[SYCL][UR][L0 v2] fix mem buffer for integrated graphics (#18345)

ur_integrated_buffer_handle_t was missing logic for writing back memory
to the hostPtr suplied during buffer construction.

getDevicePtr and mapHostPtr did not take into account offset.

Author: igchor

unified-runtime/source/adapters/level_zero/v2/memory.cpp

@@ -94,6 +94,7 @@ ur_integrated_buffer_handle_t::ur_integrated_buffer_handle_t(
 
     if (hostPtr) {
       std::memcpy(this->ptr.get(), hostPtr, size);
+      writeBackPtr = hostPtr;
     }
   }
 }
@@ -110,17 +111,23 @@ ur_integrated_buffer_handle_t::ur_integrated_buffer_handle_t(
   });
 }
 
+ur_integrated_buffer_handle_t::~ur_integrated_buffer_handle_t() {
+  if (writeBackPtr) {
+    std::memcpy(writeBackPtr, this->ptr.get(), size);
+  }
+}
+
 void *ur_integrated_buffer_handle_t::getDevicePtr(
     ur_device_handle_t /*hDevice*/, device_access_mode_t /*access*/,
-    size_t /*offset*/, size_t /*size*/,
+    size_t offset, size_t /*size*/,
     std::function<void(void *src, void *dst, size_t)> /*migrate*/) {
-  return ptr.get();
+  return ur_cast<char *>(ptr.get()) + offset;
 }
 
 void *ur_integrated_buffer_handle_t::mapHostPtr(
-    ur_map_flags_t /*flags*/, size_t /*offset*/, size_t /*size*/,
+    ur_map_flags_t /*flags*/, size_t offset, size_t /*size*/,
     std::function<void(void *src, void *dst, size_t)> /*migrate*/) {
-  return ptr.get();
+  return ur_cast<char *>(ptr.get()) + offset;
 }
 
 void ur_integrated_buffer_handle_t::unmapHostPtr(

unified-runtime/source/adapters/level_zero/v2/memory.hpp

@@ -87,6 +87,8 @@ struct ur_integrated_buffer_handle_t : ur_mem_buffer_t {
                                 size_t size, device_access_mode_t accesMode,
                                 bool ownHostPtr);
 
+  ~ur_integrated_buffer_handle_t();
+
   void *
   getDevicePtr(ur_device_handle_t, device_access_mode_t, size_t offset,
                size_t size,
@@ -98,6 +100,7 @@ struct ur_integrated_buffer_handle_t : ur_mem_buffer_t {
 
 private:
   usm_unique_ptr_t ptr;
+  void *writeBackPtr = nullptr;
 };
 
 struct host_allocation_desc_t {