Re: [PATCH v4 1/2] acpi/ghes: Process CXL Component Events
From: Ira Weiny
Date: Mon Apr 29 2024 - 12:47:54 EST
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 inform
> the OS of these events via UEFI.
+ linux-acpi
[I missed adding this list.]
>
> 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 lies in the use of a
> GUID as the CPER Section Type which matches the UUID defined in CXL 3.1
> Table 8-43.
>
> Currently a configuration such as this will trace a non standard event
> in the log omitting useful details of the event. In addition the CXL
> sub-system contains additional region and HPA information useful to the
> user.[0]
>
> The CXL code is required to be called from process context as it needs
> to take a device lock. The GHES code may be in interrupt context. This
> complicated the use of a callback. Dan Williams suggested the use of
> work items as an atomic way of switching between the callback execution
> and a default handler.[1]
>
> The use of a kfifo simplifies queue processing by providing lock free
> fifo operations. cxl_cper_kfifo_get() allows easier management of the
> kfifo between the ghes and cxl modules.
>
> CXL 3.1 Table 8-127 requires a device to have a queue depth of 1 for
> each of the four event logs. A combined queue depth of 32 is chosen to
> provide room for 8 entries of each log type.
>
> Add GHES support to detect CXL CPER records. Add the ability for the
> CXL sub-system to register a work queue to process the events.
>
> This patch adds back the functionality which was removed to fix the
> report by Dan Carpenter[2].
>
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> Cc: Tony Luck <tony.luck@xxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Link: http://lore.kernel.org/r/cover.1711598777.git.alison.schofield@xxxxxxxxx [0]
> Link: http://lore.kernel.org/r/65d111eb87115_6c745294ac@xxxxxxxxxxxxxxxxxxxxxxxxx.notmuch [1]
> Link: http://lore.kernel.org/r/b963c490-2c13-4b79-bbe7-34c6568423c7@moroto.mountain [2]
> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
> Changes:
> [iweiny: pick up tag]
> [djbw: use proper link format]
> ---
> drivers/acpi/apei/ghes.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/cxl-event.h | 27 ++++++++++++
> 2 files changed, 137 insertions(+)
>
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 512067cac170..2247a1535b52 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -26,6 +26,8 @@
> #include <linux/interrupt.h>
> #include <linux/timer.h>
> #include <linux/cper.h>
> +#include <linux/cleanup.h>
> +#include <linux/cxl-event.h>
> #include <linux/platform_device.h>
> #include <linux/mutex.h>
> #include <linux/ratelimit.h>
> @@ -33,6 +35,7 @@
> #include <linux/irq_work.h>
> #include <linux/llist.h>
> #include <linux/genalloc.h>
> +#include <linux/kfifo.h>
> #include <linux/pci.h>
> #include <linux/pfn.h>
> #include <linux/aer.h>
> @@ -673,6 +676,101 @@ static void ghes_defer_non_standard_event(struct acpi_hest_generic_data *gdata,
> schedule_work(&entry->work);
> }
>
> +/* CXL Event record UUIDs are formated as GUIDs and reported in section type */
> +
> +/*
> + * General Media Event Record
> + * CXL rev 3.0 Section 8.2.9.2.1.1; Table 8-43
> + */
> +#define CPER_SEC_CXL_GEN_MEDIA_GUID \
> + GUID_INIT(0xfbcd0a77, 0xc260, 0x417f, \
> + 0x85, 0xa9, 0x08, 0x8b, 0x16, 0x21, 0xeb, 0xa6)
> +
> +/*
> + * DRAM Event Record
> + * CXL rev 3.0 section 8.2.9.2.1.2; Table 8-44
> + */
> +#define CPER_SEC_CXL_DRAM_GUID \
> + GUID_INIT(0x601dcbb3, 0x9c06, 0x4eab, \
> + 0xb8, 0xaf, 0x4e, 0x9b, 0xfb, 0x5c, 0x96, 0x24)
> +
> +/*
> + * Memory Module Event Record
> + * CXL rev 3.0 section 8.2.9.2.1.3; Table 8-45
> + */
> +#define CPER_SEC_CXL_MEM_MODULE_GUID \
> + GUID_INIT(0xfe927475, 0xdd59, 0x4339, \
> + 0xa5, 0x86, 0x79, 0xba, 0xb1, 0x13, 0xb7, 0x74)
> +
> +/* Room for 8 entries for each of the 4 event log queues */
