+ mm-add-a-vmap_pfn-function.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm: add a vmap_pfn function
has been added to the -mm tree.  Its filename is
     mm-add-a-vmap_pfn-function.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-add-a-vmap_pfn-function.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-add-a-vmap_pfn-function.patch

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: mm: add a vmap_pfn function

Add a proper helper to remap PFNs into kernel virtual space so that
drivers don't have to abuse alloc_vm_area and open coded PTE manipulation
for it.

Link: https://lkml.kernel.org/r/20200930175133.1252382-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/vmalloc.h |    1 
 mm/Kconfig              |    3 ++
 mm/vmalloc.c            |   45 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)

--- a/include/linux/vmalloc.h~mm-add-a-vmap_pfn-function
+++ a/include/linux/vmalloc.h
@@ -122,6 +122,7 @@ extern void vfree_atomic(const void *add
 
 extern void *vmap(struct page **pages, unsigned int count,
 			unsigned long flags, pgprot_t prot);
+void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot);
 extern void vunmap(const void *addr);
 
 extern int remap_vmalloc_range_partial(struct vm_area_struct *vma,
--- a/mm/Kconfig~mm-add-a-vmap_pfn-function
+++ a/mm/Kconfig
@@ -816,6 +816,9 @@ config DEVICE_PRIVATE
 	  memory; i.e., memory that is only accessible from the device (or
 	  group of devices). You likely also want to select HMM_MIRROR.
 
+config VMAP_PFN
+	bool
+
 config FRAME_VECTOR
 	bool
 
--- a/mm/vmalloc.c~mm-add-a-vmap_pfn-function
+++ a/mm/vmalloc.c
@@ -2413,6 +2413,51 @@ void *vmap(struct page **pages, unsigned
 }
 EXPORT_SYMBOL(vmap);
 
+#ifdef CONFIG_VMAP_PFN
+struct vmap_pfn_data {
+	unsigned long	*pfns;
+	pgprot_t	prot;
+	unsigned int	idx;
+};
+
+static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private)
+{
+	struct vmap_pfn_data *data = private;
+
+	if (WARN_ON_ONCE(pfn_valid(data->pfns[data->idx])))
+		return -EINVAL;
+	*pte = pte_mkspecial(pfn_pte(data->pfns[data->idx++], data->prot));
+	return 0;
+}
+
+/**
+ * vmap_pfn - map an array of PFNs into virtually contiguous space
+ * @pfns: array of PFNs
+ * @count: number of pages to map
+ * @prot: page protection for the mapping
+ *
+ * Maps @count PFNs from @pfns into contiguous kernel virtual space and returns
+ * the start address of the mapping.
+ */
+void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot)
+{
+	struct vmap_pfn_data data = { .pfns = pfns, .prot = pgprot_nx(prot) };
+	struct vm_struct *area;
+
+	area = get_vm_area_caller(count * PAGE_SIZE, VM_IOREMAP,
+			__builtin_return_address(0));
+	if (!area)
+		return NULL;
+	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
+			count * PAGE_SIZE, vmap_pfn_apply, &data)) {
+		free_vm_area(area);
+		return NULL;
+	}
+	return area->addr;
+}
+EXPORT_SYMBOL_GPL(vmap_pfn);
+#endif /* CONFIG_VMAP_PFN */
+
 static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 				 pgprot_t prot, int node)
 {
_

Patches currently in -mm which might be from hch@lst.de are

mm-add-a-vm_map_put_pages-flag-for-vmap.patch
mm-add-a-vmap_pfn-function.patch
mm-allow-a-null-fn-callback-in-apply_to_page_range.patch
zsmalloc-switch-from-alloc_vm_area-to-get_vm_area.patch
drm-i915-use-vmap-in-shmem_pin_map.patch
drm-i915-use-vmap-in-i915_gem_object_map.patch
xen-xenbus-use-apply_to_page_range-directly-in-xenbus_map_ring_pv.patch
x86-xen-open-code-alloc_vm_area-in-arch_gnttab_valloc.patch
mm-remove-alloc_vm_area.patch