From: James Morse james.morse@arm.com
maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7ZC0H
Reference: https://lore.kernel.org/all/20211015161416.2196-1-james.morse@arm.com/t/#u
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If the CPUs support HPDS2, and there is a DT description of PBHA values that only affect performance, enable those bits for both TTBR0 and TTBR1.
Enabling PBHA requires the hierarchical-permissions to be disabled. Commit 87143f404f33 ("arm64: mm: use XN table mapping attributes for the linear region") used these, but only as an optimisation.
Only the necessary PBHA bits are enabled to reduce the risk of an unsafe bit/value being used by accident.
Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Ma Wupeng mawupeng1@huawei.com --- arch/arm64/Kconfig | 13 +++++ arch/arm64/include/asm/cpucaps.h | 1 + arch/arm64/include/asm/pgtable-hwdef.h | 4 ++ arch/arm64/kernel/cpufeature.c | 81 ++++++++++++++++++++++++++ 4 files changed, 99 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 143c2209368d..48bd8258bd34 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1691,6 +1691,19 @@ config ARM64_CNP at runtime, and does not affect PEs that do not implement this feature.
+config ARM64_PBHA + bool "Enable support for Page Based Hardware Attributes (PBHA)" + default n + help + Page Based Hardware Attributes (PBHA) allow the SoC hardware to + change behaviour depending on which mapping was used to access + a page of memory. e.g. access via one mapping may always result + in the data being cached, whereas using another mapping of the same + physical memory. + + The behaviour of each PBHA bit is not defined. Say no unless you + are very sure you want this + endmenu
menu "ARMv8.3 architectural features" diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index f7e15076a12c..5afb9b1e10e8 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -77,6 +77,7 @@ #define ARM64_WORKAROUND_HISILICON_ERRATUM_162100125 69 #define ARM64_HAS_LDAPR 70 #define ARM64_HAS_PBHA 71 +#define ARM64_HAS_PBHA_STAGE1 72
#define ARM64_NCAPS 80
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 01a96d07ae74..bb80c1f0405f 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -260,6 +260,10 @@ #define TCR_TBI1 (UL(1) << 38) #define TCR_HA (UL(1) << 39) #define TCR_HD (UL(1) << 40) +#define TCR_HPD0 (UL(1) << 41) +#define TCR_HPD1 (UL(1) << 42) +#define TCR_HWU0nn_MASK (UL(0xf) << 43) +#define TCR_HWU1nn_MASK (UL(0xf) << 47) #define TCR_NFD0 (UL(1) << 53) #define TCR_NFD1 (UL(1) << 54) #define TCR_E0PD0 (UL(1) << 55) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6590ea28add3..a55040cddab9 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -70,6 +70,7 @@ #include <linux/stop_machine.h> #include <linux/types.h> #include <linux/mm.h> +#include <linux/of.h> #include <linux/cpu.h>
#include <asm/cpu.h> @@ -110,6 +111,8 @@ EXPORT_SYMBOL(arm64_use_ng_mappings);
DEFINE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector) = vectors;
+unsigned long __ro_after_init arm64_pbha_perf_only_values; + /* * Flag to indicate if we have computed the system wide * capabilities based on the boot time active CPUs. This @@ -1574,6 +1577,71 @@ static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
#endif
+#ifdef CONFIG_ARM64_PBHA +static u8 pbha_stage1_enable_bits; + +static bool plat_can_use_pbha_stage1(const struct arm64_cpu_capabilities *cap, + int scope) +{ + u8 val; + struct device_node *cpus; + const u8 *perf_only_vals; + int num_perf_only_vals, i; + + if (!has_cpuid_feature(cap, scope)) + return false; + + /* + * Calls with scope == SCOPE_LOCAL_CPU need only testing whether this + * cpu has the feature. A later 'system' scope call will check for a + * firmware description. + */ + if (scope == SCOPE_LOCAL_CPU) + return true; + + cpus = of_find_node_by_path("/cpus"); + if (!cpus) + goto done; + + perf_only_vals = of_get_property(cpus, "arm,pbha-performance-only", + &num_perf_only_vals); + if (!perf_only_vals) + goto done; + + /* any listed value is usable at stage 1 */ + for (i = 0 ; i < num_perf_only_vals; i++) { + val = perf_only_vals[i]; + if (val > 0xf) + continue; + + pbha_stage1_enable_bits |= val; + set_bit(val, &arm64_pbha_perf_only_values); + } + +done: + of_node_put(cpus); + + return !!pbha_stage1_enable_bits; +} + +static void cpu_enable_pbha(struct arm64_cpu_capabilities const *cap) +{ + u64 tcr; + + if (!pbha_stage1_enable_bits) + return; + + tcr = read_sysreg(tcr_el1); + tcr |= FIELD_PREP(TCR_HWU0nn_MASK, pbha_stage1_enable_bits); + tcr |= FIELD_PREP(TCR_HWU1nn_MASK, pbha_stage1_enable_bits); + tcr |= FIELD_PREP(TCR_HPD0, 1) | FIELD_PREP(TCR_HPD1, 1); + + write_sysreg(tcr, tcr_el1); + isb(); + local_flush_tlb_all(); +} +#endif /* CONFIG_ARM64_PBHA */ + #ifdef CONFIG_ARM64_AMU_EXTN
/* @@ -2304,6 +2372,19 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = has_cpuid_feature, .min_field_value = 2, }, +#ifdef CONFIG_ARM64_PBHA + { + .desc = "Page Based Hardware Attributes (PBHA)", + .capability = ARM64_HAS_PBHA_STAGE1, + .type = ARM64_CPUCAP_SYSTEM_FEATURE, + .sys_reg = SYS_ID_AA64MMFR1_EL1, + .sign = FTR_UNSIGNED, + .field_pos = ID_AA64MMFR1_HPD_SHIFT, + .matches = plat_can_use_pbha_stage1, + .min_field_value = 2, + .cpu_enable = cpu_enable_pbha, + }, +#endif {}, };