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drm/i915: Introduce remap_io_sg() to prefault discontiguous objects

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Provide a way to set the PTE within apply_page_range for discontiguous
objects in addition to the existing method of just incrementing the pfn
for a page range.

Fixes: cc662126b413 ("drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET")
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191231200356.409475-1-chris@chris-wilson.co.uk
This commit is contained in:
Abdiel Janulgue 2019-12-31 20:03:56 +00:00 committed by Chris Wilson
parent cc39da0e4c
commit 1764b992be
3 changed files with 74 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/gpu/drm/i915/gem/i915_gem_mman.c
View File

@ -236,42 +236,34 @@ static vm_fault_t vm_fault_cpu(struct vm_fault *vmf)
struct vm_area_struct *area = vmf->vma;
struct i915_mmap_offset *mmo = area->vm_private_data;
struct drm_i915_gem_object *obj = mmo->obj;
unsigned long i, size = area->vm_end - area->vm_start;
bool write = area->vm_flags & VM_WRITE;
vm_fault_t ret = VM_FAULT_SIGBUS;
int err;
if (!i915_gem_object_has_struct_page(obj))
return ret;
if (unlikely(!i915_gem_object_has_struct_page(obj)))
return VM_FAULT_SIGBUS;
/* Sanity check that we allow writing into this object */
if (i915_gem_object_is_readonly(obj) && write)
return ret;
if (unlikely(i915_gem_object_is_readonly(obj) &&
area->vm_flags & VM_WRITE))
return VM_FAULT_SIGBUS;
err = i915_gem_object_pin_pages(obj);
if (err)
return i915_error_to_vmf_fault(err);
goto out;
/* PTEs are revoked in obj->ops->put_pages() */
for (i = 0; i < size >> PAGE_SHIFT; i++) {
struct page *page = i915_gem_object_get_page(obj, i);
err = remap_io_sg_page(area,
area->vm_start, area->vm_end - area->vm_start,
obj->mm.pages->sgl);
ret = vmf_insert_pfn(area,
(unsigned long)area->vm_start + i * PAGE_SIZE,
page_to_pfn(page));
if (ret != VM_FAULT_NOPAGE)
break;
}
if (write) {
if (area->vm_flags & VM_WRITE) {
GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
obj->cache_dirty = true; /* XXX flush after PAT update? */
obj->mm.dirty = true;
}
i915_gem_object_unpin_pages(obj);
return ret;
out:
return i915_error_to_vmf_fault(err);
}
static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)

3
drivers/gpu/drm/i915/i915_drv.h
View File

@ -2015,6 +2015,9 @@ int i915_reg_read_ioctl(struct drm_device *dev, void *data,
int remap_io_mapping(struct vm_area_struct *vma,
unsigned long addr, unsigned long pfn, unsigned long size,
struct io_mapping *iomap);
int remap_io_sg_page(struct vm_area_struct *vma,
unsigned long addr, unsigned long size,
struct scatterlist *sgl);
static inline int intel_hws_csb_write_index(struct drm_i915_private *i915)
{

59
drivers/gpu/drm/i915/i915_mm.c
View File

@ -33,6 +33,8 @@ struct remap_pfn {
struct mm_struct *mm;
unsigned long pfn;
pgprot_t prot;
struct sgt_iter sgt;
};
static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
@ -46,6 +48,30 @@ static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
return 0;
}
static inline unsigned long sgt_pfn(const struct sgt_iter *sgt)
{
return sgt->pfn + (sgt->curr >> PAGE_SHIFT);
}
static int remap_sg_page(pte_t *pte, unsigned long addr, void *data)
{
struct remap_pfn *r = data;
if (GEM_WARN_ON(!r->sgt.pfn))
return -EINVAL;
/* Special PTE are not associated with any struct page */
set_pte_at(r->mm, addr, pte,
pte_mkspecial(pfn_pte(sgt_pfn(&r->sgt), r->prot)));
r->pfn++; /* track insertions in case we need to unwind later */
r->sgt.curr += PAGE_SIZE;
if (r->sgt.curr >= r->sgt.max)
r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), false);
return 0;
}
/**
* remap_io_mapping - remap an IO mapping to userspace
* @vma: user vma to map to
@ -80,3 +106,36 @@ int remap_io_mapping(struct vm_area_struct *vma,
return 0;
}
/**
* remap_io_sg_page - remap an IO mapping to userspace
* @vma: user vma to map to
* @addr: target user address to start at
* @size: size of map area
* @sgl: Start sg entry
*
* Note: this is only safe if the mm semaphore is held when called.
*/
int remap_io_sg_page(struct vm_area_struct *vma,
unsigned long addr, unsigned long size,
struct scatterlist *sgl)
{
struct remap_pfn r = {
.mm = vma->vm_mm,
.prot = vma->vm_page_prot,
.sgt = __sgt_iter(sgl, false),
};
int err;
/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
flush_cache_range(vma, addr, size);
err = apply_to_page_range(r.mm, addr, size, remap_sg_page, &r);
if (unlikely(err)) {
zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
return err;
}
return 0;
}