Re: [PATCH v5 2/2] acpi: apei: Add SEI notification type support for ARMv8

[James Morse]

Hi Dongjiu Geng,

On 17/10/17 09:02, Dongjiu Geng wrote:
> ARMv8.2 requires implementation of the RAS extension, in
> this extension it adds SEI(SError Interrupt) notification
> type, this patch adds new GHES error source SEI handling
> functions.

This paragraph is merging two things that aren't related.
The 'ARM v8.2 architecture extensions' have some RAS bits, which if your CPU
implements v8.2 are required.

ACPIv6.1 added NOTIFY_SEI as a notification type for ARMv8 systems.

This patch adds a GHES function for NOTIFY_SEI. Please leave the CPU RAS
extensions out of it.


> Because this error source parsing and handling
> methods are similar with the SEA. So share some SEA handling
> functions with the SEI
> 
> Expose one API ghes_notify_abort() to external users. External
> modules can call this exposed API to parse and handle the
> SEA or SEI.

This series doesn't add a caller/user for this new API, so why do we need to do
this now?

(I still haven't had a usable answer for 'what does your firmware do when SError
is masked', but I'll go beat that drum on the other thread).


More important for the APEI code is: How do SEA and SEI interact?

As far as I can see they can both interrupt each other, which isn't something
the single in_nmi() path in APEI can handle. I thinks we should fix this first.
(I'll try and polish my RFC that had a stab at that...)


SEA gets away with a lot of things because its synchronous. SEI isn't. Xie XiuQi
pointed to the memory_failure_queue() code. We can use this directly from SEA,
but not SEI. (what happens if an SError arrives while we are queueing
memory_failure work from an IRQ).

The one that scares me is the trace-point reporting stuff. What happens if an
SError arrives while we are enabling a trace point? (these are static-keys right?)


I don't think we can just plumb SEI in like this and be done with it.
(I'm looking at teasing out the estatus cache code from being x86:NMI only. This
way we solve the same 'cant do this from NMI context' with the same code'.)


Thanks,

James



boring nits below:

> Note: For the SEI(SError Interrupt), it is asynchronous external
> abort, the error address recorded by firmware may be not accurate.
> If not accurate, EL3 firmware needs to identify the address to a
> invalid value.

This paragraph keeps cropping up. Who expects an address with an SError?
We don't get one for IRQs, but that never needs stating.


> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Dongjiu Geng <gengdongjiu@xxxxxxxxxx>
> Tested-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>

> Tested-by: Dongjiu Geng <gengdongjiu@xxxxxxxxxx>

(It's expected you test your own code)



> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 2509e4f..c98c1b3 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -585,7 +585,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  		if (interrupts_enabled(regs))
>  			nmi_enter();
>  
> -		ret = ghes_notify_sea();
> +		ret = ghes_notify_abort(ACPI_HEST_NOTIFY_SEA);
>  
>  		if (interrupts_enabled(regs))
>  			nmi_exit();
> @@ -682,7 +682,7 @@ int handle_guest_sea(phys_addr_t addr, unsigned int esr)
>  	int ret = -ENOENT;
>  
>  	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA))
> -		ret = ghes_notify_sea();
> +		ret = ghes_notify_abort(ACPI_HEST_NOTIFY_SEA);
>  
>  	return ret;
>  }
> diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
> index de14d49..47fcb0c 100644
> --- a/drivers/acpi/apei/Kconfig
> +++ b/drivers/acpi/apei/Kconfig
> @@ -54,6 +54,21 @@ config ACPI_APEI_SEA
>  	  option allows the OS to look for such hardware error record, and
>  	  take appropriate action.
>  
> +config ACPI_APEI_SEI
> +	bool "APEI Asynchronous SError Interrupt logging/recovering support"
> +	depends on ARM64 && ACPI_APEI_GHES
> +	default y
> +	help
> +	  This option should be enabled if the system supports
> +	  firmware first handling of SEI (asynchronous SError interrupt).
> +
> +	  SEI happens with asynchronous external abort for errors on device
> +	  memory reads on ARMv8 systems. If a system supports firmware first
> +	  handling of SEI, the platform analyzes and handles hardware error
> +	  notifications from SEI, and it may then form a HW error record for
> +	  the OS to parse and handle. This option allows the OS to look for
> +	  such hardware error record, and take appropriate action.
> +
>  config ACPI_APEI_MEMORY_FAILURE
>  	bool "APEI memory error recovering support"
>  	depends on ACPI_APEI && MEMORY_FAILURE
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 3eee30a..24b4233 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -815,43 +815,67 @@ static struct notifier_block ghes_notifier_hed = {
>  
>  #ifdef CONFIG_ACPI_APEI_SEA
>  static LIST_HEAD(ghes_sea);
> +#endif
> +
> +#ifdef CONFIG_ACPI_APEI_SEI
> +static LIST_HEAD(ghes_sei);
> +#endif
>  
> +#if defined(CONFIG_ACPI_APEI_SEA) || defined(CONFIG_ACPI_APEI_SEI)
>  /*
> - * Return 0 only if one of the SEA error sources successfully reported an error
> - * record sent from the firmware.
> + * Return 0 only if one of the SEA or SEI error sources successfully
> + * reported an error record sent from the firmware.
>   */
> -int ghes_notify_sea(void)
> +int ghes_notify_abort(u8 type)
>  {
>  	struct ghes *ghes;
> +	struct list_head *head = NULL;
>  	int ret = -ENOENT;
>  
> -	rcu_read_lock();
> -	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
> -		if (!ghes_proc(ghes))
> -			ret = 0;

