Re: [PATCH] drm/radeon/kms: forbid big bo allocation (fdo 31708) v2

[Thomas Hellstrom <thomas@shipmail.org>]

On 11/22/2010 06:07 PM, Jerome Glisse wrote:
> 2010/11/22 Michel Dänzer<michel@daenzer.net>:
>    
>> On Fre, 2010-11-19 at 16:34 -0500, jglisse@redhat.com wrote:
>>      
>>> From: Jerome Glisse<jglisse@redhat.com>
>>>
>>> Forbid allocating buffer bigger than visible VRAM or GTT, also
>>> properly set lpfn field.
>>>
>>> v2 - use max macro
>>>     - silence warning
>>>
>>> Signed-off-by: Jerome Glisse<jglisse@redhat.com>
>>> ---
>>>   drivers/gpu/drm/radeon/radeon_object.c |   34 ++++++++++++++++++++++++++-----
>>>   1 files changed, 28 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
>>> index 1d06774..c2fa64c 100644
>>> --- a/drivers/gpu/drm/radeon/radeon_object.c
>>> +++ b/drivers/gpu/drm/radeon/radeon_object.c
>>> @@ -69,18 +69,28 @@ void radeon_ttm_placement_from_domain(struct radeon_bo *rbo, u32 domain)
>>>        u32 c = 0;
>>>
>>>        rbo->placement.fpfn = 0;
>>> -     rbo->placement.lpfn = rbo->rdev->mc.active_vram_size>>  PAGE_SHIFT;
>>> +     rbo->placement.lpfn = 0;
>>>        rbo->placement.placement = rbo->placements;
>>>        rbo->placement.busy_placement = rbo->placements;
>>> -     if (domain&  RADEON_GEM_DOMAIN_VRAM)
>>> +     if (domain&  RADEON_GEM_DOMAIN_VRAM) {
>>> +             rbo->placement.lpfn = max((unsigned)rbo->placement.lpfn, (unsigned)rbo->rdev->mc.active_vram_size>>  PAGE_SHIFT);
>>>                rbo->placements[c++] = TTM_PL_FLAG_WC | TTM_PL_FLAG_UNCACHED |
>>>                                        TTM_PL_FLAG_VRAM;
>>> -     if (domain&  RADEON_GEM_DOMAIN_GTT)
>>> +     }
>>> +     if (domain&  RADEON_GEM_DOMAIN_GTT) {
>>> +             rbo->placement.lpfn = max((unsigned)rbo->placement.lpfn, (unsigned)rbo->rdev->mc.gtt_size>>  PAGE_SHIFT);
>>>                rbo->placements[c++] = TTM_PL_MASK_CACHING | TTM_PL_FLAG_TT;
>>> -     if (domain&  RADEON_GEM_DOMAIN_CPU)
>>> +     }
>>> +     if (domain&  RADEON_GEM_DOMAIN_CPU) {
>>> +             /* 4G limit for CPU domain */
>>> +             rbo->placement.lpfn = max(rbo->placement.lpfn, 0xFFFFFFFF>>  PAGE_SHIFT);
>>>                rbo->placements[c++] = TTM_PL_MASK_CACHING | TTM_PL_FLAG_SYSTEM;
>>> -     if (!c)
>>> +     }
>>> +     if (!c) {
>>> +             /* 4G limit for CPU domain */
>>> +             rbo->placement.lpfn = max(rbo->placement.lpfn, 0xFFFFFFFF>>  PAGE_SHIFT);
>>>                rbo->placements[c++] = TTM_PL_MASK_CACHING | TTM_PL_FLAG_SYSTEM;
>>> +     }
>>>        
>> I don't think taxing the maximum is the right thing to do: If domain is
>> (RADEON_GEM_DOMAIN_VRAM | RADEON_GEM_DOMAIN_GTT) and VRAM doesn't happen
>> to be the same size as GTT, lpfn will end up larger than one of them.
>>
>> AFAICT radeon_ttm_placement_from_domain() should just set lpfn to 0
>> (i.e. unrestricted), the callers that need it to be non-0 already set it
>> afterwards.
>>
>> Out of curiosity, where does the 4G limit come from?
>>
>>
>>      
> > From my hat, but iirc ttm limit things to 1G anyway (vm size for
> mapping object in drm file and iirc we will report error if we can't
> find a mapping for userspace object). I guess at one point we should
> start thinking about what we want to do on that front.
>    

That limit is taken from *my* hat. Nothing prevents us to increase that 
limit to whatever.

/Thomas



> Doing a v3.
>
> Cheers,
> Jerome
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