efifb: ignore frame buffer with invalid configuration

On one of my boxes when the HDMI cable is not plugged in the
FrameBufferBase of the EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE structure is
set to 0 by the firmware (while some of the other fields looking
plausible).

Such (bogus address) ends up mapped in vesa_init(), and since it
overlaps with a RAM region the whole system goes down pretty badly,
see:

(XEN) vesafb: framebuffer at 0x0000000000000000, mapped to 0xffff82c000201000, using 35209k, total 35209k
(XEN) vesafb: mode is 0x37557x32, linelength=960, font 8x16
(XEN) vesafb: Truecolor: size=8:8:8:8, shift=24:0:8:16
(XEN) (XEN) (XEN) (XEN) (XEN) (XEN) (XEN) (XEN) �ERROR: Class:0; Subclass:0; Operation: 0
ERROR: No ConOut
ERROR: No ConIn

Do like Linux and prevent using the EFI Frame Buffer if the base
address is 0.  This is inline with the logic in Linuxes
fb_base_is_valid() function at drivers/video/fbdev/efifb.c v6.0.9.

See also Linux commit 133bb070e94ab41d750c6f2160c8843e46f11b78 for
further reference.

Also prevent using Frame Buffers that have a 0 height or width, as
those are also invalid.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>

diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index e82ac9daa7ad665d5b5985df3bda37c5bae1b80f..27f928ed3c143afd5bb921655e16d49431b4d7d0 100644 (file)
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -506,6 +506,13 @@ static void __init efi_arch_video_init(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
 #ifdef CONFIG_VIDEO
     int bpp = 0;
 
+    if ( !gop->Mode->FrameBufferBase || !mode_info->HorizontalResolution ||
+         !mode_info->VerticalResolution )
+    {
+        PrintErr(L"Invalid Frame Buffer configuration found\r\n");
+        return;
+    }
+
     switch ( mode_info->PixelFormat )
     {
     case PixelRedGreenBlueReserved8BitPerColor: