[SYCL][CUDA] Implement sycl_ext_oneapi_peer_access extension (#8303)

This implements the current extension doc from
intel/llvm#6104 in the CUDA backend only.

Fixes intel/llvm#7543.
Fixes intel/llvm#6749.

---------

Signed-off-by: JackAKirk <jack.kirk@codeplay.com>
Co-authored-by: Nicolas Miller <nicolas.miller@codeplay.com>
Co-authored-by: JackAKirk <chezjakirk@gmail.com>
Co-authored-by: Steffen Larsen <steffen.larsen@intel.com>

ur_interface_loader.cpp

@@ -330,3 +330,16 @@ UR_DLLEXPORT ur_result_t UR_APICALL urGetCommandBufferExpProcAddrTable(
 
   return retVal;
 }
+
+UR_DLLEXPORT ur_result_t UR_APICALL urGetUsmP2PExpProcAddrTable(
+    ur_api_version_t version, ur_usm_p2p_exp_dditable_t *pDdiTable) {
+  auto retVal = validateProcInputs(version, pDdiTable);
+  if (UR_RESULT_SUCCESS != retVal) {
+    return retVal;
+  }
+  pDdiTable->pfnEnablePeerAccessExp = urUsmP2PEnablePeerAccessExp;
+  pDdiTable->pfnDisablePeerAccessExp = urUsmP2PDisablePeerAccessExp;
+  pDdiTable->pfnPeerAccessGetInfoExp = urUsmP2PPeerAccessGetInfoExp;
+
+  return retVal;
+}

usm_p2p.cpp

@@ -0,0 +1,43 @@
+//===----------- usm_p2p.cpp - L0 Adapter ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===-----------------------------------------------------------------===//
+
+#include "ur_level_zero.hpp"
+
+UR_APIEXPORT ur_result_t UR_APICALL urUsmP2PEnablePeerAccessExp(
+    ur_device_handle_t commandDevice, ur_device_handle_t peerDevice) {
+
+  std::ignore = commandDevice;
+  std::ignore = peerDevice;
+
+  urPrint("[UR][L0] %s function not implemented!\n", __FUNCTION__);
+  return UR_RESULT_ERROR_UNSUPPORTED_FEATURE;
+}
+
+UR_APIEXPORT ur_result_t UR_APICALL urUsmP2PDisablePeerAccessExp(
+    ur_device_handle_t commandDevice, ur_device_handle_t peerDevice) {
+
+  std::ignore = commandDevice;
+  std::ignore = peerDevice;
+
+  urPrint("[UR][L0] %s function not implemented!\n", __FUNCTION__);
+  return UR_RESULT_ERROR_UNSUPPORTED_FEATURE;
+}
+
+UR_APIEXPORT ur_result_t UR_APICALL urUsmP2PPeerAccessGetInfoExp(
+    ur_device_handle_t commandDevice, ur_device_handle_t peerDevice,
+    ur_exp_peer_info_t propName, size_t propSize, void *pPropValue,
+    size_t *pPropSizeRet) {
+
+  std::ignore = commandDevice;
+  std::ignore = peerDevice;
+  std::ignore = propName;
+
+  UrReturnHelper ReturnValue(propSize, pPropValue, pPropSizeRet);
+  // Zero return value indicates that all of the queries currently return false.
+  return ReturnValue(uint32_t{0});
+}