From: Mark Rutland <mark.rutland@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Kees Cook <keescook@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Christoffer Dall <christoffer.dall@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Julien Grall <julien.grall@arm.com>
Subject: Re: [PATCH v2 08/17] arm64: ssbd: Restore mitigation status on CPU resume
Date: Tue, 29 May 2018 14:35:13 +0100 [thread overview]
Message-ID: <20180529133510.xopxpmxf7ypjeksc@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20180529121121.24927-9-marc.zyngier@arm.com>
On Tue, May 29, 2018 at 01:11:12PM +0100, Marc Zyngier wrote:
> 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.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
With teh fixup in swsusp_arch_suspend(), this looks good to me. FWIW:
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> ---
> 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 b0fc3224ce8a..55bc1f073bfb 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -553,6 +553,12 @@ 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 2fef634e6953..2b9a31a6a16a 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -303,7 +303,7 @@ 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 1ec5f28c39fc..6b2686d54411 100644
> --- a/arch/arm64/kernel/hibernate.c
> +++ b/arch/arm64/kernel/hibernate.c
> @@ -313,6 +313,17 @@ 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_daif_restore(flags);
> diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
> index a307b9e13392..70c283368b64 100644
> --- a/arch/arm64/kernel/suspend.c
> +++ b/arch/arm64/kernel/suspend.c
> @@ -62,6 +62,14 @@ 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);
> }
>
> /*
> --
> 2.14.2
>
next prev parent reply other threads:[~2018-05-29 13:35 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-29 12:11 [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 01/17] arm/arm64: smccc: Add SMCCC-specific return codes Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 02/17] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 03/17] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 04/17] arm64: Add ARCH_WORKAROUND_2 probing Marc Zyngier
2018-05-29 13:39 ` Suzuki K Poulose
2018-05-29 12:11 ` [PATCH v2 05/17] arm64: Add 'ssbd' command-line option Marc Zyngier
2018-06-09 12:53 ` Jon Masters
2018-06-09 13:19 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 06/17] arm64: ssbd: Add global mitigation state accessor Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 07/17] arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation Marc Zyngier
2018-06-09 13:03 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 08/17] arm64: ssbd: Restore mitigation status on CPU resume Marc Zyngier
2018-05-29 13:35 ` Mark Rutland [this message]
2018-05-29 12:11 ` [PATCH v2 09/17] arm64: ssbd: Introduce thread flag to control userspace mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 10/17] arm64: ssbd: Add prctl interface for per-thread mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 11/17] arm64: KVM: Add HYP per-cpu accessors Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 12/17] arm64: KVM: Add ARCH_WORKAROUND_2 support for guests Marc Zyngier
2018-06-09 13:09 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 13/17] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 14/17] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 15/17] arm64: Add test_and_clear_flag and set_flag atomic assembler primitives Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 16/17] arm64: ssbd: Enable delayed setting of TIF_SSBD Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 17/17] arm64: ssbd: Implement arch_seccomp_spec_mitigate Marc Zyngier
2018-05-30 15:58 ` [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Will Deacon
2018-05-31 16:41 ` Catalin Marinas
2018-05-31 16:55 ` Marc Zyngier
2018-06-09 13:16 ` Jon Masters
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