s390x/mm: simplify gmap_protect_rmap()

Web:        https://git.kernel.org/torvalds/c/5c528db0df6999cc7bf2151b0f9fb6446109ec54
Commit:     5c528db0df6999cc7bf2151b0f9fb6446109ec54
Parent:     15e5020e575d0c1a4eddd99bf7ffdc1f34a3b17d
Refname:    refs/heads/master
Author:     David Hildenbrand <[email protected]>
AuthorDate: Tue Jan 23 22:26:18 2018 +0100
Committer:  Christian Borntraeger <[email protected]>
CommitDate: Wed Jan 24 16:16:57 2018 +0100

    s390x/mm: simplify gmap_protect_rmap()
    
    We never call it with anything but PROT_READ. This is a left over from
    an old prototype. For creation of shadow page tables, we always only
    have to protect the original table in guest memory from write accesses,
    so we can properly invalidate the shadow on writes. Other protections
    are not needed.
    
    Signed-off-by: David Hildenbrand <[email protected]>
    Message-Id: <[email protected]>
    Reviewed-by: Janosch Frank <[email protected]>
    Signed-off-by: Christian Borntraeger <[email protected]>
---
 arch/s390/mm/gmap.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 4e9d12af95cc..2c55a2b9d6c6 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -1021,18 +1021,17 @@ static inline void gmap_insert_rmap(struct gmap *sg, unsigned long vmaddr,
 }
 
 /**
- * gmap_protect_rmap - modify access rights to memory and create an rmap
+ * gmap_protect_rmap - restrict access rights to memory (RO) and create an rmap
  * @sg: pointer to the shadow guest address space structure
  * @raddr: rmap address in the shadow gmap
  * @paddr: address in the parent guest address space
  * @len: length of the memory area to protect
- * @prot: indicates access rights: none, read-only or read-write
  *
  * Returns 0 if successfully protected and the rmap was created, -ENOMEM
  * if out of memory and -EFAULT if paddr is invalid.
  */
 static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
-			     unsigned long paddr, unsigned long len, int prot)
+			     unsigned long paddr, unsigned long len)
 {
 	struct gmap *parent;
 	struct gmap_rmap *rmap;
@@ -1060,7 +1059,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
 		ptep = gmap_pte_op_walk(parent, paddr, &ptl);
 		if (ptep) {
 			spin_lock(&sg->guest_table_lock);
-			rc = ptep_force_prot(parent->mm, paddr, ptep, prot,
+			rc = ptep_force_prot(parent->mm, paddr, ptep, PROT_READ,
 					     PGSTE_VSIE_BIT);
 			if (!rc)
 				gmap_insert_rmap(sg, vmaddr, rmap);
@@ -1070,7 +1069,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
 		radix_tree_preload_end();
 		if (rc) {
 			kfree(rmap);
-			rc = gmap_pte_op_fixup(parent, paddr, vmaddr, prot);
+			rc = gmap_pte_op_fixup(parent, paddr, vmaddr, PROT_READ);
 			if (rc)
 				return rc;
 			continue;
@@ -1609,7 +1608,7 @@ int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
 	origin = r2t & _REGION_ENTRY_ORIGIN;
 	offset = ((r2t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
 	len = ((r2t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
-	rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
+	rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
 	spin_lock(&sg->guest_table_lock);
 	if (!rc) {
 		table = gmap_table_walk(sg, saddr, 4);
@@ -1692,7 +1691,7 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
 	origin = r3t & _REGION_ENTRY_ORIGIN;
 	offset = ((r3t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
 	len = ((r3t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
-	rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
+	rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
 	spin_lock(&sg->guest_table_lock);
 	if (!rc) {
 		table = gmap_table_walk(sg, saddr, 3);
@@ -1776,7 +1775,7 @@ int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
 	origin = sgt & _REGION_ENTRY_ORIGIN;
 	offset = ((sgt & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
 	len = ((sgt & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
-	rc = gmap_protect_rmap(sg, raddr, origin + offset, len, PROT_READ);
+	rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
 	spin_lock(&sg->guest_table_lock);
 	if (!rc) {
 		table = gmap_table_walk(sg, saddr, 2);
@@ -1895,7 +1894,7 @@ int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
 	/* Make pgt read-only in parent gmap page table (not the pgste) */
 	raddr = (saddr & _SEGMENT_MASK) | _SHADOW_RMAP_SEGMENT;
 	origin = pgt & _SEGMENT_ENTRY_ORIGIN & PAGE_MASK;
-	rc = gmap_protect_rmap(sg, raddr, origin, PAGE_SIZE, PROT_READ);
+	rc = gmap_protect_rmap(sg, raddr, origin, PAGE_SIZE);
 	spin_lock(&sg->guest_table_lock);
 	if (!rc) {
 		table = gmap_table_walk(sg, saddr, 1);
--
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