kvm_find_free_descriptor(): Skip descriptor 0

The GDT/LDT descriptor 0 should always be empty. Start search for free
descriptor table entry at index 1.

Link: https://lore.kernel.org/ltp/[email protected]/
Reviewed-by: Petr Vorel <[email protected]>
Signed-off-by: Martin Doucha <[email protected]>

Author: mdoucha

testcases/kernel/kvm/lib_x86.c

@@ -174,7 +174,7 @@ int kvm_find_free_descriptor(const struct segment_descriptor *table,
 	const struct segment_descriptor *ptr;
 	size_t i;
 
-	for (i = 0, ptr = table; i < size; i++, ptr++) {
+	for (i = 1, ptr = table + 1; i < size; i++, ptr++) {
 		if (!(ptr->flags_lo & SEGFLAG_PRESENT))
 			return i;