[tip: ras/core] x86/mce: Add messages for panic errors in AMD's MCE grading

[tip-bot2 for Carlos Bilbao]

The following commit has been merged into the ras/core branch of tip:

Commit-ID:     fa619f5156cf1ee3773edc6d756be262c9ef35de
Gitweb:        https://git.kernel.org/tip/fa619f5156cf1ee3773edc6d756be262c9ef35de
Author:        Carlos Bilbao <carlos.bilbao@xxxxxxx>
AuthorDate:    Tue, 05 Apr 2022 13:32:14 -05:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Mon, 25 Apr 2022 12:40:48 +02:00

x86/mce: Add messages for panic errors in AMD's MCE grading

When a machine error is graded as PANIC by the AMD grading logic, the
MCE handler calls mce_panic(). The notification chain does not come
into effect so the AMD EDAC driver does not decode the errors. In these
cases, the messages displayed to the user are more cryptic and miss
information that might be relevant, like the context in which the error
took place.

Add messages to the grading logic for machine errors so that it is clear
what error it was.

  [ bp: Massage commit message. ]

Signed-off-by: Carlos Bilbao <carlos.bilbao@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
Link: https://lore.kernel.org/r/20220405183212.354606-3-carlos.bilbao@xxxxxxx
---
 arch/x86/kernel/cpu/mce/severity.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index d842148..00483d1 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -304,6 +304,7 @@ static noinstr int error_context(struct mce *m, struct pt_regs *regs)
 /* See AMD PPR(s) section Machine Check Error Handling. */
 static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **msg, bool is_excp)
 {
+	char *panic_msg = NULL;
 	int ret;
 
 	/*
@@ -314,6 +315,7 @@ static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **
 
 	/* Processor Context Corrupt, no need to fumble too much, die! */
 	if (m->status & MCI_STATUS_PCC) {
+		panic_msg = "Processor Context Corrupt";
 		ret = MCE_PANIC_SEVERITY;
 		goto out;
 	}
@@ -337,19 +339,26 @@ static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, char **
 	 * system will not be able to recover, panic.
 	 */
 	if ((m->status & MCI_STATUS_OVER) && !mce_flags.overflow_recov) {
+		panic_msg = "Overflowed uncorrected error without MCA Overflow Recovery";
 		ret = MCE_PANIC_SEVERITY;
 		goto out;
 	}
 
 	if (!mce_flags.succor) {
+		panic_msg = "Uncorrected error without MCA Recovery";
 		ret = MCE_PANIC_SEVERITY;
 		goto out;
 	}
 
-	if (error_context(m, regs) == IN_KERNEL)
+	if (error_context(m, regs) == IN_KERNEL) {
+		panic_msg = "Uncorrected unrecoverable error in kernel context";
 		ret = MCE_PANIC_SEVERITY;
+	}
 
 out:
+	if (msg && panic_msg)
+		*msg = panic_msg;
+
 	return ret;
 }