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Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Alexander Shishkin , Maxime Coquelin , Alexandre Torgue , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Bodo Stroesser , "Martin K . Petersen" , David Howells , Marc Dionne , Alexander Viro , Christian Brauner , Jan Kara , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-mtd@lists.infradead.org, linux-staging@lists.linux.dev, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Ryan Roberts Subject: [PATCH v4 11/21] mm: add mmap_action_simple_ioremap() Date: Fri, 20 Mar 2026 22:39:37 +0000 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 5aw7gwj4wu5f8xi6wrk7bbi1f8xs518r X-Rspamd-Queue-Id: 4B30B180007 X-Rspamd-Server: rspam03 X-HE-Tag: 1774046438-649931 X-HE-Meta: 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 EtNJHtQJ LTbS/E9a4tSM7EpbCon4El0Iknce01APaxYNggEoZ/KpwS36fxXcG04MDEm3gagxucscDVhX8XVxqUpB+Q8zCrylBQ/TSnfFixSUNFOPcSzbSntseW/+Ylc2G024Bca23cYoduchO3Tj06h7iXgDcDgmdj5LulHvePiRfqXevKPRZyrXFkKYWdqycweuA2vgUsmngp0VcVwueNvjmz6UTobOgESKyb1EsG67rSl7F95OzXwYVvR1YvH1vNo46rvGxWtDjJ8ZGoOaTW2Te7jeDJAlMKcgDV8c/zOFoQ9760vhcBCzVO34ACsmG4BQUu1+oMXeC3aOn5VtNpFMSoV9/W/XfbwuyTUrvcZN7AncnlB7oEMU0AuXlijs3x5Ot3+LUG91H3C0mX9/o8kd3Ox2yj1ztrFW5cnFbnEIP Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently drivers use vm_iomap_memory() as a simple helper function for I/O remapping memory over a range starting at a specified physical address over a specified length. In order to utilise this from mmap_prepare, separate out the core logic into __simple_ioremap_prep(), update vm_iomap_memory() to use it, and add simple_ioremap_prepare() to do the same with a VMA descriptor object. We also add MMAP_SIMPLE_IO_REMAP and relevant fields to the struct mmap_action type to permit this operation also. We use mmap_action_ioremap() to set up the actual I/O remap operation once we have checked and figured out the parameters, which makes simple_ioremap_prepare() easy to implement. We then add mmap_action_simple_ioremap() to allow drivers to make use of this mode. We update the mmap_prepare documentation to describe this mode. Finally, we update the VMA tests to reflect this change. Reviewed-by: Suren Baghdasaryan Signed-off-by: Lorenzo Stoakes (Oracle) --- Documentation/filesystems/mmap_prepare.rst | 3 + include/linux/mm.h | 24 +++++- include/linux/mm_types.h | 6 +- mm/internal.h | 1 + mm/memory.c | 85 +++++++++++++++------- mm/util.c | 5 ++ tools/testing/vma/include/dup.h | 6 +- 7 files changed, 102 insertions(+), 28 deletions(-) diff --git a/Documentation/filesystems/mmap_prepare.rst b/Documentation/filesystems/mmap_prepare.rst index f14b35ee11d5..14bb057be564 100644 --- a/Documentation/filesystems/mmap_prepare.rst +++ b/Documentation/filesystems/mmap_prepare.rst @@ -153,5 +153,8 @@ pointer. These are: * mmap_action_ioremap_full() - Same as mmap_action_ioremap(), only remaps the entire mapping from ``start_pfn`` onward. +* mmap_action_simple_ioremap() - Sets up an I/O remap from a specified + physical address and over a specified length. + **NOTE:** The ``action`` field should never normally be manipulated directly, rather you ought to use one of these helpers. diff --git a/include/linux/mm.h b/include/linux/mm.h index ad1b8c3c0cfd..df8fa6e6402b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4337,11 +4337,33 @@ static inline void mmap_action_ioremap(struct vm_area_desc *desc, * @start_pfn: The first PFN in the range to remap. */ static inline void