[PATCH 1/2] drm/amdgpu: insert partial mappings before and after directly

[Zhang, Jerry]

> -----Original Message-----
> From: Christian König [mailto:deathsimple at vodafone.de]
> Sent: Thursday, March 16, 2017 15:33
> To: Zhang, Jerry; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH 1/2] drm/amdgpu: insert partial mappings before and after
> directly
> 
> Am 16.03.2017 um 04:44 schrieb Junwei Zhang:
> > Currently it may miss one page before or after the target mapping
> 
> I don't think that this will work correctly. The interval tree still contains the old
> mapping at this point and as far as I know inserting overlapping mappings is not
> allowed here.

Ah, I missed that, so this insert op should be after free up.
I will revise the patch

> 
> But what do you mean with miss one page before or after the target mapping?

I did a unit test to verify it and found that:

If the before mapping is 1 page size, so its start and last will be same.
Thus below condition will become false then to free the before mapping.
   > if (before->it.start != before->it.last)
But in this case, we need the before mapping of 1 page size.
So does after mapping.

e.g.
Initialize a mapping: [0, 8] pages size.
A replace mapping: [1, 2] page size.
Before mapping is [0, 1], before.it.start = 0, before.it = 1 - 1 = 0.

Additionally, if we create a bo as 1 page size, the corresponding mapping also has start==last, I think.

Jerry.

> 
> Christian.
> 
> >
> > Signed-off-by: Junwei Zhang <Jerry.Zhang at amd.com>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 26 ++++++++------------------
> >   1 file changed, 8 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index f7c02a9..511c6c9 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -1767,7 +1767,11 @@ int amdgpu_vm_bo_clear_mappings(struct
> amdgpu_device *adev,
> >   			before->it.last = saddr - 1;
> >   			before->offset = tmp->offset;
> >   			before->flags = tmp->flags;
> > +
> >   			list_add(&before->list, &tmp->list);
> > +			interval_tree_insert(&before->it, &vm->va);
> > +			if (before->flags & AMDGPU_PTE_PRT)
> > +				amdgpu_vm_prt_get(adev);
> >   		}
> >
> >   		/* Remember mapping split at the end */ @@ -1777,7 +1781,11
> @@ int
> > amdgpu_vm_bo_clear_mappings(struct amdgpu_device *adev,
> >   			after->offset = tmp->offset;
> >   			after->offset += after->it.start - tmp->it.start;
> >   			after->flags = tmp->flags;
> > +
> >   			list_add(&after->list, &tmp->list);
> > +			interval_tree_insert(&after->it, &vm->va);
> > +			if (after->flags & AMDGPU_PTE_PRT)
> > +				amdgpu_vm_prt_get(adev);
> >   		}
> >
> >   		list_del(&tmp->list);
> > @@ -1799,24 +1807,6 @@ int amdgpu_vm_bo_clear_mappings(struct
> amdgpu_device *adev,
> >   		trace_amdgpu_vm_bo_unmap(NULL, tmp);
> >   	}
> >
> > -	/* Insert partial mapping before the range*/
> > -	if (before->it.start != before->it.last) {
> > -		interval_tree_insert(&before->it, &vm->va);
> > -		if (before->flags & AMDGPU_PTE_PRT)
> > -			amdgpu_vm_prt_get(adev);
> > -	} else {
> > -		kfree(before);
> > -	}
> > -
> > -	/* Insert partial mapping after the range */
> > -	if (after->it.start != after->it.last) {
> > -		interval_tree_insert(&after->it, &vm->va);
> > -		if (after->flags & AMDGPU_PTE_PRT)
> > -			amdgpu_vm_prt_get(adev);
> > -	} else {
> > -		kfree(after);
> > -	}
> > -
> >   	return 0;
> >   }
> >
>