5.10-stable review patch. If anyone has any objections, please let me know.
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From: James Morse james.morse@arm.com
[ 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 james.morse@arm.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com [The conflicts were due to not include bitmap of mitigations] Signed-off-by: Pu Lehui pulehui@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/spectre.h | 1 + arch/arm64/kernel/proton-pack.c | 8 ++++++++ 2 files changed, 9 insertions(+)
--- a/arch/arm64/include/asm/spectre.h +++ b/arch/arm64/include/asm/spectre.h @@ -32,6 +32,7 @@ void spectre_v4_enable_task_mitigation(s
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); --- 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 cha 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 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)