linux-kernel - [tip:ras/core] x86/mce: Grade uncorrected errors for SMCA-enabled systems

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Date:	Tue, 3 May 2016 00:47:17 -0700
From:	tip-bot for Aravind Gopalakrishnan <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	luto@...capital.net, dvlasenk@...hat.com, Yazen.Ghannam@....com,
	aravindksg.lkml@...il.com, bp@...e.de, tglx@...utronix.de,
	Aravind.Gopalakrishnan@....com, mingo@...nel.org,
	peterz@...radead.org, brgerst@...il.com, bp@...en8.de,
	torvalds@...ux-foundation.org, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org, tony.luck@...el.com, hpa@...or.com
Subject: [tip:ras/core] x86/mce: Grade uncorrected errors for SMCA-enabled
 systems

Commit-ID:  6bda529ec42e1cd4dde1c3d0a1a18000ffd3d419
Gitweb:     http://git.kernel.org/tip/6bda529ec42e1cd4dde1c3d0a1a18000ffd3d419
Author:     Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
AuthorDate: Sat, 30 Apr 2016 14:33:52 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 3 May 2016 08:24:15 +0200

x86/mce: Grade uncorrected errors for SMCA-enabled systems

For upcoming processors with Scalable MCA feature, we need to check the
"succor" CPUID bit and the TCC bit in the MCx_STATUS register in order
to grade an MCE's severity.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
Signed-off-by: Yazen Ghannam <Yazen.Ghannam@....com>
[ Simplified code flow, shortened comments. ]
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Aravind Gopalakrishnan <aravindksg.lkml@...il.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: linux-edac <linux-edac@...r.kernel.org>
Link: http://lkml.kernel.org/r/1459886686-13977-3-git-send-email-Yazen.Ghannam@amd.com
Link: http://lkml.kernel.org/r/1462019637-16474-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/mcheck/mce-severity.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/x86/kernel/cpu/mcheck/mce-severity.c b/arch/x86/kernel/cpu/mcheck/mce-severity.c
index 5119766..631356c 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-severity.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-severity.c
@@ -204,6 +204,33 @@ static int error_context(struct mce *m)
 	return IN_KERNEL;
 }
 
+static int mce_severity_amd_smca(struct mce *m, int err_ctx)
+{
+	u32 addr = MSR_AMD64_SMCA_MCx_CONFIG(m->bank);
+	u32 low, high;
+
+	/*
+	 * We need to look at the following bits:
+	 * - "succor" bit (data poisoning support), and
+	 * - TCC bit (Task Context Corrupt)
+	 * in MCi_STATUS to determine error severity.
+	 */
+	if (!mce_flags.succor)
+		return MCE_PANIC_SEVERITY;
+
+	if (rdmsr_safe(addr, &low, &high))
+		return MCE_PANIC_SEVERITY;
+
+	/* TCC (Task context corrupt). If set and if IN_KERNEL, panic. */
+	if ((low & MCI_CONFIG_MCAX) &&
+	    (m->status & MCI_STATUS_TCC) &&
+	    (err_ctx == IN_KERNEL))
+		return MCE_PANIC_SEVERITY;
+
+	 /* ...otherwise invoke hwpoison handler. */
+	return MCE_AR_SEVERITY;
+}
+
 /*
  * See AMD Error Scope Hierarchy table in a newer BKDG. For example
  * 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features"
@@ -225,6 +252,9 @@ static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_exc
 		 * to at least kill process to prolong system operation.
 		 */
 		if (mce_flags.overflow_recov) {
+			if (mce_flags.smca)
+				return mce_severity_amd_smca(m, ctx);
+
 			/* software can try to contain */
 			if (!(m->mcgstatus & MCG_STATUS_RIPV) && (ctx == IN_KERNEL))
 				return MCE_PANIC_SEVERITY;