[PATCH] drm/amdgpu: Fix amdgpu_vm_alloc_pts failed

[Christian König]

Hi guys,

yeah the root PD doesn't necessarily have a power of two entries.

But what exactly was the problem with the original code? Why does 
0xffffffff doesn't work?

The only possible explanation I can see is that somebody tried to use an 
address which is above max_pfn, or how did that trigger?

Thanks,
Christian.

Am 23.10.18 um 07:42 schrieb Zhu, Rex:
>
> No, if the vm size is small, there may only on root pd entry.
>
> we need to make sure the mask >= 0;
>
>
> Maybe this change revert Christian's commit:
>
>
> commit 72af632549b97ead9251bb155f08fefd1fb6f5c3
> Author: Christian König <christian.koenig at amd.com>
> Date:   Sat Sep 15 10:02:13 2018 +0200
>
>     drm/amdgpu: add amdgpu_vm_entries_mask v2
>
>     We can't get the mask for the root directory from the number of 
> entries.
>
>     So add a new function to avoid that problem.
>
>
> Best Regards
>
> Rex
>
>
>
> ------------------------------------------------------------------------
> *From:* amd-gfx <amd-gfx-bounces at lists.freedesktop.org> on behalf of 
> Zhang, Jerry(Junwei) <Jerry.Zhang at amd.com>
> *Sent:* Tuesday, October 23, 2018 1:12 PM
> *To:* Zhu, Rex; amd-gfx at lists.freedesktop.org; Deucher, Alexander; 
> Koenig, Christian
> *Subject:* Re: [PATCH] drm/amdgpu: Fix amdgpu_vm_alloc_pts failed
> On 10/23/2018 11:29 AM, Rex Zhu wrote:
> > when the VA address located in the last PD entries,
> > the alloc_pts will faile.
> >
> > Use the right PD mask instand of hardcode, suggested
> > by jerry.zhang.
> >
> > Signed-off-by: Rex Zhu <Rex.Zhu at amd.com>
>
> Thanks to verify that.
> Feel free to add
> Reviewed-by: Junwei Zhang <Jerry.Zhang at amd.com>
>
> Also like to get to know some background about these two functions from
> Christian.
> Perhaps we may make it more simple, e.g. merging them together.
>
> Regards,
> Jerry
>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > index 054633b..3939013 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> > @@ -202,8 +202,11 @@ static unsigned amdgpu_vm_num_entries(struct 
> amdgpu_device *adev,
> >   static uint32_t amdgpu_vm_entries_mask(struct amdgpu_device *adev,
> >                                       unsigned int level)
> >   {
> > +     unsigned shift = amdgpu_vm_level_shift(adev,
> > + adev->vm_manager.root_level);
> > +
> >        if (level <= adev->vm_manager.root_level)
> > -             return 0xffffffff;
> > +             return (round_up(adev->vm_manager.max_pfn, 1 << shift) 
> >> shift) - 1;
> >        else if (level != AMDGPU_VM_PTB)
> >                return 0x1ff;
> >        else
>
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