In an SMT CPU, upon a squash, the mis-predicted(squashing) instructions
can still be executing at IEW and own phys registers. If these registers
are added back to the rename freelist on this Tick, the registers may be
renamed to be used by other SMT thread(s). This causes register
ownership hazards, which may eventually freeze the CPU. This problem
seems to date back to 2014
(https://www.mail-archive.com/gem5-users@gem5.org/msg10180.html).
This patch delays the freelist update to avoid the hazard.
I tested that this patch does not cause any performance impact for my
set of benchmarks on default non-SMT O3CPU.
In an SMT CPU, upon a squash, the phys regs used by
mispredicted instructions can still be owned by executing
instructions in IEW. If the regs are added back to freelist
on this tick, the reg may be renamed to be used by another
SMT thread. This causes reg ownership hazard, which may
eventually freeze the CPU.
This patch delays the freelist update to avoid the hazard.
Change-Id: I993b3c7d357269f01146db61fc8a7b83a989ea45
This merges initial support for RVV. Currently, only the simple CPUs are supported.
The decoder stalls for every vsetvl instruction.
In the future, we will implement vsetvl as a control instruction as described in #144
Since the O3 and Minor CPU models do not support RVV right now as the
implementation stalls the decode until vsetvl instructions are exectued,
this change calls `fatal` if RVV is not explicitly enabled.
It is possible to override this if you explicitly enable RVV in the
config file.
Change-Id: Ia801911141bb2fb2bedcff3e139bf41ba8936085
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
TODOs:
+ vcompress.vm
Change-Id: I86eceae66e90380416fd3be2c10ad616512b5eba
Co-authored-by: Yang Liu <numbksco@gmail.com>
Co-authored-by: Fan Yang <1209202421@qq.com>
Co-authored-by: Jerin Joy <joy@rivosinc.com>
arch-riscv: Add LICENCE to template files
Change-Id: I825e72bffb84cce559d2e4c1fc2246c3b05a1243
* TODOs:
+ Vector Segment Load/Store
+ Vector Fault-only-first Load
Change-Id: I2815c76404e62babab7e9466e4ea33ea87e66e75
Co-authored-by: Yang Liu <numbksco@gmail.com>
Co-authored-by: Fan Yang <1209202421@qq.com>
Co-authored-by: Jerin Joy <joy@rivosinc.com>
Change-Id: I84363164ca327151101e8a1c3d8441a66338c909
Co-authored-by: Yang Liu <numbksco@gmail.com>
Co-authored-by: Fan Yang <1209202421@qq.com>
arch-riscv: Add a todo to fix vsetvl stall on decode
Change-Id: Iafb129648fba89009345f0c0ad3710f773379bf6
This commit add regs and configs for vector extension
* Add 32 vector arch regs as spec defined and 8 internal regs for
uop-based vector implementation.
* Add default vector configs(VLEN = 256, ELEN = 64). These cannot
be changed yet, since the vector implementation has only be tested
with such configs.
* Add disassamble register name v0~v31 and vtmp0~vtmp7.
* Add CSR registers defined in RISCV Vector Spec v1.0.
* Add vector bitfields.
* Add vector operand_types and operands.
Change-Id: I7bbab1ee9e0aa804d6f15ef7b77fac22d4f7212a
Co-authored-by: Yang Liu <numbksco@gmail.com>
Co-authored-by: Fan Yang <1209202421@qq.com>
Co-authored-by: Jerin Joy <joy@rivosinc.com>
arch-riscv: enable rvv flags only for RV64
Change-Id: I6586e322dfd562b598f63a18964d17326c14d4cf
Starting with ROCm 5.4+, MI100 and MI200 make use of the translate
further bit in the page table. This bit enables mixing 4kiB and 2MiB
pages and is functionally equivalent to mixing page sizes using the
PDE.P bit for which gem5 currently has support.
With PDE.P bit set, we stop walking and the page size is equal to the
level in the page table we stopped at. For example, stopping at level
2 would be a 1GiB page, stopping at level 3 would be a 2MiB page.
This assumes most pages are 4kiB.
When the F bit is used, it is assumed most pages are 2MiB and we will
stop walking at the 3rd level of the page table unless the F bit is set.
When the F bit is set, the 2nd level PDE contains a block fragment size
representing the page size of the next PDE in the form of 2^(12+size).
If the next page has the F bit set we continue walking to the 4th level.
The block fragment size is hardcoded to 9 in the driver therefore we
assert that the block fragment size must be 0 or 9.
This enables MI200 with ROCm 5.4+ in gem5. This functionality was
determine by examining the driver source code in Linux and there is no
public documentation about this feature or why the change is made in or
around ROCm 5.4.
Change-Id: I603c0208cd9e821f7ad6eeb1d94ae15eaa146fb9
This SDMA packet is much more common starting around ROCm 5.4.
Previously this was mostly used to clear page tables after an
application ended and was therefore left unimplemented. It is
now used for basic operation like device memsets.
This patch implements constant fill as it is now necessary.
Change-Id: I9b2cf076ec17f5ed07c20bb820e7db0c082bbfbc
When using the new operator, delete should be called
on any allocated memory after it's use is complete.
Change-Id: Id5fcfb264b6ddc252c0a9dcafc2d3b020f7b5019
A previous change added a vop2Helper to remove 100s of lines of common
code from VOP2 instructions related to processing SDWA and DPP support.
That change inadvertently changed the type of operand source 0 from
const to non-const. The vector container operator[] does not allow
reading a scalar value such as a constant, a dword literal, etc. The
error shows up in the form of: assert(!scalar) in operand.hh.
Since the SDWA and DPP cases need to modify the source vector and
non-SDWA/DPP cases might require const, we make a non-const copy of the
const source 0 vector and place it in a temporary non-const vector. This
non-const vector is passed to the lambda function implementation of the
instruction. This prevents needing a const and non-const version of the
lambda and avoids needing to propagate the template parameters through
the various SDWA/DPP helper methods which seems like it will not work
anyways as they need to modify the vector.
As a result of this, as more VOP2 instructions are implemented using
this helper, they will need to specify the const and non-const template
parameters of the vector container needed for the instruction.
Change-Id: Ia0b3c550d7de32b830040007a110f4821e3385aa
When using the new operator, delete should be called
on any allocated memory after it's use is complete.
Change-Id: Id5fcfb264b6ddc252c0a9dcafc2d3b020f7b5019
In "src/cpu/testers/gpu_ruby_test" a random number generator was used.
This was using the CPP "<random>" library. This patch changes it to the
gem5 random class (that declared in "base/random.hh").
In addition to this, undeterministic behavior has been removed. Via
"protocol_tester.cc" the RNG is either seeded with a seed specified by
the user, or goes with the gem5 default seed. This ensures reproducable
runs. Prior to this patch the RNG was seeded with `time(NULL)`. This
made finding faults difficult.
This, at least partially, addresses Issue #138
Change-Id: Ia8e9f7b87e91323f828e0b7f6c3906c0c5793b2c
In "src/cpu/testers/gpu_ruby_test" a random number generator was used.
This was using the CPP "<random>" library. This patch changes it to the
gem5 random class (that declared in "base/random.hh").
In addition to this, undeterministic behavior has been removed. Via
"protocol_tester.cc" the RNG is either seeded with a seed specified by
the user, or goes with the gem5 default seed. This ensures reproducable
runs. Prior to this patch the RNG was seeded with `time(NULL)`. This
made finding faults difficult.
Change-Id: Ia8e9f7b87e91323f828e0b7f6c3906c0c5793b2c
A previous change added a vop2Helper to remove 100s of lines of common
code from VOP2 instructions related to processing SDWA and DPP support.
That change inadvertently changed the type of operand source 0 from
const to non-const. The vector container operator[] does not allow
reading a scalar value such as a constant, a dword literal, etc. The
error shows up in the form of: assert(!scalar) in operand.hh.
