Re: [PATCH v2 3/8] drm/ttm: Add unampping of the entire device address space

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 23.06.20 um 12:25 schrieb Daniel Vetter:
> On Tue, Jun 23, 2020 at 01:00:02AM -0400, Andrey Grodzovsky wrote:
>> On 6/22/20 5:45 AM, Daniel Vetter wrote:
>>> On Sun, Jun 21, 2020 at 02:03:03AM -0400, Andrey Grodzovsky wrote:
>>>> Helper function to be used to invalidate all BOs CPU mappings
>>>> once device is removed.
>>>>
>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>> This seems to be missing the code to invalidate all the dma-buf mmaps?
>>>
>>> Probably needs more testcases if you're not yet catching this. Or am I
>>> missing something, and we're exchanging the the address space also for
>>> dma-buf?
>>> -Daniel
>>
>> IMHO the device address space includes all user clients having a CPU view of
>> the BO either from direct mapping though drm file or by  mapping through
>> imported BO's FD.
> Uh this is all very confusing and very much midlayer-y thanks to ttm.
>
> I think a much better solution would be to have a core gem helper for
> this (well not even gem really, this is core drm), which directly uses
> drm_device->anon_inode->i_mapping.
>
> Then
> a) it clearly matches what drm_prime.c does on export
> b) can be reused across all drivers, not just ttm
>
> So much better.
>
> What's more, we could then very easily make the generic
> drm_dev_unplug_and_unmap helper I've talked about for the amdgpu patch,
> which I think would be really neat&pretty.

Good point, that is indeed a rather nice idea.

Christian.

>
> Thoughts?
> -Daniel
>
>> Andrey
>>
>>
>>>> ---
>>>>    drivers/gpu/drm/ttm/ttm_bo.c    | 8 ++++++--
>>>>    include/drm/ttm/ttm_bo_driver.h | 7 +++++++
>>>>    2 files changed, 13 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>>>> index c5b516f..926a365 100644
>>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>>> @@ -1750,10 +1750,14 @@ void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo)
>>>>    	ttm_bo_unmap_virtual_locked(bo);
>>>>    	ttm_mem_io_unlock(man);
>>>>    }
>>>> -
>>>> -
>>>>    EXPORT_SYMBOL(ttm_bo_unmap_virtual);
>>>> +void ttm_bo_unmap_virtual_address_space(struct ttm_bo_device *bdev)
>>>> +{
>>>> +	unmap_mapping_range(bdev->dev_mapping, 0, 0, 1);
>>>> +}
>>>> +EXPORT_SYMBOL(ttm_bo_unmap_virtual_address_space);
>>>> +
>>>>    int ttm_bo_wait(struct ttm_buffer_object *bo,
>>>>    		bool interruptible, bool no_wait)
>>>>    {
>>>> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
>>>> index c9e0fd0..39ea44f 100644
>>>> --- a/include/drm/ttm/ttm_bo_driver.h
>>>> +++ b/include/drm/ttm/ttm_bo_driver.h
>>>> @@ -601,6 +601,13 @@ int ttm_bo_device_init(struct ttm_bo_device *bdev,
>>>>    void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo);
>>>>    /**
>>>> + * ttm_bo_unmap_virtual_address_space
>>>> + *
>>>> + * @bdev: tear down all the virtual mappings for this device
>>>> + */
>>>> +void ttm_bo_unmap_virtual_address_space(struct ttm_bo_device *bdev);
>>>> +
>>>> +/**
>>>>     * ttm_bo_unmap_virtual
>>>>     *
>>>>     * @bo: tear down the virtual mappings for this BO
>>>> -- 
>>>> 2.7.4
>>>>

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