Re: [PATCH] drm/amdkfd: Set pte_flags for actual BO location

[Felix Kuehling <felix.kuehling@xxxxxxx>]

Am 2022-08-29 um 11:38 schrieb Christian König:
> Am 27.08.22 um 01:16 schrieb Felix Kuehling:
> > BOs can be in a different location than was intended at allocation time,
> > for example when restoring fails after an eviction or BOs get pinned in
> > system memory. On some GPUs the MTYPE for coherent mappings depends on
> > the actual memory location.
> >
> > Use the actual location to determine the pte_flags every time the page
> > tables are updated.
>
> For a workaround ok, but looks a bit awkward. Basically we need 
> different MTYPE based on the location, right?

Yes. On Aldebaran and Arcturus we need different MTYPEs for fine-grained 
coherence depending on the location.

Regards,
  Felix


> Christian.
>
> > Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> > ---
> >   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |  9 ++++++++-
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c        | 19 +++++++++++++++++++
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h        |  1 +
> >   3 files changed, 28 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > index cbd593f7d553..5dd89f5a032f 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > @@ -405,6 +405,7 @@ static int vm_update_pds(struct amdgpu_vm *vm, 
> > struct amdgpu_sync *sync)
> >   static uint64_t get_pte_flags(struct amdgpu_device *adev, struct 
> > kgd_mem *mem)
> >   {
> >       struct amdgpu_device *bo_adev = 
> > amdgpu_ttm_adev(mem->bo->tbo.bdev);
> > +    bool is_vram = mem->bo->tbo.resource->mem_type == TTM_PL_VRAM;
> >       bool coherent = mem->alloc_flags & 
> > KFD_IOC_ALLOC_MEM_FLAGS_COHERENT;
> >       bool uncached = mem->alloc_flags & 
> > KFD_IOC_ALLOC_MEM_FLAGS_UNCACHED;
> >       uint32_t mapping_flags;
> > @@ -420,7 +421,7 @@ static uint64_t get_pte_flags(struct 
> > amdgpu_device *adev, struct kgd_mem *mem)
> >       switch (adev->asic_type) {
> >       case CHIP_ARCTURUS:
> >       case CHIP_ALDEBARAN:
> > -        if (mem->alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_VRAM) {
> > +        if (is_vram) {
> >               if (bo_adev == adev) {
> >                   if (uncached)
> >                       mapping_flags |= AMDGPU_VM_MTYPE_UC;
> > @@ -1236,12 +1237,18 @@ static int update_gpuvm_pte(struct kgd_mem *mem,
> >   {
> >       struct amdgpu_bo_va *bo_va = entry->bo_va;
> >       struct amdgpu_device *adev = entry->adev;
> > +    uint64_t pte_flags = get_pte_flags(adev, mem);
> >       int ret;
> >         ret = kfd_mem_dmamap_attachment(mem, entry);
> >       if (ret)
> >           return ret;
> >   +    if (unlikely(entry->pte_flags != pte_flags)) {
> > +        amdgpu_vm_bo_update_flags(bo_va, pte_flags);
> > +        entry->pte_flags = pte_flags;
> > +    }
> > +
> >       /* Update the page tables  */
> >       ret = amdgpu_vm_bo_update(adev, bo_va, false);
> >       if (ret) {
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index 59cac347baa3..954a40d5d828 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -1862,6 +1862,25 @@ void amdgpu_vm_bo_invalidate(struct 
> > amdgpu_device *adev,
> >       }
> >   }
> >   +/**
> > + * amdgpu_vm_bo_update_flags - Update mapping flags of invalid mappings
> > + *
> > + * @bo_va: identifies the BO and VM
> > + * @flags: new mapping flags
> > + *
> > + * The update is only applied to invalid mappings. This allows 
> > updating the
> > + * mapping flags after a migration to maintain the desired 
> > coherence. The next
> > + * call to amdgpu_vm_bo_update() will apply the new @flags to the 
> > page table.
> > + */
> > +void amdgpu_vm_bo_update_flags(struct amdgpu_bo_va *bo_va,
> > +                   uint64_t flags)
> > +{
> > +    struct amdgpu_bo_va_mapping *mapping;
> > +
> > +    list_for_each_entry(mapping, &bo_va->invalids, list)
> > +        mapping->flags = flags;
> > +}
> > +
> >   /**
> >    * amdgpu_vm_get_block_size - calculate VM page table size as power 
> > of two
> >    *
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > index 9ecb7f663e19..11793716cd8b 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > @@ -413,6 +413,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev,
> >   bool amdgpu_vm_evictable(struct amdgpu_bo *bo);
> >   void amdgpu_vm_bo_invalidate(struct amdgpu_device *adev,
> >                    struct amdgpu_bo *bo, bool evicted);
> > +void amdgpu_vm_bo_update_flags(struct amdgpu_bo_va *bo_va, uint64_t 
> > flags);
> >   uint64_t amdgpu_vm_map_gart(const dma_addr_t *pages_addr, uint64_t 
> > addr);
> >   struct amdgpu_bo_va *amdgpu_vm_bo_find(struct amdgpu_vm *vm,
> >                          struct amdgpu_bo *bo);