[RFC] tools/libxl: Remove libxl_cpuid_{set, apply_policy}() from the API
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Message ID 20200108130433.7102-1-andrew.cooper3@citrix.com
State New
Headers show
Series
  • [RFC] tools/libxl: Remove libxl_cpuid_{set, apply_policy}() from the API
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Commit Message

Andrew Cooper Jan. 8, 2020, 1:04 p.m. UTC
These functions should never have been exposed.  They don't have exernal
users, and can't usefully be used for several reasons.

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

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Ian Jackson <Ian.Jackson@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Anthony PERARD <anthony.perard@citrix.com>

RFC for obvious reasons.  An alternative would be to #if 0 them, which would
result in a compile failure rather than silent stubbing.  I'm not sure which
is least bad, but I don't think either are going to cause a problem in
practice.
---
 tools/libxl/libxl.h          | 26 ++++++++++++++++++++++----
 tools/libxl/libxl_cpuid.c    |  6 +++---
 tools/libxl/libxl_dom.c      |  4 ++--
 tools/libxl/libxl_internal.h |  4 ++++
 tools/libxl/libxl_nocpuid.c  |  6 +++---
 5 files changed, 34 insertions(+), 12 deletions(-)

Patch
diff mbox series

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 54abb9db1f..a02548f595 100644
--- a/tools/libxl/libxl.h
+++ b/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
@@ -2323,9 +2323,27 @@  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
diff --git a/tools/libxl/libxl_cpuid.c b/tools/libxl/libxl_cpuid.c
index 5c52cbe0f9..505ec1b048 100644
--- a/tools/libxl/libxl_cpuid.c
+++ b/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];
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index cdb294ab8d..e2926cf190 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -625,9 +625,9 @@  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)) {
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index ba8c9b41ab..3194702284 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2042,6 +2042,10 @@  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);
diff --git a/tools/libxl/libxl_nocpuid.c b/tools/libxl/libxl_nocpuid.c
index ef1161c434..a39babe754 100644
--- a/tools/libxl/libxl_nocpuid.c
+++ b/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)
 {
 }