From: Kai Shen shenkai8@huawei.com

hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8MKTT CVE: NA

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Random performance decreases appear on cases of Hackbench which test pipe or socket communication among multi-threads on Hisi HIP08 SoC. Cache sharing which caused by the change of the data layout and the cache readunique prefetch mechanism both lead to this problem.

Readunique mechanism which may caused by store operation will invalid cachelines on other cores during data fetching stage which can cause cacheline invalidation happens frequently in a sharing data access situation.

Disable cache readunique prefetch can trackle this problem. Test cases are like: for i in 20;do echo "--------pipe thread num=$i----------" for j in $(seq 1 10);do ./hackbench -pipe $i thread 1000 done done

We disable readunique prefetch only in el2 for in el1 disabling readunique prefetch may cause panic due to lack of related priority which often be set in BIOS.

Introduce CONFIG_HISILICON_ERRATUM_HIP08_RU_PREFETCH and disable RU prefetch using boot cmdline 'readunique_prefetch=off'.

Signed-off-by: Kai Shen shenkai8@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- arch/arm64/Kconfig | 18 +++++++++++ arch/arm64/kernel/cpu_errata.c | 56 ++++++++++++++++++++++++++++++++++ arch/arm64/tools/cpucaps | 1 + 3 files changed, 75 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1685fbd4b6f2..8225fb4a20a8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1240,6 +1240,24 @@ config SOCIONEXT_SYNQUACER_PREITS

If unsure, say Y.

+config HISILICON_ERRATUM_HIP08_RU_PREFETCH + bool "HIP08 RU: HiSilicon HIP08 cache readunique might cause performance drop" + default y + help + The HiSilicon HIP08 cache readunique might compromise performance, + use cmdline "readunique_prefetch_disable" to disable RU prefetch. + + If unsure, say Y. + +config HISILICON_HIP08_RU_PREFETCH_DEFAULT_OFF + bool "HIP08 RU: disable HiSilicon HIP08 cache readunique by default" + depends on HISILICON_ERRATUM_HIP08_RU_PREFETCH + default n + help + Disable HiSilicon HIP08 cache readunique by default. + + If unsure, say N. + endmenu # "ARM errata workarounds via the alternatives framework"

choice diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 74c4ecc4a980..e40b76ac4711 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -13,6 +13,11 @@ #include <asm/cpufeature.h> #include <asm/kvm_asm.h> #include <asm/smp_plat.h> +#ifdef CONFIG_HISILICON_ERRATUM_HIP08_RU_PREFETCH +#include <asm/ptrace.h> +#include <asm/sysreg.h> +#include <linux/smp.h> +#endif

static bool __maybe_unused is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope) @@ -121,6 +126,48 @@ cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused) sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCI, 0); }

+#ifdef CONFIG_HISILICON_ERRATUM_HIP08_RU_PREFETCH +# ifdef CONFIG_HISILICON_HIP08_RU_PREFETCH_DEFAULT_OFF +static bool readunique_prefetch_enabled; +# else +static bool readunique_prefetch_enabled = true; +# endif +static int __init readunique_prefetch_switch(char *data) +{ + if (!data) + return -EINVAL; + + if (strcmp(data, "off") == 0) + readunique_prefetch_enabled = false; + else if (strcmp(data, "on") == 0) + readunique_prefetch_enabled = true; + else + return -EINVAL; + + return 0; +} +early_param("readunique_prefetch", readunique_prefetch_switch); + +static bool +should_disable_hisi_hip08_ru_prefetch(const struct arm64_cpu_capabilities *entry, int unused) +{ + u64 el; + + if (readunique_prefetch_enabled) + return false; + + el = read_sysreg(CurrentEL); + return el == CurrentEL_EL2; +} + +#define CTLR_HISI_HIP08_RU_PREFETCH (1L << 40) +static void __maybe_unused +hisi_hip08_ru_prefetch_disable(const struct arm64_cpu_capabilities *__unused) +{ + sysreg_clear_set(S3_1_c15_c6_4, 0, CTLR_HISI_HIP08_RU_PREFETCH); +} +#endif + static DEFINE_RAW_SPINLOCK(reg_user_mask_modification); static void __maybe_unused cpu_clear_bf16_from_user_emulation(const struct arm64_cpu_capabilities *__unused) @@ -758,6 +805,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .capability = ARM64_WORKAROUND_AMPERE_AC03_CPU_38, ERRATA_MIDR_ALL_VERSIONS(MIDR_AMPERE1), }, +#endif +#ifdef CONFIG_HISILICON_ERRATUM_HIP08_RU_PREFETCH + { + .desc = "HiSilicon HIP08 Cache Readunique Prefetch Disable", + .capability = ARM64_WORKAROUND_HISI_HIP08_RU_PREFETCH, + ERRATA_MIDR_ALL_VERSIONS(MIDR_HISI_TSV110), + .matches = should_disable_hisi_hip08_ru_prefetch, + .cpu_enable = hisi_hip08_ru_prefetch_disable, + }, #endif { } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index d85d4a741aed..cb4996edc09f 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -101,3 +101,4 @@ WORKAROUND_QCOM_FALKOR_E1003 WORKAROUND_REPEAT_TLBI WORKAROUND_SPECULATIVE_AT WORKAROUND_HISILICON_ERRATUM_162100125 +WORKAROUND_HISI_HIP08_RU_PREFETCH