[PATCH v4 0/9] mm: Use vm_map_pages() and vm_map_pages_zero() API

From: Souptick Joarder
Date: Thu Feb 14 2019 - 21:36:56 EST

Previouly drivers have their own way of mapping range of
kernel pages/memory into user vma and this was done by
invoking vm_insert_page() within a loop.

As this pattern is common across different drivers, it can
be generalized by creating new functions and use it across
the drivers.

vm_map_pages() is the API which could be used to map
kernel memory/pages in drivers which has considered vm_pgoff.

vm_map_pages_zero() is the API which could be used to map
range of kernel memory/pages in drivers which has not considered
vm_pgoff. vm_pgoff is passed default as 0 for those drivers.

We _could_ then at a later "fix" these drivers which are using
vm_map_pages_zero() to behave according to the normal vm_pgoff
offsetting simply by removing the _zero suffix on the function
name and if that causes regressions, it gives us an easy way to revert.

Tested on Rockchip hardware and display is working fine, including talking
to Lima via prime.

v1 -> v2:
Few Reviewed-by.

Updated the change log in [8/9]

In [7/9], vm_pgoff is treated in V4L2 API as a 'cookie'
to select a buffer, not as a in-buffer offset by design
and it always want to mmap a whole buffer from its beginning.
Added additional changes after discussing with Marek and
vm_map_pages() could be used instead of vm_map_pages_zero().

v2 -> v3:
Corrected the documentation as per review comment.

As suggested in v2, renaming the interfaces to -
*vm_insert_range() -> vm_map_pages()* and
*vm_insert_range_buggy() -> vm_map_pages_zero()*.
As the interface is renamed, modified the code accordingly,
updated the change logs and modified the subject lines to use the
new interfaces. There is no other change apart from renaming and
using the new interface.

Patch[1/9] & [4/9], Tested on Rockchip hardware.

v3 -> v4:
Fixed build warnings on patch [8/9] reported by kbuild test robot.

Souptick Joarder (9):
mm: Introduce new vm_map_pages() and vm_map_pages_zero() API
arm: mm: dma-mapping: Convert to use vm_map_pages()
drivers/firewire/core-iso.c: Convert to use vm_map_pages_zero()
drm/rockchip/rockchip_drm_gem.c: Convert to use vm_map_pages()
drm/xen/xen_drm_front_gem.c: Convert to use vm_map_pages()
iommu/dma-iommu.c: Convert to use vm_map_pages()
videobuf2/videobuf2-dma-sg.c: Convert to use vm_map_pages()
xen/gntdev.c: Convert to use vm_map_pages()
xen/privcmd-buf.c: Convert to use vm_map_pages_zero()

arch/arm/mm/dma-mapping.c | 22 ++----
drivers/firewire/core-iso.c | 15 +---
drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 17 +----
drivers/gpu/drm/xen/xen_drm_front_gem.c | 18 ++---
drivers/iommu/dma-iommu.c | 12 +---
drivers/media/common/videobuf2/videobuf2-core.c | 7 ++
.../media/common/videobuf2/videobuf2-dma-contig.c | 6 --
drivers/media/common/videobuf2/videobuf2-dma-sg.c | 22 ++----
drivers/xen/gntdev.c | 11 ++-
drivers/xen/privcmd-buf.c | 8 +--
include/linux/mm.h | 4 ++
mm/memory.c | 81 ++++++++++++++++++++++
mm/nommu.c | 14 ++++
13 files changed, 134 insertions(+), 103 deletions(-)