xen: Remove support for PV ACPI cpu/memory hotplug

Commit 76fc2537 ("xen/acpi-stub: Disable it b/c the acpi_processor_add
is no longer called.") declared as BROKEN support for Xen ACPI stub (which
is required for xen-acpi-{cpu|memory}-hotplug) and suggested that this
is temporary and will be soon fixed. This was in March 2013.

Further, commit cfafae94 ("xen: rename dom0_op to platform_op")
renamed an interface used by memory hotplug code without updating that
code (as it was BROKEN and therefore not compiled). This was
in November 2015 and has gone unnoticed for over 5 year.

It is now clear that this code is of no interest to anyone and therefore
should be removed.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/1618336344-3162-1-git-send-email-boris.ostrovsky@oracle.comSigned-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/Kconfig

@@ -238,37 +238,6 @@ config XEN_PRIVCMD
 	depends on XEN
 	default m
 
-config XEN_STUB
-	bool "Xen stub drivers"
-	depends on XEN && X86_64 && BROKEN
-	help
-	  Allow kernel to install stub drivers, to reserve space for Xen drivers,
-	  i.e. memory hotplug and cpu hotplug, and to block native drivers loaded,
-	  so that real Xen drivers can be modular.
-
-	  To enable Xen features like cpu and memory hotplug, select Y here.
-
-config XEN_ACPI_HOTPLUG_MEMORY
-	tristate "Xen ACPI memory hotplug"
-	depends on XEN_DOM0 && XEN_STUB && ACPI
-	help
-	  This is Xen ACPI memory hotplug.
-
-	  Currently Xen only support ACPI memory hot-add. If you want
-	  to hot-add memory at runtime (the hot-added memory cannot be
-	  removed until machine stop), select Y/M here, otherwise select N.
-
-config XEN_ACPI_HOTPLUG_CPU
-	tristate "Xen ACPI cpu hotplug"
-	depends on XEN_DOM0 && XEN_STUB && ACPI
-	select ACPI_CONTAINER
-	help
-	  Xen ACPI cpu enumerating and hotplugging
-
-	  For hotplugging, currently Xen only support ACPI cpu hotadd.
-	  If you want to hotadd cpu at runtime (the hotadded cpu cannot
-	  be removed until machine stop), select Y/M here.
-
 config XEN_ACPI_PROCESSOR
 	tristate "Xen ACPI processor"
 	depends on XEN && XEN_DOM0 && X86 && ACPI_PROCESSOR && CPU_FREQ

drivers/xen/Makefile

@@ -26,9 +26,6 @@ obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
 obj-$(CONFIG_XEN_MCE_LOG)		+= mcelog.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)		+= xen-privcmd.o
-obj-$(CONFIG_XEN_STUB)			+= xen-stub.o
-obj-$(CONFIG_XEN_ACPI_HOTPLUG_MEMORY)	+= xen-acpi-memhotplug.o
-obj-$(CONFIG_XEN_ACPI_HOTPLUG_CPU)	+= xen-acpi-cpuhotplug.o
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)	+= xen-acpi-processor.o
 obj-$(CONFIG_XEN_EFI)			+= efi.o
 obj-$(CONFIG_XEN_SCSI_BACKEND)		+= xen-scsiback.o

drivers/xen/pcpu.c

@@ -345,41 +345,6 @@ static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-/* Sync with Xen hypervisor after cpu hotadded */
-void xen_pcpu_hotplug_sync(void)
-{
-	schedule_work(&xen_pcpu_work);
-}
-EXPORT_SYMBOL_GPL(xen_pcpu_hotplug_sync);
-
-/*
- * For hypervisor presented cpu, return logic cpu id;
- * For hypervisor non-presented cpu, return -ENODEV.
- */
-int xen_pcpu_id(uint32_t acpi_id)
-{
-	int cpu_id = 0, max_id = 0;
-	struct xen_platform_op op;
-
-	op.cmd = XENPF_get_cpuinfo;
-	while (cpu_id <= max_id) {
-		op.u.pcpu_info.xen_cpuid = cpu_id;
-		if (HYPERVISOR_platform_op(&op)) {
-			cpu_id++;
-			continue;
-		}
-
-		if (acpi_id == op.u.pcpu_info.acpi_id)
-			return cpu_id;
-		if (op.u.pcpu_info.max_present > max_id)
-			max_id = op.u.pcpu_info.max_present;
-		cpu_id++;
-	}
-
-	return -ENODEV;
-}
-EXPORT_SYMBOL_GPL(xen_pcpu_id);
-
 static int __init xen_pcpu_init(void)
 {
 	int irq, ret;

