x86/mm: Replace compile-time checks for 5-level paging with runtime-time checks

This patch converts the of CONFIG_X86_5LEVEL check to runtime checks for
p4d folding.

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/20180214182542.69302-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 10 insertions, 13 deletions

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 81462e9a34f6..81dda8d1d0bd 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -217,29 +217,26 @@ static inline pgd_t pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
 
 static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
 {
-#if defined(CONFIG_PAGE_TABLE_ISOLATION) && !defined(CONFIG_X86_5LEVEL)
-	p4dp->pgd = pti_set_user_pgd(&p4dp->pgd, p4d.pgd);
-#else
-	*p4dp = p4d;
-#endif
+	pgd_t pgd;
+
+	if (pgtable_l5_enabled || !IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION)) {
+		*p4dp = p4d;
+		return;
+	}
+
+	pgd = native_make_pgd(p4d_val(p4d));
+	pgd = pti_set_user_pgd((pgd_t *)p4dp, pgd);
+	*p4dp = native_make_p4d(pgd_val(pgd));
 }
 
 static inline void native_p4d_clear(p4d_t *p4d)
 {
-#ifdef CONFIG_X86_5LEVEL
 	native_set_p4d(p4d, native_make_p4d(0));
-#else
-	native_set_p4d(p4d, (p4d_t) { .pgd = native_make_pgd(0)});
-#endif
 }
 
 static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
 {
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
 	*pgdp = pti_set_user_pgd(pgdp, pgd);
-#else
-	*pgdp = pgd;
-#endif
 }
 
 static inline void native_pgd_clear(pgd_t *pgd)