Re: [PATCH v2] cxl/events: Use a common struct for DRAM and General Media events

From: Jonathan Cameron
Date: Thu May 16 2024 - 12:33:34 EST

On Thu, 16 May 2024 12:19:53 +0200
"Fabio M. De Francesco" <fabio.m.de.francesco@xxxxxxxxxxxxxxx> wrote:

> cxl_event_common was a poor naming choice and caused confusion with the
> existing Common Event Record.
>
> Use cxl_event_media as a common structure to record information about DRAM
> and General Media events because it simplifies handling the two events.
>
> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Fixes: 6aec00139d3a ("cxl/core: Add region info to cxl_general_media and cxl_dram events")
> Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@xxxxxxxxxxxxxxx>
> ---

Packing question inline.

>
> Changes for v2:
> - Extend the commit message (Alison);
> - Add a "Fixes" tag (Alison, thanks).
>
> drivers/cxl/core/mbox.c | 6 ++--
> drivers/cxl/core/trace.h | 4 +--
> include/linux/cxl-event.h | 70 +++++++++++++++---------------------
> tools/testing/cxl/test/mem.c | 4 +--
> 4 files changed, 36 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 2626f3fff201..ad4d7b0f7f4d 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -875,16 +875,16 @@ void cxl_event_trace_record(const struct cxl_memdev *cxlmd,
> guard(rwsem_read)(&cxl_region_rwsem);
> guard(rwsem_read)(&cxl_dpa_rwsem);
>
> - dpa = le64_to_cpu(evt->common.phys_addr) & CXL_DPA_MASK;
> + dpa = le64_to_cpu(evt->media_common.phys_addr) & CXL_DPA_MASK;
> cxlr = cxl_dpa_to_region(cxlmd, dpa);
> if (cxlr)
> hpa = cxl_trace_hpa(cxlr, cxlmd, dpa);
>
> if (event_type == CXL_CPER_EVENT_GEN_MEDIA)
> trace_cxl_general_media(cxlmd, type, cxlr, hpa,
> - &evt->gen_media);
> + &evt->media_general);
> else if (event_type == CXL_CPER_EVENT_DRAM)
> - trace_cxl_dram(cxlmd, type, cxlr, hpa, &evt->dram);
> + trace_cxl_dram(cxlmd, type, cxlr, hpa, &evt->media_dram);
> }
> }
> EXPORT_SYMBOL_NS_GPL(cxl_event_trace_record, CXL);
> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
> index 07a0394b1d99..2c7293761bb2 100644
> --- a/drivers/cxl/core/trace.h
> +++ b/drivers/cxl/core/trace.h
> @@ -316,7 +316,7 @@ TRACE_EVENT(cxl_generic_event,
> TRACE_EVENT(cxl_general_media,
>
> TP_PROTO(const struct cxl_memdev *cxlmd, enum cxl_event_log_type log,
> - struct cxl_region *cxlr, u64 hpa, struct cxl_event_gen_media *rec),
> + struct cxl_region *cxlr, u64 hpa, struct cxl_event_media *rec),
>
> TP_ARGS(cxlmd, log, cxlr, hpa, rec),
>
> @@ -413,7 +413,7 @@ TRACE_EVENT(cxl_general_media,
> TRACE_EVENT(cxl_dram,
>
> TP_PROTO(const struct cxl_memdev *cxlmd, enum cxl_event_log_type log,
> - struct cxl_region *cxlr, u64 hpa, struct cxl_event_dram *rec),
> + struct cxl_region *cxlr, u64 hpa, struct cxl_event_media *rec),
>
> TP_ARGS(cxlmd, log, cxlr, hpa, rec),
>
> diff --git a/include/linux/cxl-event.h b/include/linux/cxl-event.h
> index 60b25020281f..e417556cc120 100644
> --- a/include/linux/cxl-event.h
> +++ b/include/linux/cxl-event.h
> @@ -32,41 +32,38 @@ struct cxl_event_generic {
> * CXL rev 3.0 Section 8.2.9.2.1.1; Table 8-43
> */
> #define CXL_EVENT_GEN_MED_COMP_ID_SIZE 0x10
> -struct cxl_event_gen_media {
> - struct cxl_event_record_hdr hdr;
> - __le64 phys_addr;
> - u8 descriptor;
> - u8 type;
> - u8 transaction_type;
> - u8 validity_flags[2];
> - u8 channel;
> - u8 rank;
> - u8 device[3];
> - u8 component_id[CXL_EVENT_GEN_MED_COMP_ID_SIZE];
> - u8 reserved[46];
> -} __packed;
> -
> /*
> * DRAM Event Record - DER
> * CXL rev 3.0 section 8.2.9.2.1.2; Table 3-44
> */
> #define CXL_EVENT_DER_CORRECTION_MASK_SIZE 0x20
> -struct cxl_event_dram {
> +struct cxl_event_media {
> struct cxl_event_record_hdr hdr;
> - __le64 phys_addr;
> - u8 descriptor;
> - u8 type;
> - u8 transaction_type;
> - u8 validity_flags[2];
> - u8 channel;
> - u8 rank;
> - u8 nibble_mask[3];
> - u8 bank_group;
> - u8 bank;
> - u8 row[3];
> - u8 column[2];
> - u8 correction_mask[CXL_EVENT_DER_CORRECTION_MASK_SIZE];
> - u8 reserved[0x17];
> + struct_group_tagged(cxl_event_media_hdr, media_hdr,
> + __le64 phys_addr;
> + u8 descriptor;
> + u8 type;
> + u8 transaction_type;
> + u8 validity_flags[2];
> + u8 channel;
> + u8 rank;
> + );

