spapr: Simplify ovec diff

spapr_ovec_diff(ov, old, new) has somewhat complex semantics.  ov is set
to those bits which are in new but not old, and it returns as a boolean
whether or not there are any bits in old but not new.

It turns out that both callers only care about the second, not the first.
This is basically equivalent to a bitmap subset operation, which is easier
to understand and implement.  So replace spapr_ovec_diff() with
spapr_ovec_subset().

Cc: Mike Roth <mdroth@linux.vnet.ibm.com>

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cedric Le Goater <clg@fr.ibm.com>

1 files changed, 10 insertions, 20 deletions

diff --git a/hw/ppc/spapr_ovec.c b/hw/ppc/spapr_ovec.c
index 811fadf..0ff6d1a 100644
--- a/hw/ppc/spapr_ovec.c
+++ b/hw/ppc/spapr_ovec.c
@@ -76,31 +76,21 @@ void spapr_ovec_intersect(SpaprOptionVector *ov,
     bitmap_and(ov->bitmap, ov1->bitmap, ov2->bitmap, OV_MAXBITS);
 }
 
-/* returns true if options bits were removed, false otherwise */
-bool spapr_ovec_diff(SpaprOptionVector *ov,
-                     SpaprOptionVector *ov_old,
-                     SpaprOptionVector *ov_new)
+/* returns true if ov1 has a subset of bits in ov2 */
+bool spapr_ovec_subset(SpaprOptionVector *ov1, SpaprOptionVector *ov2)
 {
-    unsigned long *change_mask = bitmap_new(OV_MAXBITS);
-    unsigned long *removed_bits = bitmap_new(OV_MAXBITS);
-    bool bits_were_removed = false;
+    unsigned long *tmp = bitmap_new(OV_MAXBITS);
+    bool result;
 
-    g_assert(ov);
-    g_assert(ov_old);
-    g_assert(ov_new);
-
-    bitmap_xor(change_mask, ov_old->bitmap, ov_new->bitmap, OV_MAXBITS);
-    bitmap_and(ov->bitmap, ov_new->bitmap, change_mask, OV_MAXBITS);
-    bitmap_and(removed_bits, ov_old->bitmap, change_mask, OV_MAXBITS);
+    g_assert(ov1);
+    g_assert(ov2);
 
-    if (!bitmap_empty(removed_bits, OV_MAXBITS)) {
-        bits_were_removed = true;
-    }
+    bitmap_andnot(tmp, ov1->bitmap, ov2->bitmap, OV_MAXBITS);
+    result = bitmap_empty(tmp, OV_MAXBITS);
 
-    g_free(change_mask);
-    g_free(removed_bits);
+    g_free(tmp);
 
-    return bits_were_removed;
+    return result;
 }
 
 void spapr_ovec_cleanup(SpaprOptionVector *ov)