tools/libxl: Remove libxl_cpuid_{set,apply_policy}() from the API

These functions should never have been exposed.  They don't have external
users, and can't usefully be used for several reasons.

Move libxl_cpuid_{set,apply_policy}() to being internal functions, and leave
an equivalent of the nop stubs in the API for caller compatibility.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/libxl/libxl.h

@@ -665,7 +665,7 @@ typedef struct libxl__ctx libxl_ctx;
 #if LIBXL_API_VERSION != 0x040200 && LIBXL_API_VERSION != 0x040300 && \
     LIBXL_API_VERSION != 0x040400 && LIBXL_API_VERSION != 0x040500 && \
     LIBXL_API_VERSION != 0x040700 && LIBXL_API_VERSION != 0x040800 && \
-    LIBXL_API_VERSION != 0x041300
+    LIBXL_API_VERSION != 0x041300 && LIBXL_API_VERSION != 0x041400
 #error Unknown LIBXL_API_VERSION
 #endif
 #endif
@@ -2325,9 +2325,27 @@ libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num);
 int libxl_cpuid_parse_config(libxl_cpuid_policy_list *cpuid, const char* str);
 int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
                                   const char* str);
-void libxl_cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid);
-void libxl_cpuid_set(libxl_ctx *ctx, uint32_t domid,
-                     libxl_cpuid_policy_list cpuid);
+#if LIBXL_API_VERSION < 0x041400
+/*
+ * Dropped from the API in Xen 4.14.  At the time of writing, these functions
+ * don't appear to ever have had external callers.
+ *
+ * These have always been used internally during domain construction, and
+ * can't easily be used externally because of their implicit parameters in
+ * other pieces of global state.
+ *
+ * Furthermore, an API user can't usefully determine whether they get
+ * libxl_cpuid (the real implementation) or libxl_nocpuid (no-op stubs).
+ *
+ * The internal behaviour of these functions also needs to change.  Therefore
+ * for simplicitly, provide the no-op stubs.  Yes technically this is an API
+ * change in some cases for existing software, but there is 0 of that in
+ * practice.
+ */
+static inline void libxl_cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid) {}
+static inline void libxl_cpuid_set(libxl_ctx *ctx, uint32_t domid,
+                                   libxl_cpuid_policy_list cpuid) {}
+#endif
 
 /*
  * Functions for allowing users of libxl to store private data

tools/libxl/libxl_cpuid.c

@@ -410,13 +410,13 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl_cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid)
+void libxl__cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid)
 {
     xc_cpuid_apply_policy(ctx->xch, domid, NULL, 0);
 }
 
-void libxl_cpuid_set(libxl_ctx *ctx, uint32_t domid,
-                     libxl_cpuid_policy_list cpuid)
+void libxl__cpuid_set(libxl_ctx *ctx, uint32_t domid,
+                      libxl_cpuid_policy_list cpuid)
 {
     int i;
     char *cpuid_res[4];

tools/libxl/libxl_dom.c

@@ -454,9 +454,9 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
     if (rc)
         return rc;
 
-    libxl_cpuid_apply_policy(ctx, domid);
+    libxl__cpuid_apply_policy(ctx, domid);
     if (info->cpuid != NULL)
-        libxl_cpuid_set(ctx, domid, info->cpuid);
+        libxl__cpuid_set(ctx, domid, info->cpuid);
 
     if (info->type == LIBXL_DOMAIN_TYPE_HVM
         && !libxl_ms_vm_genid_is_zero(&info->u.hvm.ms_vm_genid)) {

tools/libxl/libxl_internal.h

@@ -2056,6 +2056,10 @@ struct libxl__cpuid_policy {
     char *policy[4];
 };
 
+_hidden void libxl__cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid);
+_hidden void libxl__cpuid_set(libxl_ctx *ctx, uint32_t domid,
+                              libxl_cpuid_policy_list cpuid);
+
 /* Calls poll() again - useful to check whether a signaled condition
  * is still true.  Cannot fail.  Returns currently-true revents. */
 _hidden short libxl__fd_poll_recheck(libxl__egc *egc, int fd, short events);

tools/libxl/libxl_nocpuid.c

@@ -34,12 +34,12 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl_cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid)
+void libxl__cpuid_apply_policy(libxl_ctx *ctx, uint32_t domid)
 {
 }
 
-void libxl_cpuid_set(libxl_ctx *ctx, uint32_t domid,
-                     libxl_cpuid_policy_list cpuid)
+void libxl__cpuid_set(libxl_ctx *ctx, uint32_t domid,
+                      libxl_cpuid_policy_list cpuid)
 {
 }