+ /*
+ * For /dev/mem mmap, we use user mappings, but if the region is
+ * in kern_memmap (and hence may be covered by a kernel mapping),
+ * we must use the same attribute as the kernel mapping.
+ */
+ attr = kern_mem_attribute(phys_addr, size);
+ if (attr & EFI_MEMORY_WB)
+ return pgprot_cacheable(vma_prot);
+ else if (attr & EFI_MEMORY_UC)
+ return pgprot_noncached(vma_prot);
+
+ /*
+ * Some chipsets don't support UC access to memory. If
+ * WB is supported, we prefer that.
+ */
+ if (efi_mem_attribute(phys_addr, size) & EFI_MEMORY_WB)
+ return pgprot_cacheable(vma_prot);
+
+ return pgprot_noncached(vma_prot);