fix malloc L3 failed bug for kunlun (#30745)

* fix malloc L3 failed bug for kunlun

* minor

paddle/fluid/platform/device_context.cc

@@ -189,13 +189,25 @@ XPUDeviceContext::XPUDeviceContext(XPUPlace place) : place_(place) {
                         "Baidu Kunlun Card is properly installed.",
                         ret));
   context_ = xpu::create_context();
-  void* l3ptr = nullptr;
-  int l3_size = 13.5 * 1024 * 1024;
-  xpu_malloc(static_cast<void**>(&l3ptr), l3_size, XPU_MEM_L3);
-  if (l3ptr != nullptr) {
-    context_->_l3_mgr.set(l3ptr, l3_size);
-    std::cout << "set l3 size " << l3_size << std::endl;
+  const int MAX_XPU_NUM = 16;
+  const int l3_size = 13.5 * 1024 * 1024;
+  static void* l3ptrs[MAX_XPU_NUM] = {nullptr};
+
+  auto selected_xpus = GetXPUSelectedDevices();
+  for (unsigned int i = 0; i < selected_xpus.size(); i++) {
+    if (place.device == selected_xpus[i]) {
+      if (l3ptrs[place.device] == nullptr) {
+        xpu_malloc(static_cast<void**>(&l3ptrs[place.device]), l3_size,
+                   XPU_MEM_L3);
+      }
+      if (l3ptrs[place.device] != nullptr) {
+        context_->_l3_mgr.set(l3ptrs[place.device], l3_size);
+        VLOG(3) << "xpu place " << place.device << " set l3 size " << l3_size;
+      }
+      break;
+    }
   }
+
   ret = xpu_set_device(dev_id);
   PADDLE_ENFORCE_EQ(ret, XPU_SUCCESS,
                     platform::errors::External(