[PATCH] drm/amdgpu: Unmap CSA under SR-IOV in KFD path

[Koenig, Christian]

Am 30.04.19 um 11:53 schrieb Huang, Trigger:
> Hi Christian & Felix,
>
> Thanks for the information.
>
> But actually currently CSA is mapped only in amdgpu_driver_open_kms under SR-IOV.
> So would you give more information about ' Well that is exactly what we already do here'? Where I can find its implementation?

Well the plan was to move this to when the actually execution context is 
created. But Rex left the company, could be that the patches for this 
where never committed.

>
> On the other hand, I will  try the method 'Instead of checking if some page tables are already filled we check if some mapping is already made'

Yeah, that should certainly work as well. Just check all entries of the 
root PD in a for loop if any subsequent PDs are allocated and abort if 
you find one.

Christian.

>
> Thanks & Best Wishes,
> Trigger Huang
>
> -----Original Message-----
> From: Christian König <ckoenig.leichtzumerken at gmail.com>
> Sent: Tuesday, April 30, 2019 5:23 PM
> To: Kuehling, Felix <Felix.Kuehling at amd.com>; Huang, Trigger <Trigger.Huang at amd.com>; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amdgpu: Unmap CSA under SR-IOV in KFD path
>
> [CAUTION: External Email]
>
> Well that is exactly what we already do here. The only problem is we do the wrong check amdgpu_vm_make_compute().
>
> Instead of checking if some page tables are already filled we check if some mapping is already made.
>
> Regards,
> Christian.
>
> Am 30.04.19 um 01:34 schrieb Kuehling, Felix:
>> I remember a past discussion to change the CSA allocation/mapping
>> scheme to avoid this issue in the first place. Can adding the CSA to
>> the VM be delayed a little to a point after the VM gets converted to a compute VM?
>> Maybe the first command submission?
>>
>> Regards,
>>      Felix
>>
>> On 2019-04-28 6:25 a.m., Trigger Huang wrote:
>>> In amdgpu open path, CSA will be mappened in VM, so when opening KFD,
>>> calling mdgpu_vm_make_compute  will fail because it found this VM is
>>> not a clean VM with some mappings, as a result, it will lead to
>>> failed to create process VM object
>>>
>>> The fix is try to unmap CSA, and actually CSA is not needed in
>>> compute VF world switch
>>>
>>> Signed-off-by: Trigger Huang <Trigger.Huang at amd.com>
>>> ---
>>>     drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 10 ++++++++++
>>>     drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c          |  2 +-
>>>     2 files changed, 11 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> index 697b8ef..e0bc457 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> @@ -956,6 +956,16 @@ int amdgpu_amdkfd_gpuvm_acquire_process_vm(struct kgd_dev *kgd,
>>>       if (avm->process_info)
>>>               return -EINVAL;
>>>
>>> +    /* Delete CSA mapping to make sure this VM is a clean VM  before
>>> +     *  converting VM
>>> +     */
>>> +    if (amdgpu_sriov_vf(adev) && drv_priv->csa_va) {
>>> +            amdgpu_bo_reserve(adev->virt.csa_obj, true);
>>> +            amdgpu_vm_bo_rmv(adev, drv_priv->csa_va);
>>> +            drv_priv->csa_va = NULL;
>>> +            amdgpu_bo_unreserve(adev->virt.csa_obj);
>>> +    }
>>> +
>>>       /* Convert VM into a compute VM */
>>>       ret = amdgpu_vm_make_compute(adev, avm, pasid);
>>>       if (ret)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>> index da7b4fe..361c2e5 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>> @@ -1069,7 +1069,7 @@ void amdgpu_driver_postclose_kms(struct
>>> drm_device *dev,
>>>
>>>       amdgpu_vm_bo_rmv(adev, fpriv->prt_va);
>>>
>>> -    if (amdgpu_sriov_vf(adev)) {
>>> +    if (amdgpu_sriov_vf(adev) && fpriv->csa_va) {
>>>               /* TODO: how to handle reserve failure */
>>>               BUG_ON(amdgpu_bo_reserve(adev->virt.csa_obj, true));
>>>               amdgpu_vm_bo_rmv(adev, fpriv->csa_va);
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