RE: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug

From: Zheng, Lv
Date: Sun Jul 30 2017 - 22:12:57 EST


Hi,

> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Song
> liwei
> Subject: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug
>
> From: Liwei Song <liwei.song@xxxxxxxxxxxxx>
>
> This is a follow up to commit f712c71f7b2b ("ACPI, APEI: Fixup common
> access width firmware bug") fix the following firmware bug:
>
> [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
>
> This is due to an 8-bit access width is specified for a 16-bit register,
> Rearrange the condition and add 8-bit width check.
>
> Signed-off-by: Liwei Song <liwei.song@xxxxxxxxxxxxx>
> ---
> drivers/acpi/apei/apei-base.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
> index da370e1..eca3d7a 100644
> --- a/drivers/acpi/apei/apei-base.c
> +++ b/drivers/acpi/apei/apei-base.c
> @@ -604,12 +604,12 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr,
> *access_bit_width = 1UL << (access_size_code + 2);
>
> /* Fixup common BIOS bug */
> - if (bit_width == 32 && bit_offset == 0 && (*paddr & 0x03) == 0 &&
> - *access_bit_width < 32)
> - *access_bit_width = 32;
> - else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
> - *access_bit_width < 64)
> - *access_bit_width = 64;
> + if (*access_bit_width < bit_width && bit_offset == 0) {
> + if ((bit_width == 16 && (*paddr & 0x01) == 0) ||
> + (bit_width == 32 && (*paddr & 0x03) == 0) ||
> + (bit_width == 64 && (*paddr & 0x07) == 0))
> + *access_bit_width = bit_width;
> + }
>
> if ((bit_width + bit_offset) > *access_bit_width) {
> pr_warning(FW_BUG APEI_PFX

IMO, such problem could also be fixed by this commit and a cleanup of APEI
GAR code to invoke generic ACPICA GAR API - acpi_read()/acpi_write() directly.
https://github.com/acpica/acpica/pull/209

Thanks and best regards
Lv