[PATCH 3/6] drm/amdgpu: Flush VM updates for split bindings eagerly.
Christian König
christian.koenig at amd.com
Mon Nov 6 13:33:57 UTC 2023
Am 06.11.23 um 08:56 schrieb Tatsuyuki Ishi:
>
>> On Oct 31, 2023, at 23:07, Christian König <christian.koenig at amd.com>
>> wrote:
>>
>> Am 31.10.23 um 14:59 schrieb Bas Nieuwenhuizen:
>>>
>>>
>>> On Tue, Oct 31, 2023 at 2:57 PM Christian König
>>> <christian.koenig at amd.com> wrote:
>>>
>>> Am 31.10.23 um 14:40 schrieb Tatsuyuki Ishi:
>>> > The current amdgpu_gem_va_update_vm only tries to perform
>>> updates for the
>>> > BO specified in the GEM ioctl; however, when a binding is
>>> split, the
>>> > adjacent bindings also need to be updated. Such updates
>>> currently ends up
>>> > getting deferred until next submission which causes stalls.
>>>
>>> Yeah, that is a necessity. The hardware simply doesn't support
>>> what you
>>> try to do here in all cases.
>>>
>>>
>>> What can the hardware not do here? Is this just needing to wait for
>>> TLB flushes before we can free pagetables, can we just delay that?
>>
>> On some hardware generations (especially Navi1x, but also everything
>> older than Polaris) you can't invalidate the TLB while it is in use.
>>
>> For Polaris and older it just means that you don't have a guarantee
>> that the shader can't access the memory any more. So delaying the
>> free operation helps here.
>>
>> But for Navi1x it's a workaround for a hardware bug. If you try to
>> invalidate the TLB while it is in use you can potentially triggering
>> memory accesses to random addresses.
>>
>> That's why we still delay TLB invalidation's to the next CS and use a
>> new VMID for each submission instead of invalidating the old one.
>
> Thanks for the information. I looked into the VMID allocation logic
> and I see that if concurrent_flush is false, then we defer any flush
> (or VMID reuse that requires a flush) until that VMID is idle.
>
> What patch #3 ends up doing is just performing the PT update right
> away. Any required TLB update is deferred by amdgpu_vm_update_range
> through the increment of tlb_seq, and amdgpu_vmid.c is responsible for
> doing the actual TLB flush in a manner that does not trigger the bug.
>
> Can you confirm that this would be fine for the current hardware?
Yeah, that should work. I'm just think about the UAPI a bit, we should
probably improve this to use something like a drm_syncobj instead of
just a flag to be future prove.
Christian.
>
> Tatsuyuki.
>
>>
>> I'm currently working on changing that for Navi2x and newer (maybe
>> Vega as well), but this is something you can really only do on some
>> hw generations after validating that it works.
>>
>> Regards,
>> Christian.
>>
>>>
>>>
>>> So this approach won't work in general.
>>>
>>> Regards,
>>> Christian.
>>>
>>> >
>>> > Introduce a new state "dirty", shared between per-VM BOs and
>>> traditional
>>> > BOs, containing all BOs that have pending updates in `invalids`.
>>> > amdgpu_gem_va_update_vm will now simply flush any pending
>>> updates for BOs
>>> > in the dirty state.
>>> >
>>> > Signed-off-by: Tatsuyuki Ishi <ishitatsuyuki at gmail.com>
>>> > ---
>>> > drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 18 ++++---
>>> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 66
>>> ++++++++++++++++++-------
>>> > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 3 ++
>>> > 3 files changed, 63 insertions(+), 24 deletions(-)
>>> >
>>> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> > index a1b15d0d6c48..01d3a97248b0 100644
>>> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> > @@ -604,10 +604,9 @@ int amdgpu_gem_metadata_ioctl(struct
>>> drm_device *dev, void *data,
>>> > * vital here, so they are not reported back to userspace.
