ACPICA: avoid "Info: mapping multiple BARs. Your kernel is fine."

Ensure that memory mappings created for operation regions
do not cross page boundaries.  Crossing a page boundary
while mapping regions can cause warnings if the pages have different attributes.

Such regions are probably BIOS bugs, and this is the workaround.

http://bugzilla.kernel.org/show_bug.cgi?id=14445

[Kernel summit hacking hour]

Signed-off-by: Bob Moore <robert.moore@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 27 insertions, 12 deletions

diff --git a/drivers/acpi/acpica/acconfig.h b/drivers/acpi/acpica/acconfig.h
index 8e679ef5b231..a4471e3d3853 100644
--- a/drivers/acpi/acpica/acconfig.h
+++ b/drivers/acpi/acpica/acconfig.h
@@ -103,9 +103,9 @@
 
 #define ACPI_MAX_REFERENCE_COUNT        0x1000
 
-/* Size of cached memory mapping for system memory operation region */
+/* Default page size for use in mapping memory for operation regions */
 
-#define ACPI_SYSMEM_REGION_WINDOW_SIZE  4096
+#define ACPI_DEFAULT_PAGE_SIZE          4096    /* Must be power of 2 */
 
 /* owner_id tracking. 8 entries allows for 255 owner_ids */
 
diff --git a/drivers/acpi/acpica/exregion.c b/drivers/acpi/acpica/exregion.c
index 3a54b737d2da..2bd83ac57c3a 100644
--- a/drivers/acpi/acpica/exregion.c
+++ b/drivers/acpi/acpica/exregion.c
@@ -77,7 +77,8 @@ acpi_ex_system_memory_space_handler(u32 function,
         void *logical_addr_ptr = NULL;
         struct acpi_mem_space_context *mem_info = region_context;
         u32 length;
-        acpi_size window_size;
+        acpi_size map_length;
+        acpi_size page_boundary_map_length;
 #ifdef ACPI_MISALIGNMENT_NOT_SUPPORTED
         u32 remainder;
 #endif
@@ -144,25 +145,39 @@ acpi_ex_system_memory_space_handler(u32 function,
                 }
 
                 /*
-                 * Don't attempt to map memory beyond the end of the region, and
-                 * constrain the maximum mapping size to something reasonable.
+                 * Attempt to map from the requested address to the end of the region.
+                 * However, we will never map more than one page, nor will we cross
+                 * a page boundary.
                  */
-                window_size = (acpi_size)
+                map_length = (acpi_size)
                     ((mem_info->address + mem_info->length) - address);
 
-                if (window_size > ACPI_SYSMEM_REGION_WINDOW_SIZE) {
-                        window_size = ACPI_SYSMEM_REGION_WINDOW_SIZE;
+                /*
+                 * If mapping the entire remaining portion of the region will cross
+                 * a page boundary, just map up to the page boundary, do not cross.
+                 * On some systems, crossing a page boundary while mapping regions
+                 * can cause warnings if the pages have different attributes
+                 * due to resource management
+                 */
+                page_boundary_map_length =
+                    ACPI_ROUND_UP(address, ACPI_DEFAULT_PAGE_SIZE) - address;
+
+                if (!page_boundary_map_length) {
+                        page_boundary_map_length = ACPI_DEFAULT_PAGE_SIZE;
+                }
+
+                if (map_length > page_boundary_map_length) {
+                        map_length = page_boundary_map_length;
                 }
 
                 /* Create a new mapping starting at the address given */
 
-                mem_info->mapped_logical_address =
-                        acpi_os_map_memory((acpi_physical_address) address, window_size);
+                mem_info->mapped_logical_address = acpi_os_map_memory((acpi_physical_address) address, map_length);
                 if (!mem_info->mapped_logical_address) {
                         ACPI_ERROR((AE_INFO,
                                     "Could not map memory at %8.8X%8.8X, size %X",
                                     ACPI_FORMAT_NATIVE_UINT(address),
-                                    (u32) window_size));
+                                    (u32) map_length));
                         mem_info->mapped_length = 0;
                         return_ACPI_STATUS(AE_NO_MEMORY);
                 }
@@ -170,7 +185,7 @@ acpi_ex_system_memory_space_handler(u32 function,
                 /* Save the physical address and mapping size */
 
                 mem_info->mapped_physical_address = address;
-                mem_info->mapped_length = window_size;
+                mem_info->mapped_length = map_length;
         }
 
         /*