arm64: errata: Add Cortex-A510 speculative unprivileged load workaround

Implement the workaround for ARM Cortex-A510 erratum 3117295. On an
affected Cortex-A510 core, a speculatively executed unprivileged load
might leak data from a privileged load via a cache side channel. The
issue only exists for loads within a translation regime with the same
translation (e.g. same ASID and VMID). Therefore, the issue only affects
the return to EL0.

The erratum and workaround are the same as ARM Cortex-A520 erratum
2966298, so reuse the existing workaround.

Cc: [email protected]
Signed-off-by: Rob Herring <[email protected]>
Reviewed-by: Mark Rutland <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: robherring

Documentation/arch/arm64/silicon-errata.rst

@@ -71,6 +71,8 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A510     | #2658417        | ARM64_ERRATUM_2658417       |
 +----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #3117295        | ARM64_ERRATUM_3117295       |
++----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A520     | #2966298        | ARM64_ERRATUM_2966298       |
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A53      | #826319         | ARM64_ERRATUM_826319        |

arch/arm64/Kconfig

@@ -1054,6 +1054,20 @@ config ARM64_ERRATUM_2966298
 
 	  If unsure, say Y.
 
+config ARM64_ERRATUM_3117295
+	bool "Cortex-A510: 3117295: workaround for speculatively executed unprivileged load"
+	select ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
+	default y
+	help
+	  This option adds the workaround for ARM Cortex-A510 erratum 3117295.
+
+	  On an affected Cortex-A510 core, a speculatively executed unprivileged
+	  load might leak data from a privileged level via a cache side channel.
+
+	  Work around this problem by executing a TLBI before returning to EL0.
+
+	  If unsure, say Y.
+
 config CAVIUM_ERRATUM_22375
 	bool "Cavium erratum 22375, 24313"
 	default y

arch/arm64/kernel/cpu_errata.c

@@ -416,6 +416,19 @@ static struct midr_range broken_aarch32_aes[] = {
 };
 #endif /* CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE */
 
+#ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
+static const struct midr_range erratum_spec_unpriv_load_list[] = {
+#ifdef CONFIG_ARM64_ERRATUM_3117295
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A510),
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_2966298
+	/* Cortex-A520 r0p0 to r0p1 */
+	MIDR_REV_RANGE(MIDR_CORTEX_A520, 0, 0, 1),
+#endif
+	{},
+};
+#endif
+
 const struct arm64_cpu_capabilities arm64_errata[] = {
 #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
 	{
@@ -715,10 +728,10 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 #endif
 #ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
 	{
-		.desc = "ARM erratum 2966298",
+		.desc = "ARM errata 2966298, 3117295",
 		.capability = ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD,
 		/* Cortex-A520 r0p0 - r0p1 */
-		ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A520, 0, 0, 1),
+		ERRATA_MIDR_RANGE_LIST(erratum_spec_unpriv_load_list),
 	},
 #endif
 #ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_38