Nouveau - Feb 2020 - [PATCH 8/8] drm/ttm: do not keep GPU dependent addresses

Am 18.02.20 um 19:28 schrieb Thomas Zimmermann:
> Hi
>
> Am 18.02.20 um 19:23 schrieb Christian K?nig:
>> Am 18.02.20 um 19:16 schrieb Thomas Zimmermann:
>>> Hi
>>>
>>> Am 18.02.20 um 18:13 schrieb Nirmoy:
>>>> On 2/18/20 1:44 PM, Christian K?nig wrote:
>>>>> Am 18.02.20 um 13:40 schrieb Thomas Zimmermann:
>>>>>> Hi
>>>>>>
>>>>>> Am 17.02.20 um 16:04 schrieb Nirmoy Das:
>>>>>>> GPU address handling is device specific and should
be handle by its
>>>>>>> device
>>>>>>> driver.
>>>>>>>
>>>>>>> Signed-off-by: Nirmoy Das <nirmoy.das at
amd.com>
>>>>>>> ---
>>>>>>>  ?? drivers/gpu/drm/ttm/ttm_bo.c??? | 7 -------
>>>>>>>  ?? include/drm/ttm/ttm_bo_api.h??? | 2 --
>>>>>>>  ?? include/drm/ttm/ttm_bo_driver.h | 1 -
>>>>>>>  ?? 3 files changed, 10 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>> b/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>> index 151edfd8de77..d5885cd609a3 100644
>>>>>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>> @@ -85,7 +85,6 @@ static void
ttm_mem_type_debug(struct
>>>>>>> ttm_bo_device *bdev, struct drm_printer *p
>>>>>>>  ?????? drm_printf(p, "??? has_type:
%d\n", man->has_type);
>>>>>>>  ?????? drm_printf(p, "??? use_type:
%d\n", man->use_type);
>>>>>>>  ?????? drm_printf(p, "??? flags:
0x%08X\n", man->flags);
>>>>>>> -??? drm_printf(p, "??? gpu_offset:
0x%08llX\n", man->gpu_offset);
>>>>>>>  ?????? drm_printf(p, "??? size: %llu\n",
man->size);
>>>>>>>  ?????? drm_printf(p, "??? available_caching:
0x%08X\n",
>>>>>>> man->available_caching);
>>>>>>>  ?????? drm_printf(p, "??? default_caching:
0x%08X\n",
>>>>>>> man->default_caching);
>>>>>>> @@ -345,12 +344,6 @@ static int
ttm_bo_handle_move_mem(struct
>>>>>>> ttm_buffer_object *bo,
>>>>>>>  ?? moved:
>>>>>>>  ?????? bo->evicted = false;
>>>>>>>  ?? -??? if (bo->mem.mm_node)
>>>>>>> -??????? bo->offset = (bo->mem.start <<
PAGE_SHIFT) +
>>>>>>> -???????????
bdev->man[bo->mem.mem_type].gpu_offset;
>>>>>>> -??? else
>>>>>>> -??????? bo->offset = 0;
>>>>>>> -
>>>>>> After moving this into users, the else branch has been
lost. Is
>>>>>> 'bo->mem.mm_node' always true?
>>>>> At least for the amdgpu and radeon use cases, yes.
>>>>>
>>>>> But that is a rather good question I mean for it is illegal
to get the
>>>>> GPU BO address if it is inaccessible (e.g. in the system
domain).
>>>>>
>>>>> Could be that some driver relied on the behavior to get 0
for the
>>>>> system domain here.
>>>> I wonder how to verify that ?
>>>>
>>>> If I understand correctly:
>>>>
>>>> 1 qxl uses bo->offset only in qxl_bo_physical_address()
which is not in
>>>> system domain.
>>>>
>>>> 2 unfortunately I can't say the same for bochs but it works
with this
>>>> patch series so I think bochs is fine as well.
>>>>
>>>> 3 vmwgfx uses bo->offset only when bo->mem.mem_type ==
TTM_PL_VRAM so
>>>> vmwgfx should be fine.
>>>>
>>>> 4 amdgpu and radeon runs with 'bo->mem.mm_node'
always true
>>>>
>>>> I am not sure about? nouveau as bo->offset is being used in
many places.
