tpm: Clean up model registration & lookup

We have a strict separation between enum TpmModel and tpm_models[]:

* TpmModel may have any number of members.  It just happens to have one.

* tpm_register_model() uses the first empty slot in tpm_models[].

  If you register more than tpm_models[] has space,
  tpn_register_model() fails.  Its caller silently ignores the
  failure.

  Register the same TpmModel more than once has no effect other than
  wasting tpm_models[] slots: tpm_model_is_registered() is happy with
  the first one it finds.

Since we only ever register one model, and tpm_models[] has space for
just that one, this contraption even works.

Turn tpm_models[] into a straight map from enum TpmType to bool.  Much
simpler.

Cc: Stefan Berger <stefanb@us.ibm.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1503564371-26090-5-git-send-email-armbru@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
[Commit message typo fixed]

include/sysemu/tpm_backend.h

@@ -226,7 +226,7 @@ TPMVersion tpm_backend_get_tpm_version(TPMBackend *s);
 TPMBackend *qemu_find_tpm(const char *id);
 
 const TPMDriverOps *tpm_get_backend_driver(const char *type);
-int tpm_register_model(enum TpmModel model);
+void tpm_register_model(enum TpmModel model);
 void tpm_register_driver(const TPMDriverOps *tdo);
 
 #endif

tpm.c

@@ -24,39 +24,12 @@
 static QLIST_HEAD(, TPMBackend) tpm_backends =
     QLIST_HEAD_INITIALIZER(tpm_backends);
 
-
-#define TPM_MAX_MODELS      1
-
 static TPMDriverOps const *be_drivers[TPM_TYPE__MAX];
+static bool tpm_models[TPM_MODEL__MAX];
 
-static enum TpmModel tpm_models[TPM_MAX_MODELS] = {
-    TPM_MODEL__MAX,
-};
-
-int tpm_register_model(enum TpmModel model)
-{
-    int i;
-
-    for (i = 0; i < TPM_MAX_MODELS; i++) {
-        if (tpm_models[i] == TPM_MODEL__MAX) {
-            tpm_models[i] = model;
-            return 0;
-        }
-    }
-    error_report("Could not register TPM model");
-    return 1;
-}
-
-static bool tpm_model_is_registered(enum TpmModel model)
+void tpm_register_model(enum TpmModel model)
 {
-    int i;
-
-    for (i = 0; i < TPM_MAX_MODELS; i++) {
-        if (tpm_models[i] == model) {
-            return true;
-        }
-    }
-    return false;
+    tpm_models[model] = true;
 }
 
 const TPMDriverOps *tpm_get_backend_driver(const char *type)
@@ -270,7 +243,7 @@ TPMInfoList *qmp_query_tpm(Error **errp)
     TPMInfoList *info, *head = NULL, *cur_item = NULL;
 
     QLIST_FOREACH(drv, &tpm_backends, list) {
-        if (!tpm_model_is_registered(drv->fe_model)) {
+        if (!tpm_models[drv->fe_model]) {
             continue;
         }
         info = g_new0(TPMInfoList, 1);
@@ -317,7 +290,7 @@ TpmModelList *qmp_query_tpm_models(Error **errp)
     TpmModelList *head = NULL, *prev = NULL, *cur_item;
 
     for (i = 0; i < TPM_MODEL__MAX; i++) {
-        if (!tpm_model_is_registered(i)) {
+        if (!tpm_models[i]) {
             continue;
         }
         cur_item = g_new0(TpmModelList, 1);