libxl/libxc: Move libxl_get_cpu_topology()'s hypercall buffer management to libxc

xc_cputopoinfo() is not expected to be used on a hot path and therefore
hypercall buffer management can be pushed into libxc. This will simplify
life for callers.

Also update error reporting macros.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxc/include/xenctrl.h

@@ -1238,7 +1238,7 @@ int xc_readconsolering(xc_interface *xch,
 int xc_send_debug_keys(xc_interface *xch, char *keys);
 
 typedef xen_sysctl_physinfo_t xc_physinfo_t;
-typedef xen_sysctl_cputopoinfo_t xc_cputopoinfo_t;
+typedef xen_sysctl_cputopo_t xc_cputopo_t;
 typedef xen_sysctl_numainfo_t xc_numainfo_t;
 
 typedef uint32_t xc_cpu_to_node_t;
@@ -1249,7 +1249,8 @@ typedef uint64_t xc_node_to_memfree_t;
 typedef uint32_t xc_node_to_node_dist_t;
 
 int xc_physinfo(xc_interface *xch, xc_physinfo_t *info);
-int xc_cputopoinfo(xc_interface *xch, xc_cputopoinfo_t *info);
+int xc_cputopoinfo(xc_interface *xch, unsigned *max_cpus,
+                   xc_cputopo_t *cputopo);
 int xc_numainfo(xc_interface *xch, xc_numainfo_t *info);
 
 int xc_sched_id(xc_interface *xch,

tools/libxc/xc_misc.c

@@ -203,22 +203,31 @@ int xc_physinfo(xc_interface *xch,
     return 0;
 }
 
-int xc_cputopoinfo(xc_interface *xch,
-                   xc_cputopoinfo_t *put_info)
+int xc_cputopoinfo(xc_interface *xch, unsigned *max_cpus,
+                   xc_cputopo_t *cputopo)
 {
     int ret;
     DECLARE_SYSCTL;
+    DECLARE_HYPERCALL_BOUNCE(cputopo, *max_cpus * sizeof(*cputopo),
+                             XC_HYPERCALL_BUFFER_BOUNCE_OUT);
+
+    if ( (ret = xc_hypercall_bounce_pre(xch, cputopo)) )
+        goto out;
+
+    sysctl.u.cputopoinfo.num_cpus = *max_cpus;
+    set_xen_guest_handle(sysctl.u.cputopoinfo.cputopo, cputopo);
 
     sysctl.cmd = XEN_SYSCTL_cputopoinfo;
 
-    memcpy(&sysctl.u.cputopoinfo, put_info, sizeof(*put_info));
-
     if ( (ret = do_sysctl(xch, &sysctl)) != 0 )
-        return ret;
+        goto out;
 
-    memcpy(put_info, &sysctl.u.cputopoinfo, sizeof(*put_info));
+    *max_cpus = sysctl.u.cputopoinfo.num_cpus;
 
-    return 0;
+out:
+    xc_hypercall_bounce_post(xch, cputopo);
+
+    return ret;
 }
 
 int xc_numainfo(xc_interface *xch,

tools/libxl/libxl.c

@@ -5102,37 +5102,28 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo *physinfo)
 libxl_cputopology *libxl_get_cpu_topology(libxl_ctx *ctx, int *nb_cpu_out)
 {
     GC_INIT(ctx);
-    xc_cputopoinfo_t tinfo;
-    DECLARE_HYPERCALL_BUFFER(xen_sysctl_cputopo_t, cputopo);
+    xc_cputopo_t *cputopo;
     libxl_cputopology *ret = NULL;
     int i;
+    unsigned num_cpus;
 
-    /* Setting buffer to NULL makes the hypercall return number of CPUs */
-    set_xen_guest_handle(tinfo.cputopo, HYPERCALL_BUFFER_NULL);
-    if (xc_cputopoinfo(ctx->xch, &tinfo) != 0)
+    /* Setting buffer to NULL makes the call return number of CPUs */
+    if (xc_cputopoinfo(ctx->xch, &num_cpus, NULL))
     {
-        LIBXL__LOG(ctx, XTL_ERROR, "Unable to determine number of CPUS");
-        ret = NULL;
+        LOGE(ERROR, "Unable to determine number of CPUS");
         goto out;
     }
 
-    cputopo = xc_hypercall_buffer_alloc(ctx->xch, cputopo,
-                                        sizeof(*cputopo) * tinfo.num_cpus);
-    if (cputopo == NULL) {
-        LIBXL__LOG_ERRNOVAL(ctx, XTL_ERROR, ENOMEM,
-                            "Unable to allocate hypercall arguments");
-        goto fail;
-    }
-    set_xen_guest_handle(tinfo.cputopo, cputopo);
+    cputopo = libxl__zalloc(gc, sizeof(*cputopo) * num_cpus);
 
-    if (xc_cputopoinfo(ctx->xch, &tinfo) != 0) {
-        LIBXL__LOG_ERRNO(ctx, XTL_ERROR, "CPU topology info hypercall failed");
-        goto fail;
+    if (xc_cputopoinfo(ctx->xch, &num_cpus, cputopo)) {
+        LOGE(ERROR, "CPU topology info hypercall failed");
+        goto out;
     }
 
