[PATCH 6.1 131/215] x86/decompressor: Assign paging related global variables earlier

Greg Kroah-Hartman
2024-03-04T21:48:25Z

From: Ard Biesheuvel <ardb@kernel.org>

commit 00c6b0978ec182f1a672095930872168b9d5b1e2 upstream.

There is no need to defer the assignment of the paging related global
variables 'pgdir_shift' and 'ptrs_per_p4d' until after the trampoline is
cleaned up, so assign them as soon as it is clear that 5-level paging
will be enabled.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230807162720.545787-9-ardb@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/boot/compressed/misc.h | 2 --
arch/x86/boot/compressed/pgtable_64.c | 14 +++++---------
2 files changed, 5 insertions(+), 11 deletions(-)

--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -170,9 +170,7 @@ static inline int count_immovable_mem_re
#endif

/* ident_map_64.c */
-#ifdef CONFIG_X86_5LEVEL
extern unsigned int __pgtable_l5_enabled, pgdir_shift, ptrs_per_p4d;
-#endif
extern void kernel_add_identity_map(unsigned long start, unsigned long end);

/* Used by PAGE_KERN* macros: */
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -130,6 +130,11 @@ struct paging_config paging_prepare(void
native_cpuid_eax(0) >= 7 &&
(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) {
paging_config.l5_required = 1;
+
+ /* Initialize variables for 5-level paging */
+ __pgtable_l5_enabled = 1;
+ pgdir_shift = 48;
+ ptrs_per_p4d = 512;
}

paging_config.trampoline_start = find_trampoline_placement();
@@ -206,13 +211,4 @@ void cleanup_trampoline(void *pgtable)

/* Restore trampoline memory */
memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);
-
- /* Initialize variables for 5-level paging */
-#ifdef CONFIG_X86_5LEVEL
- if (__read_cr4() & X86_CR4_LA57) {
- __pgtable_l5_enabled = 1;
- pgdir_shift = 48;
- ptrs_per_p4d = 512;
- }
-#endif
}