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Message-ID: <mazejvrglvtqdfsevduahqxvlvjv6hlo3apivossn2jnxpsuds@os6kxmmsq3xt>
Date: Fri, 18 Jul 2025 09:11:15 -0700
From: Breno Leitao <leitao@...ian.org>
To: "Luck, Tony" <tony.luck@...el.com>, xueshuai@...ux.alibaba.com,
mahesh@...ux.ibm.com, oohall@...il.com
Cc: Borislav Petkov <bp@...en8.de>,
"Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, James Morse <james.morse@....com>,
"Moore, Robert" <robert.moore@...el.com>, "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "acpica-devel@...ts.linux.dev" <acpica-devel@...ts.linux.dev>,
"kernel-team@...a.com" <kernel-team@...a.com>, osandov@...ndov.com, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] ghes: Track number of recovered hardware errors
Hello Tony,
On Thu, Jul 17, 2025 at 05:29:14PM +0000, Luck, Tony wrote:
>
> If the intent is still to add this information to vmcore (as in
> earlier discussions in this thread). Then it could go into
> kernel/vmcore_info.c (and be configured with CONFIG_VMCORE_INFO).
>
> Would just need an empty stub in some header file for the
> log_recovered_error() function.
Thanks for the suggestion.
I found that I don't need to expose the metrics in vmcore info at all to
be able to read them from vmcore, given crash/drgn can read those
symbols.
Global variable hwerror_tracking will be write-only during kernel
run-time, and only read during post morten analyzes. I am still not sure
if the compiler might not get rid of them completely, given no on reads.
I am wondering if I should EXPORT_SYMBOL_GPL(hwerror_tracking) to avoid
any optimization there.
Anyway, this is the patch I am using and it solves the problem I am
interested in. Any opinion?
Thanks for your support,
--breno
commit 396d9bd5266607731b535f4246fd3e4971df9016
Author: Breno Leitao <leitao@...ian.org>
Date: Thu Jul 17 07:39:26 2025 -0700
vmcoreinfo: Track and log recoverable hardware errors
Introduce a generic infrastructure for tracking recoverable hardware
errors (HW errors that did not cause a panic) and record them for vmcore
consumption. This aids post-mortem crash analysis tools by preserving
a count and timestamp for the last occurrence of such errors.
This patch adds centralized logging for three common sources of
recoverable hardware errors:
- PCIe AER Correctable errors
- x86 Machine Check Exceptions (MCE)
- APEI/CPER GHES corrected or recoverable errors
Each source logs to a shared `hwerror_tracking` array, protected by a
spinlock, and maintains a per-source error count and timestamp of the
most recent event.
hwerror_tracking is write-only at kernel runtime, and it is meant to be
read from vmcore using tools like crash/drgn. For example, this is how
it looks like from drgn:
>>> prog['hwerror_tracking']
(struct hwerror_tracking_info [3]){
{
.count = (int)0,
.timestamp = (time64_t)0,
},
{
.count = (int)0,
.timestamp = (time64_t)0,
},
{
.count = (int)844,
.timestamp = (time64_t)1752852018,
},
}
Suggested-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Breno Leitao <leitao@...ian.org>
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 4da4eab56c81d..781cf574642eb 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -45,6 +45,7 @@
#include <linux/task_work.h>
#include <linux/hardirq.h>
#include <linux/kexec.h>
+#include <linux/vmcore_info.h>
#include <asm/fred.h>
#include <asm/cpu_device_id.h>
@@ -1692,6 +1693,8 @@ noinstr void do_machine_check(struct pt_regs *regs)
out:
instrumentation_end();
+ /* Given it didn't panic, mark it as recoverable */
+ hwerror_tracking_log(HWE_RECOV_MCE);
clear:
mce_wrmsrq(MSR_IA32_MCG_STATUS, 0);
}
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index f0584ccad4519..255453cdc72e9 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -43,6 +43,7 @@
#include <linux/uuid.h>
#include <linux/ras.h>
#include <linux/task_work.h>
+#include <linux/vmcore_info.h>
#include <acpi/actbl1.h>
#include <acpi/ghes.h>
@@ -1100,13 +1101,16 @@ static int ghes_proc(struct ghes *ghes)
{
struct acpi_hest_generic_status *estatus = ghes->estatus;
u64 buf_paddr;
- int rc;
+ int rc, sev;
rc = ghes_read_estatus(ghes, estatus, &buf_paddr, FIX_APEI_GHES_IRQ);
if (rc)
goto out;
- if (ghes_severity(estatus->error_severity) >= GHES_SEV_PANIC)
+ sev = ghes_severity(estatus->error_severity);
+ if (sev == GHES_SEV_RECOVERABLE || sev == GHES_SEV_CORRECTED)
+ hwerror_tracking_log(HWE_RECOV_GHES);
+ else if (sev >= GHES_SEV_PANIC)
__ghes_panic(ghes, estatus, buf_paddr, FIX_APEI_GHES_IRQ);
if (!ghes_estatus_cached(estatus)) {
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 70ac661883672..9d4fa1cb8afb9 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -30,6 +30,7 @@
#include <linux/kfifo.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
+#include <linux/vmcore_info.h>
#include <acpi/apei.h>
#include <acpi/ghes.h>
#include <ras/ras_event.h>
@@ -746,6 +747,7 @@ static void pci_dev_aer_stats_incr(struct pci_dev *pdev,
switch (info->severity) {
case AER_CORRECTABLE:
aer_info->dev_total_cor_errs++;
+ hwerror_tracking_log(HWE_RECOV_AER);
counter = &aer_info->dev_cor_errs[0];
max = AER_MAX_TYPEOF_COR_ERRS;
break;
diff --git a/include/linux/vmcore_info.h b/include/linux/vmcore_info.h
index 37e003ae52626..5894da92a6ba4 100644
--- a/include/linux/vmcore_info.h
+++ b/include/linux/vmcore_info.h
@@ -77,4 +77,18 @@ extern u32 *vmcoreinfo_note;
Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
void *data, size_t data_len);
void final_note(Elf_Word *buf);
+
+enum hwerror_tracking_source {
+ HWE_RECOV_AER,
+ HWE_RECOV_MCE,
+ HWE_RECOV_GHES,
+ HWE_RECOV_MAX,
+};
+
+#ifdef CONFIG_VMCORE_INFO
+void hwerror_tracking_log(enum hwerror_tracking_source src);
+#else
+void hwerror_tracking_log(enum hwerror_tracking_source src) {};
+#endif
+
#endif /* LINUX_VMCORE_INFO_H */
diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c
index e066d31d08f89..c3d2bfffec298 100644
--- a/kernel/vmcore_info.c
+++ b/kernel/vmcore_info.c
@@ -31,6 +31,14 @@ u32 *vmcoreinfo_note;
/* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
static unsigned char *vmcoreinfo_data_safecopy;
+static struct hwerror_tracking_info {
+ int count;
+ time64_t timestamp;
+};
+
+static struct hwerror_tracking_info hwerror_tracking[HWE_RECOV_MAX];
+static DEFINE_SPINLOCK(hwerror_tracking_lock);
+
Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
void *data, size_t data_len)
{
@@ -118,6 +126,23 @@ phys_addr_t __weak paddr_vmcoreinfo_note(void)
}
EXPORT_SYMBOL(paddr_vmcoreinfo_note);
+void hwerror_tracking_log(enum hwerror_tracking_source src)
+{
+ struct hwerror_tracking_info *hwet;
+ unsigned long flags;
+
+ if (src < 0 || src >= HWE_RECOV_MAX)
+ return;
+
+ hwet = &hwerror_tracking[src];
+
+ spin_lock_irqsave(&hwerror_tracking_lock, flags);
+ hwet->count++;
+ hwet->timestamp = ktime_get_real_seconds();
+ spin_unlock_irqrestore(&hwerror_tracking_lock, flags);
+}
+EXPORT_SYMBOL_GPL(hwerror_tracking_log);
+
static int __init crash_save_vmcoreinfo_init(void)
{
vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
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