **errp)
+{
+    return;
+}
+
+void legacy_acpi_cpu_plug_cb(HotplugHandler *hotplug_dev,
+                             AcpiCpuHotplug *g, DeviceState *dev, Error **errp)
+{
+    return;
+}
+
+void acpi_cpu_unplug_cb(CPUHotplugState *cpu_st,
+                        DeviceState *dev, Error **errp)
+{
+    return;
+}
+
+void acpi_cpu_unplug_request_cb(HotplugHandler *hotplug_dev,
+                                CPUHotplugState *cpu_st,
+                                DeviceState *dev, Error **errp)
+{
+    return;
+}