[Xen-changelog] [xen stable-4.11] efi/boot: make sure graphics mode is set while booting through MB2

[patchbot@xxxxxxx]

commit b5433e7ed0114f447d8d1d9fa3c6778ee52f8486
Author:     Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
AuthorDate: Fri Oct 25 12:01:55 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Oct 25 12:01:55 2019 +0200

    efi/boot: make sure graphics mode is set while booting through MB2
    
    If a bootloader is using native driver instead of EFI GOP it might
    reset graphics mode to be different from what has been originally set
    by firmware. While booting through MB2 Xen either need to parse video
    setting passed by MB2 and use them instead of what GOP reports or
    reset the mode to synchronise it with firmware - prefer the latter.
    
    Observed while booting Xen using MB2 with EFI GRUB2 compiled with
    all possible video drivers where native drivers take priority over firmware.
    
    Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: af9f357fb8dbceb9c5dd1c5cb8b4e198f6149456
    master date: 2019-10-10 10:58:45 +0200
---
 xen/common/efi/boot.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 43115387b5..868ceeb539 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -986,8 +986,12 @@ static void __init 
efi_set_gop_mode(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop, UINTN gop
     EFI_STATUS status;
     UINTN info_size;
 
-    /* Set graphics mode. */
-    if ( gop_mode < gop->Mode->MaxMode && gop_mode != gop->Mode->Mode )
+    /*
+     * Set graphics mode to a selected one and reset it if we didn't come
+     * directly from EFI loader as video settings might have been already 
modified.
+     */
+    if ( gop_mode < gop->Mode->MaxMode &&
+         (gop_mode != gop->Mode->Mode || !efi_enabled(EFI_LOADER)) )
         gop->SetMode(gop, gop_mode);
 
     /* Get graphics and frame buffer info. */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.11

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