>>> > */
>>> > static void amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
>>> > - struct amdgpu_vm *vm,
>>> > - struct amdgpu_bo_va *bo_va,
>>> > - uint32_t operation)
>>> > + struct amdgpu_vm *vm)
>>> > {
>>> > + struct amdgpu_bo_va *bo_va;
>>> > int r;
>>> >
>>> > if (!amdgpu_vm_ready(vm))
>>> > @@ -617,12 +616,18 @@ static void
>>> amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
>>> > if (r)
>>> > goto error;
>>> >
>>> > - if (operation == AMDGPU_VA_OP_MAP ||
>>> > - operation == AMDGPU_VA_OP_REPLACE) {
>>> > + spin_lock(&vm->status_lock);
>>> > + while (!list_empty(&vm->dirty)) {
>>> > + bo_va = list_first_entry(&vm->dirty, struct
>>> amdgpu_bo_va,
>>> > + base.vm_status);
>>> > + spin_unlock(&vm->status_lock);
>>> > +
>>> > r = amdgpu_vm_bo_update(adev, bo_va, false);
>>> > if (r)
>>> > goto error;
>>> > + spin_lock(&vm->status_lock);
>>> > }
>>> > + spin_unlock(&vm->status_lock);
>>> >
>>> > r = amdgpu_vm_update_pdes(adev, vm, false);
>>> >
>>> > @@ -792,8 +797,7 @@ int amdgpu_gem_va_ioctl(struct drm_device
>>> *dev, void *data,
>>> > break;
>>> > }
>>> > if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) &&
>>> !amdgpu_vm_debug)
>>> > - amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
>>> > - args->operation);
>>> > + amdgpu_gem_va_update_vm(adev, &fpriv->vm);
>>> >
>>> > error:
>>> > drm_exec_fini(&exec);
>>> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> > index dd6f72e2a1d6..01d31891cd05 100644
>>> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> > @@ -191,6 +191,21 @@ static void
>>> amdgpu_vm_bo_set_evicted(struct amdgpu_vm_bo_base *vm_bo, bool evict
>>> > spin_unlock(&vm_bo->vm->status_lock);
>>> > }
>>> >
>>> > +/**
>>> > + * amdgpu_vm_bo_dirty - vm_bo is dirty
>>> > + *
>>> > + * @vm_bo: vm_bo which is dirty
>>> > + *
>>> > + * State for normal and per VM BOs that are not moved, but
>>> have new entries in
>>> > + * bo_va->invalids.
>>> > + */
>>> > +static void amdgpu_vm_bo_dirty(struct amdgpu_vm_bo_base *vm_bo)
>>> > +{
>>> > + spin_lock(&vm_bo->vm->status_lock);
>>> > + list_move(&vm_bo->vm_status, &vm_bo->vm->dirty);
>>> > + spin_unlock(&vm_bo->vm->status_lock);
>>> > +}
>>> > +
>>> > /**
>>> > * amdgpu_vm_bo_moved - vm_bo is moved
>>> > *
>>> > @@ -1042,6 +1057,9 @@ void amdgpu_vm_get_memory(struct
>>> amdgpu_vm *vm,
>>> > list_for_each_entry_safe(bo_va, tmp, &vm->evicted,
>>> base.eviction_status)
>>> > amdgpu_vm_bo_get_memory(bo_va, stats);
>>> >
>>> > + list_for_each_entry_safe(bo_va, tmp, &vm->dirty,
>>> base.vm_status)
>>> > + amdgpu_vm_bo_get_memory(bo_va, stats);
>>> > +
>>> > list_for_each_entry_safe(bo_va, tmp, &vm->relocated,
>>> base.vm_status)
>>> > amdgpu_vm_bo_get_memory(bo_va, stats);
>>> >
>>> > @@ -1411,6 +1429,17 @@ int amdgpu_vm_handle_moved(struct
>>> amdgpu_device *adev,
>>> > dma_resv_unlock(resv);
