5 files changed, 82 insertions, 22 deletions

diff --git a/arch/x86/include/asm/iomap.h b/arch/x86/include/asm/iomap.h
index 86af26091d6c..bd46495ff7de 100644
--- a/arch/x86/include/asm/iomap.h
+++ b/arch/x86/include/asm/iomap.h
@@ -24,7 +24,10 @@
 #include <asm/tlbflush.h>
 
 int
-is_io_mapping_possible(resource_size_t base, unsigned long size);
+reserve_io_memtype_wc(u64 base, unsigned long size, pgprot_t *prot);
+
+void
+free_io_memtype(u64 base, unsigned long size);
 
 void *
 iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot);
diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h
index 9709fdff6615..b0e70056838e 100644
--- a/arch/x86/include/asm/pat.h
+++ b/arch/x86/include/asm/pat.h
@@ -15,4 +15,7 @@ extern int reserve_memtype(u64 start, u64 end,
                 unsigned long req_type, unsigned long *ret_type);
 extern int free_memtype(u64 start, u64 end);
 
+extern int kernel_map_sync_memtype(u64 base, unsigned long size,
+                unsigned long flag);
+
 #endif /* _ASM_X86_PAT_H */
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 6c2b1af16926..d5e28424622c 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -21,13 +21,13 @@
 #include <linux/module.h>
 
 #ifdef CONFIG_X86_PAE
-int
+static int
 is_io_mapping_possible(resource_size_t base, unsigned long size)
 {
         return 1;
 }
 #else
-int
+static int
 is_io_mapping_possible(resource_size_t base, unsigned long size)
 {
         /* There is no way to map greater than 1 << 32 address without PAE */
@@ -38,6 +38,46 @@ is_io_mapping_possible(resource_size_t base, unsigned long size)
 }
 #endif
 
+int
+reserve_io_memtype_wc(u64 base, unsigned long size, pgprot_t *prot)
+{
+        unsigned long ret_flag;
+
+        if (!is_io_mapping_possible(base, size))
+                goto out_err;
+
+        if (!pat_enabled) {
+                *prot = pgprot_noncached(PAGE_KERNEL);
+                return 0;
+        }
+
+        if (reserve_memtype(base, base + size, _PAGE_CACHE_WC, &ret_flag))
+                goto out_err;
+
+        if (ret_flag == _PAGE_CACHE_WB)
+                goto out_free;
+
+        if (kernel_map_sync_memtype(base, size, ret_flag))
+                goto out_free;
+
+        *prot = __pgprot(__PAGE_KERNEL | ret_flag);
+        return 0;
+
+out_free:
+        free_memtype(base, base + size);
+out_err:
+        return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(reserve_io_memtype_wc);
+
+void
+free_io_memtype(u64 base, unsigned long size)
+{
+        if (pat_enabled)
+                free_memtype(base, base + size);
+}
+EXPORT_SYMBOL_GPL(free_io_memtype);
+
 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  */
 void *
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 05f9aef6818a..fdfedb65d45a 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -634,6 +634,33 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
 }
 
 /*
+ * Change the memory type for the physial address range in kernel identity
+ * mapping space if that range is a part of identity map.
+ */
+int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
+{
+        unsigned long id_sz;
+
+        if (!pat_enabled || base >= __pa(high_memory))
+                return 0;
+
+        id_sz = (__pa(high_memory) < base + size) ?
+                                __pa(high_memory) - base :
+                                size;
+
+        if (ioremap_change_attr((unsigned long)__va(base), id_sz, flags) < 0) {
+                printk(KERN_INFO
+                        "%s:%d ioremap_change_attr failed %s "
+                        "for %Lx-%Lx\n",
+                        current->comm, current->pid,
+                        cattr_name(flags),
+                        base, (unsigned long long)(base + size));
+                return -EINVAL;
+        }
+        return 0;
+}
+
+/*
  * Internal interface to reserve a range of physical memory with 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.
@@ -642,7 +669,7 @@ 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);
 
@@ -679,23 +706,8 @@ 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) < 0) {
                 free_memtype(paddr, paddr + size);
-                printk(KERN_ERR
-                        "%s:%d reserve_pfn_range ioremap_change_attr failed %s "
-                        "for %Lx-%Lx\n",
-                        current->comm, current->pid,
-                        cattr_name(flags),
-                        (unsigned long long)paddr,
-                        (unsigned long long)(paddr + size));
                 return -EINVAL;
         }
         return 0;
diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h
index cbc2f0cd631b..f1ed66c43787 100644
--- a/include/linux/io-mapping.h
+++ b/include/linux/io-mapping.h
@@ -49,8 +49,9 @@ static inline struct io_mapping *
 io_mapping_create_wc(resource_size_t base, unsigned long size)
 {
         struct io_mapping *iomap;
+        pgprot_t prot;
 
-        if (!is_io_mapping_possible(base, size))
+        if (!reserve_io_memtype_wc(base, size, &prot))
                 return NULL;
 
         iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
@@ -59,13 +60,14 @@ io_mapping_create_wc(resource_size_t base, unsigned long size)
 
         iomap->base = base;
         iomap->size = size;
-        iomap->prot = pgprot_writecombine(__pgprot(__PAGE_KERNEL));
+        iomap->prot = prot;
         return iomap;
 }
 
 static inline void
 io_mapping_free(struct io_mapping *mapping)
 {
+        free_io_memtype(mapping->base, mapping->size);
         kfree(mapping);
 }