[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 15:59
> 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 08:46 schrieb 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.
> 
> Ups, that's indeed not correct.
> 
> Yeah we need a better criteria if we should insert the ranges or not.

How about check the init before->list and after->list, then check if the list is not empty?
Otherwise, it may add a bool flag for each of them, I don't like that.

I have sent the patch as v2.
Please check it.
Thanks.

Jerry

> 
> Christian.
> 
> >
> > 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;
> >>>    }
> >>>