On 12.06.2017 at 17:24 wrote Greg Kroah-Hartman:
> 4.11-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Dave Young <dyoung@xxxxxxxxxx>
>
> commit 7425826f4f7ac60f2538b06a7f0a5d1006405159 upstream.
>
> Sabrina Dubroca reported an early panic:
>
> BUG: unable to handle kernel paging request at ffffffffff240001
> IP: efi_bgrt_init+0xdc/0x134
>
> [...]
>
> ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
>
> ... which was introduced by:
>
> 7b0a911478c7 ("efi/x86: Move the EFI BGRT init code to early init code")
>
> The cause is that on this machine the firmware provides the EFI ACPI BGRT
> table even on legacy non-EFI bootups - which table should be EFI only.
>
> The garbage BGRT data causes the efi_bgrt_init() panic.
>
> Add a check to skip efi_bgrt_init() in case non-EFI bootup to work around
> this firmware bug.
>
> Tested-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
> Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: linux-efi@xxxxxxxxxxxxxxx
> Fixes: 7b0a911478c7 ("efi/x86: Move the EFI BGRT init code to early init code")
> Link: http://lkml.kernel.org/r/20170526113652.21339-6-matt@xxxxxxxxxxxxxxxxxxx
> [ Rewrote the changelog to be more readable. ]
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
> arch/x86/platform/efi/efi-bgrt.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> --- a/arch/x86/platform/efi/efi-bgrt.c
> +++ b/arch/x86/platform/efi/efi-bgrt.c
> @@ -36,6 +36,9 @@ void __init efi_bgrt_init(struct acpi_ta
> if (acpi_disabled)
> return;
>
> + if (!efi_enabled(EFI_BOOT))
> + return;
> +
> if (table->length < sizeof(bgrt_tab)) {
> pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
> table->length, sizeof(bgrt_tab));
>
>
>
The patch is ok but it only fixes BIOS systems.
To fix the regression above (commit 7b0a911478c7) for EFI systems
it needs this patch as well:
commit 792ef14df5c585c19b2831673a077504a09e5203 master
(efi: Fix boot panic because of invalid BGRT image address)