>>> > spin_lock(&vm->status_lock);
>>> > }
>>> > +
>>> > + while (!list_empty(&vm->dirty)) {
>>> > + bo_va = list_first_entry(&vm->dirty, struct
>>> amdgpu_bo_va,
>>> > + base.vm_status);
>>> > + spin_unlock(&vm->status_lock);
>>> > +
>>> > + r = amdgpu_vm_bo_update(adev, bo_va, false);
>>> > + if (r)
>>> > + return r;
>>> > + spin_lock(&vm->status_lock);
>>> > + }
>>> > spin_unlock(&vm->status_lock);
>>> >
>>> > return 0;
>>> > @@ -1476,19 +1505,16 @@ static void
>>> amdgpu_vm_bo_insert_map(struct amdgpu_device *adev,
>>> > struct amdgpu_bo_va_mapping
>>> *mapping)
>>> > {
>>> > struct amdgpu_vm *vm = bo_va->base.vm;
>>> > - struct amdgpu_bo *bo = bo_va->base.bo <http://base.bo/>;
>>> >
>>> > mapping->bo_va = bo_va;
>>> > list_add(&mapping->list, &bo_va->invalids);
>>> > amdgpu_vm_it_insert(mapping, &vm->va);
>>> > + if (!bo_va->base.moved)
>>> > + amdgpu_vm_bo_dirty(&bo_va->base);
>>> >
>>> > if (mapping->flags & AMDGPU_PTE_PRT)
>>> > amdgpu_vm_prt_get(adev);
>>> >
>>> > - if (bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv &&
>>> > - !bo_va->base.moved) {
>>> > - amdgpu_vm_bo_moved(&bo_va->base);
>>> > - }
>>> > trace_amdgpu_vm_bo_map(bo_va, mapping);
>>> > }
>>> >
>>> > @@ -1725,6 +1751,8 @@ int amdgpu_vm_bo_clear_mappings(struct
>>> amdgpu_device *adev,
>>> > before->flags = tmp->flags;
>>> > before->bo_va = tmp->bo_va;
>>> > list_add(&before->list, &tmp->bo_va->invalids);
>>> > + if (!tmp->bo_va->base.moved)
>>> > + amdgpu_vm_bo_dirty(&tmp->bo_va->base);
>>> > }
>>> >
>>> > /* Remember mapping split at the end */
>>> > @@ -1736,6 +1764,8 @@ int amdgpu_vm_bo_clear_mappings(struct
>>> amdgpu_device *adev,
>>> > after->flags = tmp->flags;
>>> > after->bo_va = tmp->bo_va;
>>> > list_add(&after->list, &tmp->bo_va->invalids);
>>> > + if (!tmp->bo_va->base.moved)
>>> > + amdgpu_vm_bo_dirty(&tmp->bo_va->base);
>>> > }
>>> >
>>> > list_del(&tmp->list);
>>> > @@ -1761,30 +1791,18 @@ int amdgpu_vm_bo_clear_mappings(struct
>>> amdgpu_device *adev,
>>> >
>>> > /* Insert partial mapping before the range */
>>> > if (!list_empty(&before->list)) {
>>> > - struct amdgpu_bo *bo = before->bo_va->base.bo
>>> <http://base.bo/>;
>>> > -
>>> > amdgpu_vm_it_insert(before, &vm->va);
>>> > if (before->flags & AMDGPU_PTE_PRT)
>>> > amdgpu_vm_prt_get(adev);
>>> > -
>>> > - if (bo && bo->tbo.base.resv ==
>>> vm->root.bo->tbo.base.resv &&
>>> > - !before->bo_va->base.moved)
>>> > - amdgpu_vm_bo_moved(&before->bo_va->base);
>>> > } else {
>>> > kfree(before);
>>> > }
>>> >
>>> > /* Insert partial mapping after the range */
>>> > if (!list_empty(&after->list)) {
>>> > - struct amdgpu_bo *bo = after->bo_va->base.bo
>>> <http://base.bo/>;
>>> > -
>>> > amdgpu_vm_it_insert(after, &vm->va);
>>> > if (after->flags & AMDGPU_PTE_PRT)
>>> > amdgpu_vm_prt_get(adev);
>>> > -
>>> > - if (bo && bo->tbo.base.resv ==
