Re: [RFC PATCH 1/2] drm/amdkfd: Move TLB flushing logic into amdgpu

[Felix Kuehling <felix.kuehling@xxxxxxx>]

Am 2023-03-13 um 03:36 schrieb Christian König:
> Am 10.03.23 um 23:16 schrieb Felix Kuehling:
> > This will make it possible for amdgpu GEM ioctls to flush TLBs on 
> > compute
> > VMs.
> >
> > This removes VMID-based TLB flushing and always uses PASID-based
> > flushing. This still works because it scans the VMID-PASID mapping
> > registers to find the right VMID. It's only slightly less efficient. 
> > This
> > is not a production use case.
>
> On the one hand it looks nice that we can now flush based on the pasid 
> without having the NO_HWS dependency (I hope that this was intentional).

The intention was to be able to trigger PASID TLB flushes from AMDGPU. I 
need it for flushing compute VMs when their mappings are modified by the 
GEM VA ioctl. Removing the NO_HWS dependency was a useful simplification 
to get there.


> On the other hand I really don't like to have any variables in the 
> amdgpu_vm structure which are not worked with by the VM code itself.

So what's the solution? Move that code into amdgpu_vm.c? Or find a 
different data structure to store the sequence number? I guess I could 
put it in struct amdgpu_fpriv, which amdgpu_vm is part of.


> That already backfired with the pd_phys_addr before.

Can you clarify this concern? I'm not aware of any issues with pd_phys_addr.

