[PATCH 1/2] mm: s390: Only notify on 4k pages

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

Let's try this

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
 arch/s390/include/asm/gmap.h |  5 ++-
 arch/s390/mm/gmap.c          | 72 ++++++++------------------------------------
 2 files changed, 14 insertions(+), 63 deletions(-)

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index 6287aca..4120360 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -13,9 +13,8 @@
 #define GMAP_NOTIFY_SHADOW	0x2
 #define GMAP_NOTIFY_MPROT	0x1
 
-/* Status bits in huge and non-huge gmap segment entries. */
-#define _SEGMENT_ENTRY_GMAP_IN		0x0001	/* invalidation notify bit */
-#define _SEGMENT_ENTRY_GMAP_SPLIT	0x0002  /* split huge pmd */
+/* Status bit in huge and non-huge gmap segment entries. */
+#define _SEGMENT_ENTRY_GMAP_SPLIT	0x0001  /* split huge pmd */
 /* Status bits only for huge segment entries */
 #define _SEGMENT_ENTRY_GMAP_UC		0x4000	/* user dirty (migration) */
 #define _SEGMENT_ENTRY_GMAP_VSIE	0x8000	/* vsie bit */
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 10e0690..c47964f 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -998,7 +998,7 @@ static void gmap_pte_transfer_prot(struct mm_struct *mm, unsigned long addr,
  * and requested access rights are incompatible.
  */
 static int gmap_pmdp_force_prot(struct gmap *gmap, unsigned long addr,
-				pmd_t *pmdp, int prot, unsigned long bits)
+				pmd_t *pmdp, int prot)
 {
 	int pmd_i = pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID;
 	int pmd_p = pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT;
@@ -1018,7 +1018,6 @@ static int gmap_pmdp_force_prot(struct gmap *gmap, unsigned long addr,
 		pmd_val(new) |= _SEGMENT_ENTRY_PROTECT;
 		gmap_pmdp_xchg(gmap, pmdp, new, addr);
 	}
-	pmd_val(*pmdp) |=  bits;
 	return 0;
 }
 
@@ -1136,21 +1135,18 @@ static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
 			    unsigned long vmaddr, pmd_t *pmdp, pmd_t *hpmdp,
 			    int prot, unsigned long bits)
 {
-	unsigned long sbits = 0;
 	int ret = 0;
 
-	sbits |= (bits & GMAP_NOTIFY_MPROT) ? _SEGMENT_ENTRY_GMAP_IN : 0;
-	sbits |= (bits & GMAP_NOTIFY_SHADOW) ? _SEGMENT_ENTRY_GMAP_VSIE : 0;
-
-	if (((prot != PROT_WRITE) && (bits & GMAP_NOTIFY_SHADOW))) {
+	/* We notify only on the smallest possible frame size, a 4k page. */
+	if (bits) {
 		ret = gmap_pmd_split(gmap, gaddr, pmdp);
 		if (ret)
 			return ret;
 		return -EFAULT;
 	}
 
-	/* Protect gmap pmd */
-	ret = gmap_pmdp_force_prot(gmap, gaddr, pmdp, prot, sbits);
+	/* Protect gmap pmd for dirty tracking. */
+	ret = gmap_pmdp_force_prot(gmap, gaddr, pmdp, prot);
 	/*
 	 * Transfer protection back to the host pmd, so userspace has
 	 * never more access rights than the VM.
@@ -1167,7 +1163,7 @@ static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
  * @gaddr: virtual address in the guest address space
  * @len: size of area
  * @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
  * -EFAULT if gaddr is invalid (or mapping for shadows is missing).
@@ -1196,11 +1192,6 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
 		pmdp = gmap_pmd_op_walk(gmap, gaddr);
 		if (pmdp) {
 			if (!pmd_large(*pmdp)) {
-				if (gmap_pmd_is_split(pmdp) &&
-				    (bits & GMAP_NOTIFY_MPROT)) {
-					pmd_val(*pmdp) |= _SEGMENT_ENTRY_GMAP_IN;
-				}
-
 				rc = gmap_protect_pte(gmap, gaddr, vmaddr,
 						      pmdp, hpmdp, prot, bits);
 				if (!rc) {
@@ -2562,53 +2553,20 @@ static void gmap_shadow_notify_pmd(struct gmap *sg, unsigned long vmaddr,
 				   unsigned long gaddr)
 {
 	struct gmap_rmap *rmap, *rnext, *head;
-	unsigned long start, end, bits, raddr;
+	unsigned long bits, raddr;
 