Since the SDWA and DPP cases need to modify the source vector and
non-SDWA/DPP cases might require const, we make a non-const copy of the
const source 0 vector and place it in a tempoary non-const vector. This
non-const vector is passed to the lambda function implementation of the
instruction. This prevents needing a const and non-const version of the
lambda and avoids needing to propagate the template parameters through
the various SDWA/DPP helper methods which seems like it will not work
anyways as they need to modify the vector.
As a result of this, as more VOP2 instructions are implemented using
this helper,they will need to specify the const and non-const template
parameters of the vector container needed for the instruction.
Change-Id: Ia0b3c550d7de32b830040007a110f4821e3385aa
The extended state CPUID function is used to set the values of the XCR0
register as well as specify the size of storage for context switching
storage for x87 and AVX+. This function is iterative and therefore
requires (1) marking it as such in the hsaSignificantIndex function (2)
setting multiple sets of 4-tuples for the default CPUID values where the
last 4-tuple ends with all zeros.
Change-Id: Ib6a43925afb1cae75f61d8acff52a3cc26ce17c8
Related to the recent changes with moving CPUID values to python, this
value is needed to enable AVX and needs a way to be exposed to python as
well in order to set the bit and the corresponding CPUID values at the
same time.
Change-Id: I3cadb0fe61ff4ebf6de903018a8d8a411bfdb4e0
Various CPUID functions will return different values depending on the
value of ECX when executing the CPUID instruction. Add support for this
in the X86 KVM CPU. A subsequent patch will add a CPUID function which
requires iterating through multiple ECX values.
Change-Id: Ib44a52be52ea632d5e2cee3fb2ca390b60a7202a
CPUID values for X86 are currently hard-coded in the C++ source file.
This makes it difficult to configure the bits if needed. Move these to
python instead. This will provide a few benefits:
1. We can enable features for certain configurations, for example AVX
can be enabled when the KVM CPU is used, but otherwise should not be
enabled as gem5 does not have full AVX support.
2. We can more accurately communicate things like cache/TLB sizes based
on the actual gem5 configuration. The CPUID values are can be used by
some libraries, e.g., MPI, to query system topology.
3. Enabling some bits breaks things in certain configurations and this
can be prevented by configuring in python. For example, enabling AVX
seems to currently be breaking SMP, meaning gem5 can only boot one CPU
in that configuration.
Change-Id: Ib3866f39c86d61374b9451e60b119a3155575884
This fixes#131 by reverting to the old behavior of performing all
atomics at the system level. To do this the SLC bit needs to be set for
all atomic requests.
Change-Id: I63f4e449be1b02c933832d09700237f8c8026f4c
In the memory controller, MemCtrl::MemoryPort::recvFunctional,
when the functional request is satisfied by the ctrl-response queue,
correctly make the packet a response.
This change mirrors AbstractMemory::functionalAccess, which uses
Packet::makeResponse() after satisfying the request.
Change-Id: I47917062d3270915a97eed2c9fade66ba17019eb
In https://gem5-review.googlesource.com/c/public/gem5/+/52047 inst.pc
was changed from an object to a pointer. It is possible that this
pointer is null (e.g., if there is an interrupt and there is a bubble).
Make sure to check that it's not null before printing.
I believe that other places this pointer is dereferenced without an
explicit null check are safe, but I'm not certain.
Should fix#97
Change-Id: Idbe246cfdb62d4d75416d41b451fb3c076233bbc
When compiling with clang-14 I received the following error:
```
src/base/bitfield.hh:328:1: error: function 'findLsbSetFallback' is not needed and will not be emitted [-Werror,-Wunneeded-internal-declaration]
```
This function was introduced in PR #76.
This fixes this compiler warning/error by using `[[maybe_unused]]`.
Change-Id: I0b99eab0a9e42ee1687e7a0594a5a7bf9588b422
