On 18/09/2020 17:37, Christoph Hellwig wrote:

i915_gem_object_map implements fairly low-level vmap functionality in a driver. Split it into two helpers, one for remapping kernel memory which can use vmap, and one for I/O memory that uses vmap_pfn.

The only practical difference is that alloc_vm_area prefeaults the vmalloc area PTEs, which doesn't seem to be required here for the kernel memory case (and could be added to vmap using a flag if actually required).

Patch looks good to me.

Series did not get a CI run from our side because of a different base so I don't know if you would like to have a run there? If so you would need to rebase against git://anongit.freedesktop.org/drm-tip drm-tip and you could even send a series to intel-gfx-trybot@lists.freedesktop.org, suppressing cc, to check it out without sending a copy to the real mailing list.

Regards,

Tvrtko

Signed-off-by: Christoph Hellwig hch@lst.de

drivers/gpu/drm/i915/Kconfig | 1 + drivers/gpu/drm/i915/gem/i915_gem_pages.c | 101 ++++++++++------------ 2 files changed, 47 insertions(+), 55 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig index 9afa5c4a6bf006..1e1cb245fca778 100644 --- a/drivers/gpu/drm/i915/Kconfig +++ b/drivers/gpu/drm/i915/Kconfig @@ -25,6 +25,7 @@ config DRM_I915 select CRC32 select SND_HDA_I915 if SND_HDA_CORE select CEC_CORE if CEC_NOTIFIER

• select VMAP_PFN help Choose this option if you have a system that has "Intel Graphics Media Accelerator" or "HD Graphics" integrated graphics,

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c index e8a083743e0927..90029ea83aede9 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c @@ -234,50 +234,24 @@ int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj) return err; }

-static inline pte_t iomap_pte(resource_size_t base,

• 	      dma_addr_t offset,
  

• 	      pgprot_t prot)
  

-{

• return pte_mkspecial(pfn_pte((base + offset) >> PAGE_SHIFT, prot));

-}

• /* The 'mapping' part of i915_gem_object_pin_map() below */

-static void *i915_gem_object_map(struct drm_i915_gem_object *obj, +static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj, enum i915_map_type type) {

• unsigned long n_pte = obj->base.size >> PAGE_SHIFT;
• struct sg_table *sgt = obj->mm.pages;
• pte_t *stack[32], **mem;
• struct vm_struct *area;

• unsigned long n_pages = obj->base.size >> PAGE_SHIFT, i;
• struct page *stack[32], **pages = stack, *page;
• struct sgt_iter iter; pgprot_t pgprot;

• if (!i915_gem_object_has_struct_page(obj) && type != I915_MAP_WC)

• return NULL;
  

• /* A single page can always be kmapped */
• if (n_pte == 1 && type == I915_MAP_WB)

• return kmap(sg_page(sgt->sgl));
  

• mem = stack;
• if (n_pte > ARRAY_SIZE(stack)) {

• /* Too big for stack -- allocate temporary array instead */
  

• mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
  

• if (!mem)
  

• 	return NULL;
  

• }
• area = alloc_vm_area(obj->base.size, mem);
• if (!area) {

• if (mem != stack)
  

• 	kvfree(mem);
  

• return NULL;
  

• }

• void *vaddr;

  switch (type) { default: MISSING_CASE(type); fallthrough; /* to use PAGE_KERNEL anyway */ case I915_MAP_WB:

• /* A single page can always be kmapped */
  

• if (n_pages == 1)
  

• 	return kmap(sg_page(obj->mm.pages->sgl));
  

  pgprot = PAGE_KERNEL; break; case I915_MAP_WC:

@@ -285,30 +259,44 @@ static void *i915_gem_object_map(struct drm_i915_gem_object *obj, break; }

• if (i915_gem_object_has_struct_page(obj)) {

• struct sgt_iter iter;
  

• struct page *page;
  

• pte_t **ptes = mem;
  

• for_each_sgt_page(page, iter, sgt)
  

• 	**ptes++ = mk_pte(page, pgprot);
  

• } else {

• resource_size_t iomap;
  

• struct sgt_iter iter;
  

• pte_t **ptes = mem;
  

• dma_addr_t addr;
  

• if (n_pages > ARRAY_SIZE(stack)) {

• /* Too big for stack -- allocate temporary array instead */
  

• pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
  

• if (!pages)
  

• 	return NULL;
  

• }

• iomap = obj->mm.region->iomap.base;
  

• iomap -= obj->mm.region->region.start;
  

• for_each_sgt_page(page, iter, obj->mm.pages)

• pages[i++] = page;
  

• vaddr = vmap(pages, n_pages, 0, pgprot);
• if (pages != stack)

• kvfree(pages);
  

• return vaddr;

+}

• for_each_sgt_daddr(addr, iter, sgt)
  

• 	**ptes++ = iomap_pte(iomap, addr, pgprot);
  

+static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj) +{

• resource_size_t iomap = obj->mm.region->iomap.base -

• obj->mm.region->region.start;
  

• unsigned long n_pfn = obj->base.size >> PAGE_SHIFT;
• unsigned long stack[32], *pfns = stack, i;
• struct sgt_iter iter;
• dma_addr_t addr;
• void *vaddr;
• if (n_pfn > ARRAY_SIZE(stack)) {

• /* Too big for stack -- allocate temporary array instead */
  

• pfns = kvmalloc_array(n_pfn, sizeof(*pfns), GFP_KERNEL);
  

• if (!pfns)
  

• 	return NULL;
  

  }

• if (mem != stack)

• kvfree(mem);
  

• return area->addr;

• for_each_sgt_daddr(addr, iter, obj->mm.pages)

• pfns[i++] = (iomap + addr) >> PAGE_SHIFT;
  

• vaddr = vmap_pfn(pfns, n_pfn, pgprot_writecombine(PAGE_KERNEL_IO));

• if (pfns != stack)

• kvfree(pfns);
  

• return vaddr; }

  /* get, pin, and map the pages of the object into kernel space */

@@ -360,7 +348,10 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, }

if (!ptr) {

• ptr = i915_gem_object_map(obj, type);
  

• if (i915_gem_object_has_struct_page(obj))
  

• 	ptr = i915_gem_object_map_page(obj, type);
  

• else if (type == I915_MAP_WC)
  

• 	ptr = i915_gem_object_map_pfn(obj);
  

  if (!ptr) { err = -ENOMEM; goto err_unpin;