diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2018-02-14 21:25:42 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-02-16 10:48:49 +0100 |
| commit | 6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 (patch) | |
| tree | 974d247b3c7459a2d595cc837d69ab84f57913a5 /arch | |
| parent | 91f606a8fa68264224cbc76888fa8649cdbe9990 (diff) | |
x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y
All pieces of the puzzle are in place and we can now allow to boot with
CONFIG_X86_5LEVEL=y on a machine without LA57 support.
Kernel will detect that LA57 is missing and fold p4d at runtime.
Update the documentation and the Kconfig option description to reflect the
change.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214182542.69302-10-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/Kconfig | 4 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/misc.c | 16 | ||||
| -rw-r--r-- | arch/x86/include/asm/required-features.h | 8 |
3 files changed, 3 insertions, 25 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index fcc3f88996b3..1c4f7b6a94f4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1440,8 +1440,8 @@ config X86_5LEVEL It will be supported by future Intel CPUs. - Note: a kernel with this option enabled can only be booted - on machines that support the feature. + A kernel with the option enabled can be booted on machines that + support 4- or 5-level paging. See Documentation/x86/x86_64/5level-paging.txt for more information. diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 98761a1576ce..b50c42455e25 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -169,16 +169,6 @@ void __puthex(unsigned long value) } } -static bool l5_supported(void) -{ - /* Check if leaf 7 is supported. */ - if (native_cpuid_eax(0) < 7) - return 0; - - /* Check if la57 is supported. */ - return native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)); -} - #if CONFIG_X86_NEED_RELOCS static void handle_relocations(void *output, unsigned long output_len, unsigned long virt_addr) @@ -372,12 +362,6 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, console_init(); debug_putstr("early console in extract_kernel\n"); - if (IS_ENABLED(CONFIG_X86_5LEVEL) && !l5_supported()) { - error("This linux kernel as configured requires 5-level paging\n" - "This CPU does not support the required 'cr4.la57' feature\n" - "Unable to boot - please use a kernel appropriate for your CPU\n"); - } - free_mem_ptr = heap; /* Heap */ free_mem_end_ptr = heap + BOOT_HEAP_SIZE; diff --git a/arch/x86/include/asm/required-features.h b/arch/x86/include/asm/required-features.h index fb3a6de7440b..6847d85400a8 100644 --- a/arch/x86/include/asm/required-features.h +++ b/arch/x86/include/asm/required-features.h @@ -53,12 +53,6 @@ # define NEED_MOVBE 0 #endif -#ifdef CONFIG_X86_5LEVEL -# define NEED_LA57 (1<<(X86_FEATURE_LA57 & 31)) -#else -# define NEED_LA57 0 -#endif - #ifdef CONFIG_X86_64 #ifdef CONFIG_PARAVIRT /* Paravirtualized systems may not have PSE or PGE available */ @@ -104,7 +98,7 @@ #define REQUIRED_MASK13 0 #define REQUIRED_MASK14 0 #define REQUIRED_MASK15 0 -#define REQUIRED_MASK16 (NEED_LA57) +#define REQUIRED_MASK16 0 #define REQUIRED_MASK17 0 #define REQUIRED_MASK18 0 #define REQUIRED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 19) |