-    ret = libxl__zalloc(NOGC, sizeof(libxl_cputopology) * tinfo.num_cpus);
+    ret = libxl__zalloc(NOGC, sizeof(libxl_cputopology) * num_cpus);
 
-    for (i = 0; i < tinfo.num_cpus; i++) {
+    for (i = 0; i < num_cpus; i++) {
 #define V(map, i, invalid) ( cputopo[i].map == invalid) ? \
    LIBXL_CPUTOPOLOGY_INVALID_ENTRY : cputopo[i].map
         ret[i].core = V(core, i, XEN_INVALID_CORE_ID);
@@ -5141,11 +5132,7 @@ libxl_cputopology *libxl_get_cpu_topology(libxl_ctx *ctx, int *nb_cpu_out)
 #undef V
     }
 
-fail:
-    xc_hypercall_buffer_free(ctx->xch, cputopo);
-
-    if (ret)
-        *nb_cpu_out = tinfo.num_cpus;
+    *nb_cpu_out = num_cpus;
 
  out:
     GC_FREE;

tools/misc/xenpm.c

@@ -355,20 +355,17 @@ static void signal_int_handler(int signo)
     int i, j, k;
     struct timeval tv;
     int cx_cap = 0, px_cap = 0;
-    DECLARE_HYPERCALL_BUFFER(xen_sysctl_cputopo_t, cputopo);
-    xc_cputopoinfo_t info = { 0 };
+    xc_cputopo_t *cputopo;
+    unsigned max_cpus;
 
-    set_xen_guest_handle(info.cputopo, HYPERCALL_BUFFER_NULL);
-    if ( xc_cputopoinfo(xc_handle, &info) != 0 )
+    if ( xc_cputopoinfo(xc_handle, &max_cpus, NULL) != 0 )
     {
         fprintf(stderr, "failed to discover number of CPUs: %s\n",
                 strerror(errno));
         goto out;
     }
 
-    cputopo = xc_hypercall_buffer_alloc(xc_handle, cputopo,
-                                        sizeof(*cputopo) * info.num_cpus);
-
+    cputopo = calloc(max_cpus, sizeof(*cputopo));
     if ( cputopo == NULL )
     {
 	fprintf(stderr, "failed to allocate hypercall buffers\n");
@@ -453,28 +450,26 @@ static void signal_int_handler(int signo)
             printf("  Avg freq\t%d\tKHz\n", avgfreq[i]);
     }
 
-    set_xen_guest_handle(info.cputopo, cputopo);
-
-    if ( cx_cap && !xc_cputopoinfo(xc_handle, &info) )
+    if ( cx_cap && !xc_cputopoinfo(xc_handle, &max_cpus, cputopo) )
     {
         uint32_t socket_ids[MAX_NR_CPU];
         uint32_t core_ids[MAX_NR_CPU];
         uint32_t socket_nr = 0;
         uint32_t core_nr = 0;
 
-        if ( info.num_cpus > MAX_NR_CPU )
-            info.num_cpus = MAX_NR_CPU;
+        if ( max_cpus > MAX_NR_CPU )
+            max_cpus = MAX_NR_CPU;
         /* check validity */
-        for ( i = 0; i < info.num_cpus; i++ )
+        for ( i = 0; i < max_cpus; i++ )
         {
             if ( cputopo[i].core == XEN_INVALID_CORE_ID ||
                  cputopo[i].socket == XEN_INVALID_SOCKET_ID )
                 break;
         }
-        if ( i >= info.num_cpus )
+        if ( i >= max_cpus )
         {
             /* find socket nr & core nr per socket */
-            for ( i = 0; i < info.num_cpus; i++ )
+            for ( i = 0; i < max_cpus; i++ )
             {
                 for ( j = 0; j < socket_nr; j++ )
                     if ( cputopo[i].socket == socket_ids[j] )
@@ -501,7 +496,7 @@ static void signal_int_handler(int signo)
                 unsigned int n;
                 uint64_t res;
 
-                for ( j = 0; j < info.num_cpus; j++ )
+                for ( j = 0; j < max_cpus; j++ )
                 {
                     if ( cputopo[j].socket == socket_ids[i] )
                         break;
@@ -520,7 +515,7 @@ static void signal_int_handler(int signo)
                 }
                 for ( k = 0; k < core_nr; k++ )
                 {
-                    for ( j = 0; j < info.num_cpus; j++ )
+                    for ( j = 0; j < max_cpus; j++ )
                     {
                         if ( cputopo[j].socket == socket_ids[i] &&
                              cputopo[j].core == core_ids[k] )
@@ -558,7 +553,7 @@ static void signal_int_handler(int signo)
     free(sum);
     free(avgfreq);
 out:
-    xc_hypercall_buffer_free(xc_handle, cputopo);
+    free(cputopo);
     xc_interface_close(xc_handle);
     exit(0);
 }
@@ -965,12 +960,11 @@ void scaling_governor_func(int argc, char *argv[])
 
 void cpu_topology_func(int argc, char *argv[])
 {
-    DECLARE_HYPERCALL_BUFFER(xen_sysctl_cputopo_t, cputopo);
-    xc_cputopoinfo_t info = { 0 };
-    int i, rc = ENOMEM;
+    xc_cputopo_t *cputopo;
+    unsigned max_cpus;
+    int i, rc;
 
