linux-kernel - [PATCH 2/3] x86/64/mm: Make SPARSEMEM

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Date: Fri, 21 Jun 2024 19:44:05 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>
Cc: Jonathan Corbet <corbet@....net>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ard Biesheuvel <ardb@...nel.org>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Kieran Bingham <kbingham@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Michael Roth <michael.roth@....com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Brijesh Singh <brijesh.singh@....com>,
	Sandipan Das <sandipan.das@....com>,
	Juergen Gross <jgross@...e.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-efi@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH 2/3] x86/64/mm: Make SPARSEMEM_VMEMMAP the only memory model

5-level paging only supports SPARSEMEM_VMEMMAP. CONFIG_X86_5LEVEL is
being phased out, making 5-level paging support mandatory.

Make CONFIG_SPARSEMEM_VMEMMAP mandatory for x86-64 and eliminate
any associated conditional statements.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/Kconfig      | 2 +-
 arch/x86/mm/init_64.c | 9 +--------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 827928680ed6..54ad2462e9ef 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1501,7 +1501,6 @@ config X86_PAE
 config X86_5LEVEL
 	bool "Enable 5-level page tables support"
 	default y
-	select SPARSEMEM_VMEMMAP
 	depends on X86_64
 	help
 	  5-level paging enables access to larger address space:
@@ -1625,6 +1624,7 @@ config ARCH_SPARSEMEM_ENABLE
 	depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
 	select SPARSEMEM_STATIC if X86_32
 	select SPARSEMEM_VMEMMAP_ENABLE if X86_64
+	select SPARSEMEM_VMEMMAP if X86_64
 
 config ARCH_SPARSEMEM_DEFAULT
 	def_bool X86_64 || (NUMA && X86_32)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 28002cc7a37d..552a11d5829a 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -835,7 +835,6 @@ void __init paging_init(void)
 	zone_sizes_init();
 }
 
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
 #define PAGE_UNUSED 0xFD
 
 /*
@@ -934,7 +933,6 @@ static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long
 	if (!IS_ALIGNED(end, PMD_SIZE))
 		unused_pmd_start = end;
 }
-#endif
 
 /*
  * Memory hotplug specific functions
@@ -1133,16 +1131,13 @@ remove_pmd_table(pmd_t *pmd_start, unsigned long addr, unsigned long end,
 				pmd_clear(pmd);
 				spin_unlock(&init_mm.page_table_lock);
 				pages++;
-			}
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
-			else if (vmemmap_pmd_is_unused(addr, next)) {
+			} else if (vmemmap_pmd_is_unused(addr, next)) {
 					free_hugepage_table(pmd_page(*pmd),
 							    altmap);
 					spin_lock(&init_mm.page_table_lock);
 					pmd_clear(pmd);
 					spin_unlock(&init_mm.page_table_lock);
 			}
-#endif
 			continue;
 		}
 
@@ -1490,7 +1485,6 @@ unsigned long memory_block_size_bytes(void)
 	return memory_block_size_probed;
 }
 
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
 /*
  * Initialise the sparsemem vmemmap using huge-pages at the PMD level.
  */
@@ -1639,4 +1633,3 @@ void __meminit vmemmap_populate_print_last(void)
 		node_start = 0;
 	}
 }
-#endif
-- 
2.43.0