[PATCH v2] arm64: cpufeature: Add "or" to mitigations for multiple errata

[PATCH v2] arm64: cpufeature: Add "or" to mitigations for multiple errata

[Geert Uytterhoeven]

Several actions are not mitigations for a single erratum, but for
multiple errata.  However, printing a line like

    CPU features: detected: ARM errata 1165522, 1530923

may give the false impression that all three listed errata have been
detected.  This can confuse the user, who may think his Cortex-A55 is
suddenly affected by a Cortex-A76 erratum.

Add "or" to all descriptions for mitigations for multiple errata, to
make it clear that only one or more of the errata printed are
applicable, and not necessarily all of them.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v2:
  - Rebased on top of arm64 for-next/kconfig, which required updating the
    example and the explanation.

 arch/arm64/kernel/cpu_errata.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index df56d2295d165a0d..c8cb98a4fa6d5bf5 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -774,7 +774,7 @@ static const struct midr_range erratum_speculative_at_vhe_list[] = {
 const struct arm64_cpu_capabilities arm64_errata[] = {
 #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
 	{
-		.desc = "ARM errata 826319, 827319, 824069, 819472",
+		.desc = "ARM errata 826319, 827319, 824069, or 819472",
 		.capability = ARM64_WORKAROUND_CLEAN_CACHE,
 		ERRATA_MIDR_RANGE_LIST(workaround_clean_cache),
 		.cpu_enable = cpu_enable_cache_maint_trap,
@@ -856,7 +856,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 #endif
 #ifdef CONFIG_ARM64_WORKAROUND_REPEAT_TLBI
 	{
-		.desc = "Qualcomm erratum 1009, ARM erratum 1286807",
+		.desc = "Qualcomm erratum 1009, or ARM erratum 1286807",
 		.capability = ARM64_WORKAROUND_REPEAT_TLBI,
 		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
 		.matches = cpucap_multi_entry_cap_matches,
@@ -899,7 +899,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 #endif
 #ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_AT_VHE
 	{
-		.desc = "ARM errata 1165522, 1530923",
+		.desc = "ARM errata 1165522 or 1530923",
 		.capability = ARM64_WORKAROUND_SPECULATIVE_AT_VHE,
 		ERRATA_MIDR_RANGE_LIST(erratum_speculative_at_vhe_list),
 	},
-- 
2.17.1

Re: [PATCH v2] arm64: cpufeature: Add "or" to mitigations for multiple errata

[Will Deacon]

On Tue, 12 May 2020 16:52:55 +0200, Geert Uytterhoeven wrote:
> Several actions are not mitigations for a single erratum, but for
> multiple errata.  However, printing a line like
> 
>     CPU features: detected: ARM errata 1165522, 1530923
> 
> may give the false impression that all three listed errata have been
> detected.  This can confuse the user, who may think his Cortex-A55 is
> suddenly affected by a Cortex-A76 erratum.
> 
> [...]

Applied to arm64 (for-next/kconfig), thanks!

[1/1] arm64: cpufeature: Add "or" to mitigations for multiple errata
      https://git.kernel.org/arm64/c/357dd8a2aff2

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev