From 277a1ae3879a82a15a2e2d6741e38e31ea6487ee Mon Sep 17 00:00:00 2001 From: Chunyan Zhang Date: Thu, 13 Nov 2025 15:28:01 +0800 Subject: mm: softdirty: add pgtable_supports_soft_dirty() Patch series "mm: Add soft-dirty and uffd-wp support for RISC-V", v15. This patchset adds support for Svrsw60t59b [1] extension which is ratified now, also add soft dirty and userfaultfd write protect tracking for RISC-V. The patches 1 and 2 add macros to allow architectures to define their own checks if the soft-dirty / uffd_wp PTE bits are available, in other words for RISC-V, the Svrsw60t59b extension is supported on which device the kernel is running. Also patch1-2 are removing "ifdef CONFIG_MEM_SOFT_DIRTY" "ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP" and "ifdef CONFIG_PTE_MARKER_UFFD_WP" in favor of checks which if not overridden by the architecture, no change in behavior is expected. This patchset has been tested with kselftest mm suite in which soft-dirty, madv_populate, test_unmerge_uffd_wp, and uffd-unit-tests run and pass, and no regressions are observed in any of the other tests. This patch (of 6): Some platforms can customize the PTE PMD entry soft-dirty bit making it unavailable even if the architecture provides the resource. Add an API which architectures can define their specific implementations to detect if soft-dirty bit is available on which device the kernel is running. This patch is removing "ifdef CONFIG_MEM_SOFT_DIRTY" in favor of pgtable_supports_soft_dirty() checks that defaults to IS_ENABLED(CONFIG_MEM_SOFT_DIRTY), if not overridden by the architecture, no change in behavior is expected. We make sure to never set VM_SOFTDIRTY if !pgtable_supports_soft_dirty(), so we will never run into VM_SOFTDIRTY checks. [lorenzo.stoakes@oracle.com: fix VMA selftests] Link: https://lkml.kernel.org/r/dac6ddfe-773a-43d5-8f69-021b9ca4d24b@lucifer.local Link: https://lkml.kernel.org/r/20251113072806.795029-1-zhangchunyan@iscas.ac.cn Link: https://lkml.kernel.org/r/20251113072806.795029-2-zhangchunyan@iscas.ac.cn Link: https://github.com/riscv-non-isa/riscv-iommu/pull/543 [1] Signed-off-by: Chunyan Zhang Acked-by: David Hildenbrand Cc: Albert Ou Cc: Alexandre Ghiti Cc: Al Viro Cc: Arnd Bergmann Cc: Axel Rasmussen Cc: Christian Brauner Cc: Conor Dooley Cc: Deepak Gupta Cc: Jan Kara Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Xu Cc: Rob Herring Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Yuanchu Xie Cc: Alexandre Ghiti Cc: Andrew Jones Cc: Conor Dooley Signed-off-by: Andrew Morton --- include/linux/mm.h | 3 +++ include/linux/pgtable.h | 12 ++++++++++++ 2 files changed, 15 insertions(+) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index bf660d5b6e97..75f894c3f521 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -859,6 +859,7 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm) static inline void vm_flags_init(struct vm_area_struct *vma, vm_flags_t flags) { + VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY)); ACCESS_PRIVATE(vma, __vm_flags) = flags; } @@ -870,6 +871,7 @@ static inline void vm_flags_init(struct vm_area_struct *vma, static inline void vm_flags_reset(struct vm_area_struct *vma, vm_flags_t flags) { + VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY)); vma_assert_write_locked(vma); vm_flags_init(vma, flags); } @@ -891,6 +893,7 @@ static inline void vm_flags_set(struct vm_area_struct *vma, static inline void vm_flags_clear(struct vm_area_struct *vma, vm_flags_t flags) { + VM_WARN_ON_ONCE(!pgtable_supports_soft_dirty() && (flags & VM_SOFTDIRTY)); vma_start_write(vma); ACCESS_PRIVATE(vma, __vm_flags) &= ~flags; } diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 32e8457ad535..b13b6f42be3c 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1553,6 +1553,18 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) #define arch_start_context_switch(prev) do {} while (0) #endif +/* + * Some platforms can customize the PTE soft-dirty bit making it unavailable + * even if the architecture provides the resource. + * Adding this API allows architectures to add their own checks for the + * devices on which the kernel is running. + * Note: When overriding it, please make sure the CONFIG_MEM_SOFT_DIRTY + * is part of this macro. + */ +#ifndef pgtable_supports_soft_dirty +#define pgtable_supports_soft_dirty() IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) +#endif + #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY #ifndef CONFIG_ARCH_ENABLE_THP_MIGRATION static inline pmd_t pmd_swp_mksoft_dirty(pmd_t pmd) -- cgit v1.2.3