kernel.git/arch/x86/include/asm/pgtable.h, branch linux-6.15.y

x86/headers: Replace ASSEMBLY with ASSEMBLER in non-UAPI headers

2025-03-19T10:47:30Z

While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembly code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. This can be very confusing when switching between userspace and kernelspace coding, or when dealing with UAPI headers that rather should use __ASSEMBLER__ instead. So let's standardize on the __ASSEMBLER__ macro that is provided by the compilers now. This is mostly a mechanical patch (done with a simple "sed -i" statement), with some manual tweaks in , and that mentioned this macro in comments with some missing underscores. Signed-off-by: Thomas Huth Signed-off-by: Ingo Molnar Cc: Brian Gerst Cc: Juergen Gross Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250314071013.1575167-38-thuth@redhat.com

mm: move set_pxd_safe() helpers from generic to platform

2024-11-07T04:11:09Z

set_pxd_safe() helpers that serve a specific purpose for both x86 and riscv platforms, do not need to be in the common memory code. Otherwise they just unnecessarily make the common API more complicated. This moves the helpers from common code to platform instead. Link: https://lkml.kernel.org/r/20241003044842.246016-1-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Suggested-by: David Hildenbrand Acked-by: Dave Hansen Acked-by: David Hildenbrand Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Thomas Gleixner Cc: David Hildenbrand Cc: Ryan Roberts Signed-off-by: Andrew Morton

mm/x86: support large pfn mappings

2024-09-17T08:06:59Z

Helpers to install and detect special pmd/pud entries. In short, bit 9 on x86 is not used for pmd/pud, so we can directly define them the same as the pte level. One note is that it's also used in _PAGE_BIT_CPA_TEST but that is only used in the debug test, and shouldn't conflict in this case. One note is that pxx_set|clear_flags() for pmd/pud will need to be moved upper so that they can be referenced by the new special bit helpers. There's no change in the code that was moved. Link: https://lkml.kernel.org/r/20240826204353.2228736-18-peterx@redhat.com Signed-off-by: Peter Xu Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Alexander Gordeev Cc: Alex Williamson Cc: Aneesh Kumar K.V Cc: Catalin Marinas Cc: Christian Borntraeger Cc: David Hildenbrand Cc: Gavin Shan Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Jason Gunthorpe Cc: Matthew Wilcox Cc: Niklas Schnelle Cc: Paolo Bonzini Cc: Ryan Roberts Cc: Sean Christopherson Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Will Deacon Cc: Zi Yan Signed-off-by: Andrew Morton

mm/x86: add missing pud helpers

2024-09-02T03:26:09Z

Some new helpers will be needed for pud entry updates soon. Introduce these helpers by referencing the pmd ones. Namely: - pudp_invalidate(): this helper invalidates a huge pud before a split happens, so that the invalidated pud entry will make sure no race will happen (either with software, like a concurrent zap, or hardware, like a/d bit lost). - pud_modify(): this helper applies a new pgprot to an existing huge pud mapping. For more information on why we need these two helpers, please refer to the corresponding pmd helpers in the mprotect() code path. When at it, simplify the pud_modify()/pmd_modify() comments on shadow stack pgtable entries to reference pte_modify() to avoid duplicating the whole paragraph three times. Link: https://lkml.kernel.org/r/20240812181225.1360970-7-peterx@redhat.com Signed-off-by: Peter Xu Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Aneesh Kumar K.V Cc: Christophe Leroy Cc: Dan Williams Cc: Dave Jiang Cc: David Hildenbrand Cc: David Rientjes Cc: "Edgecombe, Rick P" Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Paolo Bonzini Cc: Rik van Riel Cc: Sean Christopherson Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/x86: implement arch_check_zapped_pud()

2024-09-02T03:26:09Z

Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD zaps. It has the same logic as the PMD helper. One thing to mention is, it might be a good idea to use page_table_check in the future for trapping wrong setups of shadow stack pgtable entries [1]. That is left for the future as a separate effort. [1] https://lore.kernel.org/all/59d518698f664e07c036a5098833d7b56b953305.camel@intel.com Link: https://lkml.kernel.org/r/20240812181225.1360970-6-peterx@redhat.com Signed-off-by: Peter Xu Acked-by: David Hildenbrand Cc: "Edgecombe, Rick P" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Aneesh Kumar K.V Cc: Christophe Leroy Cc: Dan Williams Cc: Dave Jiang Cc: David Rientjes Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Paolo Bonzini Cc: Rik van Riel Cc: Sean Christopherson Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/x86: make pud_leaf() only care about PSE bit

