File 637b5f4f-efifb-ignore-invalid.patch of Package xen.36362

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File 637b5f4f-efifb-ignore-invalid.patch of Package xen.36362

# Commit 57f07cca82521088cca0c1fc36d6ffd06cb7de80
# Date 2022-11-21 12:21:51 +0100
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Jan Beulich <jbeulich@suse.com>
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>

--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -497,6 +497,13 @@ static void __init efi_arch_video_init(E
 #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:

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File 637b5f4f-efifb-ignore-invalid.patch of Package xen.36362

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