On 02/02/18 02:09 PM, Christian König wrote: > 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; This comparison fails for both IOMMU and non-IOMMU devices in my carrizo+polaris10 box. The address being read from is what the VM decodes to (checked with strace). Tom