mmap_action_ioremap_full(struct vm_area_desc *desc, - unsigned long start_pfn) + unsigned long start_pfn) { mmap_action_ioremap(desc, desc->start, start_pfn, vma_desc_size(desc)); } +/** + * mmap_action_simple_ioremap - helper for mmap_prepare hook to specify that the + * physical range in [start_phys_addr, start_phys_addr + size) should be I/O + * remapped. + * @desc: The VMA descriptor for the VMA requiring remap. + * @start_phys_addr: Start of the physical memory to be mapped. + * @size: Size of the area to map. + * + * NOTE: Some drivers might want to tweak desc->page_prot for purposes of + * write-combine or similar. + */ +static inline void mmap_action_simple_ioremap(struct vm_area_desc *desc, + phys_addr_t start_phys_addr, + unsigned long size) +{ + struct mmap_action *action = &desc->action; + + action->simple_ioremap.start_phys_addr = start_phys_addr; + action->simple_ioremap.size = size; + action->type = MMAP_SIMPLE_IO_REMAP; +} + int mmap_action_prepare(struct vm_area_desc *desc); int mmap_action_complete(struct vm_area_struct *vma, struct mmap_action *action); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 16d31045e26e..174286f9ecf0 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -814,6 +814,7 @@ enum mmap_action_type { MMAP_NOTHING, /* Mapping is complete, no further action. */ MMAP_REMAP_PFN, /* Remap PFN range. */ MMAP_IO_REMAP_PFN, /* I/O remap PFN range. */ + MMAP_SIMPLE_IO_REMAP, /* I/O remap with guardrails. */ }; /* @@ -822,13 +823,16 @@ enum mmap_action_type { */ struct mmap_action { union { - /* Remap range. */ struct { unsigned long start; unsigned long start_pfn; unsigned long size; pgprot_t pgprot; } remap; + struct { + phys_addr_t start_phys_addr; + unsigned long size; + } simple_ioremap; }; enum mmap_action_type type; diff --git a/mm/internal.h b/mm/internal.h index 760fbff9c430..46cc1a695a0e 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1796,6 +1796,7 @@ int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm); int remap_pfn_range_prepare(struct vm_area_desc *desc); int remap_pfn_range_complete(struct vm_area_struct *vma, struct mmap_action *action); +int simple_ioremap_prepare(struct vm_area_desc *desc); static inline int io_remap_pfn_range_prepare(struct vm_area_desc *desc) { diff --git a/mm/memory.c b/mm/memory.c index 9dec67a18116..b3bcc21af20a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3170,6 +3170,58 @@ int remap_pfn_range_complete(struct vm_area_struct *vma, return do_remap_pfn_range(vma, start, pfn, size, prot); } +static int __simple_ioremap_prep(unsigned long vm_len, pgoff_t vm_pgoff, + phys_addr_t start_phys, unsigned long size, + unsigned long *pfnp) +{ + unsigned long pfn, pages; + + /* Check that the physical memory area passed in looks valid */ + if (start_phys + size < start_phys) + return -EINVAL; + /* + * You *really* shouldn't map things that aren't page-aligned, + * but we've historically allowed it because IO memory might + * just have smaller alignment. + */ + size += start_phys & ~PAGE_MASK; + pfn = start_phys >> PAGE_SHIFT; + pages = (size + ~PAGE_MASK) >> PAGE_SHIFT; + if (pfn + pages < pfn) + return -EINVAL; + + /* We start the mapping 'vm_pgoff' pages into the area */ + if (vm_pgoff > pages) + return -EINVAL; + pfn += vm_pgoff; + pages -= vm_pgoff; + + /* Can we fit all of the mapping? */ + if ((vm_len >> PAGE_SHIFT) > pages) + return -EINVAL; + + *pfnp = pfn; + return 0; +} + +int simple_ioremap_prepare(struct vm_area_desc *desc) +{ + struct mmap_action *action = &desc->action; + const