pgtable_l5_enabled indicates which paging mode we are using. We need to
initialize it at boot-time according to machine capability.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/kaslr.c | 8 +++++++-
arch/x86/kernel/head64.c | 24 +++++++++++++++++++++++-
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index b18e8f9512de..d02a838c0ce4 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -47,7 +47,7 @@
#include <linux/decompress/mm.h>
#ifdef CONFIG_X86_5LEVEL
-unsigned int pgtable_l5_enabled __ro_after_init = 1;
+unsigned int pgtable_l5_enabled __ro_after_init;
unsigned int pgdir_shift __ro_after_init = 48;
unsigned int ptrs_per_p4d __ro_after_init = 512;
#endif
@@ -729,6 +729,12 @@ void choose_random_location(unsigned long input,
return;
}
+#ifdef CONFIG_X86_5LEVEL
+ if (__read_cr4() & X86_CR4_LA57) {
+ pgtable_l5_enabled = 1;
+ }
+#endif
+
boot_params->hdr.loadflags |= KASLR_FLAG;
/* Prepare to add new identity pagetables on demand. */
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 98b0ff49b220..ffb31c50d515 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,7 +40,7 @@ static unsigned int __initdata next_early_pgt;
pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
#ifdef CONFIG_X86_5LEVEL
-unsigned int pgtable_l5_enabled __ro_after_init = 1;
+unsigned int pgtable_l5_enabled __ro_after_init;
EXPORT_SYMBOL(pgtable_l5_enabled);
unsigned int pgdir_shift __ro_after_init = 48;
EXPORT_SYMBOL(pgdir_shift);
@@ -64,6 +64,26 @@ static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
return ptr - (void *)_text + (void *)physaddr;
}
+#ifdef CONFIG_X86_5LEVEL
+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)
+{
+ if (native_cpuid_eax(0) < 7)
+ return;
+
+ if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
+ return;
+
+ *fixup_int(&pgtable_l5_enabled, physaddr) = 1;
+}
+#else
+static void __head check_la57_support(unsigned long physaddr) {}
+#endif
+
unsigned long __head __startup_64(unsigned long physaddr,
struct boot_params *bp)
{
@@ -76,6 +96,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
int i;
unsigned int *next_pgt_ptr;
+ check_la57_support(physaddr);
+
/* Is the address too large? */
if (physaddr >> MAX_PHYSMEM_BITS)
for (;;);
--
2.15.1
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