[Intel-gfx] [PATCH 1/2] drm/i915: Add lmem fault handler

[Chris Wilson]

Quoting Abdiel Janulgue (2019-12-17 11:57:49)
> Fault handler to handle missing pages for lmem objects.
> 
> v4: Restore non-contigous fault handling in addition to remap_io_mapping
> 
> 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 | 13 +++++
>  drivers/gpu/drm/i915/gem/i915_gem_lmem.h |  4 ++
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c | 71 ++++++++++++++++++++++--
>  3 files changed, 84 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> index 520cc9cac471..e8326d8b66f7 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
> @@ -6,6 +6,7 @@
>  #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"
>  
>  const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops = {
> @@ -56,6 +57,18 @@ 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;
> +
> +       return (mem->io_start + offset) >> PAGE_SHIFT;
> +}
> +
>  bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj)
>  {
>         return obj->ops == &i915_gem_lmem_obj_ops;
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
> index 7c176b8b7d2f..4d5fca1a3e0e 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
> @@ -7,6 +7,7 @@
>  #define __I915_GEM_LMEM_H
>  
>  #include <linux/types.h>
> +#include <linux/mman.h>
>  
>  struct drm_i915_private;
>  struct drm_i915_gem_object;
> @@ -22,6 +23,9 @@ void __iomem *
>  i915_gem_object_lmem_io_map_page_atomic(struct drm_i915_gem_object *obj,
>                                         unsigned long n);
>  
> +unsigned long i915_gem_object_lmem_io_pfn(struct drm_i915_gem_object *obj,
> +                                         unsigned long n);
> +
>  bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj);
>  
>  struct drm_i915_gem_object *
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> index 879fff8adc48..f5f7af745d1d 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -11,6 +11,7 @@
>  #include "gt/intel_gt.h"
>  #include "gt/intel_gt_requests.h"
>  
> +#include "i915_gem_lmem.h"
>  #include "i915_drv.h"
>  #include "i915_gem_gtt.h"
>  #include "i915_gem_ioctls.h"
> @@ -216,6 +217,7 @@ static vm_fault_t i915_error_to_vmf_fault(int err)
>  
>         case -ENOSPC: /* shmemfs allocation failure */
>         case -ENOMEM: /* our allocation failure */
> +       case -ENXIO:
>                 return VM_FAULT_OOM;
>  
>         case 0:
> @@ -274,6 +276,47 @@ static vm_fault_t vm_fault_cpu(struct vm_fault *vmf)
>         return ret;
>  }
>  
> +vm_fault_t vm_fault_iomem(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;
> +       struct intel_memory_region *mem = obj->mm.region;
> +       unsigned long i, size = area->vm_end - area->vm_start;
> +       bool write = area->vm_flags & VM_WRITE;
> +       int 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);
> +
> +       if (obj->flags & I915_BO_ALLOC_CONTIGUOUS) {
> +               ret = remap_io_mapping(area, area->vm_start,
> +                                      i915_gem_object_lmem_io_pfn(obj, 0), size,
> +                                      &mem->iomap);
> +               i915_gem_object_unpin_pages(obj);
> +               return i915_error_to_vmf_fault(ret);
> +       } else {
> +               vm_fault_t vmf_ret = VM_FAULT_SIGBUS;
> +               if (GEM_WARN_ON(size < PAGE_SIZE))
> +                       return vmf_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));

Sigh.
-Chris