Re: [PATCH 1/3] drm/amdgpu: Add amdgpu_bo_is_vm_bo helper

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>]

On 03/05/2024 07:26, Christian König wrote:
> Am 29.04.24 um 18:47 schrieb Tvrtko Ursulin:
> > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
> >
> > Help code readability by replacing a bunch of:
> >
> > bo->tbo.base.resv == vm->root.bo->tbo.base.resv
> >
> > With:
> >
> > amdgpu_vm_is_bo_always_valid(vm, bo)
> >
> > No functional changes.
> >
> > v2:
> >   * Rename helper and move to amdgpu_vm. (Christian)
> >
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
> > Cc: Christian König <christian.koenig@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c |  2 +-
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c  | 40 +++++++++++++++----------
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h  |  2 ++
> >   3 files changed, 28 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > index 67c234bcf89f..e698d65e9508 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > @@ -174,7 +174,7 @@ static int amdgpu_gem_object_open(struct 
> > drm_gem_object *obj,
> >           return -EPERM;
> >       if (abo->flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID &&
> > -        abo->tbo.base.resv != vm->root.bo->tbo.base.resv)
> > +        !amdgpu_vm_is_bo_always_valid(vm, abo))
> >           return -EPERM;
> >       r = amdgpu_bo_reserve(abo, false);
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index 8af3f0fd3073..01ca4b35b369 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -333,7 +333,7 @@ void amdgpu_vm_bo_base_init(struct 
> > amdgpu_vm_bo_base *base,
> >       base->next = bo->vm_bo;
> >       bo->vm_bo = base;
> > -    if (bo->tbo.base.resv != vm->root.bo->tbo.base.resv)
> > +    if (!amdgpu_vm_is_bo_always_valid(vm, bo))
> >           return;
> >       dma_resv_assert_held(vm->root.bo->tbo.base.resv);
> > @@ -1101,13 +1101,13 @@ static void amdgpu_vm_bo_get_memory(struct 
> > amdgpu_bo_va *bo_va,
> >        * For now ignore BOs which are currently locked and potentially
> >        * changing their location.
> >        */
> > -    if (bo->tbo.base.resv != vm->root.bo->tbo.base.resv &&
> > +    if (!amdgpu_vm_is_bo_always_valid(vm, bo) &&
> >           !dma_resv_trylock(bo->tbo.base.resv))
> >           return;
> >       amdgpu_bo_get_memory(bo, stats);
> > -    if (bo->tbo.base.resv != vm->root.bo->tbo.base.resv)
> > -        dma_resv_unlock(bo->tbo.base.resv);
> > +    if (amdgpu_vm_is_bo_always_valid(vm, bo))
> > +        dma_resv_unlock(bo->tbo.base.resv);
> >   }
> >   void amdgpu_vm_get_memory(struct amdgpu_vm *vm,
> > @@ -1203,8 +1203,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device 
> > *adev, struct amdgpu_bo_va *bo_va,
> >           uncached = false;
> >       }
> > -    if (clear || (bo && bo->tbo.base.resv ==
> > -              vm->root.bo->tbo.base.resv))
> > +    if (clear || amdgpu_vm_is_bo_always_valid(vm, bo))
> >           last_update = &vm->last_update;
> >       else
> >           last_update = &bo_va->last_pt_update;
> > @@ -1246,7 +1245,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device 
> > *adev, struct amdgpu_bo_va *bo_va,
> >        * the evicted list so that it gets validated again on the
> >        * next command submission.
> >        */
> > -    if (bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv) {
> > +    if (amdgpu_vm_is_bo_always_valid(vm, bo)) {
> >           uint32_t mem_type = bo->tbo.resource->mem_type;
> >           if (!(bo->preferred_domains &
> > @@ -1640,10 +1639,9 @@ static void amdgpu_vm_bo_insert_map(struct 
> > amdgpu_device *adev,
> >       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) {
> > +    if (amdgpu_vm_is_bo_always_valid(vm, bo) && !bo_va->base.moved)
> >           amdgpu_vm_bo_moved(&bo_va->base);
> > -    }
> > +
> >       trace_amdgpu_vm_bo_map(bo_va, mapping);
> >   }
> > @@ -1922,7 +1920,7 @@ int amdgpu_vm_bo_clear_mappings(struct 
> > amdgpu_device *adev,
> >           if (before->flags & AMDGPU_PTE_PRT)
> >               amdgpu_vm_prt_get(adev);
> > -        if (bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv &&
> > +        if (amdgpu_vm_is_bo_always_valid(vm, bo) &&
> >               !before->bo_va->base.moved)
> >               amdgpu_vm_bo_moved(&before->bo_va->base);
> >       } else {
> > @@ -1937,7 +1935,7 @@ int amdgpu_vm_bo_clear_mappings(struct 
> > amdgpu_device *adev,
> >           if (after->flags & AMDGPU_PTE_PRT)
> >               amdgpu_vm_prt_get(adev);
> > -        if (bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv &&
> > +        if (amdgpu_vm_is_bo_always_valid(vm, bo) &&
> >               !after->bo_va->base.moved)
> >               amdgpu_vm_bo_moved(&after->bo_va->base);
> >       } else {
> > @@ -2017,7 +2015,7 @@ void amdgpu_vm_bo_del(struct amdgpu_device *adev,
> >       if (bo) {
> >           dma_resv_assert_held(bo->tbo.base.resv);
> > -        if (bo->tbo.base.resv == vm->root.bo->tbo.base.resv)
> > +        if (amdgpu_vm_is_bo_always_valid(vm, bo))
> >               ttm_bo_set_bulk_move(&bo->tbo, NULL);
> >           for (base = &bo_va->base.bo->vm_bo; *base;
> > @@ -2111,7 +2109,7 @@ void amdgpu_vm_bo_invalidate(struct 
> > amdgpu_device *adev,
> >       for (bo_base = bo->vm_bo; bo_base; bo_base = bo_base->next) {
> >           struct amdgpu_vm *vm = bo_base->vm;
> > -        if (evicted && bo->tbo.base.resv == 
> > vm->root.bo->tbo.base.resv) {
> > +        if (evicted && amdgpu_vm_is_bo_always_valid(vm, bo)) {
> >               amdgpu_vm_bo_evicted(bo_base);
> >               continue;
> >           }
> > @@ -2122,7 +2120,7 @@ void amdgpu_vm_bo_invalidate(struct 
> > amdgpu_device *adev,
> >           if (bo->tbo.type == ttm_bo_type_kernel)
> >               amdgpu_vm_bo_relocated(bo_base);
> > -        else if (bo->tbo.base.resv == vm->root.bo->tbo.base.resv)
> > +        else if (amdgpu_vm_is_bo_always_valid(vm, bo))
> >               amdgpu_vm_bo_moved(bo_base);
> >           else
> >               amdgpu_vm_bo_invalidated(bo_base);
> > @@ -2986,3 +2984,15 @@ void amdgpu_vm_update_fault_cache(struct 
> > amdgpu_device *adev,
> >       xa_unlock_irqrestore(&adev->vm_manager.pasids, flags);
> >   }
> > +/**
> > + * amdgpu_vm_is_bo_always_valid - check if the BO is VM always valid
> > + *
> > + * @vm: VM to test against.
> > + * @abo: BO to be tested.
> > + *
> > + * Returns true if the BO is VM always valid.
>
> Maybe improve that a bit, e.g. something like this:
>
> "Returns true if the BO shares the dma_resv object with the root PD and 
> is always guaranteed to be valid inside the VM."

