s390/mm: Allow large pages only for aligned physical addresses

Do not allow creation of large pages against physical addresses,
which itself are not aligned on the correct boundary. Failure to
do so might lead to referencing wrong memory as result of the way
DAT works.

Fixes: c98d2ec ("s390/mm: Uncouple physical vs virtual address spaces")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: Alexander Gordeev

arch/s390/boot/vmem.c

@@ -267,15 +267,21 @@ static bool large_allowed(enum populate_mode mode)
 static bool can_large_pud(pud_t *pu_dir, unsigned long addr, unsigned long end,
 			  enum populate_mode mode)
 {
+	unsigned long size = end - addr;
+
 	return machine.has_edat2 && large_allowed(mode) &&
-	       IS_ALIGNED(addr, PUD_SIZE) && (end - addr) >= PUD_SIZE;
+	       IS_ALIGNED(addr, PUD_SIZE) && (size >= PUD_SIZE) &&
+	       IS_ALIGNED(_pa(addr, size, mode), PUD_SIZE);
 }
 
 static bool can_large_pmd(pmd_t *pm_dir, unsigned long addr, unsigned long end,
 			  enum populate_mode mode)
 {
+	unsigned long size = end - addr;
+
 	return machine.has_edat1 && large_allowed(mode) &&
-	       IS_ALIGNED(addr, PMD_SIZE) && (end - addr) >= PMD_SIZE;
+	       IS_ALIGNED(addr, PMD_SIZE) && (size >= PMD_SIZE) &&
+	       IS_ALIGNED(_pa(addr, size, mode), PMD_SIZE);
 }
 
 static void pgtable_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long end,