rocrtst: Fix segfault on p2p copies

Fix segfault on p2p copies when 2 agents cannot access each other's
memory (usually because the PCI BAR's are out of range). The
AcquireAsyncCopyAccess function should return NULL in that case, so that
the test can be skipped.

Change-Id: If018f3609dd21a01c56eaec94de3bca52c385c4d


[ROCm/ROCR-Runtime commit: 4ba4867fa5]

projects/rocr-runtime/rocrtst/suites/performance/memory_async_copy.cc

@@ -168,27 +168,38 @@ hsa_status_t AcquireAccess(hsa_agent_t agent,
 
 // Provided a destination pointer, pool and agent, and a source ptr, pool,
 // and agent, get access for one of the 2 agents to the other agent's pool.
-// Return the selected agent. This function will first attempt attempt to
-// gain access for the first agent to the second pool. If that succeeds, it
-// will return a pointer to the first agent. Otherwise, the function will
-// attempt to again access to the first pool by the second agent. If that
-// succeeds a pointer to the second agent will be returned. If it fails, a
-// nullptr will be returned.
+// Return the selected agent. This function will first attempt to gain access
+// for the first agent to the second pool. If that succeeds, it will return a
+// pointer to the first agent. Otherwise, the function will attempt to again
+// access to the first pool by the second agent. If that succeeds a pointer to
+// the second agent will be returned. If it fails, nullptr will be returned.
+// We prefer to use GPU agents over CPU agents to avoid poor copy performance
+// due to reading of uncached device memory by CPU.
 hsa_agent_t *
 MemoryAsyncCopy::AcquireAsyncCopyAccess(
          void *dst_ptr, hsa_amd_memory_pool_t dst_pool, hsa_agent_t *dst_ag,
          void *src_ptr, hsa_amd_memory_pool_t src_pool, hsa_agent_t *src_ag) {
   hsa_status_t err;
+  bool can_use_src_agent = false;
+  hsa_device_type_t type = HSA_DEVICE_TYPE_CPU;
 
   err = AcquireAccess(*src_ag, dst_pool, dst_ptr);
-  if (err == HSA_STATUS_SUCCESS && src_ag->handle != cpu_agent_.handle)
-    return src_ag;
+  if (err == HSA_STATUS_SUCCESS) {
+    can_use_src_agent = true;
+
+    if (hsa_agent_get_info(*src_ag, HSA_AGENT_INFO_DEVICE, &type) != HSA_STATUS_SUCCESS)
+      return NULL;
+
+    // We prefer GPU agents over CPU agents, so if this is not a GPU agent,
+    // try using the destination agent
+    if (type == HSA_DEVICE_TYPE_GPU) return src_ag;
+  }
 
   err = AcquireAccess(*dst_ag, src_pool, src_ptr);
-  if (err == HSA_STATUS_SUCCESS && dst_ag->handle != cpu_agent_.handle)
-    return dst_ag;
+  if (err == HSA_STATUS_SUCCESS) return dst_ag;
 
-  return &cpu_agent_;
+  if (can_use_src_agent) return src_ag;
+  return NULL;
 }
 
 void MemoryAsyncCopy::PrintTransactionType(Transaction *t) {