2024-09-02T03:26:09Z

When working on mprotect() on 1G dax entries, I hit an zap bad pud error when zapping a huge pud that is with PROT_NONE permission. Here the problem is x86's pud_leaf() requires both PRESENT and PSE bits set to report a pud entry as a leaf, but that doesn't look right, as it's not following the pXd_leaf() definition that we stick with so far, where PROT_NONE entries should be reported as leaves. To fix it, change x86's pud_leaf() implementation to only check against PSE bit to report a leaf, irrelevant of whether PRESENT bit is set. Link: https://lkml.kernel.org/r/20240812181225.1360970-5-peterx@redhat.com Signed-off-by: Peter Xu Acked-by: Dave Hansen Reviewed-by: David Hildenbrand Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Aneesh Kumar K.V Cc: Christophe Leroy Cc: Dan Williams Cc: Dave Jiang Cc: David Rientjes Cc: "Edgecombe, Rick P" Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Paolo Bonzini Cc: Rik van Riel Cc: Sean Christopherson Cc: Vlastimil Babka Signed-off-by: Andrew Morton

x86/tdx: Convert shared memory back to private on kexec

2024-06-17T15:46:05Z

TDX guests allocate shared buffers to perform I/O. It is done by allocating pages normally from the buddy allocator and converting them to shared with set_memory_decrypted(). The second, kexec-ed kernel has no idea what memory is converted this way. It only sees E820_TYPE_RAM. Accessing shared memory via private mapping is fatal. It leads to unrecoverable TD exit. On kexec, walk direct mapping and convert all shared memory back to private. It makes all RAM private again and second kernel may use it normally. The conversion occurs in two steps: stopping new conversions and unsharing all memory. In the case of normal kexec, the stopping of conversions takes place while scheduling is still functioning. This allows for waiting until any ongoing conversions are finished. The second step is carried out when all CPUs except one are inactive and interrupts are disabled. This prevents any conflicts with code that may access shared memory. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Rick Edgecombe Reviewed-by: Kai Huang Tested-by: Tao Liu Link: https://lore.kernel.org/r/20240614095904.1345461-12-kirill.shutemov@linux.intel.com

mm/page_table_check: support userfault wr-protect entries

2024-05-06T00:53:41Z

Allow page_table_check hooks to check over userfaultfd wr-protect criteria upon pgtable updates. The rule is no co-existance allowed for any writable flag against userfault wr-protect flag. This should be better than c2da319c2e, where we used to only sanitize such issues during a pgtable walk, but when hitting such issue we don't have a good chance to know where does that writable bit came from [1], so that even the pgtable walk exposes a kernel bug (which is still helpful on triaging) but not easy to track and debug. Now we switch to track the source. It's much easier too with the recent introduction of page table check. There are some limitations with using the page table check here for userfaultfd wr-protect purpose: - It is only enabled with explicit enablement of page table check configs and/or boot parameters, but should be good enough to track at least syzbot issues, as syzbot should enable PAGE_TABLE_CHECK[_ENFORCED] for x86 [1]. We used to have DEBUG_VM but it's now off for most distros, while distros also normally not enable PAGE_TABLE_CHECK[_ENFORCED], which is similar. - It conditionally works with the ptep_modify_prot API. It will be bypassed when e.g. XEN PV is enabled, however still work for most of the rest scenarios, which should be the common cases so should be good enough. - Hugetlb check is a bit hairy, as the page table check cannot identify hugetlb pte or normal pte via trapping at set_pte_at(), because of the current design where hugetlb maps every layers to pte_t... For example, the default set_huge_pte_at() can invoke set_pte_at() directly and lose the hugetlb context, treating it the same as a normal pte_t. So far it's fine because we have huge_pte_uffd_wp() always equals to pte_uffd_wp() as long as supported (x86 only). It'll be a bigger problem when we'll define _PAGE_UFFD_WP differently at various pgtable levels, because then one huge_pte_uffd_wp() per-arch will stop making sense first.. as of now we can leave this for later too. This patch also removes commit c2da319c2e altogether, as we have something better now. [1] https://lore.kernel.org/all/000000000000dce0530615c89210@google.com/ Link: https://lkml.kernel.org/r/20240417212549.2766883-1-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: Pasha Tatashin Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Nadav Amit Signed-off-by: Andrew Morton

