From: James Morse Date: Sat, 7 Jun 2025 15:25:12 +0000 (+0000) Subject: arm64: proton-pack: Expose whether the platform is mitigated by firmware X-Git-Tag: v5.10.239~28 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cde8ad8a7aa5f2edc1ca6ed5c3931295f5bdee05;p=thirdparty%2Fkernel%2Fstable.git arm64: proton-pack: Expose whether the platform is mitigated by firmware [ Upstream commit e7956c92f396a44eeeb6eaf7a5b5e1ad24db6748 ] is_spectre_bhb_fw_affected() allows the caller to determine if the CPU is known to need a firmware mitigation. CPUs are either on the list of CPUs we know about, or firmware has been queried and reported that the platform is affected - and mitigated by firmware. This helper is not useful to determine if the platform is mitigated by firmware. A CPU could be on the know list, but the firmware may not be implemented. Its affected but not mitigated. spectre_bhb_enable_mitigation() handles this distinction by checking the firmware state before enabling the mitigation. Add a helper to expose this state. This will be used by the BPF JIT to determine if calling firmware for a mitigation is necessary and supported. Signed-off-by: James Morse Reviewed-by: Catalin Marinas [The conflicts were due to not include bitmap of mitigations] Signed-off-by: Pu Lehui Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm64/include/asm/spectre.h b/arch/arm64/include/asm/spectre.h index e48afcb69392b..9c8ed2c4629dc 100644 --- a/arch/arm64/include/asm/spectre.h +++ b/arch/arm64/include/asm/spectre.h @@ -32,6 +32,7 @@ void spectre_v4_enable_task_mitigation(struct task_struct *tsk); enum mitigation_state arm64_get_spectre_bhb_state(void); bool is_spectre_bhb_affected(const struct arm64_cpu_capabilities *entry, int scope); +bool is_spectre_bhb_fw_mitigated(void); u8 spectre_bhb_loop_affected(int scope); void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *__unused); bool try_emulate_el1_ssbs(struct pt_regs *regs, u32 instr); diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 45fdfe70b69fc..95b8d76670c80 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -1059,6 +1059,8 @@ static void kvm_setup_bhb_slot(const char *hyp_vecs_start) static void kvm_setup_bhb_slot(const char *hyp_vecs_start) { } #endif /* CONFIG_KVM */ +static bool spectre_bhb_fw_mitigated; + void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) { enum mitigation_state fw_state, state = SPECTRE_VULNERABLE; @@ -1103,12 +1105,18 @@ void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) this_cpu_set_vectors(EL1_VECTOR_BHB_FW); state = SPECTRE_MITIGATED; + spectre_bhb_fw_mitigated = true; } } update_mitigation_state(&spectre_bhb_state, state); } +bool is_spectre_bhb_fw_mitigated(void) +{ + return spectre_bhb_fw_mitigated; +} + /* Patched to correct the immediate */ void noinstr spectre_bhb_patch_loop_iter(struct alt_instr *alt, __le32 *origptr, __le32 *updptr, int nr_inst)