Re: [PATCH 1/4] drm/amdkfd: Add flush-type parameter to kfd_flush_tlb

[philip yang <yangp@xxxxxxx>]

On 2021-06-02 2:53 a.m., Christian König wrote:

> Mostly a
>       question for Felix and Philip:
>       
>       
>       I've been thinking for a bit about how that case happens in the
>       first place?
>       
>       
>       I mean if we have a PDE which points to PTEs and then switch that
>       into a 2MiB PTE then why wasn't that range invalidated before?
>       
>       
>       In other words when the PDE points to the PTEs we should have had
>       an unmap operation on that range before which should have
>       invalidated the TLB.
>       
>

Because one cache line has 8 PDE0, after unmap flush tlb, access address on same PDE0 cache line will load PDE0 back into tlb. For example:

1. map and access 0x7ffff6210000, unmap it, tlb flush

2. map and access 0x7ffff6400000, PDE0 for 0x7ffff6200000 into tlb, which is P=0, V=1

3. map 0x7ffff6200000 update page table, access has vm fault because tlb has PDE0 P=0,V=1, to recover this fault, map need update page table and flush tlb.

Regards,

Philip

>       
>       Regards,
>       
>       Christian.
>       
>       
>       Am 02.06.21 um 00:59 schrieb Eric Huang:
>       
> > It is to provide more tlb flush types
> >         opotion for different
> >         
> >         case scenario.
> >         
> >         
> >         Signed-off-by: Eric Huang <jinhuieric.huang@xxxxxxx>
> >         
> >         ---
> >         
> >           drivers/gpu/drm/amd/amdkfd/kfd_chardev.c              | 2 +-
> >         
> >           drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c | 6
> >         +++---
> >         
> >           drivers/gpu/drm/amd/amdkfd/kfd_priv.h                 | 2 +-
> >         
> >           drivers/gpu/drm/amd/amdkfd/kfd_process.c              | 4 ++--
> >         
> >           4 files changed, 7 insertions(+), 7 deletions(-)
> >         
> >         
> >         diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> >         b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> >         
> >         index 960913a35ee4..4da8aff3df27 100644
> >         
> >         --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> >         
> >         +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> >         
> >         @@ -1666,7 +1666,7 @@ static int
> >         kfd_ioctl_map_memory_to_gpu(struct file *filep,
> >         
> >                   if (WARN_ON_ONCE(!peer_pdd))
> >         
> >                       continue;
> >         
> >                   if (!amdgpu_read_lock(peer->ddev, true)) {
> >         
> >         -            kfd_flush_tlb(peer_pdd);
> >         
> >         +            kfd_flush_tlb(peer_pdd, TLB_FLUSH_LEGACY);
> >         
> >                       amdgpu_read_unlock(peer->ddev);
> >         
> >                   }
> >         
> >               }
> >         
> >         diff --git
> >         a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> >         b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> >         
> >         index 2bd621eee4e0..904b8178c1d7 100644
> >         
> >         --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> >         
> >         +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> >         
> >         @@ -278,7 +278,7 @@ static int allocate_vmid(struct
> >         device_queue_manager *dqm,
> >         
> >                       qpd->vmid,
> >         
> >                       qpd->page_table_base);
> >         
> >               /* invalidate the VM context after pasid and vmid mapping
> >         is set up */
> >         
> >         -    kfd_flush_tlb(qpd_to_pdd(qpd));
> >         
> >         +    kfd_flush_tlb(qpd_to_pdd(qpd), TLB_FLUSH_LEGACY);
> >         
> >                 if (dqm->dev->kfd2kgd->set_scratch_backing_va)
> >         
> >                  
> >         dqm->dev->kfd2kgd->set_scratch_backing_va(dqm->dev->kgd,
> >         
> >         @@ -314,7 +314,7 @@ static void deallocate_vmid(struct
> >         device_queue_manager *dqm,
> >         
> >                   if (flush_texture_cache_nocpsch(q->device, qpd))
> >         
> >                       pr_err("Failed to flush TC\n");
> >         
> >           -    kfd_flush_tlb(qpd_to_pdd(qpd));
> >         
> >         +    kfd_flush_tlb(qpd_to_pdd(qpd), TLB_FLUSH_LEGACY);
> >         
> >                 /* Release the vmid mapping */
> >         
> >               set_pasid_vmid_mapping(dqm, 0, qpd->vmid);
> >         
> >         @@ -885,7 +885,7 @@ static int
> >         restore_process_queues_nocpsch(struct device_queue_manager *dqm,
> >         
> >                           dqm->dev->kgd,
> >         
> >                           qpd->vmid,
> >         
> >                           qpd->page_table_base);
> >         
> >         -        kfd_flush_tlb(pdd);
> >         
> >         +        kfd_flush_tlb(pdd, TLB_FLUSH_LEGACY);
> >         
> >               }
> >         
> >                 /* Take a safe reference to the mm_struct, which may
> >         otherwise
> >         
> >         diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> >         b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> >         
> >         index ecdd5e782b81..edce3ecf207d 100644
> >         
> >         --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> >         
> >         +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> >         
> >         @@ -1338,7 +1338,7 @@ 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);
> >         
> >         +void kfd_flush_tlb(struct kfd_process_device *pdd, enum
> >         TLB_FLUSH_TYPE type);
> >         
> >             int dbgdev_wave_reset_wavefronts(struct kfd_dev *dev, struct
> >         kfd_process *p);
> >         
> >           diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> >         b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> >         
> >         index 3995002c582b..72741f6579d3 100644
> >         
> >         --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> >         
> >         +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> >         
> >         @@ -2159,7 +2159,7 @@ 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)
> >         
> >         +void kfd_flush_tlb(struct kfd_process_device *pdd, enum
> >         TLB_FLUSH_TYPE type)
> >         
> >           {
> >         
> >               struct kfd_dev *dev = pdd->dev;
> >         
> >           @@ -2172,7 +2172,7 @@ void kfd_flush_tlb(struct
> >         kfd_process_device *pdd)
> >         
> >                                       pdd->qpd.vmid);
> >         
> >               } else {
> >         
> >                   amdgpu_amdkfd_flush_gpu_tlb_pasid(dev->kgd,
> >         
> >         -                    pdd->process->pasid,
> >         TLB_FLUSH_LEGACY);
> >         
> >         +                    pdd->process->pasid, type);
> >         
> >               }
> >         
> >           }
> >         
> >           
>       
>     
  

_______________________________________________
amd-gfx mailing list
amd-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/amd-gfx