Re: [PATCH v4 2/3] arm64: hibernate: Resume when hibernate image created on non-boot CPU

[James Morse <james.morse@arm.com>]

Hi Catalin,

On 05/07/16 18:49, Catalin Marinas wrote:
> On Mon, Jul 04, 2016 at 03:52:29PM +0100, James Morse wrote:
>> diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
>> index 024d623f662e..9b3e8d9bfc8c 100644
>> --- a/arch/arm64/include/asm/suspend.h
>> +++ b/arch/arm64/include/asm/suspend.h
>> @@ -47,4 +47,8 @@ int swsusp_arch_resume(void);
>>  int arch_hibernation_header_save(void *addr, unsigned int max_size);
>>  int arch_hibernation_header_restore(void *addr);
>>  
>> +/* Used to resume on the CPU we hibernated on */
>> +int _arch_hibernation_disable_cpus(bool suspend);
>> +#define arch_hibernation_disable_cpus(x) _arch_hibernation_disable_cpus(x)
> 
> Nitpick: we normally tend to use the same name for the function an macro
> but it's fine like this as well:
> 
> +int arch_hibernation_disable_cpus(bool suspend);
> +#define arch_hibernation_disable_cpus arch_hibernation_disable_cpus
> 
> BTW, do you expect an architecture to define ARCH_HIBERNATION_CPU_HOOKS
> but not arch_hibernation_disable_cpus? Or you'd expect more hooks in the
> future?

The macro and kconfig symbol are gone in the new version... they were both part
of avoiding a weak symbol.


>> diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
>> index 21ab5df9fa76..bae45abde7a2 100644
>> --- a/arch/arm64/kernel/hibernate.c
>> +++ b/arch/arm64/kernel/hibernate.c

>> @@ -66,6 +69,12 @@ extern char hibernate_el2_vectors[];
>>  extern char __hyp_stub_vectors[];
>>  
>>  /*
>> + * The logical cpu number we should resume on, initialised to a non-cpu
>> + * number.
>> + */
>> +static int sleep_cpu = -EINVAL;
>> +
>> +/*
>>   * Values that may not change over hibernate/resume. We put the build number
>>   * and date in here so that we guarantee not to resume with a different
>>   * kernel.
>> @@ -87,6 +96,8 @@ static struct arch_hibernate_hdr {
>>  	 * re-configure el2.
>>  	 */
>>  	phys_addr_t	__hyp_stub_vectors;
>> +
>> +	u64		sleep_cpu_mpidr;
>>  } resume_hdr;
>>  
>>  static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
>> @@ -129,12 +140,18 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
>>  	else
>>  		hdr->__hyp_stub_vectors = 0;
>>  
>> +	/* Save the mpidr of the cpu we called cpu_suspend() on... */
>> +	hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
>> +	pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
>> +		hdr->sleep_cpu_mpidr);
> 
> Do we have a guarantee that sleep_cpu != -EINVAL here?

This depends on the order the core code calls these functions, I will add a
check and return an error just in case it ever changes.


> If the above is fine, feel free to add:
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks!



James