>>>>
>>>> I could probably mirror the removed logic to nouveau as
>>> I suggest to introduce a ttm helper that contains the original
branching
>>> and use it everywhere. Something like
>>>
>>>  ?? s64 ttm_bo_offset(struct ttm_buffer_object *bo)
>>>  ?? {
>>>  ????? if (WARN_ON_ONCE(!bo->mem.mm_node))
>>>  ????????? return 0;
>>>  ????? return bo->mem.start << PAGE_SHIFT;
>>>  ?? }
>>>
>>> Could be static inline. The warning should point to broken drivers.
This
>>> also gets rid of the ugly shift in the drivers.
>> Big NAK on this. That is exactly what we should NOT do.
>>
>> See the shift belongs into the driver, because it is driver dependent
if
>> we work with page or byte offsets.
>>
>> For amdgpu we for example want to work with byte offsets and TTM should
>> not make any assumption about what bo->mem.start actually contains.
> OK. What about something like ttm_bo_pg_offset()? Same code without the
> shift. Would also make it clear that it's a page offset.
That is a rather good idea. We could name that ttm_bo_man_offset() and 
put it into ttm_bo_manager.c next to the manager which allocates them.

It's just that this manager is not used by everybody, so amdgpu, radeon 
and nouveau would still need a separate function.

Christian.
>
> Best regards
> Thomas
>
>> Regards,
>> Christian.
>>
>>> Best regards
>>> Thomas
>>>
>>>
>>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>> b/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>> index f8015e0318d7..5a6a2af91318 100644
>>>> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>> @@ -1317,6 +1317,10 @@ nouveau_bo_move_ntfy(struct
ttm_buffer_object
>>>> *bo, bool evict,
>>>>  ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
>>>>  ???????????????????????? nouveau_vma_map(vma, mem);
>>>>  ???????????????? }
>>>> +?????????????? if (bo->mem.mm_node)
>>>> +?????????????????????? nvbo->offset = (new_reg->start
<< PAGE_SHIFT);
>>>> +?????????????? else
>>>> +?????????????????????? nvbo->offset = 0;
>>>>  ???????? } else {
>>>>  ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
>>>>  ???????????????????????? WARN_ON(ttm_bo_wait(bo, false,
false));
>>>>
>>>> Regards,
>>>>
>>>> Nirmoy
>>>>
>>>>
>>>>> Regards,
>>>>> Christian.
>>>>>
>>>>>> Best regards
>>>>>> Thomas
>>>>>>
>>>>>>>  ?????? ctx->bytes_moved += bo->num_pages
<< PAGE_SHIFT;
>>>>>>>  ?????? return 0;
>>>>>>>  ?? diff --git a/include/drm/ttm/ttm_bo_api.h
>>>>>>> b/include/drm/ttm/ttm_bo_api.h
>>>>>>> index b9bc1b00142e..d6f39ee5bf5d 100644
>>>>>>> --- a/include/drm/ttm/ttm_bo_api.h
>>>>>>> +++ b/include/drm/ttm/ttm_bo_api.h
>>>>>>> @@ -213,8 +213,6 @@ struct ttm_buffer_object {
>>>>>>>  ??????? * either of these locks held.
