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Subject[PATCH v3 1/1] Resolve WMI query failures on some devices
Date
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.

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
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