Re: [PATCH 02/14] drm/amdgpu/gfxhub: Enable retry fault interrupts when needed

["Timur Kristóf" <timur.kristof@gmail.com>]

On Thursday, July 2, 2026 2:02:50 PM Central European Summer Time Christian 
König wrote:
> On 7/2/26 11:14, Timur Kristóf wrote:
> > On 2026. július 2., csütörtök 10:10:10 közép-európai nyári idő Christian
> > König> 
> > wrote:
> >> On 7/1/26 18:17, Timur Kristóf wrote:
> >>> Enable retry fault interrupts when initializing the GFXHUB
> >>> system aperture registers according to whether retrying
> >>> page faults is enabled in amdgpu (ie. amdgpu.noretry=0).
> >>> 
> >>> Needs to be done for each GFXHUB version at once,
> >>> because none of them actually enabled this interrupt.
> >> 
> >> Thinking more about it we are clearly missing something here. The retry
> >> fault interrupt itself should be enabled all the time.
> > 
> > Why would it be enabled all the time?
> > I haven't seen any retry faults on neither Navi 3 nor Navi 4 without
> > enabling the ENABLE_RETRY_FAULT_INTERRUPT bit.
> 
> As far as I understand it the GCVM_L2_PROTECTION_FAULT_CNTL2 is actually a
> debug register for the fault behavior of the GC block.

After our last conversation I tested this again and I can confirm that I do NOT 
get any retry fault interrupts on Navi 3 if I remove the code that enables 
this bit. That makes me think this is not enabled by default.

> According to the register spec for Navi 44 the ENABLE_RETRY_FAULT_INTERRUPT
> should be default 1 and always be set under normal cricumstances.

This is definitely not the case on Navi 31 and also on Strix Halo.
I haven't checked on Navi 4x but judging by the fact that the gfxhub_v12_1 
code has to enable this bit explicitly, I doubt it would be enabled on Navi 4x 
either.

> >> IIRC only the RETRY_PERMISSION_OR_INVALID_PAGE_FAULT bit in the
> >> VM_CONTEXT0_CNTL register should be set or cleared by the kernel driver
> >> or
> >> firmware to control if the HW retries the access or not.
> > 
> > That is clearly not the case on GFX12.1 and I haven't seen any indication
> > that it would be different on GFX11.x and 12.0 either.
> 
> Mhm, then either the FW or golden register settings for that register is not
> correct.
> 
> That we set ACTIVE_PAGE_MIGRATION_PTE_READ_RETRY to one is rather strange as
> well since we don't use that feature in the Linux driver.
> 
> My suggestion is to always set the ENABLE_RETRY_FAULT_INTERRUPT in
> GCVM_L2_PROTECTION_FAULT_CNTL2 no matter what the noretry flag says, but
> I'm going to ask Alex and our ROCm people about that again when I have
> time.

I don't see why we should enable this bit when we don't want to enable retry 
faults.

Thanks & best regards,
Timur