>>>>>>>  ??????? */
>>>>>>>  ?? -??? uint64_t offset; /* GPU address space is
independent of CPU
>>>>>>> word size */
>>>>>>> -
>>>>>>>  ?????? struct sg_table *sg;
>>>>>>>  ?? };
>>>>>>>  ?? diff --git a/include/drm/ttm/ttm_bo_driver.h
>>>>>>> b/include/drm/ttm/ttm_bo_driver.h
>>>>>>> index c9e0fd09f4b2..c8ce6c181abe 100644
>>>>>>> --- a/include/drm/ttm/ttm_bo_driver.h
>>>>>>> +++ b/include/drm/ttm/ttm_bo_driver.h
>>>>>>> @@ -177,7 +177,6 @@ struct ttm_mem_type_manager {
>>>>>>>  ?????? bool has_type;
>>>>>>>  ?????? bool use_type;
>>>>>>>  ?????? uint32_t flags;
>>>>>>> -??? uint64_t gpu_offset; /* GPU address space is
independent of CPU
>>>>>>> word size */
>>>>>>>  ?????? uint64_t size;
>>>>>>>  ?????? uint32_t available_caching;
>>>>>>>  ?????? uint32_t default_caching;
>>>>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> dri-devel at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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On Tue, Feb 18, 2020 at 07:37:44PM +0100, Christian K?nig
wrote:
> Am 18.02.20 um 19:28 schrieb Thomas Zimmermann:
> > Hi
> > 
> > Am 18.02.20 um 19:23 schrieb Christian K?nig:
> > > Am 18.02.20 um 19:16 schrieb Thomas Zimmermann:
> > > > Hi
> > > > 
> > > > Am 18.02.20 um 18:13 schrieb Nirmoy:
> > > > > On 2/18/20 1:44 PM, Christian K?nig wrote:
> > > > > > Am 18.02.20 um 13:40 schrieb Thomas Zimmermann:
> > > > > > > Hi
> > > > > > > 
> > > > > > > Am 17.02.20 um 16:04 schrieb Nirmoy Das:
> > > > > > > > GPU address handling is device specific
and should be handle by its
> > > > > > > > device
> > > > > > > > driver.
> > > > > > > > 
> > > > > > > > Signed-off-by: Nirmoy Das <nirmoy.das
at amd.com>
> > > > > > > > ---
> > > > > > > >  ?? drivers/gpu/drm/ttm/ttm_bo.c??? | 7
-------
> > > > > > > >  ?? include/drm/ttm/ttm_bo_api.h??? | 2
--
> > > > > > > >  ?? include/drm/ttm/ttm_bo_driver.h | 1
-
> > > > > > > >  ?? 3 files changed, 10 deletions(-)
> > > > > > > > 
> > > > > > > > diff --git
a/drivers/gpu/drm/ttm/ttm_bo.c
> > > > > > > > b/drivers/gpu/drm/ttm/ttm_bo.c
> > > > > > > > index 151edfd8de77..d5885cd609a3 100644
> > > > > > > > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > > > > > > > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > > > > > > > @@ -85,7 +85,6 @@ static void
ttm_mem_type_debug(struct
> > > > > > > > ttm_bo_device *bdev, struct drm_printer
*p
> > > > > > > >  ?????? drm_printf(p, "???
has_type: %d\n", man->has_type);
> > > > > > > >  ?????? drm_printf(p, "???
use_type: %d\n", man->use_type);
> > > > > > > >  ?????? drm_printf(p, "??? flags:
0x%08X\n", man->flags);
> > > > > > > > -??? drm_printf(p, "??? gpu_offset:
0x%08llX\n", man->gpu_offset);
> > > > > > > >  ?????? drm_printf(p, "??? size:
%llu\n", man->size);
> > > > > > > >  ?????? drm_printf(p, "???
available_caching: 0x%08X\n",
> > > > > > > > man->available_caching);
> > > > > > > >  ?????? drm_printf(p, "???
default_caching: 0x%08X\n",
> > > > > > > > man->default_caching);
> > > > > > > > @@ -345,12 +344,6 @@ static int
ttm_bo_handle_move_mem(struct
> > > > > > > > ttm_buffer_object *bo,
> > > > > > > >  ?? moved:
> > > > > > > >  ?????? bo->evicted = false;
> > > > > > > >  ?? -??? if (bo->mem.mm_node)
> > > > > > > > -??????? bo->offset =
(bo->mem.start << PAGE_SHIFT) +
> > > > > > > > -???????????
bdev->man[bo->mem.mem_type].gpu_offset;
> > > > > > > > -??? else
> > > > > > > > -??????? bo->offset = 0;
> > > > > > > > -
> > > > > > > After moving this into users, the else branch
has been lost. Is
> > > > > > > 'bo->mem.mm_node' always true?
> > > > > > At least for the amdgpu and radeon use cases, yes.
> > > > > > 
> > > > > > But that is a rather good question I mean for it
is illegal to get the
> > > > > > GPU BO address if it is inaccessible (e.g. in the
system domain).
