x86: PAT: hooks in generic vm code to help archs to track pfnmap regions - v3

Impact: Introduces new hooks, which are currently null.

Introduce generic hooks in remap_pfn_range and vm_insert_pfn and
corresponding copy and free routines with reserve and free tracking.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 75 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 8ca6bbf34ad6..1e8f0d347c0e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -99,6 +99,50 @@ int randomize_va_space __read_mostly =
                                         2;
 #endif
 
+#ifndef track_pfn_vma_new
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * track_pfn_vma_new is called when a _new_ pfn mapping is being established
+ * for physical range indicated by pfn and size.
+ */
+int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
+                        unsigned long pfn, unsigned long size)
+{
+        return 0;
+}
+#endif
+
+#ifndef track_pfn_vma_copy
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
+ * copied through copy_page_range().
+ */
+int track_pfn_vma_copy(struct vm_area_struct *vma)
+{
+        return 0;
+}
+#endif
+
+#ifndef untrack_pfn_vma
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * untrack_pfn_vma is called while unmapping a pfnmap for a region.
+ * untrack can be called for a specific region indicated by pfn and size or
+ * can be for the entire vma (in which case size can be zero).
+ */
+void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
+                        unsigned long size)
+{
+}
+#endif
+
 static int __init disable_randmaps(char *s)
 {
         randomize_va_space = 0;
@@ -669,6 +713,16 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
         if (is_vm_hugetlb_page(vma))
                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
 
+        if (is_pfn_mapping(vma)) {
+                /*
+                 * We do not free on error cases below as remove_vma
+                 * gets called on error from higher level routine
+                 */
+                ret = track_pfn_vma_copy(vma);
+                if (ret)
+                        return ret;
+        }
+
         /*
          * We need to invalidate the secondary MMU mappings only when
          * there could be a permission downgrade on the ptes of the
@@ -915,6 +969,9 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,
                 if (vma->vm_flags & VM_ACCOUNT)
                         *nr_accounted += (end - start) >> PAGE_SHIFT;
 
+                if (is_pfn_mapping(vma))
+                        untrack_pfn_vma(vma, 0, 0);
+
                 while (start != end) {
                         if (!tlb_start_valid) {
                                 tlb_start = start;
@@ -1473,6 +1530,7 @@ out:
 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
                         unsigned long pfn)
 {
+        int ret;
         /*
          * Technically, architectures with pte_special can avoid all these
          * restrictions (same for remap_pfn_range).  However we would like
@@ -1487,7 +1545,15 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 
         if (addr < vma->vm_start || addr >= vma->vm_end)
                 return -EFAULT;
-        return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+        if (track_pfn_vma_new(vma, vma->vm_page_prot, pfn, PAGE_SIZE))
+                return -EINVAL;
+
+        ret = insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+
+        if (ret)
+                untrack_pfn_vma(vma, pfn, PAGE_SIZE);
+
+        return ret;
 }
 EXPORT_SYMBOL(vm_insert_pfn);
 
@@ -1625,6 +1691,10 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 
         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
 
+        err = track_pfn_vma_new(vma, prot, pfn, PAGE_ALIGN(size));
+        if (err)
+                return -EINVAL;
+
         BUG_ON(addr >= end);
         pfn -= addr >> PAGE_SHIFT;
         pgd = pgd_offset(mm, addr);
@@ -1636,6 +1706,10 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
                 if (err)
                         break;
         } while (pgd++, addr = next, addr != end);
+
+        if (err)
+                untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
+
         return err;
 }
 EXPORT_SYMBOL(remap_pfn_range);