> +#define CXL_CPER_FIFO_DEPTH 32
> +DEFINE_KFIFO(cxl_cper_fifo, struct cxl_cper_work_data, CXL_CPER_FIFO_DEPTH);
> +
> +/* Synchronize schedule_work() with cxl_cper_work changes */
> +static DEFINE_SPINLOCK(cxl_cper_work_lock);
> +struct work_struct *cxl_cper_work;
> +
> +static void cxl_cper_post_event(enum cxl_event_type event_type,
> + struct cxl_cper_event_rec *rec)
> +{
> + struct cxl_cper_work_data wd;
> +
> + if (rec->hdr.length <= sizeof(rec->hdr) ||
> + rec->hdr.length > sizeof(*rec)) {
> + pr_err(FW_WARN "CXL CPER Invalid section length (%u)\n",
> + rec->hdr.length);
> + return;
> + }
> +
> + if (!(rec->hdr.validation_bits & CPER_CXL_COMP_EVENT_LOG_VALID)) {
> + pr_err(FW_WARN "CXL CPER invalid event\n");
> + return;
> + }
> +
> + guard(spinlock_irqsave)(&cxl_cper_work_lock);
> +
> + if (!cxl_cper_work)
> + return;
> +
> + wd.event_type = event_type;
> + memcpy(&wd.rec, rec, sizeof(wd.rec));
> +
> + if (!kfifo_put(&cxl_cper_fifo, wd)) {
> + pr_err_ratelimited("CXL CPER kfifo overflow\n");
> + return;
> + }
> +
> + schedule_work(cxl_cper_work);
> +}
> +
> +int cxl_cper_register_work(struct work_struct *work)
> +{
> + if (cxl_cper_work)
> + return -EINVAL;
> +
> + guard(spinlock)(&cxl_cper_work_lock);
> + cxl_cper_work = work;
> + return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_register_work, CXL);
> +
> +int cxl_cper_unregister_work(struct work_struct *work)
> +{
> + if (cxl_cper_work != work)
> + return -EINVAL;
> +
> + guard(spinlock)(&cxl_cper_work_lock);
> + cxl_cper_work = NULL;
> + return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_work, CXL);
> +
> +int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd)
> +{
> + return kfifo_get(&cxl_cper_fifo, wd);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_kfifo_get, CXL);
> +
> static bool ghes_do_proc(struct ghes *ghes,
> const struct acpi_hest_generic_status *estatus)
> {
> @@ -707,6 +805,18 @@ static bool ghes_do_proc(struct ghes *ghes,
> }
> else if (guid_equal(sec_type, &CPER_SEC_PROC_ARM)) {
> queued = ghes_handle_arm_hw_error(gdata, sev, sync);
> + } else if (guid_equal(sec_type, &CPER_SEC_CXL_GEN_MEDIA_GUID)) {
> + struct cxl_cper_event_rec *rec = acpi_hest_get_payload(gdata);
> +
> + cxl_cper_post_event(CXL_CPER_EVENT_GEN_MEDIA, rec);
> + } else if (guid_equal(sec_type, &CPER_SEC_CXL_DRAM_GUID)) {
> + struct cxl_cper_event_rec *rec = acpi_hest_get_payload(gdata);
> +
> + cxl_cper_post_event(CXL_CPER_EVENT_DRAM, rec);
> + } else if (guid_equal(sec_type, &CPER_SEC_CXL_MEM_MODULE_GUID)) {
> + struct cxl_cper_event_rec *rec = acpi_hest_get_payload(gdata);
> +
> + cxl_cper_post_event(CXL_CPER_EVENT_MEM_MODULE, rec);
> } else {
> void *err = acpi_hest_get_payload(gdata);
>
> diff --git a/include/linux/cxl-event.h b/include/linux/cxl-event.h
> index 03fa6d50d46f..a0067c49e2ca 100644
> --- a/include/linux/cxl-event.h
> +++ b/include/linux/cxl-event.h
> @@ -3,6 +3,8 @@
> #ifndef _LINUX_CXL_EVENT_H
> #define _LINUX_CXL_EVENT_H
>
> +#include <linux/workqueue_types.h>
> +
> /*
> * Common Event Record Format
> * CXL rev 3.0 section 8.2.9.2.1; Table 8-42
> @@ -140,4 +142,29 @@ struct cxl_cper_event_rec {
> union cxl_event event;
> } __packed;
>
> +struct cxl_cper_work_data {
> + enum cxl_event_type event_type;
> + struct cxl_cper_event_rec rec;
> +};
> +
> +#ifdef CONFIG_ACPI_APEI_GHES
> +int cxl_cper_register_work(struct work_struct *work);
> +int cxl_cper_unregister_work(struct work_struct *work);
> +int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd);
> +#else
> +static inline int cxl_cper_register_work(struct work_struct *work);
> +{
> + return 0;
> +}
> +
> +static inline int cxl_cper_unregister_work(struct work_struct *work);
> +{
> + return 0;
> +}
> +static inline int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd)
> +{
> + return 0;
> +}
> +#endif
> +
> #endif /* _LINUX_CXL_EVENT_H */
>
> --
> 2.44.0
>