> > > > > > 
> > > > > > Could be that some driver relied on the behavior
to get 0 for the
> > > > > > system domain here.
> > > > > I wonder how to verify that ?
> > > > > 
> > > > > If I understand correctly:
> > > > > 
> > > > > 1 qxl uses bo->offset only in
qxl_bo_physical_address() which is not in
> > > > > system domain.
> > > > > 
> > > > > 2 unfortunately I can't say the same for bochs but
it works with this
> > > > > patch series so I think bochs is fine as well.
> > > > > 
> > > > > 3 vmwgfx uses bo->offset only when
bo->mem.mem_type == TTM_PL_VRAM so
> > > > > vmwgfx should be fine.
> > > > > 
> > > > > 4 amdgpu and radeon runs with
'bo->mem.mm_node' always true
> > > > > 
> > > > > I am not sure about? nouveau as bo->offset is being
used in many places.
> > > > > 
> > > > > I could probably mirror the removed logic to nouveau as
> > > > I suggest to introduce a ttm helper that contains the
original branching
> > > > and use it everywhere. Something like
> > > > 
> > > >  ?? s64 ttm_bo_offset(struct ttm_buffer_object *bo)
> > > >  ?? {
> > > >  ????? if (WARN_ON_ONCE(!bo->mem.mm_node))
> > > >  ????????? return 0;
> > > >  ????? return bo->mem.start << PAGE_SHIFT;
> > > >  ?? }
> > > > 
> > > > Could be static inline. The warning should point to broken
drivers. This
> > > > also gets rid of the ugly shift in the drivers.
> > > Big NAK on this. That is exactly what we should NOT do.
> > > 
> > > See the shift belongs into the driver, because it is driver
dependent if
> > > we work with page or byte offsets.
> > > 
> > > For amdgpu we for example want to work with byte offsets and TTM
should
> > > not make any assumption about what bo->mem.start actually
contains.
> > OK. What about something like ttm_bo_pg_offset()? Same code without
the
> > shift. Would also make it clear that it's a page offset.
> 
> That is a rather good idea. We could name that ttm_bo_man_offset() and put
> it into ttm_bo_manager.c next to the manager which allocates them.
> 
> It's just that this manager is not used by everybody, so amdgpu, radeon
and
> nouveau would still need a separate function.
Let me pile on with my bikeshed color choice :-)

I'd do this a wrapper, but for drivers individually. And only for those we
haven't audited yet, or where we think the WARN_ON actually provides
value. So maybe in vram helpers, since that might be used by some drivers
that get stuff wrong. Or maybe noveau isn't audited yet.

That also sidesteps the "what should we call this, drivers are
different?"
problem.

Anyway feel free to ignore me, really just a bikeshed at this point.

Cheers, Daniel
> 
> Christian.
> 
> > 
> > Best regards
> > Thomas
> > 
> > > Regards,
> > > Christian.
> > > 
> > > > Best regards
> > > > Thomas
> > > > 
> > > > 
> > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
> > > > > b/drivers/gpu/drm/nouveau/nouveau_bo.c
> > > > > index f8015e0318d7..5a6a2af91318 100644
> > > > > --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
> > > > > +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
> > > > > @@ -1317,6 +1317,10 @@ nouveau_bo_move_ntfy(struct
ttm_buffer_object
> > > > > *bo, bool evict,
> > > > >  ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
> > > > >  ???????????????????????? nouveau_vma_map(vma, mem);
> > > > >  ???????????????? }
> > > > > +?????????????? if (bo->mem.mm_node)
> > > > > +?????????????????????? nvbo->offset =
(new_reg->start << PAGE_SHIFT);
> > > > > +?????????????? else
> > > > > +?????????????????????? nvbo->offset = 0;
> > > > >  ???????? } else {
> > > > >  ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
> > > > >  ???????????????????????? WARN_ON(ttm_bo_wait(bo,
false, false));
> > > > > 
> > > > > Regards,
> > > > > 
> > > > > Nirmoy
> > > > > 
> > > > > 
> > > > > > Regards,
> > > > > > Christian.
