Enforce uncached memory on AllocatePCIeRW request

Change-Id: Ib5a624ab979220d50205448ef37b4550672fb97d

runtime/hsa-runtime/core/runtime/amd_memory_region.cpp

@@ -190,6 +190,7 @@ hsa_status_t MemoryRegion::AllocateImpl(size_t& size, AllocateFlags alloc_flags,
 
   // Allocate pseudo fine grain memory
   kmt_alloc_flags.ui32.CoarseGrain = (alloc_flags & AllocatePCIeRW ? 0 : kmt_alloc_flags.ui32.CoarseGrain);
+  kmt_alloc_flags.ui32.Uncached  = (alloc_flags & AllocatePCIeRW ? 1 : kmt_alloc_flags.ui32.Uncached);
 
   // Only allow using the suballocator for ordinary VRAM.
   if (IsLocalMemory()) {