[PATCH 5.15 2/4] arm64: errata: Add workaround for TSB flush failures
Easwar Hariharan
eahariha at linux.microsoft.com
Thu Jul 20 16:23:32 PDT 2023
From: Suzuki K Poulose <suzuki.poulose at arm.com>
commit fa82d0b4b833790ac4572377fb777dcea24a9d69 upstream
Arm Neoverse-N2 (#2067961) and Cortex-A710 (#2054223) suffers
from errata, where a TSB (trace synchronization barrier)
fails to flush the trace data completely, when executed from
a trace prohibited region. In Linux we always execute it
after we have moved the PE to trace prohibited region. So,
we can apply the workaround every time a TSB is executed.
The work around is to issue two TSB consecutively.
NOTE: This errata is defined as LOCAL_CPU_ERRATUM, implying
that a late CPU could be blocked from booting if it is the
first CPU that requires the workaround. This is because we
do not allow setting a cpu_hwcaps after the SMP boot. The
other alternative is to use "this_cpu_has_cap()" instead
of the faster system wide check, which may be a bit of an
overhead, given we may have to do this in nvhe KVM host
before a guest entry.
Cc: Will Deacon <will at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Mathieu Poirier <mathieu.poirier at linaro.org>
Cc: Mike Leach <mike.leach at linaro.org>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Anshuman Khandual <anshuman.khandual at arm.com>
Cc: Marc Zyngier <maz at kernel.org>
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier at linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual at arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
Link: https://lore.kernel.org/r/20211019163153.3692640-4-suzuki.poulose@arm.com
Signed-off-by: Will Deacon <will at kernel.org>
---
Documentation/arm64/silicon-errata.rst | 4 ++++
arch/arm64/Kconfig | 33 ++++++++++++++++++++++++++
arch/arm64/include/asm/barrier.h | 16 ++++++++++++-
arch/arm64/kernel/cpu_errata.c | 19 +++++++++++++++
arch/arm64/tools/cpucaps | 1 +
5 files changed, 72 insertions(+), 1 deletion(-)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 076861b0f5ac..1de575fc135b 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -104,6 +104,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A710 | #2119858 | ARM64_ERRATUM_2119858 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A710 | #2054223 | ARM64_ERRATUM_2054223 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |
@@ -112,6 +114,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N2 | #2139208 | ARM64_ERRATUM_2139208 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Neoverse-N2 | #2067961 | ARM64_ERRATUM_2067961 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e5e35470647b..6dce6e56ee53 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -774,6 +774,39 @@ config ARM64_ERRATUM_2139208
If unsure, say Y.
+config ARM64_WORKAROUND_TSB_FLUSH_FAILURE
+ bool
+
+config ARM64_ERRATUM_2054223
+ bool "Cortex-A710: 2054223: workaround TSB instruction failing to flush trace"
+ default y
+ select ARM64_WORKAROUND_TSB_FLUSH_FAILURE
+ help
+ Enable workaround for ARM Cortex-A710 erratum 2054223
+
+ Affected cores may fail to flush the trace data on a TSB instruction, when
+ the PE is in trace prohibited state. This will cause losing a few bytes
+ of the trace cached.
+
+ Workaround is to issue two TSB consecutively on affected cores.
+
+ If unsure, say Y.
+
+config ARM64_ERRATUM_2067961
+ bool "Neoverse-N2: 2067961: workaround TSB instruction failing to flush trace"
+ default y
+ select ARM64_WORKAROUND_TSB_FLUSH_FAILURE
+ help
+ Enable workaround for ARM Neoverse-N2 erratum 2067961
+
+ Affected cores may fail to flush the trace data on a TSB instruction, when
+ the PE is in trace prohibited state. This will cause losing a few bytes
+ of the trace cached.
+
+ Workaround is to issue two TSB consecutively on affected cores.
+
+ If unsure, say Y.
+
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 451e11e5fd23..1c5a00598458 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -23,7 +23,7 @@
#define dsb(opt) asm volatile("dsb " #opt : : : "memory")
#define psb_csync() asm volatile("hint #17" : : : "memory")
-#define tsb_csync() asm volatile("hint #18" : : : "memory")
+#define __tsb_csync() asm volatile("hint #18" : : : "memory")
#define csdb() asm volatile("hint #20" : : : "memory")
#ifdef CONFIG_ARM64_PSEUDO_NMI
@@ -46,6 +46,20 @@
#define dma_rmb() dmb(oshld)
#define dma_wmb() dmb(oshst)
+
+#define tsb_csync() \
+ do { \
+ /* \
+ * CPUs affected by Arm Erratum 2054223 or 2067961 needs \
+ * another TSB to ensure the trace is flushed. The barriers \
+ * don't have to be strictly back to back, as long as the \
+ * CPU is in trace prohibited state. \
+ */ \
+ if (cpus_have_final_cap(ARM64_WORKAROUND_TSB_FLUSH_FAILURE)) \
+ __tsb_csync(); \
+ __tsb_csync(); \
+ } while (0)
+
/*
* Generate a mask for array_index__nospec() that is ~0UL when 0 <= idx < sz
* and 0 otherwise.
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index d810d4b7b438..ab412b45732f 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -375,6 +375,18 @@ static const struct midr_range trbe_overwrite_fill_mode_cpus[] = {
};
#endif /* CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE */
+#ifdef CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE
+static const struct midr_range tsb_flush_fail_cpus[] = {
+#ifdef CONFIG_ARM64_ERRATUM_2067961
+ MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_2054223
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A710),
+#endif
+ {},
+};
+#endif /* CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE */
+
const struct arm64_cpu_capabilities arm64_errata[] = {
#ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
{
@@ -606,6 +618,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
CAP_MIDR_RANGE_LIST(trbe_overwrite_fill_mode_cpus),
},
+#endif
+#ifdef CONFIG_ARM64_WORKAROUND_TSB_FLUSH_FAILURE
+ {
+ .desc = "ARM erratum 2067961 or 2054223",
+ .capability = ARM64_WORKAROUND_TSB_FLUSH_FAILURE,
+ ERRATA_MIDR_RANGE_LIST(tsb_flush_fail_cpus),
+ },
#endif
{
}
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 32fe50a3a26c..36ab307c69d4 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -57,6 +57,7 @@ WORKAROUND_1542419
WORKAROUND_1742098
WORKAROUND_2457168
WORKAROUND_TRBE_OVERWRITE_FILL_MODE
+WORKAROUND_TSB_FLUSH_FAILURE
WORKAROUND_CAVIUM_23154
WORKAROUND_CAVIUM_27456
WORKAROUND_CAVIUM_30115
--
2.25.1
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