On Tue, Jan 26, 2016 at 02:53:31PM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <[email protected]>
>
> Signed-off-by: Tvrtko Ursulin <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 96
> ++++++++++++++++++++++++++++++++++++++---
> include/uapi/drm/i915_drm.h | 3 ++
> 2 files changed, 93 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index dacf6a0013c5..039d55a49fc6 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1954,6 +1954,60 @@ out:
> return i915_gem_ret_to_vm_ret(dev_priv, ret);
> }
>
> +static int
> +i915_gem_cpu_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> +{
> + struct drm_i915_gem_object *obj = to_intel_bo(vma->vm_private_data);
> + struct drm_device *dev = obj->base.dev;
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + bool write = !!(vmf->flags & FAULT_FLAG_WRITE);
> + pgoff_t page_offset;
> + struct page *page;
> + int ret;
> +
> + /* We don't use vmf->pgoff since that has the fake offset */
> + page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
> + PAGE_SHIFT;
> +
> + trace_i915_gem_object_fault(obj, page_offset, true, write);
> +
> + intel_runtime_pm_get(dev_priv);
> +
> + ret = i915_mutex_lock_interruptible(dev);
> + if (ret)
> + goto out;
> +
> + ret = i915_gem_object_set_to_cpu_domain(obj, write);
> + if (ret)
> + goto out_unlock;
That was a mistake in the GTT gem_fault(). If you do this, we also want
the nonblocking wait for obvious reasons.
> + ret = i915_gem_object_get_pages(obj);
> + if (ret)
> + goto out_unlock;
> +
> + page = i915_gem_object_get_page(obj, page_offset);
> + if (!page) {
> + ret = -ERANGE;
> + goto out_unlock;
> + }
> +
> + mutex_unlock(&dev->struct_mutex);
> +
> + ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address,
> + page_to_pfn(page));
We don't have a page ref at this point, so this obj+page could be
freed (via the shrinker at least) before we insert it.
I would also be more interested in having a version that faulted the
entire object at once - though maybe we will see more random access in
future.
> + intel_runtime_pm_put(dev_priv);
> +
> + return i915_gem_ret_to_vm_ret(dev_priv, ret);
> +
> +out_unlock:
> + mutex_unlock(&dev->struct_mutex);
> +out:
> + intel_runtime_pm_put(dev_priv);
> +
> + return i915_gem_ret_to_vm_ret(dev_priv, ret);
> +}
> +
> /**
> * i915_gem_release_mmap - remove physical page mappings
> * @obj: obj in question
> @@ -2078,11 +2132,18 @@ static void i915_gem_object_free_mmap_offset(struct
> drm_i915_gem_object *obj)
> drm_gem_free_mmap_offset(&obj->base);
> }
>
> -int
> -i915_gem_mmap_gtt(struct drm_file *file,
> - struct drm_device *dev,
> - uint32_t handle,
> - uint64_t *offset)
> +static const struct vm_operations_struct i915_gem_cpu_vm_ops = {
> + .fault = i915_gem_cpu_fault,
> + .open = drm_gem_vm_open,
> + .close = drm_gem_vm_close,
> +};
> +
> +static int
> +i915_gem_mmap(struct drm_file *file,
> + struct drm_device *dev,
> + uint32_t handle,
> + uint32_t flags,
> + uint64_t *offset)
> {
> struct drm_i915_gem_object *obj;
> int ret;
> @@ -2103,10 +2164,23 @@ i915_gem_mmap_gtt(struct drm_file *file,
> goto out;
> }
>
> + if (!obj->base.filp && (flags & I915_MMAP2_CPU)) {
> + DRM_DEBUG("Attempting to mmap non-shm based object via CPU!\n");
> + ret = -EINVAL;
> + goto out;
> + }
> +
> ret = i915_gem_object_create_mmap_offset(obj);
> if (ret)
> goto out;
>
> + if (flags & I915_MMAP2_CPU) {
> + ret = drm_vma_node_set_vm_ops(&obj->base.vma_node,
> + &i915_gem_cpu_vm_ops);
> + if (ret)
> + goto out;
> + }
We would also need a WC equivalent.
It looks fairly sane. I wanted this just a short while ago, but figured
out a way of using regular mmap() to give me the inheritance instead.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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