[PATCH v4 1/2] drm/amdgpu: implement TLB flush fence
Sharma, Shashank
shashank.sharma at amd.com
Fri Mar 1 13:08:40 UTC 2024
On 01/03/2024 13:59, Christian König wrote:
> Am 01.03.24 um 12:07 schrieb Shashank Sharma:
>> From: Christian König <christian.koenig at amd.com>
>>
>> The problem is that when (for example) 4k pages are replaced
>> with a single 2M page we need to wait for change to be flushed
>> out by invalidating the TLB before the PT can be freed.
>>
>> Solve this by moving the TLB flush into a DMA-fence object which
>> can be used to delay the freeing of the PT BOs until it is signaled.
>>
>> V2: (Shashank)
>> - rebase
>> - set dma_fence_error only in case of error
>> - add tlb_flush fence only when PT/PD BO is locked (Felix)
>> - use vm->pasid when f is NULL (Mukul)
>>
>> V4: - add a wait for (f->dependency) in tlb_fence_work (Christian)
>> - move the misplaced fence_create call to the end (Philip)
>>
>> Cc: Christian Koenig <christian.koenig at amd.com>
>> Cc: Felix Kuehling <Felix.Kuehling at amd.com>
>> Cc: Rajneesh Bhardwaj <rajneesh.bhardwaj at amd.com>
>> Cc: Alex Deucher <alexander.deucher at amd.com>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/Makefile | 3 +-
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 10 ++
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 4 +
>> .../gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c | 111 ++++++++++++++++++
>> 4 files changed, 127 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/Makefile
>> b/drivers/gpu/drm/amd/amdgpu/Makefile
>> index fa26a4e3a99d..91ab4cf29b5b 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/Makefile
>> +++ b/drivers/gpu/drm/amd/amdgpu/Makefile
>> @@ -70,7 +70,8 @@ amdgpu-y += amdgpu_device.o amdgpu_doorbell_mgr.o
>> amdgpu_kms.o \
>> amdgpu_cs.o amdgpu_bios.o amdgpu_benchmark.o \
>> atombios_dp.o amdgpu_afmt.o amdgpu_trace_points.o \
>> atombios_encoders.o amdgpu_sa.o atombios_i2c.o \
>> - amdgpu_dma_buf.o amdgpu_vm.o amdgpu_vm_pt.o amdgpu_ib.o
>> amdgpu_pll.o \
>> + amdgpu_dma_buf.o amdgpu_vm.o amdgpu_vm_pt.o amdgpu_vm_tlb_fence.o \
>> + amdgpu_ib.o amdgpu_pll.o \
>> amdgpu_ucode.o amdgpu_bo_list.o amdgpu_ctx.o amdgpu_sync.o \
>> amdgpu_gtt_mgr.o amdgpu_preempt_mgr.o amdgpu_vram_mgr.o
>> amdgpu_virt.o \
>> amdgpu_atomfirmware.o amdgpu_vf_error.o amdgpu_sched.o \
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 0960e0a665d3..310aae6fb49b 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -988,6 +988,15 @@ int amdgpu_vm_update_range(struct amdgpu_device
>> *adev, struct amdgpu_vm *vm,
>> r = vm->update_funcs->commit(¶ms, fence);
>> + /* Prepare a TLB flush fence to be attached to PTs */
>> + if (!unlocked && params.needs_flush && vm->is_compute_context) {
>> + amdgpu_vm_tlb_fence_create(adev, vm, fence);
>> +
>> + /* Makes sure no PD/PT is freed before the flush */
>> + dma_resv_add_fence(vm->root.bo->tbo.base.resv, *fence,
>> + DMA_RESV_USAGE_BOOKKEEP);
>> + }
>> +
>> error_unlock:
>> amdgpu_vm_eviction_unlock(vm);
>> drm_dev_exit(idx);
>> @@ -2237,6 +2246,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev,
>> struct amdgpu_vm *vm,
>> mutex_init(&vm->eviction_lock);
>> vm->evicting = false;
>> + vm->tlb_fence_context = dma_fence_context_alloc(1);
>> r = amdgpu_vm_pt_create(adev, vm, adev->vm_manager.root_level,
>> false, &root, xcp_id);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> index 64b3f69efa57..298f604b8e5f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> @@ -341,6 +341,7 @@ struct amdgpu_vm {
>> atomic64_t tlb_seq;
>> uint64_t tlb_seq_va;
>> uint64_t *tlb_seq_cpu_addr;
>> + uint64_t tlb_fence_context;
>> atomic64_t kfd_last_flushed_seq;
>> @@ -594,5 +595,8 @@ void amdgpu_vm_update_fault_cache(struct
>> amdgpu_device *adev,
>> uint64_t addr,
>> uint32_t status,
>> unsigned int vmhub);
>> +void amdgpu_vm_tlb_fence_create(struct amdgpu_device *adev,
>> + struct amdgpu_vm *vm,
>> + struct dma_fence **fence);
>> #endif
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>> new file mode 100644
>> index 000000000000..54c33c24fa46
>> --- /dev/null
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_tlb_fence.c
>> @@ -0,0 +1,111 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +/*
>> + * Copyright 2023 Advanced Micro Devices, Inc.
