[PATCH v3 6/6] arm64: Update silicon-errata.txt for Neoverse-N1 #1349291

[James Morse <james.morse@arm.com>]

Neoverse-N1 affected by #1349291 may report an Uncontained RAS Error
as Unrecoverable. The kernel's architecture code already considers
Unrecoverable errors as fatal as without kernel-first support no
further error-handling is possible.

Now that KVM attributes SError to the host/guest more precisely
the host's architecture code will always handle host errors that
become pending during world-switch.
Errors misclassified by this errata that affected the guest will be
re-injected to the guest as an implementation-defined SError, which can
be uncontained.

Until kernel-first support is implemented, no workaround is needed
for this issue.

Signed-off-by: James Morse <james.morse@arm.com>
---
imp-def SError can mean uncontained. In the RAS spec, 2.4.2 "ESB and other
containable errors":
| It is [imp-def] whether [imp-def] and uncategorized SError interrupts
| are containable or Uncontainable.
---
 Documentation/arm64/silicon-errata.txt | 1 +
 arch/arm64/kernel/traps.c              | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 2735462d5958..51d506a1f8dc 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -63,6 +63,7 @@ stable kernels.
 | ARM            | Cortex-A76      | #1286807        | ARM64_ERRATUM_1286807       |
 | ARM            | Cortex-A76      | #1463225        | ARM64_ERRATUM_1463225       |
 | ARM            | Neoverse-N1     | #1188873,1418040| ARM64_ERRATUM_1418040       |
+| ARM            | Neoverse-N1     | #1349291        | N/A                         |
 | ARM            | MMU-500         | #841119,826419  | N/A                         |
 |                |                 |                 |                             |
 | Cavium         | ThunderX ITS    | #22375,24313    | CAVIUM_ERRATUM_22375        |
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index e6be1a6efc0a..9f64cd609298 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -888,6 +888,10 @@ bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned int esr)
 		/*
 		 * The CPU can't make progress. The exception may have
 		 * been imprecise.
+		 *
+		 * Neoverse-N1 #1349291 means a non-KVM SError reported as
+		 * Unrecoverable should be treated as Uncontainable. We
+		 * call arm64_serror_panic() in both cases.
 		 */
 		return true;
 
-- 
2.20.1


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