Does the struct that is created end up __packed?
Also, why is tagged useful here?

> + union {
> + struct_group(general,
> + u8 device[3];
> + u8 component_id[CXL_EVENT_GEN_MED_COMP_ID_SIZE];
> + u8 gen_reserved[46];
> + );
> + struct_group(dram,
> + u8 nibble_mask[3];
> + u8 bank_group;
> + u8 bank;
> + u8 row[3];
> + u8 column[2];
> + u8 correction_mask[CXL_EVENT_DER_CORRECTION_MASK_SIZE];
> + u8 dram_reserved[0x17];
> + );
> + };
> } __packed;
>
> /*
> @@ -95,21 +92,12 @@ struct cxl_event_mem_module {
> u8 reserved[0x3d];
> } __packed;
>
> -/*
> - * General Media or DRAM Event Common Fields
> - * - provides common access to phys_addr
> - */
> -struct cxl_event_common {
> - struct cxl_event_record_hdr hdr;
> - __le64 phys_addr;
> -} __packed;
> -
> union cxl_event {
> struct cxl_event_generic generic;
> - struct cxl_event_gen_media gen_media;
> - struct cxl_event_dram dram;
> + struct cxl_event_media media_general;
> + struct cxl_event_media media_dram;
> struct cxl_event_mem_module mem_module;
> - struct cxl_event_common common;
> + struct cxl_event_media media_common;
> } __packed;
>
> /*
> diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
> index 6584443144de..0a8fd145c391 100644
> --- a/tools/testing/cxl/test/mem.c
> +++ b/tools/testing/cxl/test/mem.c
> @@ -378,7 +378,7 @@ struct cxl_event_record_raw hardware_replace = {
>
> struct cxl_test_gen_media {
> uuid_t id;
> - struct cxl_event_gen_media rec;
> + struct cxl_event_media rec;
> } __packed;
>
> struct cxl_test_gen_media gen_media = {
> @@ -402,7 +402,7 @@ struct cxl_test_gen_media gen_media = {
>
> struct cxl_test_dram {
> uuid_t id;
> - struct cxl_event_dram rec;
> + struct cxl_event_media rec;
> } __packed;
>
> struct cxl_test_dram dram = {