 
 	BUG_ON(!gmap_is_shadow(sg));
 
 	spin_lock_nested(&sg->guest_table_lock, GMAP_LOCK_SHADOW);
-	if (sg->removed) {
-		spin_unlock(&sg->guest_table_lock);
-		return;
-	}
-	/* Check for top level table */
-	start = sg->orig_asce & _ASCE_ORIGIN;
-	end = start + ((sg->orig_asce & _ASCE_TABLE_LENGTH) + 1) * 4096;
-	if (!(sg->orig_asce & _ASCE_REAL_SPACE) && gaddr >= start &&
-	    gaddr < ((end & HPAGE_MASK) + HPAGE_SIZE - 1)) {
-		/* The complete shadow table has to go */
-		gmap_unshadow(sg);
-		spin_unlock(&sg->guest_table_lock);
-		list_del(&sg->list);
-		gmap_put(sg);
-		return;
-	}
-	/* Remove the page table tree from on specific entry */
 	head = radix_tree_delete(&sg->host_to_rmap, (vmaddr & HPAGE_MASK) >> PAGE_SHIFT);
 	gmap_for_each_rmap_safe(rmap, rnext, head) {
 		bits = rmap->raddr & _SHADOW_RMAP_MASK;
 		raddr = rmap->raddr ^ bits;
-		switch (bits) {
-		case _SHADOW_RMAP_REGION1:
-			gmap_unshadow_r2t(sg, raddr);
-			break;
-		case _SHADOW_RMAP_REGION2:
-			gmap_unshadow_r3t(sg, raddr);
-			break;
-		case _SHADOW_RMAP_REGION3:
-			gmap_unshadow_sgt(sg, raddr);
-			break;
-		case _SHADOW_RMAP_SEGMENT_LP:
+		if (bits ==  _SHADOW_RMAP_SEGMENT_LP)
 			gmap_unshadow_segment(sg, raddr);
-			break;
-		case _SHADOW_RMAP_SEGMENT:
-			gmap_unshadow_pgt(sg, raddr);
-			break;
-		case _SHADOW_RMAP_PGTABLE:
-			gmap_unshadow_page(sg, raddr);
-			break;
-		}
+		else
+			BUG_ON(1);
 		kfree(rmap);
 	}
 	spin_unlock(&sg->guest_table_lock);
@@ -2777,9 +2735,8 @@ static void pmdp_notify_gmap(struct gmap *gmap, unsigned long gaddr)
 	table = gmap_table_walk(gmap, gaddr, 1);
 	if (!table)
 		return;
-	bits = *table & _SEGMENT_ENTRY_GMAP_IN;
 	if (pmd_large(__pmd(*table)) && (*table & _SEGMENT_ENTRY_GMAP_VSIE))
-		bits |= _SEGMENT_ENTRY_GMAP_VSIE;
+		bits = _SEGMENT_ENTRY_GMAP_VSIE;
 	if (!bits)
 		return;
 	*table &= ~bits;
@@ -2792,8 +2749,6 @@ static void pmdp_notify_gmap(struct gmap *gmap, unsigned long gaddr)
 			gmap_shadow_notify_pmd(sg, vmaddr, gaddr);
 		spin_unlock(&gmap->shadow_lock);
 	}
-	if (bits & _SEGMENT_ENTRY_GMAP_IN)
-		gmap_call_notifier(gmap, gaddr, gaddr + HPAGE_SIZE - 1);
 }
 
 static void pmdp_notify_split(struct mm_struct *mm, unsigned long vmaddr,
@@ -2841,9 +2796,8 @@ void pmdp_notify(struct mm_struct *mm, unsigned long vmaddr)
 			continue;
 		}
 
-		bits = *table & (_SEGMENT_ENTRY_GMAP_IN);
 		if (pmd_large(__pmd(*table)) && (*table & _SEGMENT_ENTRY_GMAP_VSIE))
-			bits |= _SEGMENT_ENTRY_GMAP_VSIE;
+			bits = _SEGMENT_ENTRY_GMAP_VSIE;
 		*table &= ~bits;
 		gaddr = __gmap_segment_gaddr(table);
 		spin_unlock(&gmap->guest_table_lock);
@@ -2854,8 +2808,6 @@ void pmdp_notify(struct mm_struct *mm, unsigned long vmaddr)
 				gmap_shadow_notify_pmd(sg, vmaddr, gaddr);
 			spin_unlock(&gmap->shadow_lock);
 		}
-		if (bits & _SEGMENT_ENTRY_GMAP_IN)
-			gmap_call_notifier(gmap, gaddr, gaddr + HPAGE_SIZE - 1);
 	}
 	rcu_read_unlock();
 }
-- 
2.7.4