Am 20.09.2017 um 13:42 schrieb Tom St Denis:
> We discovered that on some devices even with iommu enabled
> you can access all of system memory through the iommu translation.
>
> Therefore, we revert the read method to the translation only service
> and drop the write method completely.
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
Reviewed-by: Christan König <christian.koenig at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 90 +++++----------------------------
> 1 file changed, 13 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 0e5f78f3a97e..ce435dbbb398 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1784,98 +1784,34 @@ static ssize_t amdgpu_iova_to_phys_read(struct file *f, char __user *buf,
> size_t size, loff_t *pos)
> {
> struct amdgpu_device *adev = file_inode(f)->i_private;
> - ssize_t result, n;
> int r;
> uint64_t phys;
> - void *ptr;
> struct iommu_domain *dom;
>
> - dom = iommu_get_domain_for_dev(adev->dev);
> - if (!dom)
> - return -EFAULT;
> -
> - result = 0;
> - while (size) {
> - // get physical address and map
> - phys = iommu_iova_to_phys(dom, *pos);
> -
> - // copy upto one page
> - if (size > PAGE_SIZE)
> - n = PAGE_SIZE;
> - else
> - n = size;
> -
> - // to end of the page
> - if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
> - n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
> -
> - ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
> - if (!ptr)
> - return -EFAULT;
> -
> - r = copy_to_user(buf, ptr, n);
> - kunmap(pfn_to_page(PFN_DOWN(phys)));
> - if (r)
> - return -EFAULT;
> -
> - *pos += n;
> - size -= n;
> - result += n;
> - }
> -
> - return result;
> -}
> + // always return 8 bytes
> + if (size != 8)
> + return -EINVAL;
>
> -static ssize_t amdgpu_iova_to_phys_write(struct file *f, const char __user *buf,
> - size_t size, loff_t *pos)
> -{
> - struct amdgpu_device *adev = file_inode(f)->i_private;
> - ssize_t result, n;
> - int r;
> - uint64_t phys;
> - void *ptr;
> - struct iommu_domain *dom;
> + // only accept page addresses
> + if (*pos & 0xFFF)
> + return -EINVAL;
>
> dom = iommu_get_domain_for_dev(adev->dev);
> - if (!dom)
> - return -EFAULT;
> -
> - result = 0;
> - while (size) {
> - // get physical address and map
> + if (dom)
> phys = iommu_iova_to_phys(dom, *pos);
> + else
> + phys = *pos;
>
> - // copy upto one page
> - if (size > PAGE_SIZE)
> - n = PAGE_SIZE;
> - else
> - n = size;
> -
> - // to end of the page
> - if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
> - n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
> -
> - ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
> - if (!ptr)
> - return -EFAULT;
> -
> - r = copy_from_user(ptr, buf, n);
> - kunmap(pfn_to_page(PFN_DOWN(phys)));
> - if (r)
> - return -EFAULT;
> -
> - *pos += n;
> - size -= n;
> - result += n;
> - }
> + r = copy_to_user(buf, &phys, 8);
> + if (r)
> + return -EFAULT;
>
> - return result;
> + return 8;
> }
>
> static const struct file_operations amdgpu_ttm_iova_fops = {
> .owner = THIS_MODULE,
> .read = amdgpu_iova_to_phys_read,
> - .write = amdgpu_iova_to_phys_write,
> .llseek = default_llseek
> };
>
