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

[Tom St Denis]

Attached is a patch for umr{master} which should in theory support both 
iova and iomem.

I can add the write method if you want since ya it should be fairly 
simple to copy/pasta that up.

Cheers,
Tom

On 05/02/18 07:07 AM, Christian König wrote:
> Well adding write support is trivial.
> 
> What I'm more concerned about is if setting page->mapping during 
> allocation of the page could have any negative effect?
> 
> I of hand don't see any since the page isn't reclaimable directly 
> anyway, but I'm not 100% sure of that.
> 
> Christian.
> 
> Am 05.02.2018 um 12:49 schrieb Tom St Denis:
>> Another thing that occurred to me is this will break write access to 
>> GPU bound memory.  Previously we relied on iova to translate the 
>> address and then /dev/mem or /dev/fmem to read/write it.  But since 
>> this is literally a read only method obviously there's no write support.
>>
>> Tom
>>
>>
>> On 04/02/18 09:56 PM, He, Roger wrote:
>>> Patch1 & 2 & 4,   Reviewed-by: Roger He <Hongbo.He at amd.com>
>>> Patch 5:  Acked-by: Roger He <Hongbo.He at amd.com>
>>>
>>> -----Original Message-----
>>> From: dri-devel [mailto:dri-devel-bounces at lists.freedesktop.org] On 
>>> Behalf Of Christian K?nig
>>> Sent: Saturday, February 03, 2018 3:10 AM
>>> To: amd-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org
>>> Subject: [PATCH 5/5] drm/amdgpu: replace iova debugfs file with iomem
>>>
>>> This allows access to pages allocated through the driver with 
>>> optional IOMMU mapping.
>>>
>>> Signed-off-by: Christian König <christian.koenig at amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 57 
>>> ++++++++++++++++++++-------------
>>>   1 file changed, 35 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> index 648c449aaa79..795ceaeb82d5 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> @@ -1929,38 +1929,51 @@ static const struct file_operations 
>>> amdgpu_ttm_gtt_fops = {
>>>     #endif
>>>   -static ssize_t amdgpu_iova_to_phys_read(struct file *f, char 
>>> __user *buf,
>>> -                   size_t size, loff_t *pos)
>>> +static ssize_t amdgpu_iomem_read(struct file *f, char __user *buf,
>>> +                 size_t size, loff_t *pos)
>>>   {
>>>       struct amdgpu_device *adev = file_inode(f)->i_private;
>>> -    int r;
>>> -    uint64_t phys;
>>>       struct iommu_domain *dom;
>>> +    ssize_t result = 0;
>>> +    int r;
>>>   -    // always return 8 bytes
>>> -    if (size != 8)
>>> -        return -EINVAL;
>>> +    dom = iommu_get_domain_for_dev(adev->dev);
>>>   -    // only accept page addresses
>>> -    if (*pos & 0xFFF)
>>> -        return -EINVAL;
>>> +    while (size) {
>>> +        phys_addr_t addr = *pos & PAGE_MASK;
>>> +        loff_t off = *pos & ~PAGE_MASK;
>>> +        size_t bytes = PAGE_SIZE - off;
>>> +        unsigned long pfn;
>>> +        struct page *p;
>>> +        void *ptr;
>>>   -    dom = iommu_get_domain_for_dev(adev->dev);
>>> -    if (dom)
>>> -        phys = iommu_iova_to_phys(dom, *pos);
>>> -    else
>>> -        phys = *pos;
>>> +        addr = dom ? iommu_iova_to_phys(dom, addr) : addr;
>>>   -    r = copy_to_user(buf, &phys, 8);
>>> -    if (r)
>>> -        return -EFAULT;
>>> +        pfn = addr >> PAGE_SHIFT;
>>> +        if (!pfn_valid(pfn))
>>> +            return -EPERM;
>>> +
>>> +        p = pfn_to_page(pfn);
>>> +        if (p->mapping != adev->mman.bdev.dev_mapping)
>>> +            return -EPERM;
>>> +
>>> +        ptr = kmap(p);
>>> +        r = copy_to_user(buf, ptr, bytes);
>>> +        kunmap(p);
>>> +        if (r)
>>> +            return -EFAULT;
>>>   -    return 8;
>>> +        size -= bytes;
>>> +        *pos += bytes;
>>> +        result += bytes;
>>> +    }
>>> +
>>> +    return result;
>>>   }
>>>   -static const struct file_operations amdgpu_ttm_iova_fops = {
>>> +static const struct file_operations amdgpu_ttm_iomem_fops = {
>>>       .owner = THIS_MODULE,
>>> -    .read = amdgpu_iova_to_phys_read,
>>> +    .read = amdgpu_iomem_read,
>>>       .llseek = default_llseek
>>>   };
>>>   @@ -1973,7 +1986,7 @@ static const struct {  #ifdef 
>>> CONFIG_DRM_AMDGPU_GART_DEBUGFS
>>>       { "amdgpu_gtt", &amdgpu_ttm_gtt_fops, TTM_PL_TT }, #endif
>>> -    { "amdgpu_iova", &amdgpu_ttm_iova_fops, TTM_PL_SYSTEM },
>>> +    { "amdgpu_iomem", &amdgpu_ttm_iomem_fops, TTM_PL_SYSTEM },
>>>   };
>>>     #endif
>>> -- 
>>> 2.14.1
>>>
>>> _______________________________________________
>>> 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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