>>> vm->root.bo->tbo.base.resv &&
>>> > - !after->bo_va->base.moved)
>>> > - amdgpu_vm_bo_moved(&after->bo_va->base);
>>> > } else {
>>> > kfree(after);
>>> > }
>>> > @@ -2136,6 +2154,7 @@ int amdgpu_vm_init(struct amdgpu_device
>>> *adev, struct amdgpu_vm *vm, int32_t xcp
>>> > INIT_LIST_HEAD(&vm->evicted);
>>> > INIT_LIST_HEAD(&vm->relocated);
>>> > INIT_LIST_HEAD(&vm->moved);
>>> > + INIT_LIST_HEAD(&vm->dirty);
>>> > INIT_LIST_HEAD(&vm->idle);
>>> > INIT_LIST_HEAD(&vm->invalidated);
>>> > spin_lock_init(&vm->status_lock);
>>> > @@ -2648,11 +2667,13 @@ void amdgpu_debugfs_vm_bo_info(struct
>>> amdgpu_vm *vm, struct seq_file *m)
>>> > {
>>> > struct amdgpu_bo_va *bo_va, *tmp;
>>> > u64 total_idle = 0;
>>> > + u64 total_dirty = 0;
>>> > u64 total_relocated = 0;
>>> > u64 total_moved = 0;
>>> > u64 total_invalidated = 0;
>>> > u64 total_done = 0;
>>> > unsigned int total_idle_objs = 0;
>>> > + unsigned int total_dirty_objs = 0;
>>> > unsigned int total_relocated_objs = 0;
>>> > unsigned int total_moved_objs = 0;
>>> > unsigned int total_invalidated_objs = 0;
>>> > @@ -2669,6 +2690,15 @@ void amdgpu_debugfs_vm_bo_info(struct
>>> amdgpu_vm *vm, struct seq_file *m)
>>> > total_idle_objs = id;
>>> > id = 0;
>>> >
>>> > + seq_puts(m, "\tDirty BOs:\n");
>>> > + list_for_each_entry_safe(bo_va, tmp, &vm->dirty,
>>> base.vm_status) {
>>> > + if (!bo_va->base.bo <http://base.bo/>)
>>> > + continue;
>>> > + total_dirty += amdgpu_bo_print_info(id++,
>>> bo_va->base.bo <http://base.bo/>, m);
>>> > + }
>>> > + total_dirty_objs = id;
>>> > + id = 0;
>>> > +
>>> > seq_puts(m, "\tRelocated BOs:\n");
>>> > list_for_each_entry_safe(bo_va, tmp, &vm->relocated,
>>> base.vm_status) {
>>> > if (!bo_va->base.bo <http://base.bo/>)
>>> > @@ -2707,6 +2737,8 @@ void amdgpu_debugfs_vm_bo_info(struct
>>> amdgpu_vm *vm, struct seq_file *m)
>>> >
>>> > seq_printf(m, "\tTotal idle size:
>>> %12lld\tobjs:\t%d\n", total_idle,
>>> > total_idle_objs);
>>> > + seq_printf(m, "\tTotal dirty size:
>>> %12lld\tobjs:\t%d\n", total_dirty,
>>> > + total_dirty_objs);
>>> > seq_printf(m, "\tTotal relocated size:
>>> %12lld\tobjs:\t%d\n", total_relocated,
>>> > total_relocated_objs);
>>> > seq_printf(m, "\tTotal moved size:
>>> %12lld\tobjs:\t%d\n", total_moved,
>>> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> > index d9ab97eabda9..f91d4fcf80b8 100644
>>> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> > @@ -276,6 +276,9 @@ struct amdgpu_vm {
>>> > /* per VM BOs moved, but not yet updated in the PT */
>>> > struct list_head moved;
>>> >
>>> > + /* normal and per VM BOs that are not moved, but have
>>> new PT entries */
>>> > + struct list_head dirty;
>>> > +
>>> > /* All BOs of this VM not currently in the state machine */
>>> > struct list_head idle;
>>> >
>>>
>>
>
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