1 files changed, 63 insertions, 29 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 1006c15445e9..ac617f3ecd0c 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -41,6 +41,51 @@
 
 #define TTM_BO_VM_NUM_PREFAULT 16
 
+static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
+                                struct vm_area_struct *vma,
+                                struct vm_fault *vmf)
+{
+        struct ttm_bo_device *bdev = bo->bdev;
+        int ret = 0;
+
+        spin_lock(&bdev->fence_lock);
+        if (likely(!test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)))
+                goto out_unlock;
+
+        /*
+         * Quick non-stalling check for idle.
+         */
+        ret = ttm_bo_wait(bo, false, false, true);
+        if (likely(ret == 0))
+                goto out_unlock;
+
+        /*
+         * If possible, avoid waiting for GPU with mmap_sem
+         * held.
+         */
+        if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
+                ret = VM_FAULT_RETRY;
+                if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
+                        goto out_unlock;
+
+                up_read(&vma->vm_mm->mmap_sem);
+                (void) ttm_bo_wait(bo, false, true, false);
+                goto out_unlock;
+        }
+
+        /*
+         * Ordinary wait.
+         */
+        ret = ttm_bo_wait(bo, false, true, false);
+        if (unlikely(ret != 0))
+                ret = (ret != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
+                        VM_FAULT_NOPAGE;
+
+out_unlock:
+        spin_unlock(&bdev->fence_lock);
+        return ret;
+}
+
 static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
         struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
@@ -57,6 +102,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
         int retval = VM_FAULT_NOPAGE;
         struct ttm_mem_type_manager *man =
                 &bdev->man[bo->mem.mem_type];
+        struct vm_area_struct cvma;
 
         /*
          * Work around locking order reversal in fault / nopfn
@@ -91,18 +137,11 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
          * Wait for buffer data in transit, due to a pipelined
          * move.
          */
-
-        spin_lock(&bdev->fence_lock);
-        if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
-                ret = ttm_bo_wait(bo, false, true, false);
-                spin_unlock(&bdev->fence_lock);
-                if (unlikely(ret != 0)) {
-                        retval = (ret != -ERESTARTSYS) ?
-                            VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
-                        goto out_unlock;
-                }
-        } else
-                spin_unlock(&bdev->fence_lock);
+        ret = ttm_bo_vm_fault_idle(bo, vma, vmf);
+        if (unlikely(ret != 0)) {
+                retval = ret;
+                goto out_unlock;
+        }
 
         ret = ttm_mem_io_lock(man, true);
         if (unlikely(ret != 0)) {
@@ -126,26 +165,21 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
         }
 
         /*
-         * Strictly, we're not allowed to modify vma->vm_page_prot here,
-         * since the mmap_sem is only held in read mode. However, we
-         * modify only the caching bits of vma->vm_page_prot and
-         * consider those bits protected by
-         * the bo->mutex, as we should be the only writers.
-         * There shouldn't really be any readers of these bits except
-         * within vm_insert_mixed()? fork?
-         *
-         * TODO: Add a list of vmas to the bo, and change the
-         * vma->vm_page_prot when the object changes caching policy, with
-         * the correct locks held.
+         * Make a local vma copy to modify the page_prot member
+         * and vm_flags if necessary. The vma parameter is protected
+         * by mmap_sem in write mode.
          */
+        cvma = *vma;
+        cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);
+
         if (bo->mem.bus.is_iomem) {
-                vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
-                                                vma->vm_page_prot);
+                cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+                                                cvma.vm_page_prot);
         } else {
                 ttm = bo->ttm;
-                vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
-                    vm_get_page_prot(vma->vm_flags) :
-                    ttm_io_prot(bo->mem.placement, vma->vm_page_prot);
+                if (!(bo->mem.placement & TTM_PL_FLAG_CACHED))
+                        cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+                                                        cvma.vm_page_prot);
 
                 /* Allocate all page at once, most common usage */
                 if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
@@ -172,7 +206,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                         pfn = page_to_pfn(page);
                 }
 
-                ret = vm_insert_mixed(vma, address, pfn);
+                ret = vm_insert_mixed(&cvma, address, pfn);
                 /*
                  * Somebody beat us to this PTE or prefaulting to
                  * an already populated PTE, or prefaulting error.