From: Mark Brown <broonie@kernel.org> Use of FEAT_NMI requires that all the PEs in the system and the GIC have NMI support. This patch implements the PE part of that detection. In order to avoid problematic interactions between real and pseudo NMIs we disable the architected feature if the user has enabled pseudo NMIs on the command line. If this is done on a system where support for the architected feature is detected then a warning is printed during boot in order to help users spot what is likely to be a misconfiguration. In order to allow KVM to offer the feature to guests even if pseudo NMIs are in use by the host we have a separate feature for the raw feature which is used in KVM. Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jie Liu <liujie375@h-partners.com> --- arch/arm64/include/asm/cpucaps.h | 2 + arch/arm64/include/asm/cpufeature.h | 8 ++++ arch/arm64/include/asm/sysreg.h | 5 +++ arch/arm64/kernel/cpufeature.c | 64 ++++++++++++++++++++++++++++- 4 files changed, 78 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 9a2d5148f9cc..2246c379a68d 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -67,6 +67,8 @@ #define ARM64_HAS_TIDCP1 57 #define ARM64_HAS_FGT 58 #define ARM64_HAFT 59 +#define ARM64_HAS_NMI 60 +#define ARM64_USES_NMI 61 #define ARM64_NCAPS 80 diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 528115f7e361..6e7ea1750010 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -284,6 +284,8 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; * CPUs must match the state of the capability as detected by the boot CPU. */ #define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE ARM64_CPUCAP_SCOPE_BOOT_CPU +#define ARM64_CPUCAP_BOOT_CPU_FEATURE \ + (ARM64_CPUCAP_SCOPE_BOOT_CPU | ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU) struct arm64_cpu_capabilities { const char *desc; @@ -658,6 +660,12 @@ static __always_inline bool system_uses_irq_prio_masking(void) cpus_have_const_cap(ARM64_HAS_IRQ_PRIO_MASKING); } +static __always_inline bool system_uses_nmi(void) +{ + return IS_ENABLED(CONFIG_ARM64_NMI) && + cpus_have_const_cap(ARM64_USES_NMI); +} + static inline bool system_has_prio_mask_debugging(void) { return IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) && diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index fecc829377a1..64eda6356005 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -529,6 +529,8 @@ /* SCTLR_EL1 specific flags. */ #define SCTLR_EL1_TIDCP (BIT(63)) +#define SCTLR_EL1_SPINTMASK (BIT(62)) +#define SCTLR_EL1_NMI (BIT(61)) #define SCTLR_EL1_UCI (BIT(26)) #define SCTLR_EL1_E0E (BIT(24)) #define SCTLR_EL1_SPAN (BIT(23)) @@ -645,6 +647,9 @@ #define ID_AA64PFR1_SSBS_PSTATE_ONLY 1 #define ID_AA64PFR1_SSBS_PSTATE_INSNS 2 +#define ID_AA64PFR1_NMI_IMP_DEF 0x1 +#define ID_AA64PFR1_NMI_IMP_NI 0x0 + /* id_aa64zfr0 */ #define ID_AA64ZFR0_SM4_SHIFT 40 #define ID_AA64ZFR0_SHA3_SHIFT 32 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 3ad5bc874e79..43fc63acb986 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -28,6 +28,7 @@ #include <asm/traps.h> #include <asm/vectors.h> #include <asm/virt.h> +#include <asm/daifflags.h> /* Kernel representation of AT_HWCAP and AT_HWCAP2 */ static unsigned long elf_hwcap __read_mostly; @@ -181,6 +182,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { }; static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = { + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_NMI_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI), ARM64_FTR_END, }; @@ -1275,9 +1277,11 @@ static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap) } #endif /* CONFIG_ARM64_PTR_AUTH */ -#ifdef CONFIG_ARM64_PSEUDO_NMI +#if IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) || IS_ENABLED(CONFIG_ARM64_NMI) static bool enable_pseudo_nmi; +#endif +#ifdef CONFIG_ARM64_PSEUDO_NMI static int __init early_enable_pseudo_nmi(char *p) { return strtobool(p, &enable_pseudo_nmi); @@ -1291,6 +1295,41 @@ static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry, } #endif +#ifdef CONFIG_ARM64_NMI +static bool use_nmi(const struct arm64_cpu_capabilities *entry, int scope) +{ + if (!has_cpuid_feature(entry, scope)) + return false; + + /* + * Having both real and pseudo NMIs enabled simultaneously is + * likely to cause confusion. Since pseudo NMIs must be + * enabled with an explicit command line option, if the user + * has set that option on a system with real NMIs for some + * reason assume they know what they're doing. + */ + if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && enable_pseudo_nmi) { + pr_info("Pseudo NMI enabled, not using architected NMI\n"); + return false; + } + + return true; +} + +static void nmi_enable(const struct arm64_cpu_capabilities *__unused) +{ + /* + * Enable use of NMIs controlled by ALLINT, SPINTMASK should + * be clear by default but make it explicit that we are using + * this mode. Ensure that ALLINT is clear first in order to + * avoid leaving things masked. + */ + _allint_clear(); + sysreg_clear_set(sctlr_el1, SCTLR_EL1_SPINTMASK, SCTLR_EL1_NMI); + isb(); +} +#endif + static void elf_hwcap_fixup(void) { #ifdef CONFIG_ARM64_ERRATUM_1742098 @@ -1672,6 +1711,29 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .sign = FTR_UNSIGNED, .min_field_value = 1, }, +#ifdef CONFIG_ARM64_NMI + { + .desc = "Non-maskable Interrupts present", + .capability = ARM64_HAS_NMI, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .sys_reg = SYS_ID_AA64PFR1_EL1, + .sign = FTR_UNSIGNED, + .field_pos = ID_AA64PFR1_NMI_SHIFT, + .min_field_value = ID_AA64PFR1_NMI_IMP_DEF, + .matches = has_cpuid_feature, + }, + { + .desc = "Non-maskable Interrupts enabled", + .capability = ARM64_USES_NMI, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .sys_reg = SYS_ID_AA64PFR1_EL1, + .sign = FTR_UNSIGNED, + .field_pos = ID_AA64PFR1_NMI_SHIFT, + .min_field_value = ID_AA64PFR1_NMI_IMP_DEF, + .matches = use_nmi, + .cpu_enable = nmi_enable, + }, +#endif {}, }; -- 2.25.1