mm/arch: provide pud_pfn() fallback

2024-04-26T03:56:21Z

The comment in the code explains the reasons. We took a different approach comparing to pmd_pfn() by providing a fallback function. Another option is to provide some lower level config options (compare to HUGETLB_PAGE or THP) to identify which layer an arch can support for such huge mappings. However that can be an overkill. [peterx@redhat.com: fix loongson defconfig] Link: https://lkml.kernel.org/r/20240403013249.1418299-4-peterx@redhat.com Link: https://lkml.kernel.org/r/20240327152332.950956-6-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: Jason Gunthorpe Tested-by: Ryan Roberts Cc: Mike Rapoport (IBM) Cc: Matthew Wilcox Cc: Andrea Arcangeli Cc: Andrew Jones Cc: Aneesh Kumar K.V (IBM) Cc: Axel Rasmussen Cc: Christophe Leroy Cc: Christoph Hellwig Cc: David Hildenbrand Cc: James Houghton Cc: John Hubbard Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes Cc: Michael Ellerman Cc: Muchun Song Cc: Rik van Riel Cc: Vlastimil Babka Cc: Yang Shi Signed-off-by: Andrew Morton

x86: remove unneeded memblock_find_dma_reserve()

2024-04-26T03:56:10Z

Patch series "mm/mm_init.c: refactor free_area_init_core()". In function free_area_init_core(), the code calculating zone->managed_pages and the subtracting dma_reserve from DMA zone looks very confusing. From git history, the code calculating zone->managed_pages was for zone->present_pages originally. The early rough assignment is for optimize zone's pcp and water mark setting. Later, managed_pages was introduced into zone to represent the number of managed pages by buddy. Now, zone->managed_pages is zeroed out and reset in mem_init() when calling memblock_free_all(). zone's pcp and wmark setting relying on actual zone->managed_pages are done later than mem_init() invocation. So we don't need rush to early calculate and set zone->managed_pages, just set it as zone->present_pages, will adjust it in mem_init(). And also add a new function calc_nr_kernel_pages() to count up free but not reserved pages in memblock, then assign it to nr_all_pages and nr_kernel_pages after memmap pages are allocated. This patch (of 6): Variable dma_reserve and its usage was introduced in commit 0e0b864e069c ("[PATCH] Account for memmap and optionally the kernel image as holes"). Its original purpose was to accounting for the reserved pages in DMA zone to make DMA zone's watermarks calculation more accurate on x86. However, currently there's zone->managed_pages to account for all available pages for buddy, zone->present_pages to account for all present physical pages in zone. What is more important, on x86, calculating and setting the zone->managed_pages is a temporary move, all zone's managed_pages will be zeroed out and reset to the actual value according to how many pages are added to buddy allocator in mem_init(). Before mem_init(), no buddy alloction is requested. And zone's pcp and watermark setting are all done after mem_init(). So, no need to worry about the DMA zone's setting accuracy during free_area_init(). Hence, remove memblock_find_dma_reserve() to stop calculating and setting dma_reserve. Link: https://lkml.kernel.org/r/20240325145646.1044760-1-bhe@redhat.com Link: https://lkml.kernel.org/r/20240325145646.1044760-2-bhe@redhat.com Signed-off-by: Baoquan He Reviewed-by: Mike Rapoport (IBM) Signed-off-by: Andrew Morton

kernel.git/arch/x86/include/asm/pgtable.h, branch linux-6.15.y

x86/headers: Replace __ASSEMBLY__ with __ASSEMBLER__ in non-UAPI headers

mm: move set_pxd_safe() helpers from generic to platform

mm/x86: support large pfn mappings

mm/x86: add missing pud helpers

mm/x86: implement arch_check_zapped_pud()

mm/x86: make pud_leaf() only care about PSE bit

x86/tdx: Convert shared memory back to private on kexec

mm/page_table_check: support userfault wr-protect entries

mm/arch: provide pud_pfn() fallback

x86: remove unneeded memblock_find_dma_reserve()

x86/headers: Replace ASSEMBLY with ASSEMBLER in non-UAPI headers