efi: introduce efi_arch_flush_dcache_area

Objects loaded by FileHandle->Read need to be flushed from dcache,
otherwise copy_from_paddr will read stale data when copying the kernel,
causing a failure to boot.

Introduce efi_arch_flush_dcache_area and call it from read_file.

This commit introduces no functional changes on x86.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
master commit: 0d6a3c7553
master date: 2015-09-09 15:29:06 +0200

xen/arch/arm/efi/efi-boot.h

@@ -9,6 +9,7 @@
 #include <asm/smp.h>
 
 void noreturn efi_xen_start(void *fdt_ptr, uint32_t fdt_size);
+void __flush_dcache_area(const void *vaddr, unsigned long size);
 
 #define DEVICE_TREE_GUID \
 {0xb1b621d5, 0xf19c, 0x41a5, {0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0}}
@@ -571,6 +572,12 @@ static void __init efi_arch_video_init(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
                                        EFI_GRAPHICS_OUTPUT_MODE_INFORMATION *mode_info)
 {
 }
+
+static void efi_arch_flush_dcache_area(const void *vaddr, UINTN size)
+{
+    __flush_dcache_area(vaddr, size);
+}
+
 /*
  * Local variables:
  * mode: C

xen/arch/x86/efi/efi-boot.h

@@ -640,6 +640,8 @@ static bool_t __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
     return 1; /* x86 always uses a config file */
 }
 
+static void efi_arch_flush_dcache_area(const void *vaddr, UINTN size) { }
+
 /*
  * Local variables:
  * mode: C

xen/common/efi/boot.c

@@ -528,6 +528,8 @@ static bool_t __init read_file(EFI_FILE_HANDLE dir_handle, CHAR16 *name,
         PrintErrMesg(name, ret);
     }
 
+    efi_arch_flush_dcache_area(file->ptr, file->size);
+
     return 1;
 }