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SubjectRe: [PATCH 07/15] x86/split_lock: Handle suspend/hibernate and resume
Date
On Monday, May 14, 2018 8:52:17 PM CEST Fenghua Yu wrote:
> During suspend or hibernation, system enters BIOS. To avoid potential
> BIOS issue that may generate #AC exception for split locked accesses,
> handle the #AC as fatal exception, and block suspend or hibernation,
> the split lock setting is restored to BIOS setting. When resuming
> from suspend or hibernation, the split lock setting is restored to
> kernel setting.
>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
> arch/x86/include/asm/cpu.h | 2 ++
> arch/x86/kernel/cpu/split_lock.c | 54 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index 0b00033b6fa8..89d62d7051fa 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -45,11 +45,13 @@ int __init enumerate_split_lock(void);
> void setup_split_lock(void);
> bool do_split_lock_exception(struct pt_regs *regs, unsigned long error_code);
> bool restore_split_lock_ac_bios(int *enable);
> +bool restore_split_lock_ac_kernel(int *enable);
> #else /* CONFIG_SPLIT_LOCK_AC */
> static inline int enumerate_split_lock(void) { return 0; }
> static inline void setup_split_lock(void) {}
> static inline bool
> do_split_lock_exception(struct pt_regs *regs, unsigned long error_code) {}
> static inline bool restore_split_lock_ac_bios(int *enable) { return true; }
> +static inline bool restore_split_lock_ac_kernel(int *enable) { return true; }
> #endif /* CONFIG_SPLIT_LOCK_AC */
> #endif /* _ASM_X86_CPU_H */
> diff --git a/arch/x86/kernel/cpu/split_lock.c b/arch/x86/kernel/cpu/split_lock.c
> index d2735259800b..5187a9c6cea6 100644
> --- a/arch/x86/kernel/cpu/split_lock.c
> +++ b/arch/x86/kernel/cpu/split_lock.c
> @@ -14,6 +14,7 @@
> #include <linux/workqueue.h>
> #include <linux/cpu.h>
> #include <linux/reboot.h>
> +#include <linux/syscore_ops.h>
> #include <asm/msr.h>
>
> static bool split_lock_ac_supported;
> @@ -143,6 +144,15 @@ bool restore_split_lock_ac_bios(int *enable)
> return restore_split_lock_ac(split_lock_ac_bios);
> }
>
> +/* Restore kernel setting for #AC enable bit for split lock. */
> +bool restore_split_lock_ac_kernel(int *enable)
> +{
> + if (enable)
> + *enable = split_lock_ac == ENABLE_SPLIT_LOCK_AC ? 1 : 0;
> +
> + return restore_split_lock_ac(split_lock_ac);
> +}
> +
> static void split_lock_cpu_reboot(void *unused)
> {
> restore_split_lock_ac_bios(NULL);
> @@ -223,11 +233,55 @@ bool do_split_lock_exception(struct pt_regs *regs, unsigned long error_code)
> return true;
> }
>
> +static int split_lock_offline(unsigned int cpu)
> +{
> + int enable;
> +
> + if (restore_split_lock_ac_bios(&enable))
> + pr_info("%s split lock on CPU%d\n",
> + enable ? "enable" : "disable", smp_processor_id());
> +
> + return 0;
> +}
> +
> +static int split_lock_bsp_suspend(void)
> +{
> + restore_split_lock_ac_bios(NULL);
> +
> + return 0;
> +}
> +
> +static void split_lock_bsp_resume(void)
> +{
> + restore_split_lock_ac_kernel(NULL);
> +}
> +
> +static struct syscore_ops split_lock_syscore_ops = {
> + .suspend = split_lock_bsp_suspend,
> + .resume = split_lock_bsp_resume,
> +};
> +
> static int __init split_lock_init(void)
> {
> + int ret;
> +
> + if (!split_lock_ac_supported)
> + return -ENODEV;
> +
> + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> + "x86/split_lock:online:",
> + NULL, split_lock_offline);
> + if (ret < 0)
> + goto out_fail;
> +
> + register_syscore_ops(&split_lock_syscore_ops);
> +
> register_reboot_notifier(&split_lock_reboot_nb);
>
> return 0;
> +
> +out_fail:
> + return ret;
> }
>
> late_initcall(split_lock_init);
>


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