Re: [PATCH RFC v4 5/6] firmware/efi: Process CXL Component Events

Smita Koralahalli
2023-11-28T20:32:51Z

Hi Ira,

I tested this out. Just one correction below to make it work.

On 11/9/2023 2:07 PM, Ira Weiny wrote:
> BIOS can configure memory devices as firmware first. This will send CXL
> events to the firmware instead of the OS. The firmware can then send
> these events to the OS via UEFI.
>
> UEFI v2.10 section N.2.14 defines a Common Platform Error Record (CPER)
> format for CXL Component Events. The format is mostly the same as the
> CXL Common Event Record Format. The difference is a GUID is used in
> the Section Type to identify the event type.
>
> Add EFI support to detect CXL CPER records and call a notifier chain
> with the record data blobs to be processed by the CXL code.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes from RFC v3
> [Smita: ensure cper_cxl_event_rec is packed]
>
> Changes from RFC v2
> [djbw: use common event structures]
> [djbw: remove print in core cper code]
> [djbw: export register call as NS_GPL]
> [iweiny: fix 0day issues]
>
> Changes from RFC v1
> [iweiny: use an enum for know record types and skip converting GUID to UUID]
> [iweiny: commit to the UUID not being part of the event record data]
> [iweiny: use defines for GUID definitions]
> ---

[snip]

> diff --git a/include/linux/cxl-event.h b/include/linux/cxl-event.h
> index 6b689e1efc78..733ab2ab8639 100644
> --- a/include/linux/cxl-event.h
> +++ b/include/linux/cxl-event.h
> @@ -108,4 +108,53 @@ struct cxl_event_record_raw {
> union cxl_event event;
> } __packed;
>
> +enum cxl_event_type {
> + CXL_CPER_EVENT_GEN_MEDIA,
> + CXL_CPER_EVENT_DRAM,
> + CXL_CPER_EVENT_MEM_MODULE,
> +};
> +
> +#define CPER_CXL_DEVICE_ID_VALID BIT(0)
> +#define CPER_CXL_DEVICE_SN_VALID BIT(1)
> +#define CPER_CXL_COMP_EVENT_LOG_VALID BIT(2)
> +struct cper_cxl_event_rec {
> + struct {
> + u32 length;
> + u64 validation_bits;
> + struct cper_cxl_event_devid {
> + u16 vendor_id;
> + u16 device_id;
> + u8 func_num;
> + u8 device_num;
> + u8 bus_num;
> + u16 segment_num;
> + u16 slot_num; /* bits 2:0 reserved */
> + u8 reserved;
> + } device_id;
> + struct cper_cxl_event_sn {
> + u32 lower_dw;
> + u32 upper_dw;
> + } dev_serial_num;
> + } hdr;
> +
> + union cxl_event event;
> +} __packed;

__packed attribute just for cper_cxl_event_rec still fails to properly
align structure elements. Looks like, __packed attribute is needed for
all structs (cper_cxl_event_devid and cper_cxl_event_sn) inside
cper_cxl_event_rec.

Seems easier to use global pragma instead.. I could test and obtain the
output as expected using pragma..

Thanks,
Smita

> +
> +struct cxl_cper_notifier_data {
> + enum cxl_event_type event_type;
> + struct cper_cxl_event_rec *rec;
> +};
> +
> +#ifdef CONFIG_UEFI_CPER
> +int register_cxl_cper_notifier(struct notifier_block *nb);
> +void unregister_cxl_cper_notifier(struct notifier_block *nb);
> +#else
> +static inline int register_cxl_cper_notifier(struct notifier_block *nb)
> +{
> + return 0;
> +}
> +
> +static inline void unregister_cxl_cper_notifier(struct notifier_block *nb) { }
> +#endif
> +
> #endif /* _LINUX_CXL_EVENT_H */
>