[PATCH] drm/amdgpu: Fix amdgpu_vm_alloc_pts failed

[Zhu, Rex]

Hi Christian,


You can reproduce this issue by allocate CSA buffer in baremetal and map them to reserved VM address.


Please see the attached patch.


Best Regards

Rex



________________________________
From: Christian König <ckoenig.leichtzumerken at gmail.com>
Sent: Tuesday, October 23, 2018 5:01 PM
To: Zhu, Rex; Zhang, Jerry; amd-gfx at lists.freedesktop.org; Deucher, Alexander; Koenig, Christian
Subject: Re: [PATCH] drm/amdgpu: Fix amdgpu_vm_alloc_pts failed

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><mailto: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><mailto:amd-gfx-bounces at lists.freedesktop.org> on behalf of Zhang, Jerry(Junwei) <Jerry.Zhang at amd.com><mailto:Jerry.Zhang at amd.com>
Sent: Tuesday, October 23, 2018 1:12 PM
To: Zhu, Rex; amd-gfx at lists.freedesktop.org<mailto: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><mailto:Rex.Zhu at amd.com>

Thanks to verify that.
Feel free to add
Reviewed-by: Junwei Zhang <Jerry.Zhang at amd.com><mailto: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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