On Wed, 26 Aug 2020 at 14:28, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
>
> Use set_pte_at() to assign the PTE pointer returned by alloc_vm_area(),
> rather than a direct assignment.
and crucially add the missing sync stuff for the mapping?
>
> Fixes: 6056e50033d9 ("drm/i915/gem: Support discontiguous lmem object maps")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_pages.c | 33 +++++++++++++++++++----
> 1 file changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> index 51b63e05dbe4..0c3d0d6429ae 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
> @@ -241,6 +241,17 @@ static inline pte_t iomap_pte(resource_size_t base,
> return pte_mkspecial(pfn_pte((base + offset) >> PAGE_SHIFT, prot));
> }
>
> +static void sync_vm_area(struct vm_struct *area)
> +{
> + unsigned long start = (unsigned long)area->addr;
> + unsigned long end = start + area->size;
> +
> + if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_PTE_MODIFIED)
> + arch_sync_kernel_mappings(start, end); /* expected DCE */
What is DCE again?
> +
> + flush_cache_vmap(start, end);
> +}
> +
> /* The 'mapping' part of i915_gem_object_pin_map() below */
> static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
> enum i915_map_type type)
> @@ -308,24 +319,36 @@ static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
> }
>
> if (i915_gem_object_has_struct_page(obj)) {
> + unsigned long addr = (unsigned long)area->addr;
> struct sgt_iter iter;
> struct page *page;
> pte_t **ptes = mem;
>
> - for_each_sgt_page(page, iter, sgt)
> - **ptes++ = mk_pte(page, pgprot);
> + for_each_sgt_page(page, iter, sgt) {
> + set_pte_at(&init_mm, addr, *ptes, mk_pte(page, pgprot));
init_mm needs to be exported?
> + addr += PAGE_SIZE;
> + ptes++;
> + }
> + GEM_BUG_ON(addr != (unsigned long)area->addr + obj->base.size);
> } else {
> + unsigned long addr = (unsigned long)area->addr;
> resource_size_t iomap;
> struct sgt_iter iter;
> pte_t **ptes = mem;
> - dma_addr_t addr;
> + dma_addr_t offset;
>
> iomap = obj->mm.region->iomap.base;
> iomap -= obj->mm.region->region.start;
>
> - for_each_sgt_daddr(addr, iter, sgt)
> - **ptes++ = iomap_pte(iomap, addr, pgprot);
> + for_each_sgt_daddr(offset, iter, sgt) {
> + set_pte_at(&init_mm, addr, *ptes,
> + iomap_pte(iomap, offset, pgprot));
> + addr += PAGE_SIZE;
> + ptes++;
> + }
> + GEM_BUG_ON(addr != (unsigned long)area->addr + obj->base.size);
> }
> + sync_vm_area(area);
>
> if (mem != stack)
> kvfree(mem);
> --
> 2.20.1
>
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