2 files changed, 38 insertions, 17 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index e89d24815f26..4cf30dee8161 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -555,10 +555,12 @@ repeat:
         if (!pte_val(old_pte)) {
                 if (!primary)
                         return 0;
-                WARN(1, KERN_WARNING "CPA: called for zero pte. "
-                       "vaddr = %lx cpa->vaddr = %lx\n", address,
-                       *cpa->vaddr);
-                return -EINVAL;
+
+                /*
+                 *  Special error value returned, indicating that the mapping
+                 * did not exist at this address.
+                 */
+                return -EFAULT;
         }
 
         if (level == PG_LEVEL_4K) {
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 8b08fb955274..160c42d3eb8f 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -505,6 +505,35 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 }
 #endif /* CONFIG_STRICT_DEVMEM */
 
+/*
+ * Change the memory type for the physial address range in kernel identity
+ * mapping space if that range is a part of identity map.
+ */
+static int kernel_map_sync_memtype(u64 base, unsigned long size,
+                                        unsigned long flags)
+{
+        unsigned long id_sz;
+        int ret;
+
+        if (!pat_enabled || base >= __pa(high_memory))
+                return 0;
+
+        id_sz = (__pa(high_memory) < base + size) ?
+                                                __pa(high_memory) - base :
+                                                size;
+
+        ret = ioremap_change_attr((unsigned long)__va(base), id_sz, flags);
+        /*
+         * -EFAULT return means that the addr was not valid and did not have
+         * any identity mapping. That case is a success for
+         * kernel_map_sync_memtype.
+         */
+        if (ret == -EFAULT)
+                ret = 0;
+
+        return ret;
+}
+
 int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
                                 unsigned long size, pgprot_t *vma_prot)
 {
@@ -555,9 +584,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
         if (retval < 0)
                 return 0;
 
-        if (((pfn < max_low_pfn_mapped) ||
-             (pfn >= (1UL<<(32 - PAGE_SHIFT)) && pfn < max_pfn_mapped)) &&
-            ioremap_change_attr((unsigned long)__va(offset), size, flags) < 0) {
+        if (kernel_map_sync_memtype(offset, size, flags)) {
                 free_memtype(offset, offset + size);
                 printk(KERN_INFO
                 "%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n",
@@ -605,7 +632,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
                                 int strict_prot)
 {
         int is_ram = 0;
-        int id_sz, ret;
+        int ret;
         unsigned long flags;
         unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
 
@@ -646,15 +673,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
                                      flags);
         }
 
-        /* Need to keep identity mapping in sync */
-        if (paddr >= __pa(high_memory))
-                return 0;
-
-        id_sz = (__pa(high_memory) < paddr + size) ?
-                                __pa(high_memory) - paddr :
-                                size;
-
-        if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) {
+        if (kernel_map_sync_memtype(paddr, size, flags)) {
                 free_memtype(paddr, paddr + size);
                 printk(KERN_ERR
                         "%s:%d reserve_pfn_range ioremap_change_attr failed %s "