From: Janosch Frank <frankja@linux.ibm.com>
Subject: s390/mm: Abstract gmap notify bit setting
Patch-mainline: v4.19-rc1
Git-commit: 2c46e974dd8b5316e65637af0ff6d4bc78554b2e
References: FATE#326372, LTC#169184, bsc#1113484

Summary:     kernel: Introduce huge page KVM backing support
Description: This adds the KVM support for libhugetlbfs backings of
             s390 KVM guests.

Upstream-Description:

             s390/mm: Abstract gmap notify bit setting

             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 are pgste specific, but
             are used when protecting a memory range.

             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>

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/include/asm/gmap.h |    4 ++++
 arch/s390/mm/gmap.c          |   11 +++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -8,6 +8,10 @@
 #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
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -918,7 +918,7 @@ static inline void gmap_pmd_op_end(struc
  * @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.
@@ -931,6 +931,7 @@ static int gmap_protect_pte(struct gmap
 	int rc;
 	pte_t *ptep;
 	spinlock_t *ptl = NULL;
+	unsigned long pbits = 0;
 
 	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
 		return -EAGAIN;
@@ -939,8 +940,10 @@ static int gmap_protect_pte(struct gmap
 	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;
 }
@@ -1015,7 +1018,7 @@ int gmap_mprotect_notify(struct gmap *gm
 	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;
 }
@@ -1606,7 +1609,7 @@ struct gmap *gmap_shadow(struct gmap *pa
 	down_read(&parent->mm->mmap_sem);
 	rc = gmap_protect_range(parent, asce & _ASCE_ORIGIN,
 				((asce & _ASCE_TABLE_LENGTH) + 1) * 4096,
-				PROT_READ, PGSTE_VSIE_BIT);
+				PROT_READ, GMAP_NOTIFY_SHADOW);
 	up_read(&parent->mm->mmap_sem);
 	spin_lock(&parent->shadow_lock);
 	new->initialized = true;