[RFC/PATCH v3 02/16] s390/mm: Abstract gmap notify bit setting

[Janosch Frank <frankja@linux.vnet.ibm.com>]

Currently we use the software PGSTE bits PGSTE_IN_BIT and PGSTE_VSIE_BIT
to notify before an invalidation occurs on a prefix page or a VSIE page
respectively. Both bits only work for a PGSTE, which only exists for
page tables.

For huge page support we also need such bits for segments (pmds) so
let's introduce abstract GMAP_NOTIFY_* bits that will be realized into
the respective bits when gmap DAT table entries are protected.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 arch/s390/include/asm/gmap.h |  4 ++++
 arch/s390/mm/gmap.c          | 13 ++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index e07cce8..c1bc563 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -9,6 +9,10 @@
 #ifndef _ASM_S390_GMAP_H
 #define _ASM_S390_GMAP_H
 
+/* Generic bits for GMAP notification on DAT table entry changes. */
+#define GMAP_NOTIFY_SHADOW	0x2
+#define GMAP_NOTIFY_MPROT	0x1
+
 /**
  * struct gmap_struct - guest address space
  * @list: list head for the mm->context gmap list
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 549a55f..4471cb9 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -922,7 +922,7 @@ static inline void gmap_pmd_op_end(struct gmap *gmap, pmd_t *pmdp)
  * @gaddr: virtual address in the guest address space
  * @pmdp: pointer to the pmd associated with the pte
  * @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
- * @bits: pgste notification bits to set
+ * @bits: notification bits to set
  *
  * Returns 0 if successfully protected, -ENOMEM if out of memory and
  * -EAGAIN if a fixup is needed.
@@ -936,13 +936,16 @@ static int gmap_protect_pte(struct gmap *gmap, unsigned long gaddr,
 	int rc;
 	pte_t *ptep;
 	spinlock_t *ptl = NULL;
+	unsigned long pbits = 0;
 
 	ptep = pte_alloc_map_lock(gmap->mm, pmdp, gaddr, &ptl);
 	if (!ptep)
 		return -ENOMEM;
 
+	pbits |= (bits & GMAP_NOTIFY_MPROT) ? PGSTE_IN_BIT : 0;
+	pbits |= (bits & GMAP_NOTIFY_SHADOW) ? PGSTE_VSIE_BIT : 0;
 	/* Protect and unlock. */
-	rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, bits);
+	rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, pbits);
 	gmap_pte_op_end(ptl);
 	return rc;
 }
@@ -1017,7 +1020,7 @@ int gmap_mprotect_notify(struct gmap *gmap, unsigned long gaddr,
 	if (!MACHINE_HAS_ESOP && prot == PROT_READ)
 		return -EINVAL;
 	down_read(&gmap->mm->mmap_sem);
-	rc = gmap_protect_range(gmap, gaddr, len, prot, PGSTE_IN_BIT);
+	rc = gmap_protect_range(gmap, gaddr, len, prot, GMAP_NOTIFY_MPROT);
 	up_read(&gmap->mm->mmap_sem);
 	return rc;
 }
@@ -1139,7 +1142,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
 		if (ptep) {
 			spin_lock(&sg->guest_table_lock);
 			rc = ptep_force_prot(parent->mm, paddr, ptep, prot,
-					     PGSTE_VSIE_BIT);
+					     GMAP_NOTIFY_SHADOW);
 			if (!rc)
 				gmap_insert_rmap(sg, vmaddr, rmap);
 			spin_unlock(&sg->guest_table_lock);
@@ -1605,7 +1608,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
 	down_read(&parent->mm->mmap_sem);
 	rc = gmap_protect_range(parent, asce & _ASCE_ORIGIN,
 				((asce & _ASCE_TABLE_LENGTH) + 1) * PAGE_SIZE,
-				PROT_READ, PGSTE_VSIE_BIT);
+				PROT_READ, GMAP_NOTIFY_SHADOW);
 	up_read(&parent->mm->mmap_sem);
 	spin_lock(&parent->shadow_lock);
 	new->initialized = true;
-- 
2.7.4