drivers/xen/xen-stub.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * xen-stub.c - stub drivers to reserve space for Xen
- *
- * Copyright (C) 2012 Intel Corporation
- *    Author: Liu Jinsong <jinsong.liu@intel.com>
- *    Author: Jiang Yunhong <yunhong.jiang@intel.com>
- *
- * Copyright (C) 2012 Oracle Inc
- *    Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
- */
-
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/export.h>
-#include <linux/types.h>
-#include <linux/acpi.h>
-#include <xen/acpi.h>
-
-#ifdef CONFIG_ACPI
-
-/*--------------------------------------------
-	stub driver for Xen memory hotplug
---------------------------------------------*/
-
-static const struct acpi_device_id memory_device_ids[] = {
-	{ACPI_MEMORY_DEVICE_HID, 0},
-	{"", 0},
-};
-
-static struct acpi_driver xen_stub_memory_device_driver = {
-	/* same name as native memory driver to block native loaded */
-	.name = "acpi_memhotplug",
-	.class = ACPI_MEMORY_DEVICE_CLASS,
-	.ids = memory_device_ids,
-};
-
-int xen_stub_memory_device_init(void)
-{
-	if (!xen_initial_domain())
-		return -ENODEV;
-
-	/* just reserve space for Xen, block native driver loaded */
-	return acpi_bus_register_driver(&xen_stub_memory_device_driver);
-}
-EXPORT_SYMBOL_GPL(xen_stub_memory_device_init);
-subsys_initcall(xen_stub_memory_device_init);
-
-void xen_stub_memory_device_exit(void)
-{
-	acpi_bus_unregister_driver(&xen_stub_memory_device_driver);
-}
-EXPORT_SYMBOL_GPL(xen_stub_memory_device_exit);
-
-
-/*--------------------------------------------
-	stub driver for Xen cpu hotplug
---------------------------------------------*/
-
-static const struct acpi_device_id processor_device_ids[] = {
-	{ACPI_PROCESSOR_OBJECT_HID, 0},
-	{ACPI_PROCESSOR_DEVICE_HID, 0},
-	{"", 0},
-};
-
-static struct acpi_driver xen_stub_processor_driver = {
-	/* same name as native processor driver to block native loaded */
-	.name = "processor",
-	.class = ACPI_PROCESSOR_CLASS,
-	.ids = processor_device_ids,
-};
-
-int xen_stub_processor_init(void)
-{
-	if (!xen_initial_domain())
-		return -ENODEV;
-
-	/* just reserve space for Xen, block native driver loaded */
-	return acpi_bus_register_driver(&xen_stub_processor_driver);
-}
-EXPORT_SYMBOL_GPL(xen_stub_processor_init);
-subsys_initcall(xen_stub_processor_init);
-
-void xen_stub_processor_exit(void)
-{
-	acpi_bus_unregister_driver(&xen_stub_processor_driver);
-}
-EXPORT_SYMBOL_GPL(xen_stub_processor_exit);
-
-#endif

include/xen/acpi.h

@@ -40,41 +40,6 @@
 #include <xen/xen.h>
 #include <linux/acpi.h>
 
-#define ACPI_MEMORY_DEVICE_CLASS        "memory"
-#define ACPI_MEMORY_DEVICE_HID          "PNP0C80"
-#define ACPI_MEMORY_DEVICE_NAME         "Hotplug Mem Device"
-
-int xen_stub_memory_device_init(void);
-void xen_stub_memory_device_exit(void);
-
-#define ACPI_PROCESSOR_CLASS            "processor"
-#define ACPI_PROCESSOR_DEVICE_HID       "ACPI0007"
-#define ACPI_PROCESSOR_DEVICE_NAME      "Processor"
-
-int xen_stub_processor_init(void);
-void xen_stub_processor_exit(void);
-
-void xen_pcpu_hotplug_sync(void);
-int xen_pcpu_id(uint32_t acpi_id);
-
-static inline int xen_acpi_get_pxm(acpi_handle h)
-{
-	unsigned long long pxm;
-	acpi_status status;
-	acpi_handle handle;
-	acpi_handle phandle = h;
-
-	do {
-		handle = phandle;
-		status = acpi_evaluate_integer(handle, "_PXM", NULL, &pxm);
-		if (ACPI_SUCCESS(status))
-			return pxm;
-		status = acpi_get_parent(handle, &phandle);
-	} while (ACPI_SUCCESS(status));
-
-	return -ENXIO;
-}
-
 int xen_acpi_notify_hypervisor_sleep(u8 sleep_state,
 				     u32 pm1a_cnt, u32 pm1b_cnd);
 int xen_acpi_notify_hypervisor_extended_sleep(u8 sleep_state,