From 6f13c3cee13d3bbd8175b5d4a5a121d2296992e1 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 20 Jul 2018 10:56:28 +0100 Subject: [PATCH] arm64: ssbd: Restore mitigation status on CPU resume commit 647d0519b53f440a55df163de21c52a8205431cc upstream. On a system where firmware can dynamically change the state of the mitigation, the CPU will always come up with the mitigation enabled, including when coming back from suspend. If the user has requested "no mitigation" via a command line option, let's enforce it by calling into the firmware again to disable it. Similarily, for a resume from hibernate, the mitigation could have been disabled by the boot kernel. Let's ensure that it is set back on in that case. Acked-by: Will Deacon Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/cpufeature.h | 6 ++++++ arch/arm64/kernel/cpu_errata.c | 2 +- arch/arm64/kernel/hibernate.c | 11 +++++++++++ arch/arm64/kernel/suspend.c | 8 ++++++++ 4 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index e78e1e0ffc90..1dc16f5b54ec 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -243,6 +243,12 @@ static inline int arm64_get_ssbd_state(void) #endif } +#ifdef CONFIG_ARM64_SSBD +void arm64_set_ssbd_mitigation(bool state); +#else +static inline void arm64_set_ssbd_mitigation(bool state) {} +#endif + #endif /* __ASSEMBLY__ */ #endif diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 9e0b311873ef..1db97ad7b58b 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -258,7 +258,7 @@ void __init arm64_enable_wa2_handling(struct alt_instr *alt, *updptr = cpu_to_le32(aarch64_insn_gen_nop()); } -static void arm64_set_ssbd_mitigation(bool state) +void arm64_set_ssbd_mitigation(bool state) { switch (psci_ops.conduit) { case PSCI_CONDUIT_HVC: diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c index 8bed26a2d558..db603cdd44a4 100644 --- a/arch/arm64/kernel/hibernate.c +++ b/arch/arm64/kernel/hibernate.c @@ -305,6 +305,17 @@ int swsusp_arch_suspend(void) sleep_cpu = -EINVAL; __cpu_suspend_exit(); + + /* + * Just in case the boot kernel did turn the SSBD + * mitigation off behind our back, let's set the state + * to what we expect it to be. + */ + switch (arm64_get_ssbd_state()) { + case ARM64_SSBD_FORCE_ENABLE: + case ARM64_SSBD_KERNEL: + arm64_set_ssbd_mitigation(true); + } } local_dbg_restore(flags); diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c index db2089aad9a3..4c1c038644d2 100644 --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c @@ -67,6 +67,14 @@ void notrace __cpu_suspend_exit(void) */ if (hw_breakpoint_restore) hw_breakpoint_restore(cpu); + + /* + * On resume, firmware implementing dynamic mitigation will + * have turned the mitigation on. If the user has forcefully + * disabled it, make sure their wishes are obeyed. + */ + if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) + arm64_set_ssbd_mitigation(false); } /*