1 files changed, 49 insertions, 27 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index ffc88cc00fda..9127e31c7268 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -30,7 +30,7 @@
 #ifdef CONFIG_X86_PAT
 int __read_mostly pat_enabled = 1;
 
-void __cpuinit pat_disable(char *reason)
+void __cpuinit pat_disable(const char *reason)
 {
         pat_enabled = 0;
         printk(KERN_INFO "%s\n", reason);
@@ -42,6 +42,11 @@ static int __init nopat(char *str)
         return 0;
 }
 early_param("nopat", nopat);
+#else
+static inline void pat_disable(const char *reason)
+{
+        (void)reason;
+}
 #endif
 
 
@@ -78,16 +83,20 @@ void pat_init(void)
         if (!pat_enabled)
                 return;
 
-        /* Paranoia check. */
-        if (!cpu_has_pat && boot_pat_state) {
-                /*
-                 * If this happens we are on a secondary CPU, but
-                 * switched to PAT on the boot CPU. We have no way to
-                 * undo PAT.
-                 */
-                printk(KERN_ERR "PAT enabled, "
-                       "but not supported by secondary CPU\n");
-                BUG();
+        if (!cpu_has_pat) {
+                if (!boot_pat_state) {
+                        pat_disable("PAT not supported by CPU.");
+                        return;
+                } else {
+                        /*
+                         * If this happens we are on a secondary CPU, but
+                         * switched to PAT on the boot CPU. We have no way to
+                         * undo PAT.
+                         */
+                        printk(KERN_ERR "PAT enabled, "
+                               "but not supported by secondary CPU\n");
+                        BUG();
+                }
         }
 
         /* Set PWT to Write-Combining. All other bits stay the same */
@@ -618,12 +627,13 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
  * Reserved non RAM regions only and after successful reserve_memtype,
  * this func also keeps identity mapping (if any) in sync with this new prot.
  */
-static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t vma_prot)
+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;
         unsigned long flags;
-        unsigned long want_flags = (pgprot_val(vma_prot) & _PAGE_CACHE_MASK);
+        unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
 
         is_ram = pagerange_is_ram(paddr, paddr + size);
 
@@ -642,15 +652,24 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t vma_prot)
                 return ret;
 
         if (flags != want_flags) {
-                free_memtype(paddr, paddr + size);
-                printk(KERN_ERR
-                "%s:%d map pfn expected mapping type %s for %Lx-%Lx, got %s\n",
-                        current->comm, current->pid,
-                        cattr_name(want_flags),
-                        (unsigned long long)paddr,
-                        (unsigned long long)(paddr + size),
-                        cattr_name(flags));
-                return -EINVAL;
+                if (strict_prot || !is_new_memtype_allowed(want_flags, flags)) {
+                        free_memtype(paddr, paddr + size);
+                        printk(KERN_ERR "%s:%d map pfn expected mapping type %s"
+                                " for %Lx-%Lx, got %s\n",
+                                current->comm, current->pid,
+                                cattr_name(want_flags),
+                                (unsigned long long)paddr,
+                                (unsigned long long)(paddr + size),
+                                cattr_name(flags));
+                        return -EINVAL;
+                }
+                /*
+                 * We allow returning different type than the one requested in
+                 * non strict case.
+                 */
+                *vma_prot = __pgprot((pgprot_val(*vma_prot) &
+                                      (~_PAGE_CACHE_MASK)) |
+                                     flags);
         }
 
         /* Need to keep identity mapping in sync */
@@ -706,6 +725,7 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
         unsigned long vma_start = vma->vm_start;
         unsigned long vma_end = vma->vm_end;
         unsigned long vma_size = vma_end - vma_start;
+        pgprot_t pgprot;
 
         if (!pat_enabled)
                 return 0;
@@ -719,7 +739,8 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
                         WARN_ON_ONCE(1);
                         return -EINVAL;
                 }
-                return reserve_pfn_range(paddr, vma_size, __pgprot(prot));
+                pgprot = __pgprot(prot);
+                return reserve_pfn_range(paddr, vma_size, &pgprot, 1);
         }
 
         /* reserve entire vma page by page, using pfn and prot from pte */
@@ -727,7 +748,8 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
                 if (follow_phys(vma, vma_start + i, 0, &prot, &paddr))
                         continue;
 
-                retval = reserve_pfn_range(paddr, PAGE_SIZE, __pgprot(prot));
+                pgprot = __pgprot(prot);
+                retval = reserve_pfn_range(paddr, PAGE_SIZE, &pgprot, 1);
                 if (retval)
                         goto cleanup_ret;
         }
@@ -758,7 +780,7 @@ cleanup_ret:
  * Note that this function can be called with caller trying to map only a
  * subrange/page inside the vma.
  */
-int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
+int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
                         unsigned long pfn, unsigned long size)
 {
         int retval = 0;
@@ -775,14 +797,14 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
         if (is_linear_pfn_mapping(vma)) {
                 /* reserve the whole chunk starting from vm_pgoff */
                 paddr = (resource_size_t)vma->vm_pgoff << PAGE_SHIFT;
-                return reserve_pfn_range(paddr, vma_size, prot);
+                return reserve_pfn_range(paddr, vma_size, prot, 0);
         }
 
         /* reserve page by page using pfn and size */
         base_paddr = (resource_size_t)pfn << PAGE_SHIFT;
         for (i = 0; i < size; i += PAGE_SIZE) {
                 paddr = base_paddr + i;
-                retval = reserve_pfn_range(paddr, PAGE_SIZE, prot);
+                retval = reserve_pfn_range(paddr, PAGE_SIZE, prot, 0);
                 if (retval)
                         goto cleanup_ret;
         }