From: Thomas Hellström <thellstrom@xxxxxxxxxx> Graphics APIs like OpenGL 4.4 and Vulkan require the graphics driver to provide coherent graphics memory, meaning that the GPU sees any content written to the coherent memory on the next GPU operation that touches that memory, and the CPU sees any content written by the GPU to that memory immediately after any fence object trailing the GPU operation is signaled. Paravirtual drivers that otherwise require explicit synchronization needs to do this by hooking up dirty tracking to pagefault handlers and buffer object validation. Provide mm helpers needed for this and that also allow for huge pmd- and pud entries (patch 1-3), and the associated vmwgfx code (patch 4-7). The code has been tested and exercised by a tailored version of mesa where we disable all explicit synchronization and assume graphics memory is coherent. The performance loss varies of course; a typical number is around 5%. I would like to merge this code through the DRM tree, so an ack to include the new mm helpers in that merge would be greatly appreciated. Changes since RFC: - Merge conflict changes moved to the correct patch. Fixes intra-patchset compile errors. - Be more aggressive when turning ttm vm code into helpers. This makes sure we can use a const qualifier on the vmwgfx vm_ops. - Reinstate a lost comment an fix an error path that was broken when turning the ttm vm code into helpers. - Remove explicit type-casts of struct vm_area_struct::vm_private_data - Clarify the locking inversion that makes us not being able to use the mm pagewalk code. Changes since v1: - Removed the vmwgfx maintainer entry for as_dirty_helpers.c, updated commit message accordingly - Removed the TTM patches from the series as they are merged separately through DRM. Changes since v2: - Split out the pagewalk code from as_dirty_helpers.c and document locking. - Add pre_vma and post_vma callbacks to the pagewalk code. - Remove huge pmd and -pud asserts that would trip when we protect vmas with struct address_space::i_mmap_rwsem rather than with struct vm_area_struct::mmap_sem. - Do some naming cleanup in as_dirty_helpers.c Changes since v3: - Extensive renaming of the dirty helpers including the filename. - Update walk_page_mapping() doc. - Update the pagewalk code to not unconditionally split pmds if a pte_entry() callback is present. Update the dirty helper pmd_entry accordingly. - Use separate walk ops for the dirty helpers. - Update the pagewalk code to take the pagetable lock in walk_pte_range. Changes since v4: - Fix pte pointer confusion in patch 2/8 - Skip the pagewalk code conditional split patch for now, and update the mapping_dirty_helper accordingly. That problem will be solved in a cleaner way in a follow-up patchset. Changes since v5: - Fix tlb flushing when we have other pending tlb flushes. Changes since v6: - Added Andrew Morton R-Bs and acks. Series is now approved to merge through DRM: https://lore.kernel.org/r/20191105195114.f75be5e76763da5546121b41@xxxxxxxxxxxxxxxxxxxx/ - Removed an redundant assignment in patch #8 (Colin Ian King) Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: Jérôme Glisse <jglisse@xxxxxxxxxx> Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
