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References: <20220608212923.8585-1-jorge.lopez2@hp.com> <20220608212923.8585-2-jorge.lopez2@hp.com>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 9 Jun 2022 18:29:36 +0200
Message-ID: <CAHp75VfPoranKhsHJo=8jJXXhdvqn4-x2E2UJa-Yxb_=tO3QDg@mail.gmail.com>
Subject: Re: [PATCH v3 1/1] Resolve WMI query failures on some devices
To:     Jorge Lopez <jorgealtxwork@gmail.com>
Cc:     Hans de Goede <hdegoede@redhat.com>, balalic.enver@gmail.com,
        Platform Driver <platform-driver-x86@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Gross <markgross@kernel.org>
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On Wed, Jun 8, 2022 at 11:32 PM Jorge Lopez <jorgealtxwork@gmail.com> wrote:
>
> WMI queries fail on some devices where the ACPI method HWMC
> unconditionally attempts to create Fields beyond the buffer
> if the buffer is too small, this breaks essential features
> such as power profiles:
>
>          CreateByteField (Arg1, 0x10, D008)
>          CreateByteField (Arg1, 0x11, D009)
>          CreateByteField (Arg1, 0x12, D010)
>          CreateDWordField (Arg1, 0x10, D032)
>          CreateField (Arg1, 0x80, 0x0400, D128)
>
> In cases where args->data had zero length, ACPI BIOS Error
> (bug): AE_AML_BUFFER_LIMIT, Field [D008] at bit
> offset/length 128/8 exceeds size of target Buffer (128 bits)
> (20211217/dsopcode-198) was obtained.
>
> ACPI BIOS Error (bug): AE_AML_BUFFER_LIMIT, Field [D009] at bit
> offset/length 136/8 exceeds size of target Buffer (136bits)
> (20211217/dsopcode-198)
>
> The original code created a buffer size of 128 bytes regardless if
> the WMI call required a smaller buffer or not.  This particular
> behavior occurs in older BIOS and reproduced in OMEN laptops.  Newer
> BIOS handles buffer sizes properly and meets the latest specification
> requirements.  This is the reason why testing with a dynamically
> allocated buffer did not uncover any failures with the test systems at
> hand.
>
> This patch was tested on several OMEN, Elite, and Zbooks.  It was
> confirmed the patch resolves HPWMI_FAN GET/SET calls in an OMEN
> Laptop 15-ek0xxx.  No problems were reported when testing on several Elite
> and Zbooks notebooks.

Perfect!

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Also needs a Fixes tag:

Fixes: 4b4967cbd268 ("platform/x86: hp-wmi: Changing bios_args.data to
be dynamically allocated")

(I believe Hans can help you and add it on the fly)

> Signed-off-by: Jorge Lopez <jorge.lopez2@hp.com>
>
> ---
> Based on the latest platform-drivers-x86.git/for-next
> ---
>  drivers/platform/x86/hp-wmi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/hp-wmi.c b/drivers/platform/x86/hp-wmi.c
> index 0e9a25b56e0e..d3540dd62d06 100644
> --- a/drivers/platform/x86/hp-wmi.c
> +++ b/drivers/platform/x86/hp-wmi.c
> @@ -290,14 +290,16 @@ static int hp_wmi_perform_query(int query, enum hp_wmi_command command,
>         struct bios_return *bios_return;
>         union acpi_object *obj = NULL;
>         struct bios_args *args = NULL;
> -       int mid, actual_outsize, ret;
> +       int mid, actual_insize, actual_outsize;
>         size_t bios_args_size;
> +       int ret;
>
>         mid = encode_outsize_for_pvsz(outsize);
>         if (WARN_ON(mid < 0))
>                 return mid;
>
> -       bios_args_size = struct_size(args, data, insize);
> +       actual_insize = max(insize, 128);
> +       bios_args_size = struct_size(args, data, actual_insize);
>         args = kmalloc(bios_args_size, GFP_KERNEL);
>         if (!args)
>                 return -ENOMEM;
> --
> 2.25.1
>


-- 
With Best Regards,
Andy Shevchenko