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@xxxxxxx>
---
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
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