KVM: selftests: Add checks for histogram stats bucket_size field

The bucket_size field should be non-zero for linear histogram stats and
should be zero for other stats types.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210802165633.1866976-4-jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/kvm_binary_stats_test.c

@@ -109,6 +109,18 @@ static void stats_test(int stats_fd)
 		/* Check size field, which should not be zero */
 		TEST_ASSERT(pdesc->size, "KVM descriptor(%s) with size of 0",
 				pdesc->name);
+		/* Check bucket_size field */
+		switch (pdesc->flags & KVM_STATS_TYPE_MASK) {
+		case KVM_STATS_TYPE_LINEAR_HIST:
+			TEST_ASSERT(pdesc->bucket_size,
+			    "Bucket size of Linear Histogram stats (%s) is zero",
+			    pdesc->name);
+			break;
+		default:
+			TEST_ASSERT(!pdesc->bucket_size,
+			    "Bucket size of stats (%s) is not zero",
+			    pdesc->name);
+		}
 		size_data += pdesc->size * sizeof(*stats_data);
 	}
 	/* Check overlap */