> > > > > > 
> > > > > > > Best regards
> > > > > > > Thomas
> > > > > > > 
> > > > > > > >  ?????? ctx->bytes_moved +=
bo->num_pages << PAGE_SHIFT;
> > > > > > > >  ?????? return 0;
> > > > > > > >  ?? diff --git
a/include/drm/ttm/ttm_bo_api.h
> > > > > > > > b/include/drm/ttm/ttm_bo_api.h
> > > > > > > > index b9bc1b00142e..d6f39ee5bf5d 100644
> > > > > > > > --- a/include/drm/ttm/ttm_bo_api.h
> > > > > > > > +++ b/include/drm/ttm/ttm_bo_api.h
> > > > > > > > @@ -213,8 +213,6 @@ struct
ttm_buffer_object {
> > > > > > > >  ??????? * either of these locks held.
> > > > > > > >  ??????? */
> > > > > > > >  ?? -??? uint64_t offset; /* GPU address
space is independent of CPU
> > > > > > > > word size */
> > > > > > > > -
> > > > > > > >  ?????? struct sg_table *sg;
> > > > > > > >  ?? };
> > > > > > > >  ?? diff --git
a/include/drm/ttm/ttm_bo_driver.h
> > > > > > > > b/include/drm/ttm/ttm_bo_driver.h
> > > > > > > > index c9e0fd09f4b2..c8ce6c181abe 100644
> > > > > > > > --- a/include/drm/ttm/ttm_bo_driver.h
> > > > > > > > +++ b/include/drm/ttm/ttm_bo_driver.h
> > > > > > > > @@ -177,7 +177,6 @@ struct
ttm_mem_type_manager {
> > > > > > > >  ?????? bool has_type;
> > > > > > > >  ?????? bool use_type;
> > > > > > > >  ?????? uint32_t flags;
> > > > > > > > -??? uint64_t gpu_offset; /* GPU address
space is independent of CPU
> > > > > > > > word size */
> > > > > > > >  ?????? uint64_t size;
> > > > > > > >  ?????? uint32_t available_caching;
> > > > > > > >  ?????? uint32_t default_caching;
> > > > > > > > 
> > > > > _______________________________________________
> > > > > dri-devel mailing list
> > > > > dri-devel at lists.freedesktop.org
> > > > >
https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel at lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > 
> > _______________________________________________
> > amd-gfx mailing list
> > amd-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
> 
> _______________________________________________
> Nouveau mailing list
> Nouveau at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

On 2/18/20 8:06 PM, Daniel Vetter wrote:
> On Tue, Feb 18, 2020 at 07:37:44PM +0100, Christian K?nig wrote:
>> Am 18.02.20 um 19:28 schrieb Thomas Zimmermann:
>>> Hi
>>>
>>> Am 18.02.20 um 19:23 schrieb Christian K?nig:
>>>> Am 18.02.20 um 19:16 schrieb Thomas Zimmermann:
>>>>> Hi
>>>>>
>>>>> Am 18.02.20 um 18:13 schrieb Nirmoy:
>>>>>> On 2/18/20 1:44 PM, Christian K?nig wrote:
>>>>>>> Am 18.02.20 um 13:40 schrieb Thomas Zimmermann:
>>>>>>>> Hi
>>>>>>>>
>>>>>>>> Am 17.02.20 um 16:04 schrieb Nirmoy Das:
>>>>>>>>> GPU address handling is device specific and
should be handle by its
>>>>>>>>> device
>>>>>>>>> driver.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Nirmoy Das <nirmoy.das at
amd.com>
>>>>>>>>> ---
>>>>>>>>>   ?? drivers/gpu/drm/ttm/ttm_bo.c??? | 7
-------
>>>>>>>>>   ?? include/drm/ttm/ttm_bo_api.h??? | 2 --
>>>>>>>>>   ?? include/drm/ttm/ttm_bo_driver.h | 1 -
>>>>>>>>>   ?? 3 files changed, 10 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>>>> b/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>>>> index 151edfd8de77..d5885cd609a3 100644
>>>>>>>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>>>>>>>> @@ -85,7 +85,6 @@ static void
ttm_mem_type_debug(struct
>>>>>>>>> ttm_bo_device *bdev, struct drm_printer *p
>>>>>>>>>   ?????? drm_printf(p, "??? has_type:
%d\n", man->has_type);
>>>>>>>>>   ?????? drm_printf(p, "??? use_type:
%d\n", man->use_type);
>>>>>>>>>   ?????? drm_printf(p, "??? flags:
0x%08X\n", man->flags);
>>>>>>>>> -??? drm_printf(p, "??? gpu_offset:
0x%08llX\n", man->gpu_offset);
>>>>>>>>>   ?????? drm_printf(p, "??? size:
%llu\n", man->size);
>>>>>>>>>   ?????? drm_printf(p, "???
