63cabf2848
It is possible to execute a GPU atomic instruction using a memory address that is in the host memory space (e.g, HMM, __managed__, hipHostMalloc'd address). Since these are in host memory they are passed to the SystemHub DmaDevice. However, this currently executes as a write packet without modifying data. This leads to hangs in applications that use atomics for forward progress (e.g., HeteroSync). It is not clear where these are handled on a real GPU, but they are certianly not handled by the software stack nor driver, so they must be handled in hardware and therefore implemented in gem5. Handling for atomics in the SystemHub makes the most sense. To make atomics work a few extra changes need to be made to the SystemHub. (1) The atomic is implemented as a host memory read, followed by calling the AtomicOpFunctor, followed by a write. This requires a second event to handle read response, performing atomic, and issuing a write. (2) Atomics must be serialized otherwise two atomics might return the same value which is incorrect. This patch adds serialization logic for all request types to the same address to handle this. (3) With the added complexity of the SystemHub, a new debug flag explicitly for SystemHub is added. Testing done: The heterosync application with input "sleepMutex 10 16 4" previously hung before this patch. It passes with the patch applied. This application tests both (1) and (2) above, as it allocates locks with hipHostMalloc and has multiple workgroups sending an atomic request in the same Tick, verifying the serialization mechanism. Change-Id: Ife84b30037d1447dd384340cfeb06fdfd472fff9
57 lines
2.5 KiB
Python
57 lines
2.5 KiB
Python
# Copyright (c) 2021 Advanced Micro Devices, Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its
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# contributors may be used to endorse or promote products derived from this
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# software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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Import('*')
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if not env['CONF']['BUILD_GPU']:
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Return()
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# Controllers
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SimObject('AMDGPU.py', sim_objects=['AMDGPUDevice', 'AMDGPUInterruptHandler',
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'AMDGPUMemoryManager', 'AMDGPUSystemHub',
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'SDMAEngine', 'PM4PacketProcessor'],
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tags='x86 isa')
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Source('amdgpu_device.cc', tags='x86 isa')
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Source('amdgpu_nbio.cc', tags='x86 isa')
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Source('amdgpu_vm.cc', tags='x86 isa')
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Source('interrupt_handler.cc', tags='x86 isa')
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Source('memory_manager.cc', tags='x86 isa')
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Source('mmio_reader.cc', tags='x86 isa')
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Source('pm4_packet_processor.cc', tags='x86 isa')
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Source('sdma_engine.cc', tags='x86 isa')
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Source('system_hub.cc', tags='x86 isa')
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DebugFlag('AMDGPUDevice', tags='x86 isa')
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DebugFlag('AMDGPUMem', tags='x86 isa')
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DebugFlag('AMDGPUSystemHub', tags='x86 isa')
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DebugFlag('PM4PacketProcessor', tags='x86 isa')
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DebugFlag('SDMAEngine', tags='x86 isa')
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DebugFlag('SDMAData', tags='x86 isa')
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