-    set_xen_guest_handle(info.cputopo, HYPERCALL_BUFFER_NULL);
-    if ( xc_cputopoinfo(xc_handle, &info) )
+    if ( xc_cputopoinfo(xc_handle, &max_cpus, NULL) != 0 )
     {
         rc = errno;
         fprintf(stderr, "failed to discover number of CPUs (%d - %s)\n",
@@ -978,16 +972,15 @@ void cpu_topology_func(int argc, char *argv[])
         goto out;
     }
 
-    cputopo = xc_hypercall_buffer_alloc(xc_handle, cputopo,
-                                        sizeof(*cputopo) * info.num_cpus);
+    cputopo = calloc(max_cpus, sizeof(*cputopo));
     if ( cputopo == NULL )
     {
+	rc = ENOMEM;
 	fprintf(stderr, "failed to allocate hypercall buffers\n");
 	goto out;
     }
 
-    set_xen_guest_handle(info.cputopo, cputopo);
-    if ( xc_cputopoinfo(xc_handle, &info) )
+    if ( xc_cputopoinfo(xc_handle, &max_cpus, cputopo) )
     {
         rc = errno;
         fprintf(stderr, "Cannot get Xen CPU topology (%d - %s)\n",
@@ -996,7 +989,7 @@ void cpu_topology_func(int argc, char *argv[])
     }
 
     printf("CPU\tcore\tsocket\tnode\n");
-    for ( i = 0; i < info.num_cpus; i++ )
+    for ( i = 0; i < max_cpus; i++ )
     {
         if ( cputopo[i].core == XEN_INVALID_CORE_ID )
             continue;
@@ -1005,7 +998,7 @@ void cpu_topology_func(int argc, char *argv[])
     }
     rc = 0;
 out:
-    xc_hypercall_buffer_free(xc_handle, cputopo);
+    free(cputopo);
     if ( rc )
         exit(rc);
 }

tools/python/xen/lowlevel/xc/xc.c

@@ -1220,30 +1220,26 @@ static PyObject *pyxc_getcpuinfo(XcObject *self, PyObject *args, PyObject *kwds)
 
 static PyObject *pyxc_topologyinfo(XcObject *self)
 {
-    xc_cputopoinfo_t tinfo = { 0 };
-    unsigned i;
+    xc_cputopo_t *cputopo = NULL;
+    unsigned i, num_cpus;
     PyObject *ret_obj = NULL;
     PyObject *cpu_to_core_obj, *cpu_to_socket_obj, *cpu_to_node_obj;
-    DECLARE_HYPERCALL_BUFFER(xen_sysctl_cputopo_t, cputopo);
 
-    set_xen_guest_handle(tinfo.cputopo, HYPERCALL_BUFFER_NULL);
-    if ( xc_cputopoinfo(self->xc_handle, &tinfo) != 0 )
+    if ( xc_cputopoinfo(self->xc_handle, &num_cpus, NULL) != 0 )
         goto out;
 
-    cputopo = xc_hypercall_buffer_alloc(self->xc_handle, cputopo,
-                                        sizeof(*cputopo) * tinfo.num_cpus);
+    cputopo = calloc(num_cpus, sizeof(*cputopo));
     if ( cputopo == NULL )
     	goto out;
 
-    set_xen_guest_handle(tinfo.cputopo, cputopo);
-    if ( xc_cputopoinfo(self->xc_handle, &tinfo) != 0 )
+    if ( xc_cputopoinfo(self->xc_handle, &num_cpus, cputopo) != 0 )
         goto out;
 
     /* Construct cpu-to-* lists. */
     cpu_to_core_obj = PyList_New(0);
     cpu_to_socket_obj = PyList_New(0);
     cpu_to_node_obj = PyList_New(0);
-    for ( i = 0; i < tinfo.num_cpus; i++ )
+    for ( i = 0; i < num_cpus; i++ )
     {
         if ( cputopo[i].core == XEN_INVALID_CORE_ID )
         {
@@ -1279,7 +1275,7 @@ static PyObject *pyxc_topologyinfo(XcObject *self)
         }
     }
 
-    ret_obj = Py_BuildValue("{s:i}", "max_cpu_index", tinfo.num_cpus + 1);
+    ret_obj = Py_BuildValue("{s:i}", "max_cpu_index", num_cpus + 1);
 
     PyDict_SetItemString(ret_obj, "cpu_to_core", cpu_to_core_obj);
     Py_DECREF(cpu_to_core_obj);
@@ -1291,7 +1287,7 @@ static PyObject *pyxc_topologyinfo(XcObject *self)
     Py_DECREF(cpu_to_node_obj);
 
 out:
-    xc_hypercall_buffer_free(self->xc_handle, cputopo);
+    free(cputopo);
     return ret_obj ? ret_obj : pyxc_error_to_exception(self->xc_handle);
 }