linux-kernel - [PATCH v1 6/6] x86: remove memory hotplug support on X86

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Message-Id: <20210929143600.49379-7-david@redhat.com>
Date:   Wed, 29 Sep 2021 16:36:00 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>, Alex Shi <alexs@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Shuah Khan <shuah@...nel.org>, Michal Hocko <mhocko@...e.com>,
        Oscar Salvador <osalvador@...e.de>,
        Mike Rapoport <rppt@...nel.org>, x86@...nel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH v1 6/6] 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.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/x86/Kconfig      |  6 +++---
 arch/x86/mm/init_32.c | 31 -------------------------------
 2 files changed, 3 insertions(+), 34 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ab83c22d274e..85f4762429f1 100644
--- a/arch/x86/Kconfig
+++ b/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
@@ -1615,7 +1615,7 @@ 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.
@@ -2395,7 +2395,7 @@ 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
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index bd90b8fe81e4..5cd7ea6d645c 100644
--- a/arch/x86/mm/init_32.c
+++ b/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)
-- 
2.31.1