[Intel-gfx] [PATCH] drm/i915: Add lmem fault handler

[Matthew Auld]

On Thu, 5 Dec 2019 at 10:14, Abdiel Janulgue
<abdiel.janulgue at linux.intel.com> wrote:
>
> Fault handler to handle missing pages for lmem objects.
>
> Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_lmem.c | 43 ++++++++++++++++++++++++
>  drivers/gpu/drm/i915/gem/i915_gem_lmem.h |  6 ++++
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c | 15 +++++++--
>  drivers/gpu/drm/i915/gem/i915_gem_mman.h |  1 +
>  4 files changed, 63 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> index 0e2bf6b7e143..78ac8d160cd7 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> @@ -6,8 +6,40 @@
>  #include "intel_memory_region.h"
>  #include "gem/i915_gem_region.h"
>  #include "gem/i915_gem_lmem.h"
> +#include "gem/i915_gem_mman.h"
>  #include "i915_drv.h"
>
> +vm_fault_t vm_fault_lmem(struct vm_fault *vmf)
> +{
> +       struct vm_area_struct *area = vmf->vma;
> +       struct i915_mmap_offset *priv = area->vm_private_data;
> +       struct drm_i915_gem_object *obj = priv->obj;
> +       unsigned long size = area->vm_end - area->vm_start;
> +       bool write = area->vm_flags & VM_WRITE;
> +       vm_fault_t vmf_ret;
> +       int i, ret;
> +
> +       /* Sanity check that we allow writing into this object */
> +       if (i915_gem_object_is_readonly(obj) && write)
> +               return VM_FAULT_SIGBUS;
> +
> +       ret = i915_gem_object_pin_pages(obj);
> +       if (ret)
> +               return i915_error_to_vmf_fault(ret);

Don't we need to handle -ENXIO in i915_error_to_vmf_fault?

> +
> +       for (i = 0; i < size >> PAGE_SHIFT; i++) {
> +               vmf_ret = vmf_insert_pfn(area,
> +                                        (unsigned long)area->vm_start + i * PAGE_SIZE,
> +                                        i915_gem_object_lmem_io_pfn(obj, i));
> +               if (vmf_ret != VM_FAULT_NOPAGE)
> +                       break;
> +       }
> +
> +       i915_gem_object_unpin_pages(obj);
> +
> +       return vmf_ret;
> +}
> +
>  const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops = {
>         .flags = I915_GEM_OBJECT_HAS_IOMEM,
>
> @@ -56,6 +88,17 @@ i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,
>         return io_mapping_map_wc(&obj->mm.region->iomap, offset, size);
>  }
>
> +unsigned long i915_gem_object_lmem_io_pfn(struct drm_i915_gem_object *obj,
> +                                         unsigned long n)
> +{
> +       struct intel_memory_region *mem = obj->mm.region;
> +       resource_size_t offset;
> +
> +       offset = i915_gem_object_get_dma_address(obj, n);

offset -= mem->region.start; for poor old fake local-memory.