linux-kernel - [PATCH v8] x86/mce: retrieve poison range from hardware

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Message-Id: <20220826233851.1319100-1-jane.chu@oracle.com>
Date:   Fri, 26 Aug 2022 17:38:51 -0600
From:   Jane Chu <jane.chu@...cle.com>
To:     tony.luck@...el.com, bp@...en8.de, tglx@...utronix.de,
        mingo@...hat.com, dave.hansen@...ux.intel.com, x86@...nel.org,
        linux-edac@...r.kernel.org, dan.j.williams@...el.com,
        linux-kernel@...r.kernel.org, hch@....de, nvdimm@...ts.linux.dev
Subject: [PATCH v8] x86/mce: retrieve poison range from hardware

When memory poison consumption machine checks fire,
mce-notifier-handlers like nfit_handle_mce() record the impacted
physical address range which is reported by the hardware in the
MCi_MISC MSR. The error information includes data about blast radius,
i.e. how many cachelines did the hardware determine are impacted.
A recent change, commit 7917f9cdb503 ("acpi/nfit: rely on mce->misc to
determine poison granularity"), updated nfit_handle_mce() to stop hard
coding the blast radius value of 1 cacheline, and instead rely on the
blast radius reported in 'struct mce' which can be up to 4K (64 cachelines).

It turns out that apei_mce_report_mem_error() had a similar problem in
that it hard coded a blast radius of 4K rather than reading the blast
radius from the error information. Fix apei_mce_report_mem_error() to
convey the proper poison granularity.

Link: https://lore.kernel.org/r/7ed50fd8-521e-cade-77b1-738b8bfb8502@oracle.com

Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Jane Chu <jane.chu@...cle.com>
---
 arch/x86/kernel/cpu/mce/apei.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/apei.c b/arch/x86/kernel/cpu/mce/apei.c
index 717192915f28..8ed341714686 100644
--- a/arch/x86/kernel/cpu/mce/apei.c
+++ b/arch/x86/kernel/cpu/mce/apei.c
@@ -29,15 +29,26 @@
 void apei_mce_report_mem_error(int severity, struct cper_sec_mem_err *mem_err)
 {
 	struct mce m;
+	int lsb;

 	if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))
 		return;

+	/*
+	 * Even if the ->validation_bits are set for address mask,
+	 * to be extra safe, check and reject an error radius '0',
+	 * and fall back to the default page size.
+	 */
+	if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK)
+		lsb = find_first_bit((void *)&mem_err->physical_addr_mask, PAGE_SHIFT);
+	else
+		lsb = PAGE_SHIFT;
+
 	mce_setup(&m);
 	m.bank = -1;
 	/* Fake a memory read error with unknown channel */
 	m.status = MCI_STATUS_VAL | MCI_STATUS_EN | MCI_STATUS_ADDRV | MCI_STATUS_MISCV | 0x9f;
-	m.misc = (MCI_MISC_ADDR_PHYS << 6) | PAGE_SHIFT;
+	m.misc = (MCI_MISC_ADDR_PHYS << 6) | lsb;

 	if (severity >= GHES_SEV_RECOVERABLE)
 		m.status |= MCI_STATUS_UC;
-- 
2.18.4