I am only unsure if the dma_resv and root PD are too much of an 
implementation details? Or really something the API user must know? 
Considering from the uapi we have this:

/* Flag that BO is always valid in this VM */
#define AMDGPU_GEM_CREATE_VM_ALWAYS_VALID	(1 << 6)

Which is the reason I thought to keep the comment high level.

Give me a final verdict and I can change it accordingly.

Regards,

Tvrtko

> With that done the patch is Reviewed-by: Christian König 
> <christian.koenig@xxxxxxx>
>
> Thanks,
> Christian.
>
> > + */
> > +bool amdgpu_vm_is_bo_always_valid(struct amdgpu_vm *vm, struct 
> > amdgpu_bo *bo)
> > +{
> > +    return bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv;
> > +}
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > index 54d7da396de0..ec688a47dec1 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > @@ -561,6 +561,8 @@ void amdgpu_debugfs_vm_bo_info(struct amdgpu_vm 
> > *vm, struct seq_file *m);
> >   int amdgpu_vm_pt_map_tables(struct amdgpu_device *adev, struct 
> > amdgpu_vm *vm);
> > +bool amdgpu_vm_is_bo_always_valid(struct amdgpu_vm *vm, struct 
> > amdgpu_bo *bo);
> > +
> >   /**
> >    * amdgpu_vm_tlb_seq - return tlb flush sequence number
> >    * @vm: the amdgpu_vm structure to query