x86: remove memory hotplug support on X86_32

CONFIG_MEMORY_HOTPLUG was marked BROKEN over one year and we just
restricted it to 64 bit.  Let's remove the unused x86 32bit
implementation and simplify the Kconfig.

Link: https://lkml.kernel.org/r/20210929143600.49379-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/Kconfig

@@ -62,7 +62,7 @@ config X86
 	select ARCH_32BIT_OFF_T			if X86_32
 	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
-	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
+	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
 	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
 	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
@@ -1614,7 +1614,7 @@ config ARCH_SELECT_MEMORY_MODEL
 
 config ARCH_MEMORY_PROBE
 	bool "Enable sysfs memory/probe interface"
-	depends on X86_64 && MEMORY_HOTPLUG
+	depends on MEMORY_HOTPLUG
 	help
 	  This option enables a sysfs memory/probe interface for testing.
 	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
@@ -2394,7 +2394,7 @@ endmenu
 
 config ARCH_HAS_ADD_PAGES
 	def_bool y
-	depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
+	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 
 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 	def_bool y

arch/x86/mm/init_32.c

@@ -779,37 +779,6 @@ void __init mem_init(void)
 	test_wp_bit();
 }
 
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size,
-		    struct mhp_params *params)
-{
-	unsigned long start_pfn = start >> PAGE_SHIFT;
-	unsigned long nr_pages = size >> PAGE_SHIFT;
-	int ret;
-
-	/*
-	 * The page tables were already mapped at boot so if the caller
-	 * requests a different mapping type then we must change all the
-	 * pages with __set_memory_prot().
-	 */
-	if (params->pgprot.pgprot != PAGE_KERNEL.pgprot) {
-		ret = __set_memory_prot(start, nr_pages, params->pgprot);
-		if (ret)
-			return ret;
-	}
-
-	return __add_pages(nid, start_pfn, nr_pages, params);
-}
-
-void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
-{
-	unsigned long start_pfn = start >> PAGE_SHIFT;
-	unsigned long nr_pages = size >> PAGE_SHIFT;
-
-	__remove_pages(start_pfn, nr_pages, altmap);
-}
-#endif
-
 int kernel_set_to_readonly __read_mostly;
 
 static void mark_nxdata_nx(void)