Re: [PATCH 0/2] platform/x86: hp-bioscfg: fix attribute enumeration on older HP BIOS

[Muhammad Bilal]

Hi Armin,

I've posted v2 of the series, which includes an additional preparatory
patch to ensure parser iteration remains bounded before relaxing the
package-length check.

https://lore.kernel.org/all/20260704160759.236249-1-meatuni001@xxxxxxxxx/

Thanks for your review.

On Wed, Jul 1, 2026 at 1:29 AM Armin Wolf <W_Armin@xxxxxx> wrote:
>
> Am 26.06.26 um 22:49 schrieb Muhammad Bilal:
>
> > The hp_bioscfg driver silently fails to enumerate BIOS attributes on
> > HP EliteBook 840 G2 (and potentially other older HP models) because:
> >
> >    1. hp_init_bios_package_attribute() hard-fails when a WMI ACPI package
> >       contains fewer elements than the per-type expected count (11 < 13),
> >       even though only the first 10 common elements are required to
> >       register an attribute.
> >
> >    2. hp_populate_enumeration_elements_from_package() returns -EIO and
> >       discards the entire attribute when any single element has an
> >       unexpected ACPI object type — typically after a BIOS AML error
> >       returns malformed data.
>
> Hi,
>
> it could be that the ACPI firmware still transmits all the necessary data, its just
> that some package elements are combined into a single buffer element
> (see https://docs.kernel.org/wmi/acpi-interface.html section "Conversion rules for ACPI data types"
> for details).
>
> The correct solution would be to migrate the driver to the new buffer-based WMI API,
> because said API ensures that ACPI objects are properly marshaled into the common
> WMI data format. However this might require a lot of work :/.
>
> Regarding the BIOS error: this usually happens because creating a ByteField with and
> invalid length does not cause an error under Windows. Passing a larger buffer usually
> fixes this problem.
>
> Thanks,
> Armin Wolf
>
> >
> > Hardware affected:
> >    HP EliteBook 840 G2 (DMI: Hewlett-Packard HP EliteBook 840 G2/2216)
> >    BIOS: M71 Ver. 01.31 (02/24/2020)
> >
> > How to reproduce:
> >    1. Boot a kernel with CONFIG_HP_BIOSCFG=m on an HP EliteBook 840 G2
> >    2. modprobe hp_bioscfg
> >    3. Observe dmesg:
> >         hp_bioscfg: ACPI-package does not have enough elements: 11 < 13
> >         Error expected type 2 for elem 13, but got type 1 instead
> >
> > Testing notes:
> >    Tested on HP EliteBook 840 G2 running Arch Linux kernel 7.0.13-arch1-1.
> >    After patches, hp_bioscfg loads successfully and enumerates available
> >    BIOS attributes. Attributes with shortened packages are partially
> >    populated and accessible via sysfs. No regressions on systems that
> >    return full 13-element packages (checked via code inspection —
> >    pr_warn path is only reached when count < min_elements).
> >
> > Relevant dmesg (before fix):
> >    [   11.xxx] hp_bioscfg: ACPI-package does not have enough elements:
> >                11 < 13
> >    [   11.xxx] ACPI BIOS Error (bug): AE_AML_BUFFER_LIMIT,
> >                Index (0x000000032) is beyond end of object (length 0x32)
> >    [   11.xxx] ACPI Error: Aborting method \_SB.WMID.WQBE
> >    [   11.xxx] Error expected type 2 for elem 13, got type 1
> >    [   11.xxx] hp_bioscfg: Returned error 0x3
> >
> > Muhammad Bilal (2):
> >    platform/x86: hp-bioscfg: accept reduced ACPI packages from older HP
> >      BIOS
> >    platform/x86: hp-bioscfg: warn on element type mismatch instead of
> >      failing
> >
> >   drivers/platform/x86/hp/hp-bioscfg/bioscfg.c         | 11 ++++++++---
> >   drivers/platform/x86/hp/hp-bioscfg/bioscfg.h         |  3 +++
> >   drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c |  7 ++++---
> >   3 files changed, 15 insertions(+), 6 deletions(-)
> >