KVM: const-ify uses of struct kvm_userspace_memory_region

Architecture-specific helpers are not supposed to muck with
struct kvm_userspace_memory_region contents.  Add const to
enforce this.

In order to eliminate the only write in __kvm_set_memory_region,
the cleaning of deleted slots is pulled up from update_memslots
to __kvm_set_memory_region.

Reviewed-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 11 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42df724071c0..fc2dbe1c34fc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -676,8 +676,6 @@ static void update_memslots(struct kvm_memslots *slots,
         WARN_ON(mslots[i].id != id);
         if (!new->npages) {
                 WARN_ON(!mslots[i].npages);
-                new->base_gfn = 0;
-                new->flags = 0;
                 if (mslots[i].npages)
                         slots->used_slots--;
         } else {
@@ -717,7 +715,7 @@ static void update_memslots(struct kvm_memslots *slots,
         slots->id_to_index[mslots[i].id] = i;
 }
 
-static int check_memory_region_flags(struct kvm_userspace_memory_region *mem)
+static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
 {
         u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
@@ -767,7 +765,7 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
  * Must be called holding kvm->slots_lock for write.
  */
 int __kvm_set_memory_region(struct kvm *kvm,
-                            struct kvm_userspace_memory_region *mem)
+                            const struct kvm_userspace_memory_region *mem)
 {
         int r;
         gfn_t base_gfn;
@@ -806,9 +804,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
         if (npages > KVM_MEM_MAX_NR_PAGES)
                 goto out;
 
-        if (!npages)
-                mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
-
         new = old = *slot;
 
         new.id = mem->slot;
@@ -834,10 +829,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
                                 goto out;
                         }
                 }
-        } else if (old.npages) {
+        } else {
+                if (!old.npages)
+                        goto out;
+
                 change = KVM_MR_DELETE;
-        } else /* Modify a non-existent slot: disallowed. */
-                goto out;
+                new.base_gfn = 0;
+                new.flags = 0;
+        }
 
         if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
                 /* Check for overlaps */
@@ -944,7 +943,7 @@ out:
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
 
 int kvm_set_memory_region(struct kvm *kvm,
-                          struct kvm_userspace_memory_region *mem)
+                          const struct kvm_userspace_memory_region *mem)
 {
         int r;
 
@@ -960,6 +959,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 {
         if (mem->slot >= KVM_USER_MEM_SLOTS)
                 return -EINVAL;
+
         return kvm_set_memory_region(kvm, mem);
 }