From be7dacb9c1d48280aeae0830a045f4046c6ef3e2 Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (Microsoft)" Date: Thu, 3 Sep 2026 12:28:27 +0300 Subject: set_memory: add number of pages parameter to set_direct_map APIs Patch series "arch, mm/execmem: resolve confusion about set_direct_map_valid_noflush()", v3. Recent discussion about implementation of execmem's ROX caches on arm64 revealed a confusion about how set_direct_map_valid_noflush() implemented on different architectures. On arm64 it sets or clears the PTE_VALID bit marking a PTE as present or not present. On other architectures it's a range version of set_direct_map_invalid_noflush() and set_direct_map_default_noflush() Unlike arm64::set_direct_map_valid_noflush(), set_direct_map_default_noflush() not only marks PTE as present, but also sets its default protection mode. Other than that, initial design of execmem ROX caches didn't rely on restoration of large mappings that's now available on x86, but completely removed the memory allocated for the ROX cache from the direct map to ensure that large mappings are not split. This precluded usage of VM_FLUSH_RESET_PERMS for the ROX cache allocations and required execmem to implement manipulation of the direct map alias. Current implementation of ROX caches does not remove the direct map alias but simply calls set_memory_rox() that updates the permissions in both vmalloc address space and the direct map and relies on collapse_large_pages() in x86 CPA to keep large mappings. This allow using VM_FLUSH_RESET_PERMS for execmem ROX cache allocations with small adjustments to set_direct_map APIs and vmalloc::reset_perms() behaviour: adding number of pages parameter to set_direct_map APIs and making resetting of the direct map permissions in vmalloc VMAP_HUGE friendly. Implement these adjustments, make execmem always use VM_FLUSH_RESET_PERMS and revert set_direct_map_valid_noflush() changes. This patch (of 6): When set_direct_map APIs were introduced by the commit d253ca0c3865 ("x86/mm/cpa: Add set_direct_map_*() functions") the single page parameter made sense because the initial callers (vmalloc and hibernation) had sets of unsorted struct pages that required changes of their mappings in the direct map. Since there is an increasing demand for direct map manipulation and it is also desirable to be able to update larger physically contiguous mappings, for example an entire large folio, extend set_direct_map APIs to receive number of pages parameter. As there is still only a handful of callers, change the existing functions directly and update all the call sites rather than adding wrappers for single page case. Link: https://lore.kernel.org/20260903-execmem-set-vm-perms-v0-2-v3-0-949b64a9f755@kernel.org Link: https://lore.kernel.org/20260903-execmem-set-vm-perms-v0-2-v3-1-949b64a9f755@kernel.org Link: https://lore.kernel.org/all/20260611130144.1385343-4-abarnas@google.com [1] Signed-off-by: Mike Rapoport (Microsoft) Signed-off-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Reviewed-by: Kevin Brodsky Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Andy Lutomirski Cc: "Borislav Petkov (AMD)" Cc: Brendan Jackman Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Dave Hansen Cc: Gerald Schaefer Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Len Brown Cc: Palmer Dabbelt Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Ryan Roberts Cc: Sven Schnelle Cc: "Uladzislau Rezki (Sony)" Cc: Vasily Gorbik Cc: WANG Xuerui Cc: Will Deacon Cc: Dev Jain --- include/linux/set_memory.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h index 3030d9245f5a..0b77f1d7d8b9 100644 --- a/include/linux/set_memory.h +++ b/include/linux/set_memory.h @@ -25,11 +25,13 @@ static inline int set_memory_rox(unsigned long addr, int numpages) #endif #ifndef CONFIG_ARCH_HAS_SET_DIRECT_MAP -static inline int set_direct_map_invalid_noflush(struct page *page) +static inline int set_direct_map_invalid_noflush(struct page *page, + unsigned int nr) { return 0; } -static inline int set_direct_map_default_noflush(struct page *page) +static inline int set_direct_map_default_noflush(struct page *page, + unsigned int nr) { return 0; } -- cgit v1.2.3