4 files changed, 10 insertions, 23 deletions

diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 3a2ec8790ca7..a9dc7a37e6a2 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -77,13 +77,13 @@ void __iomem *
 iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
 {
         /*
-         * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
-         * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
-         * MTRR is UC or WC.  UC_MINUS gets the real intention, of the
-         * user, which is "WC if the MTRR is WC, UC if you can't do that."
+         * For non-PAT systems, translate non-WB request to UC- just in
+         * case the caller set the PWT bit to prot directly without using
+         * pgprot_writecombine(). UC- translates to uncached if the MTRR
+         * is UC or WC. UC- gets the real intention, of the user, which is
+         * "WC if the MTRR is WC, UC if you can't do that."
          */
-        if (!pat_enabled() && pgprot_val(prot) ==
-            (__PAGE_KERNEL | cachemode2protval(_PAGE_CACHE_MODE_WC)))
+        if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
                 prot = __pgprot(__PAGE_KERNEL |
                                 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
 
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index b0da3588b452..cc0f17c5ad9f 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -292,11 +292,8 @@ EXPORT_SYMBOL_GPL(ioremap_uc);
  */
 void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
 {
-        if (pat_enabled())
-                return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
+        return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
                                         __builtin_return_address(0));
-        else
-                return ioremap_nocache(phys_addr, size);
 }
 EXPORT_SYMBOL(ioremap_wc);
 
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index fae3c5366ac0..31b4f3fd1207 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1572,9 +1572,6 @@ int set_memory_wc(unsigned long addr, int numpages)
 {
         int ret;
 
-        if (!pat_enabled())
-                return set_memory_uc(addr, numpages);
-
         ret = reserve_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
                 _PAGE_CACHE_MODE_WC, NULL);
         if (ret)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 6dc7826e4797..f89e460c55a8 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -438,12 +438,8 @@ int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type,
 
         if (!pat_enabled()) {
                 /* This is identical to page table setting without PAT */
-                if (new_type) {
-                        if (req_type == _PAGE_CACHE_MODE_WC)
-                                *new_type = _PAGE_CACHE_MODE_UC_MINUS;
-                        else
-                                *new_type = req_type;
-                }
+                if (new_type)
+                        *new_type = req_type;
                 return 0;
         }
 
@@ -947,11 +943,8 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
 
 pgprot_t pgprot_writecombine(pgprot_t prot)
 {
-        if (pat_enabled())
-                return __pgprot(pgprot_val(prot) |
+        return __pgprot(pgprot_val(prot) |
                                 cachemode2protval(_PAGE_CACHE_MODE_WC));
-        else
-                return pgprot_noncached(prot);
 }
 EXPORT_SYMBOL_GPL(pgprot_writecombine);