mm: Change CONFIG option for mm->pasid field

This currently depends on CONFIG_IOMMU_SUPPORT. But it is only
needed when CONFIG_IOMMU_SVA option is enabled.

Change the CONFIG guards around definition and initialization
of mm->pasid field.

Suggested-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20220207230254.3342514-3-fenghua.yu@intel.com

include/linux/mm_types.h

@@ -631,7 +631,7 @@ struct mm_struct {
 #endif
 		struct work_struct async_put_work;
 
-#ifdef CONFIG_IOMMU_SUPPORT
+#ifdef CONFIG_IOMMU_SVA
 		u32 pasid;
 #endif
 	} __randomize_layout;

kernel/fork.c

@@ -1021,7 +1021,7 @@ static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 
 static void mm_init_pasid(struct mm_struct *mm)
 {
-#ifdef CONFIG_IOMMU_SUPPORT
+#ifdef CONFIG_IOMMU_SVA
 	mm->pasid = INIT_PASID;
 #endif
 }