available_caching: 0x%08X\n",
>>>>>>>>> man->available_caching);
>>>>>>>>>   ?????? drm_printf(p, "???
default_caching: 0x%08X\n",
>>>>>>>>> man->default_caching);
>>>>>>>>> @@ -345,12 +344,6 @@ static int
ttm_bo_handle_move_mem(struct
>>>>>>>>> ttm_buffer_object *bo,
>>>>>>>>>   ?? moved:
>>>>>>>>>   ?????? bo->evicted = false;
>>>>>>>>>   ?? -??? if (bo->mem.mm_node)
>>>>>>>>> -??????? bo->offset = (bo->mem.start
<< PAGE_SHIFT) +
>>>>>>>>> -???????????
bdev->man[bo->mem.mem_type].gpu_offset;
>>>>>>>>> -??? else
>>>>>>>>> -??????? bo->offset = 0;
>>>>>>>>> -
>>>>>>>> After moving this into users, the else branch
has been lost. Is
>>>>>>>> 'bo->mem.mm_node' always true?
>>>>>>> At least for the amdgpu and radeon use cases, yes.
>>>>>>>
>>>>>>> But that is a rather good question I mean for it is
illegal to get the
>>>>>>> GPU BO address if it is inaccessible (e.g. in the
system domain).
>>>>>>>
>>>>>>> Could be that some driver relied on the behavior to
get 0 for the
>>>>>>> system domain here.
>>>>>> I wonder how to verify that ?
>>>>>>
>>>>>> If I understand correctly:
>>>>>>
>>>>>> 1 qxl uses bo->offset only in
qxl_bo_physical_address() which is not in
>>>>>> system domain.
>>>>>>
>>>>>> 2 unfortunately I can't say the same for bochs but
it works with this
>>>>>> patch series so I think bochs is fine as well.
>>>>>>
>>>>>> 3 vmwgfx uses bo->offset only when
bo->mem.mem_type == TTM_PL_VRAM so
>>>>>> vmwgfx should be fine.
>>>>>>
>>>>>> 4 amdgpu and radeon runs with
'bo->mem.mm_node' always true
>>>>>>
>>>>>> I am not sure about? nouveau as bo->offset is being
used in many places.
>>>>>>
>>>>>> I could probably mirror the removed logic to nouveau as
>>>>> I suggest to introduce a ttm helper that contains the
original branching
>>>>> and use it everywhere. Something like
>>>>>
>>>>>   ?? s64 ttm_bo_offset(struct ttm_buffer_object *bo)
>>>>>   ?? {
>>>>>   ????? if (WARN_ON_ONCE(!bo->mem.mm_node))
>>>>>   ????????? return 0;
>>>>>   ????? return bo->mem.start << PAGE_SHIFT;
>>>>>   ?? }
>>>>>
>>>>> Could be static inline. The warning should point to broken
drivers. This
>>>>> also gets rid of the ugly shift in the drivers.
>>>> Big NAK on this. That is exactly what we should NOT do.
>>>>
>>>> See the shift belongs into the driver, because it is driver
dependent if
>>>> we work with page or byte offsets.
>>>>
>>>> For amdgpu we for example want to work with byte offsets and
TTM should
>>>> not make any assumption about what bo->mem.start actually
contains.
>>> OK. What about something like ttm_bo_pg_offset()? Same code without
the
>>> shift. Would also make it clear that it's a page offset.
>> That is a rather good idea. We could name that ttm_bo_man_offset() and
put
>> it into ttm_bo_manager.c next to the manager which allocates them.
