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

[Chris Wilson]

Quoting Abdiel Janulgue (2019-12-11 05:59:07)
> Fault handler to handle missing pages for lmem objects.
> 
> v2: Handle ENXIO in fault error, account for offset in region start
>     for fake lmem (Matt).
>     Add selftest (Chris).
> 
> 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      |  44 ++++++++
>  drivers/gpu/drm/i915/gem/i915_gem_lmem.h      |   6 +
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c      |  16 ++-
>  drivers/gpu/drm/i915/gem/i915_gem_mman.h      |   1 +
>  .../drm/i915/gem/selftests/i915_gem_mman.c    | 105 ++++++++++++++----
>  5 files changed, 147 insertions(+), 25 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..7e6d8d1546e3 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);
> +
> +       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;
> +       }

So why aren't we using remap_io_mapping() ?
-Chris