>> + *
>> + * Permission is hereby granted, free of charge, to any person
>> obtaining a
>> + * copy of this software and associated documentation files (the
>> "Software"),
>> + * to deal in the Software without restriction, including without
>> limitation
>> + * the rights to use, copy, modify, merge, publish, distribute,
>> sublicense,
>> + * and/or sell copies of the Software, and to permit persons to whom
>> the
>> + * Software is furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be
>> included in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
>> EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>> MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
>> EVENT SHALL
>> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM,
>> DAMAGES OR
>> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
>> OTHERWISE,
>> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
>> USE OR
>> + * OTHER DEALINGS IN THE SOFTWARE.
>> + */
>> +
>> +#include <linux/dma-fence.h>
>> +#include <linux/workqueue.h>
>> +
>> +#include "amdgpu.h"
>> +#include "amdgpu_vm.h"
>> +#include "amdgpu_gmc.h"
>> +
>> +struct amdgpu_tlb_fence {
>> + struct dma_fence base;
>> + struct amdgpu_device *adev;
>> + struct dma_fence *dependency;
>> + struct work_struct work;
>> + spinlock_t lock;
>> + uint16_t pasid;
>> +
>> +};
>> +
>> +static const char *amdgpu_tlb_fence_get_driver_name(struct dma_fence
>> *fence)
>> +{
>> + return "amdgpu tlb fence";
>> +}
>> +
>> +static const char *amdgpu_tlb_fence_get_timeline_name(struct
>> dma_fence *f)
>> +{
>> + return "amdgpu tlb timeline";
>> +}
>> +
>> +static void amdgpu_tlb_fence_work(struct work_struct *work)
>> +{
>> + struct amdgpu_tlb_fence *f = container_of(work, typeof(*f), work);
>> + int r;
>> +
>> + if (f->dependency) {
>> + dma_fence_wait(f->dependency, false);
>> + f->dependency = dma_fence_get_stub();
>
> That doesn't correctly drops the f->depency reference.
>
> You need something like "dma_fence_put(f->depency); f->dependency =
> NULL;" here instead.
>
> Apart from that looks good to me,
Noted, will update.
- Shashank
> Christian.
>
>> + }
>> +
>> + r = amdgpu_gmc_flush_gpu_tlb_pasid(f->adev, f->pasid, 2, true, 0);
>> + if (r) {
>> + dev_err(f->adev->dev, "TLB flush failed for PASID %d.\n",
>> + f->pasid);
>> + dma_fence_set_error(&f->base, r);
>> + }
>> +
>> + dma_fence_signal(&f->base);
>> + dma_fence_put(&f->base);
>> +}
>> +
>> +static const struct dma_fence_ops amdgpu_tlb_fence_ops = {
>> + .use_64bit_seqno = true,
>> + .get_driver_name = amdgpu_tlb_fence_get_driver_name,
>> + .get_timeline_name = amdgpu_tlb_fence_get_timeline_name
>> +};
>> +
>> +void amdgpu_vm_tlb_fence_create(struct amdgpu_device *adev, struct
>> amdgpu_vm *vm,
>> + struct dma_fence **fence)
>> +{
>> + struct amdgpu_tlb_fence *f;
>> +
>> + f = kmalloc(sizeof(*f), GFP_KERNEL);
>> + if (!f) {
>> + /*
>> + * We can't fail since the PDEs and PTEs are already
>> updated, so
>> + * just block for the dependency and execute the TLB flush
>> + */
>> + if (*fence)
>> + dma_fence_wait(*fence, false);
>> +
>> + amdgpu_gmc_flush_gpu_tlb_pasid(adev, vm->pasid, 2, true, 0);
>> + *fence = dma_fence_get_stub();
>> + return;
>> + }
>> +
>> + f->adev = adev;
>> + f->dependency = *fence;
>> + f->pasid = vm->pasid;
>> + INIT_WORK(&f->work, amdgpu_tlb_fence_work);
>> + spin_lock_init(&f->lock);
>> +
>> + dma_fence_init(&f->base, &amdgpu_tlb_fence_ops, &f->lock,
>> + vm->tlb_fence_context, atomic64_read(&vm->tlb_seq));
>> +
>> + /* TODO: We probably need a separate wq here */
>> + dma_fence_get(&f->base);
>> + schedule_work(&f->work);
>> +
>> + *fence = &f->base;
>> +}
>
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