Re: [PATCH v3 1/3] ACPI: APEI: GHES: Refactor Grace decoder helpers

[Ashok Raj <ashok.raj@oss.qualcomm.com>]

On Tue, Aug 04, 2026 at 08:23:15PM +0800, Kai-Heng Feng wrote:
> Split the Grace CPER processing into a separate decode step and a
> print step so the parser can be exercised by KUnit without a live
> ACPI device. Introduce ghes-nvidia.h to hold shared types that the
> Vera decoder added in the next commit will also reference.
> 
> Parse the Grace wire payload with __packed structs and
> get_unaligned_le*() for multi-byte fields, matching the Vera
> decoder style. Reject nvidia_ghes_grace_reg_pair() calls with a
> non-zero register count and a NULL grace_regs pointer, and
> rate-limit Grace decoder diagnostics.
> 
> Signed-off-by: Kai-Heng Feng <kaihengf@nvidia.com>

Hi Kai,

> ---
> v3:
>  - Use __packed + get_unaligned_le*() for Grace multi-byte fields,
>    including register pairs (Shuai Xue).
>  - Keep __counted_by / struct_size; reject NULL grace_regs when
>    number_regs != 0; document the helper contract.
>  - Rate-limit Grace decoder and notify error messages.
> v2:
>  - No change.
> ---
>  MAINTAINERS                     |   2 +-
>  drivers/acpi/apei/ghes-nvidia.c | 160 ++++++++++++++++++++++----------
>  drivers/acpi/apei/ghes-nvidia.h |  50 ++++++++++
>  3 files changed, 160 insertions(+), 52 deletions(-)
>  create mode 100644 drivers/acpi/apei/ghes-nvidia.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5114e6db7307..aa9c2ae58ac5 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19348,7 +19348,7 @@ NVIDIA GHES VENDOR CPER RECORD HANDLER
>  M:	Kai-Heng Feng <kaihengf@nvidia.com>
>  L:	linux-acpi@vger.kernel.org
>  S:	Maintained
> -F:	drivers/acpi/apei/ghes-nvidia.c
> +F:	drivers/acpi/apei/ghes-nvidia*
>  
>  NVIDIA VRS RTC DRIVER
>  M:	Shubhi Garg <shgarg@nvidia.com>
> diff --git a/drivers/acpi/apei/ghes-nvidia.c b/drivers/acpi/apei/ghes-nvidia.c
> index 597275d81de8..e7cc912344fd 100644
> --- a/drivers/acpi/apei/ghes-nvidia.c
> +++ b/drivers/acpi/apei/ghes-nvidia.c
> @@ -9,13 +9,18 @@
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/types.h>
> +#include <linux/unaligned.h>
>  #include <linux/uuid.h>
>  #include <acpi/ghes.h>

One naive question, do these CPER decoding for vendor specific pieces
belong in the kernel? Or you would manage them from user space?


>  
> -static const guid_t nvidia_sec_guid =
> +#include <kunit/visibility.h>
> +#include "ghes-nvidia.h"
> +
> +static const guid_t nvidia_grace_sec_guid =
>  	GUID_INIT(0x6d5244f2, 0x2712, 0x11ec,
>  		  0xbe, 0xa7, 0xcb, 0x3f, 0xdb, 0x95, 0xc7, 0x86);
>  
> +/* Grace CPER section wire layout (header without flexible register array). */
>  struct cper_sec_nvidia {
>  	char	signature[16];
>  	__le16	error_type;
> @@ -25,84 +30,137 @@ struct cper_sec_nvidia {
>  	u8	number_regs;
>  	u8	reserved;
>  	__le64	instance_base;
> -	struct {
> -		__le64	addr;
> -		__le64	val;
> -	} regs[] __counted_by(number_regs);
> -};
> +	struct nvidia_ghes_grace_reg regs[] __counted_by(number_regs);
> +} __packed;
> +

[snip]

Cheers,
Ashok