[PATCH 5/5] drm/amdgpu: replace iova debugfs file with iomem

[Tom St Denis]

On 09/02/18 09:56 AM, Christian König wrote:
> Am 09.02.2018 um 15:51 schrieb Tom St Denis:
>> On 09/02/18 09:12 AM, Christian König wrote:
>>> No, there is simply no need to initialize the system domain. What are 
>>> the values of p->mapping and adev->mman.bdev.dev_mapping when they 
>>> don't match? Maybe we are allocating memory before initializing 
>>> adev->mman.bdev.dev_mapping.
>>
>> In my test setup I'm running test 3 from libdrm (suite 1) with a pause 
>> before the unmap/free call.  So the IB should still be mapped.  Indeed 
>> the VM PTE decoding has the V bit set.
>>
>>> Or do you have more than one GPU in the system? E.g. APU+dGPU? Could 
>>> it be that you read through the wrong device?
>>
>> I found the issue:
>>
>>     while (size) {
>>         phys_addr_t addr = *pos & PAGE_MASK;
>>         loff_t off = *pos & ~PAGE_MASK;
>>         size_t bytes = PAGE_SIZE - off;
>>
>> "bytes" should be limited by the 'size' parameter passed in.  What is 
>> happening instead is it's reading the entire PTB until it hits a V=0 
>> page and then returns an error and in the process is doing "fun 
>> things" to the user mode application (by copying more data than I 
>> asked for).
> 
> Ah, obvious problem.
> 
> Do you want to fix it or should I take a look? You wanted to add write 
> support as well anyway IIRC.

Yup, I can tackle this this afternoon.

I'll take your read only patch and make it do both read/write (and fix 
the minor error).

Tom