[PATCH v2] drm/amdgpu: add safeguards for querying GMC CG state

[Lazar, Lijo]

On 1/28/2022 2:22 PM, Lang Yu wrote:
> On 01/28/ , Lazar, Lijo wrote:
>>
>>
>> On 1/28/2022 12:24 PM, Lang Yu wrote:
>>> We observed a GPU hang when querying GMC CG state(i.e.,
>>> cat amdgpu_pm_info) on cyan skillfish. Acctually, cyan
>>> skillfish doesn't support any CG features.
>>>
>>> Only allow ASICs which support GMC CG features accessing
>>> related registers. As some ASICs support GMC CG but cg_flags
>>> are not set. Use GC IP version instead of cg_flags to
>>> determine whether GMC CG is supported or not.
>>>
>>> v2:
>>>    - Use a function to encapsulate more functionality.(Christian)
>>>    - Use IP verion to determine whether CG is supported or not.(Lijo)
>>>
>>> Signed-off-by: Lang Yu <Lang.Yu at amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 10 ++++++++++
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  1 +
>>>    drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c  |  3 +++
>>>    drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c   |  3 +++
>>>    drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c   |  3 +++
>>>    5 files changed, 20 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
>>> index d426de48d299..be1f03b02af6 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
>>> @@ -876,3 +876,13 @@ int amdgpu_gmc_vram_checking(struct amdgpu_device *adev)
>>>    	return 0;
>>>    }
>>> +
>>> +bool amdgpu_gmc_cg_enabled(struct amdgpu_device *adev)
>>> +{
>>> +	switch (adev->ip_versions[GC_HWIP][0]) {
>>> +	case IP_VERSION(10, 1, 3):
>>> +		return false;
>>> +	default:
>>> +		return true;
>>> +	}
>>> +}
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
>>> index 93505bb0a36c..b916e73c7de1 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
>>> @@ -338,4 +338,5 @@ uint64_t amdgpu_gmc_vram_mc2pa(struct amdgpu_device *adev, uint64_t mc_addr);
>>>    uint64_t amdgpu_gmc_vram_pa(struct amdgpu_device *adev, struct amdgpu_bo *bo);
>>>    uint64_t amdgpu_gmc_vram_cpu_pa(struct amdgpu_device *adev, struct amdgpu_bo *bo);
>>>    int amdgpu_gmc_vram_checking(struct amdgpu_device *adev);
>>> +bool amdgpu_gmc_cg_enabled(struct amdgpu_device *adev);
>>>    #endif
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>> index 73ab0eebe4e2..4e46f618d6c1 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
>>> @@ -1156,6 +1156,9 @@ static void gmc_v10_0_get_clockgating_state(void *handle, u32 *flags)
>>>    {
>>>    	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>>> +	if (!amdgpu_gmc_cg_enabled(adev))
>>> +		return;
>>> +
>>
>> I think Christian suggested amdgpu_gmc_cg_enabled function assuming it's a
>> common logic for all ASICs based on flags. Now that assumption has changed.
>> Now the logic is a specific IP version doesn't enable CG which is known
>> beforehand. So we could maintain the check in the specific IP version block
>> itself (gmc 10 in this example). No need to call another common function
>> which checks IP version again.
> 
> Thanks. You mean just like this?
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index 73ab0eebe4e2..bddaf2417344 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -1156,6 +1156,9 @@ static void gmc_v10_0_get_clockgating_state(void *handle, u32 *flags)
>   {
>          struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> 
> +       if (adev->ip_versions[GC_HWIP][0] == IP_VERSION(10, 1, 3))
		*flags = 0;

Yes, add the above line also.

Thanks,
Lijo
> +               return;
> +
>          adev->mmhub.funcs->get_clockgating(adev, flags);
> 
>          if (adev->ip_versions[ATHUB_HWIP][0] >= IP_VERSION(2, 1, 0))
> 
> Regards,
> Lang
> 
>> Thanks,
>> Lijo
>>
>>>    	adev->mmhub.funcs->get_clockgating(adev, flags);
>>>    	if (adev->ip_versions[ATHUB_HWIP][0] >= IP_VERSION(2, 1, 0))
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>> index ca9841d5669f..ff9dff2a6cf1 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
>>> @@ -1695,6 +1695,9 @@ static void gmc_v8_0_get_clockgating_state(void *handle, u32 *flags)
>>>    	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>>>    	int data;
>>> +	if (!amdgpu_gmc_cg_enabled(adev))
>>> +		return;
>>> +
>>>    	if (amdgpu_sriov_vf(adev))
>>>    		*flags = 0;
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> index 4595027a8c63..faf017609dfe 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> @@ -1952,6 +1952,9 @@ static void gmc_v9_0_get_clockgating_state(void *handle, u32 *flags)
>>>    {
>>>    	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>>> +	if (!amdgpu_gmc_cg_enabled(adev))
>>> +		return;
>>> +
>>>    	adev->mmhub.funcs->get_clockgating(adev, flags);
>>>    	athub_v1_0_get_clockgating(adev, flags);
>>>