[PATCH 2/5] drm/radeon: add userptr flag to limit it to anonymous memory v2

[Christian König]

Am 05.08.2014 um 19:39 schrieb Jerome Glisse:
> On Tue, Aug 05, 2014 at 06:05:29PM +0200, Christian König wrote:
>> From: Christian König <christian.koenig at amd.com>
>>
>> Avoid problems with writeback by limiting userptr to anonymous memory.
>>
>> v2: add commit and code comments
> I guess, i have not expressed myself clearly. This is bogus, you pretend
> you want to avoid writeback issue but you still allow userspace to map
> file backed pages (which by the way might be a regular bo object from
> another device for instance and that would be fun).
>
> So this patch is a no go and i would rather see that this userptr to
> be restricted to anon vma only no matter what. No flags here.

Mapping of non anonymous memory (e.g. everything get_user_pages won't 
fail with) is restricted to read only access by the GPU.

I'm fine with making it a hard requirement for all mappings if you say 
it's a must have.

Christian.

>
> Cheers,
> Jérôme
>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> ---
>>   drivers/gpu/drm/radeon/radeon_gem.c |  3 ++-
>>   drivers/gpu/drm/radeon/radeon_ttm.c | 10 ++++++++++
>>   include/uapi/drm/radeon_drm.h       |  1 +
>>   3 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
>> index 993ab22..032736b 100644
>> --- a/drivers/gpu/drm/radeon/radeon_gem.c
>> +++ b/drivers/gpu/drm/radeon/radeon_gem.c
>> @@ -290,7 +290,8 @@ int radeon_gem_userptr_ioctl(struct drm_device *dev, void *data,
>>   		return -EACCES;
>>   
>>   	/* reject unknown flag values */
>> -	if (args->flags & ~RADEON_GEM_USERPTR_READONLY)
>> +	if (args->flags & ~(RADEON_GEM_USERPTR_READONLY |
>> +	    RADEON_GEM_USERPTR_ANONONLY))
>>   		return -EINVAL;
>>   
>>   	/* readonly pages not tested on older hardware */
>> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
>> index 0109090..54eb7bc 100644
>> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
>> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
>> @@ -542,6 +542,16 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
>>   		       ttm->num_pages * PAGE_SIZE))
>>   		return -EFAULT;
>>   
>> +	if (gtt->userflags & RADEON_GEM_USERPTR_ANONONLY) {
>> +		/* check that we only pin down anonymous memory
>> +		   to prevent problems with writeback */
>> +		unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
>> +		struct vm_area_struct *vma;
>> +		vma = find_vma(gtt->usermm, gtt->userptr);
>> +		if (!vma || vma->vm_file || vma->vm_end < end)
>> +			return -EPERM;
>> +	}
>> +
>>   	do {
>>   		unsigned num_pages = ttm->num_pages - pinned;
>>   		uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE;
>> diff --git a/include/uapi/drm/radeon_drm.h b/include/uapi/drm/radeon_drm.h
>> index 3a9f209..9720e1a 100644
>> --- a/include/uapi/drm/radeon_drm.h
>> +++ b/include/uapi/drm/radeon_drm.h
>> @@ -816,6 +816,7 @@ struct drm_radeon_gem_create {
>>    * perform any operation.
>>    */
>>   #define RADEON_GEM_USERPTR_READONLY	(1 << 0)
>> +#define RADEON_GEM_USERPTR_ANONONLY	(1 << 1)
>>   
>>   struct drm_radeon_gem_userptr {
>>   	uint64_t		addr;
>> -- 
>> 1.9.1
>>
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