[PATCH] drm/amdgpu: replace iova debugfs file with iomem (v2)

[Christian König]

Am 09.02.2018 um 18:28 schrieb Tom St Denis:
> On 09/02/18 12:27 PM, Tom St Denis wrote:
>> From: Christian König <ckoenig.leichtzumerken at gmail.com>
>
> Oops, I'll remove this from the commit message before pushing :-)
>
> I did give you credit below though.

The patch before this one isn't merged yet because I'm still not sure if 
that works under all circumstances or not.

Could you give it some extended testing? Especially if it work with 
eviction.

Christian.

>
> Tom
>
>>
>> This allows access to pages allocated through the driver with optional
>> IOMMU mapping.
>>
>> v2: Fix number of bytes copied and add write method
>>
>> Original-by: Christian König <christian.koenig at amd.com>
>> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 110 
>> ++++++++++++++++++++++++++------
>>   1 file changed, 89 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index b372d8d650a5..d6c56b001a2c 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -1929,38 +1929,106 @@ 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;
>> +
>> +        bytes = bytes < size ? bytes : size;
>> +
>> +        addr = dom ? iommu_iova_to_phys(dom, addr) : addr;
>> +
>> +        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);
>> +        if (ptr) {
>> +            r = copy_to_user(buf, ptr, bytes);
>> +            kunmap(p);
>> +            if (r)
>> +                return -EFAULT;
>> +        } else {
>> +            return -EFAULT;
>> +        }
>> +
>> +        size -= bytes;
>> +        *pos += bytes;
>> +        result += bytes;
>> +    }
>> +
>> +    return result;
>> +}
>> +
>> +static ssize_t amdgpu_iomem_write(struct file *f, const char __user 
>> *buf,
>> +                 size_t size, loff_t *pos)
>> +{
>> +    struct amdgpu_device *adev = file_inode(f)->i_private;
>> +    struct iommu_domain *dom;
>> +    ssize_t result = 0;
>> +    int r;
>>         dom = iommu_get_domain_for_dev(adev->dev);
>> -    if (dom)
>> -        phys = iommu_iova_to_phys(dom, *pos);
>> -    else
>> -        phys = *pos;
>>   -    r = copy_to_user(buf, &phys, 8);
>> -    if (r)
>> -        return -EFAULT;
>> +    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;
>> +
>> +        bytes = bytes < size ? bytes : size;
>> +
>> +        addr = dom ? iommu_iova_to_phys(dom, addr) : addr;
>>   -    return 8;
>> +        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);
>> +        if (ptr) {
>> +            r = copy_from_user(ptr, buf, bytes);
>> +            kunmap(p);
>> +            if (r)
>> +                return -EFAULT;
>> +        } else {
>> +            return -EFAULT;
>> +        }
>> +
>> +        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,
>> +    .write = amdgpu_iomem_write,
>>       .llseek = default_llseek
>>   };
>>   @@ -1973,7 +2041,7 @@ 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
>>
>