The patch titled
Subject: mm: add a io_mapping_map_user helper
has been added to the -mm tree. Its filename is
mm-add-a-io_mapping_map_user-helper.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-add-a-io_mapping_map_user-helper.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-add-a-io_mapping_map_user-helper.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: mm: add a io_mapping_map_user helper
Add a helper that calls remap_pfn_range for an struct io_mapping, relying
on the pgprot pre-validation done when creating the mapping instead of
doing it at runtime.
Link: https://lkml.kernel.org/r/20210326055505.1424432-3-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/io-mapping.h | 3 +++
mm/Kconfig | 3 +++
mm/Makefile | 1 +
mm/io-mapping.c | 29 +++++++++++++++++++++++++++++
4 files changed, 36 insertions(+)
--- a/include/linux/io-mapping.h~mm-add-a-io_mapping_map_user-helper
+++ a/include/linux/io-mapping.h
@@ -220,3 +220,6 @@ io_mapping_free(struct io_mapping *iomap
}
#endif /* _LINUX_IO_MAPPING_H */
+
+int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
+ unsigned long addr, unsigned long pfn, unsigned long size);
--- /dev/null
+++ a/mm/io-mapping.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/mm.h>
+#include <linux/io-mapping.h>
+
+/**
+ * io_mapping_map_user - remap an I/O mapping to userspace
+ * @iomap: the source io_mapping
+ * @vma: user vma to map to
+ * @addr: target user address to start at
+ * @pfn: physical address of kernel memory
+ * @size: size of map area
+ *
+ * Note: this is only safe if the mm semaphore is held when called.
+ */
+int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
+ unsigned long addr, unsigned long pfn, unsigned long size)
+{
+ vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+
+ if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
+ return -EINVAL;
+
+ /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
+ return remap_pfn_range_notrack(vma, addr, pfn, size,
+ __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
+ (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
+}
+EXPORT_SYMBOL_GPL(io_mapping_map_user);
--- a/mm/Kconfig~mm-add-a-io_mapping_map_user-helper
+++ a/mm/Kconfig
@@ -872,4 +872,7 @@ config MAPPING_DIRTY_HELPERS
config KMAP_LOCAL
bool
+# struct io_mapping based helper. Selected by drivers that need them
+config IO_MAPPING
+ bool
endmenu
--- a/mm/Makefile~mm-add-a-io_mapping_map_user-helper
+++ a/mm/Makefile
@@ -120,3 +120,4 @@ obj-$(CONFIG_MEMFD_CREATE) += memfd.o
obj-$(CONFIG_MAPPING_DIRTY_HELPERS) += mapping_dirty_helpers.o
obj-$(CONFIG_PTDUMP_CORE) += ptdump.o
obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
+obj-$(CONFIG_IO_MAPPING) += io-mapping.o
_
Patches currently in -mm which might be from hch@xxxxxx are
mm-add-remap_pfn_range_notrack.patch
mm-add-a-io_mapping_map_user-helper.patch
i915-use-io_mapping_map_user.patch
i915-fix-remap_io_sg-to-verify-the-pgprot.patch
samples-vfio-mdev-mdpy-use-remap_vmalloc_range.patch
mm-unexport-remap_vmalloc_range_partial.patch