Thanks,
  Felix


> Regards,
> Christian.
>
> > Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 30 +++++++++-------------
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h |  6 ++---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h     |  1 +
> >   drivers/gpu/drm/amd/amdkfd/kfd_priv.h      |  9 +++++--
> >   drivers/gpu/drm/amd/amdkfd/kfd_process.c   | 28 --------------------
> >   5 files changed, 22 insertions(+), 52 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > index 8816853e50c0..dcbd28e99b5c 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > @@ -726,31 +726,25 @@ bool amdgpu_amdkfd_is_kfd_vmid(struct 
> > amdgpu_device *adev, u32 vmid)
> >       return false;
> >   }
> >   -int amdgpu_amdkfd_flush_gpu_tlb_vmid(struct amdgpu_device *adev,
> > -                     uint16_t vmid)
> > -{
> > -    if (adev->family == AMDGPU_FAMILY_AI) {
> > -        int i;
> > -
> > -        for (i = 0; i < adev->num_vmhubs; i++)
> > -            amdgpu_gmc_flush_gpu_tlb(adev, vmid, i, 0);
> > -    } else {
> > -        amdgpu_gmc_flush_gpu_tlb(adev, vmid, AMDGPU_GFXHUB_0, 0);
> > -    }
> > -
> > -    return 0;
> > -}
> > -
> > -int amdgpu_amdkfd_flush_gpu_tlb_pasid(struct amdgpu_device *adev,
> > -                      uint16_t pasid, enum TLB_FLUSH_TYPE flush_type)
> > +int amdgpu_amdkfd_flush_tlb(struct amdgpu_device *adev, struct 
> > amdgpu_vm *vm,
> > +                enum TLB_FLUSH_TYPE type)
> >   {
> > +    uint64_t tlb_seq = amdgpu_vm_tlb_seq(vm);
> >       bool all_hub = false;
> >   +    /*
> > +     * It can be that we race and lose here, but that is extremely 
> > unlikely
> > +     * and the worst thing which could happen is that we flush the 
> > changes
> > +     * into the TLB once more which is harmless.
> > +     */
> > +    if (atomic64_xchg(&vm->kfd_last_flushed_seq, tlb_seq) == tlb_seq)
> > +        return 0;
> > +
> >       if (adev->family == AMDGPU_FAMILY_AI ||
> >           adev->family == AMDGPU_FAMILY_RV)
> >           all_hub = true;
> >   -    return amdgpu_gmc_flush_gpu_tlb_pasid(adev, pasid, flush_type, 
> > all_hub);
> > +    return amdgpu_gmc_flush_gpu_tlb_pasid(adev, vm->pasid, type, 
> > all_hub);
> >   }
> >     bool amdgpu_amdkfd_have_atomics_support(struct amdgpu_device *adev)
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > index 01ba3589b60a..dcaf69fd833c 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > @@ -157,10 +157,8 @@ int amdgpu_amdkfd_submit_ib(struct amdgpu_device 
> > *adev,
> >                   uint32_t *ib_cmd, uint32_t ib_len);
> >   void amdgpu_amdkfd_set_compute_idle(struct amdgpu_device *adev, 
> > bool idle);
> >   bool amdgpu_amdkfd_have_atomics_support(struct amdgpu_device *adev);
> > -int amdgpu_amdkfd_flush_gpu_tlb_vmid(struct amdgpu_device *adev,
> > -                uint16_t vmid);
> > -int amdgpu_amdkfd_flush_gpu_tlb_pasid(struct amdgpu_device *adev,
> > -                uint16_t pasid, enum TLB_FLUSH_TYPE flush_type);
> > +int amdgpu_amdkfd_flush_tlb(struct amdgpu_device *adev, struct 
> > amdgpu_vm *vm,
> > +                enum TLB_FLUSH_TYPE type);
> >     bool amdgpu_amdkfd_is_kfd_vmid(struct amdgpu_device *adev, u32 
> > vmid);
> >   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > index 03a3314e5b43..171de7da2959 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> > @@ -290,6 +290,7 @@ struct amdgpu_vm {
> >       /* Last finished delayed update */
> >       atomic64_t        tlb_seq;
> >       struct dma_fence    *last_tlb_flush;
> > +    atomic64_t        kfd_last_flushed_seq;
> >         /* Last unlocked submission to the scheduler entities */
> >       struct dma_fence    *last_unlocked;
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h 
> > b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > index bfa30d12406b..e029129308e7 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> > @@ -715,7 +715,6 @@ struct kfd_process_device {
> >       /* VM context for GPUVM allocations */
> >       struct file *drm_file;
> >       void *drm_priv;
> > -    atomic64_t tlb_seq;
> >         /* GPUVM allocations storage */
> >       struct idr alloc_idr;
> > @@ -1344,7 +1343,13 @@ void kfd_signal_reset_event(struct kfd_dev *dev);
> >     void kfd_signal_poison_consumed_event(struct kfd_dev *dev, u32 
> > pasid);
> >   -void kfd_flush_tlb(struct kfd_process_device *pdd, enum 
> > TLB_FLUSH_TYPE type);
> > +static inline void kfd_flush_tlb(struct kfd_process_device 
> > *pdd,                             enum TLB_FLUSH_TYPE type)
> > +{
> > +    struct amdgpu_device *adev = pdd->dev->adev;
> > +    struct amdgpu_vm *vm = drm_priv_to_vm(pdd->drm_priv);
> > +
> > +    amdgpu_amdkfd_flush_tlb(adev, vm, type);
> > +}
> >     static inline bool kfd_flush_tlb_after_unmap(struct kfd_dev *dev)
> >   {
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c 
> > b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > index ebabe92f7edb..48d7d30eeb24 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > @@ -1591,7 +1591,6 @@ int kfd_process_device_init_vm(struct 
> > kfd_process_device *pdd,
> >           return ret;
> >       }
> >       pdd->drm_priv = drm_file->private_data;
> > -    atomic64_set(&pdd->tlb_seq, 0);
> >         ret = kfd_process_device_reserve_ib_mem(pdd);
> >       if (ret)
> > @@ -1994,33 +1993,6 @@ int kfd_reserved_mem_mmap(struct kfd_dev *dev, 
> > struct kfd_process *process,
> >                      KFD_CWSR_TBA_TMA_SIZE, vma->vm_page_prot);
> >   }
> >   -void kfd_flush_tlb(struct kfd_process_device *pdd, enum 
> > TLB_FLUSH_TYPE type)
> > -{
> > -    struct amdgpu_vm *vm = drm_priv_to_vm(pdd->drm_priv);
> > -    uint64_t tlb_seq = amdgpu_vm_tlb_seq(vm);
> > -    struct kfd_dev *dev = pdd->dev;
> > -
> > -    /*
> > -     * It can be that we race and lose here, but that is extremely 
> > unlikely
> > -     * and the worst thing which could happen is that we flush the 
> > changes
> > -     * into the TLB once more which is harmless.
> > -     */
> > -    if (atomic64_xchg(&pdd->tlb_seq, tlb_seq) == tlb_seq)
> > -        return;
> > -
> > -    if (dev->dqm->sched_policy == KFD_SCHED_POLICY_NO_HWS) {
> > -        /* Nothing to flush until a VMID is assigned, which
> > -         * only happens when the first queue is created.
> > -         */
> > -        if (pdd->qpd.vmid)
> > -            amdgpu_amdkfd_flush_gpu_tlb_vmid(dev->adev,
> > -                            pdd->qpd.vmid);
> > -    } else {
> > -        amdgpu_amdkfd_flush_gpu_tlb_pasid(dev->adev,
> > -                    pdd->process->pasid, type);
> > -    }
> > -}
> > -
> >   struct kfd_process_device *kfd_process_device_data_by_id(struct 
> > kfd_process *p, uint32_t gpu_id)
> >   {
> >       int i;