[PATCH] drm/amdgpu: add print for iommu translation mode

[Sider, Graham]

[Public]

> -----Original Message-----
> From: Christian König <ckoenig.leichtzumerken at gmail.com>
> Sent: Tuesday, March 21, 2023 2:53 PM
> To: Sider, Graham <Graham.Sider at amd.com>; Russell, Kent
> <Kent.Russell at amd.com>; Mahfooz, Hamza <Hamza.Mahfooz at amd.com>;
> amd-gfx at lists.freedesktop.org
> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>
> Subject: Re: [PATCH] drm/amdgpu: add print for iommu translation mode
> 
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
> 
> 
> Am 17.03.23 um 21:04 schrieb Sider, Graham:
> > [AMD Official Use Only - General]
> >
> >
> >
> >> -----Original Message-----
> >> From: Russell, Kent <Kent.Russell at amd.com>
> >> Sent: Friday, March 17, 2023 3:58 PM
> >> To: Mahfooz, Hamza <Hamza.Mahfooz at amd.com>; Sider, Graham
> >> <Graham.Sider at amd.com>; amd-gfx at lists.freedesktop.org
> >> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>
> >> Subject: RE: [PATCH] drm/amdgpu: add print for iommu translation mode
> >>
> >> [AMD Official Use Only - General]
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
> >>> Hamza Mahfooz
> >>> Sent: Friday, March 17, 2023 3:58 PM
> >>> To: Sider, Graham <Graham.Sider at amd.com>;
> >>> amd-gfx at lists.freedesktop.org
> >>> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>
> >>> Subject: Re: [PATCH] drm/amdgpu: add print for iommu translation
> >>> mode
> >>>
> >>>
> >>> On 3/17/23 15:47, Graham Sider wrote:
> >>>> Add log to display whether RAM is direct vs DMA mapped.
> >>>>
> >>>> Signed-off-by: Graham Sider <Graham.Sider at amd.com>
> >>> If this information is only useful for debugging purposes, please
> >>> use
> >>> drm_dbg() instead of pr_info().
> > It's useful for more than just debug I would say. Just a quick way to grep
> whether IOMMU is off/pt vs device isolation mode.
> 
> Mhm, shouldn't the IOMMU code note that as well?
>

As of right now, not exactly. Copy-pasting Felix's comment here:

The kernel log [currently] tells you the default IOMMU domain, but it may not match the domain actually used for the GPU. Without this message there is no easy way to tell from a kernel log. This will help with triaging issues from logs provided by external and internal users.

Graham

> 
> Christian.
> 
> >
> > Graham
> >
> >>>> ---
> >>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 6 +++++-
> >>>>    1 file changed, 5 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>>> index 8bba5e6872a1..8797a9523244 100644
> >>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>>> @@ -3528,8 +3528,12 @@ static void
> >>> amdgpu_device_check_iommu_direct_map(struct amdgpu_device
> *adev)
> >>>>            struct iommu_domain *domain;
> >>>>
> >>>>            domain = iommu_get_domain_for_dev(adev->dev);
> >>>> -  if (!domain || domain->type == IOMMU_DOMAIN_IDENTITY)
> >>>> +  if (!domain || domain->type == IOMMU_DOMAIN_IDENTITY) {
> >>>> +          pr_info("RAM is direct mapped to GPU (not traslated by
> >> traslated -> translated
> >>
> > Thanks, my keyboard keeps skipping the on the 'n' key lately :( time for a
> clean.
> >
> > Graham
> >
> >>   Kent
> >>> IOMMU)\n");
> >>>>                    adev->ram_is_direct_mapped = true;
> >>>> +  } else {
> >>>> +          pr_info("RAM is DMA mapped to GPU (translated by
> >>> IOMMU)\n");
> >>>> +  }
> >>>>    }
> >>>>
> >>>>    static const struct attribute *amdgpu_dev_attributes[] = {
> >>> --
> >>> Hamza