Merge tag 'for-4.15/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device...

[sfrench/cifs-2.6.git] / arch / x86 / boot / compressed / misc.c

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b50c42455e25257bff89dd2d9d5f23534340076e..98761a1576ceb5c21b2d8c7e98c1217fd48abb26 100644 (file)
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -169,6 +169,16 @@ 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)
@@ -362,6 +372,12 @@ 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;