[PATCH v3 0/2] udmabuf: Add back support for mapping hugetlb pages (v3)

[Vivek Kasireddy]

The first patch ensures that the mappings needed for handling mmap
operation would be managed by using the pfn instead of struct page.
The second patch restores support for mapping hugetlb pages where
subpages of a hugepage are not directly used anymore (main reason
for revert) and instead the hugetlb pages and the relevant offsets
are used to populate the scatterlist for dma-buf export and for
mmap operation.

Testcase: default_hugepagesz=2M hugepagesz=2M hugepages=2500 options
were passed to the Host kernel and Qemu was launched with these
relevant options: qemu-system-x86_64 -m 4096m....
-device virtio-gpu-pci,max_outputs=1,blob=true,xres=1920,yres=1080
-display gtk,gl=on
-object memory-backend-memfd,hugetlb=on,id=mem1,size=4096M
-machine memory-backend=mem1

Replacing -display gtk,gl=on with -display gtk,gl=off above would
exercise the mmap handler.

v2: Updated the second patch to manually populate the scatterlist.

v3: Replaced the fields offsets with subpgoff and hpoff with mapidx
    in the second patch. This should not cause any functional changes.

Cc: David Hildenbrand <david at redhat.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Mike Kravetz <mike.kravetz at oracle.com>
Cc: Hugh Dickins <hughd at google.com>
Cc: Peter Xu <peterx at redhat.com>
Cc: Jason Gunthorpe <jgg at nvidia.com>`
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Dongwon Kim <dongwon.kim at intel.com>
Cc: Junxiao Chang <junxiao.chang at intel.com>

Vivek Kasireddy (2):
  udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap
  udmabuf: Add back support for mapping hugetlb pages (v3)

 drivers/dma-buf/udmabuf.c | 93 ++++++++++++++++++++++++++++++++-------
 1 file changed, 77 insertions(+), 16 deletions(-)

-- 
2.39.2