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[PATCHv7 13/19] x86/mm: Make early boot code support boot-time switching of paging modes

From "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Newsgroups linux.kernel
Subject [PATCHv7 13/19] x86/mm: Make early boot code support boot-time switching of paging modes
Date 2017-09-18 13:00 +0200
Message-ID <ur1Wr-5gk-35@gated-at.bofh.it> (permalink)
References <ur1Wp-5gk-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Early boot code, that setup page table should be able to initialize page
tables for both 4- and 5-level paging modes.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/kernel/head64.c  | 33 ++++++++++++++++++++++-----------
 arch/x86/kernel/head_64.S | 10 ++++------
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2dabb2d1b64b..617b42c9bdbb 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -74,13 +74,13 @@ static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
 	return fixup_pointer(ptr, physaddr);
 }
 
-static void __head check_la57_support(unsigned long physaddr)
+static bool __head check_la57_support(unsigned long physaddr)
 {
 	if (native_cpuid_eax(0) < 7)
-		return;
+		return false;
 
 	if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
-		return;
+		return false;
 
 	*fixup_int(&pgtable_l5_enabled, physaddr) = 1;
 	*fixup_int(&pgdir_shift, physaddr) = 48;
@@ -88,24 +88,30 @@ static void __head check_la57_support(unsigned long physaddr)
 	*fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE57;
 	*fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE57;
 	*fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE57;
+
+	return true;
 }
 #else
-static void __head check_la57_support(unsigned long physaddr) {}
+static bool __head check_la57_support(unsigned long physaddr)
+{
+	return false;
+}
 #endif
 
 unsigned long __head __startup_64(unsigned long physaddr,
 				  struct boot_params *bp)
 {
-	unsigned long load_delta;
+	unsigned long load_delta, *p;
 	unsigned long pgtable_flags;
 	pgdval_t *pgd;
 	p4dval_t *p4d;
 	pudval_t *pud;
 	pmdval_t *pmd, pmd_entry;
+	bool la57;
 	int i;
 	unsigned int *next_pgt_ptr;
 
-	check_la57_support(physaddr);
+	la57 = check_la57_support(physaddr);
 
 	/* Is the address too large? */
 	if (physaddr >> MAX_PHYSMEM_BITS)
@@ -130,9 +136,14 @@ unsigned long __head __startup_64(unsigned long physaddr,
 	/* Fixup the physical addresses in the page table */
 
 	pgd = fixup_pointer(&early_top_pgt, physaddr);
-	pgd[pgd_index(__START_KERNEL_map)] += load_delta;
-
-	if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+	p = pgd + pgd_index(__START_KERNEL_map);
+	if (la57)
+		*p = (unsigned long)level4_kernel_pgt;
+	else
+		*p = (unsigned long)level3_kernel_pgt;
+	*p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
+
+	if (la57) {
 		p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
 		p4d[511] += load_delta;
 	}
@@ -157,7 +168,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
 
 	pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 
-	if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+	if (la57) {
 		p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 
 		i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
@@ -254,7 +265,7 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 	 * critical -- __PAGE_OFFSET would point us back into the dynamic
 	 * range and we might end up looping forever...
 	 */
-	if (!IS_ENABLED(CONFIG_X86_5LEVEL))
+	if (!pgtable_l5_enabled)
 		p4d_p = pgd_p;
 	else if (pgd)
 		p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index a8409cd23b35..49f8bb43d107 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -121,7 +121,10 @@ ENTRY(secondary_startup_64)
 	/* Enable PAE mode, PGE and LA57 */
 	movl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
 #ifdef CONFIG_X86_5LEVEL
+	testl	$1, pgtable_l5_enabled(%rip)
+	jz	1f
 	orl	$X86_CR4_LA57, %ecx
+1:
 #endif
 	movq	%rcx, %cr4
 
@@ -350,12 +353,7 @@ GLOBAL(name)
 
 	__INITDATA
 NEXT_PAGE(early_top_pgt)
-	.fill	511,8,0
-#ifdef CONFIG_X86_5LEVEL
-	.quad	level4_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
-#else
-	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
-#endif
+	.fill	512,8,0
 
 NEXT_PAGE(early_dynamic_pgts)
 	.fill	512*EARLY_DYNAMIC_PAGE_TABLES,8,0
-- 
2.14.1

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Thread

[PATCHv7 00/19] Boot-time switching between 4- and 5-level paging for 4.15 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 18/19] x86/mm: Redefine some of page table helpers as macros "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 14/19] x86/mm: Fold p4d page table layer at runtime "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 16/19] x86/mm: Allow to boot without la57 if CONFIG_X86_5LEVEL=y "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 10/19] x86/mm: Make __PHYSICAL_MASK_SHIFT and __VIRTUAL_MASK_SHIFT dynamic "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 13/19] x86/mm: Make early boot code support boot-time switching of paging modes "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 06/19] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 04/19] x86/xen: Provide pre-built page tables only for XEN_PV and XEN_PVH "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 08/19] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
    Re: [PATCHv7 08/19] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D  variable "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-19 16:10 +0200
  [PATCHv7 19/19] x86/mm: Offset boot-time paging mode switching cost "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:00 +0200
  [PATCHv7 09/19] x86/mm: Make MAX_PHYSADDR_BITS and MAX_PHYSMEM_BITS dynamic "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  [PATCHv7 01/19] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  [PATCHv7 11/19] x86/mm: Make STACK_TOP_MAX dynamic "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  [PATCHv7 03/19] x86/kasan: Use the same shadow offset for 4- and 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  [PATCHv7 02/19] mm/zsmalloc: Prepare to variable MAX_PHYSMEM_BITS "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in early boot. "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-09-18 13:10 +0200
  Re: [PATCHv7 00/19] Boot-time switching between 4- and 5-level  paging for 4.15 "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-09-25 15:20 +0200

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