>>
>> It's just that this manager is not used by everybody, so amdgpu,
radeon and
>> nouveau would still need a separate function.
> Let me pile on with my bikeshed color choice :-)
>
> I'd do this a wrapper, but for drivers individually. And only for those
we
> haven't audited yet, or where we think the WARN_ON actually provides
> value. So maybe in vram helpers, since that might be used by some drivers
> that get stuff wrong. Or maybe noveau isn't audited yet.
I like this idea more. I will modify and resend patches with above 
suggestions.
> That also sidesteps the "what should we call this, drivers are
different?"
> problem.
>
> Anyway feel free to ignore me, really just a bikeshed at this point.
>
> Cheers, Daniel
>
>> Christian.
>>
>>> Best regards
>>> Thomas
>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>>> Best regards
>>>>> Thomas
>>>>>
>>>>>
>>>>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>>>> b/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>>>> index f8015e0318d7..5a6a2af91318 100644
>>>>>> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>>>> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
>>>>>> @@ -1317,6 +1317,10 @@ nouveau_bo_move_ntfy(struct
ttm_buffer_object
>>>>>> *bo, bool evict,
>>>>>>   ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
>>>>>>   ???????????????????????? nouveau_vma_map(vma, mem);
>>>>>>   ???????????????? }
>>>>>> +?????????????? if (bo->mem.mm_node)
>>>>>> +?????????????????????? nvbo->offset =
(new_reg->start << PAGE_SHIFT);
>>>>>> +?????????????? else
>>>>>> +?????????????????????? nvbo->offset = 0;
>>>>>>   ???????? } else {
>>>>>>   ???????????????? list_for_each_entry(vma,
&nvbo->vma_list, head) {
>>>>>>   ???????????????????????? WARN_ON(ttm_bo_wait(bo,
false, false));
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> Nirmoy
>>>>>>
>>>>>>
>>>>>>> Regards,
>>>>>>> Christian.
>>>>>>>
>>>>>>>> Best regards
>>>>>>>> Thomas
>>>>>>>>
>>>>>>>>>   ?????? ctx->bytes_moved +=
bo->num_pages << PAGE_SHIFT;
>>>>>>>>>   ?????? return 0;
>>>>>>>>>   ?? diff --git
a/include/drm/ttm/ttm_bo_api.h
>>>>>>>>> b/include/drm/ttm/ttm_bo_api.h
>>>>>>>>> index b9bc1b00142e..d6f39ee5bf5d 100644
>>>>>>>>> --- a/include/drm/ttm/ttm_bo_api.h
>>>>>>>>> +++ b/include/drm/ttm/ttm_bo_api.h
>>>>>>>>> @@ -213,8 +213,6 @@ struct
ttm_buffer_object {
>>>>>>>>>   ??????? * either of these locks held.
>>>>>>>>>   ??????? */
>>>>>>>>>   ?? -??? uint64_t offset; /* GPU address
space is independent of CPU
>>>>>>>>> word size */
>>>>>>>>> -
>>>>>>>>>   ?????? struct sg_table *sg;
>>>>>>>>>   ?? };
>>>>>>>>>   ?? diff --git
a/include/drm/ttm/ttm_bo_driver.h
>>>>>>>>> b/include/drm/ttm/ttm_bo_driver.h
>>>>>>>>> index c9e0fd09f4b2..c8ce6c181abe 100644
>>>>>>>>> --- a/include/drm/ttm/ttm_bo_driver.h
>>>>>>>>> +++ b/include/drm/ttm/ttm_bo_driver.h
>>>>>>>>> @@ -177,7 +177,6 @@ struct
ttm_mem_type_manager {
>>>>>>>>>   ?????? bool has_type;
>>>>>>>>>   ?????? bool use_type;
>>>>>>>>>   ?????? uint32_t flags;
>>>>>>>>> -??? uint64_t gpu_offset; /* GPU address
space is independent of CPU
>>>>>>>>> word size */
>>>>>>>>>   ?????? uint64_t size;
>>>>>>>>>   ?????? uint32_t available_caching;
>>>>>>>>>   ?????? uint32_t default_caching;
>>>>>>>>>
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