phys_addr_t start = action->simple_ioremap.start_phys_addr; + const unsigned long size = action->simple_ioremap.size; + unsigned long pfn; + int err; + + err = __simple_ioremap_prep(vma_desc_size(desc), desc->pgoff, + start, size, &pfn); + if (err) + return err; + + /* The I/O remap logic does the heavy lifting. */ + mmap_action_ioremap_full(desc, pfn); + return io_remap_pfn_range_prepare(desc); +} + /** * vm_iomap_memory - remap memory to userspace * @vma: user vma to map to @@ -3187,32 +3239,15 @@ int remap_pfn_range_complete(struct vm_area_struct *vma, */ int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) { - unsigned long vm_len, pfn, pages; - - /* Check that the physical memory area passed in looks valid */ - if (start + len < start) - return -EINVAL; - /* - * You *really* shouldn't map things that aren't page-aligned, - * but we've historically allowed it because IO memory might - * just have smaller alignment. - */ - len += start & ~PAGE_MASK; - pfn = start >> PAGE_SHIFT; - pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; - if (pfn + pages < pfn) - return -EINVAL; - - /* We start the mapping 'vm_pgoff' pages into the area */ - if (vma->vm_pgoff > pages) - return -EINVAL; - pfn += vma->vm_pgoff; - pages -= vma->vm_pgoff; + const unsigned long vm_start = vma->vm_start; + const unsigned long vm_end = vma->vm_end; + const unsigned long vm_len = vm_end - vm_start; + unsigned long pfn; + int err; - /* Can we fit all of the mapping? */ - vm_len = vma->vm_end - vma->vm_start; - if (vm_len >> PAGE_SHIFT > pages) - return -EINVAL; + err = __simple_ioremap_prep(vm_len, vma->vm_pgoff, start, len, &pfn); + if (err) + return err; /* Ok, let it rip */ return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); diff --git a/mm/util.c b/mm/util.c index df95ae41e09b..a19f062b84dc 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1393,6 +1393,8 @@ int mmap_action_prepare(struct vm_area_desc *desc) return remap_pfn_range_prepare(desc); case MMAP_IO_REMAP_PFN: return io_remap_pfn_range_prepare(desc); + case MMAP_SIMPLE_IO_REMAP: + return simple_ioremap_prepare(desc); } WARN_ON_ONCE(1); @@ -1421,6 +1423,7 @@ int mmap_action_complete(struct vm_area_struct *vma, err = remap_pfn_range_complete(vma, action); break; case MMAP_IO_REMAP_PFN: + case MMAP_SIMPLE_IO_REMAP: /* Should have been delegated. */ WARN_ON_ONCE(1); err = -EINVAL; @@ -1438,6 +1441,7 @@ int mmap_action_prepare(struct vm_area_desc *desc) break; case MMAP_REMAP_PFN: case MMAP_IO_REMAP_PFN: + case MMAP_SIMPLE_IO_REMAP: WARN_ON_ONCE(1); /* nommu cannot handle these. */ break; } @@ -1456,6 +1460,7 @@ int mmap_action_complete(struct vm_area_struct *vma, break; case MMAP_REMAP_PFN: case MMAP_IO_REMAP_PFN: + case MMAP_SIMPLE_IO_REMAP: WARN_ON_ONCE(1); /* nommu cannot handle this. */ err = -EINVAL; diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index b4b12fc742c1..a0c2379bd42b 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -453,6 +453,7 @@ enum mmap_action_type { MMAP_NOTHING, /* Mapping is complete, no further action. */ MMAP_REMAP_PFN, /* Remap PFN range. */ MMAP_IO_REMAP_PFN, /* I/O remap PFN range. */ + MMAP_SIMPLE_IO_REMAP, /* I/O remap with guardrails. */ }; /* @@ -461,13 +462,16 @@ enum mmap_action_type { */ struct mmap_action { union { - /* Remap range. */ struct { unsigned long start; unsigned long start_pfn; unsigned long size; pgprot_t pgprot; } remap; + struct { + phys_addr_t start_phys_addr; + unsigned long size; + } simple_ioremap; }; enum mmap_action_type type; -- 2.53.0