> +	if (type == ACPI_HEST_NOTIFY_SEA)
> +		head = &ghes_sea;
> +	else if (type == ACPI_HEST_NOTIFY_SEI)
> +		head = &ghes_sei;

Surely if I only have one of CONFIG_ACPI_APEI_SE{A,I} this can't be compiled.


> +
> +	if (head) {
> +		rcu_read_lock();
> +		list_for_each_entry_rcu(ghes, head, list) {
> +			if (!ghes_proc(ghes))
> +				ret = 0;
> +		}
> +		rcu_read_unlock();
>  	}
> -	rcu_read_unlock();
>  	return ret;
>  }
>  
> -static void ghes_sea_add(struct ghes *ghes)
> +static void ghes_abort_add(struct ghes *ghes)
>  {
> -	mutex_lock(&ghes_list_mutex);
> -	list_add_rcu(&ghes->list, &ghes_sea);
> -	mutex_unlock(&ghes_list_mutex);
> +	struct list_head *head = NULL;
> +	u8 notify_type = ghes->generic->notify.type;
> +

> +	if (notify_type == ACPI_HEST_NOTIFY_SEA)
> +		head = &ghes_sea;
> +	else if (notify_type == ACPI_HEST_NOTIFY_SEI)
> +		head = &ghes_sei;

And here.


> +
> +	if (head) {
> +		mutex_lock(&ghes_list_mutex);
> +		list_add_rcu(&ghes->list, head);
> +		mutex_unlock(&ghes_list_mutex);
> +	}
>  }
>  
> -static void ghes_sea_remove(struct ghes *ghes)
> +static void ghes_abort_remove(struct ghes *ghes)
>  {
>  	mutex_lock(&ghes_list_mutex);
>  	list_del_rcu(&ghes->list);
>  	mutex_unlock(&ghes_list_mutex);
>  	synchronize_rcu();
>  }
> -#else /* CONFIG_ACPI_APEI_SEA */
> -static inline void ghes_sea_add(struct ghes *ghes) { }
> -static inline void ghes_sea_remove(struct ghes *ghes) { }
> -#endif /* CONFIG_ACPI_APEI_SEA */
> +#else
> +static inline void ghes_abort_add(struct ghes *ghes) { }
> +static inline void ghes_abort_remove(struct ghes *ghes) { }
> +#endif
>  
>  #ifdef CONFIG_HAVE_ACPI_APEI_NMI
>  /*
> @@ -1084,6 +1108,13 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  			goto err;
>  		}
>  		break;
> +	case ACPI_HEST_NOTIFY_SEI:
> +		if (!IS_ENABLED(CONFIG_ACPI_APEI_SEI)) {
> +			pr_warn(GHES_PFX "Generic hardware error source: %d notified via SEI is not supported!\n",
> +				generic->header.source_id);
> +		goto err;
> +	}
> +	break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		if (!IS_ENABLED(CONFIG_HAVE_ACPI_APEI_NMI)) {
>  			pr_warn(GHES_PFX "Generic hardware error source: %d notified via NMI interrupt is not supported!\n",
> @@ -1153,7 +1184,8 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  		break;
>  
>  	case ACPI_HEST_NOTIFY_SEA:
> -		ghes_sea_add(ghes);
> +	case ACPI_HEST_NOTIFY_SEI:
> +		ghes_abort_add(ghes);
>  		break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		ghes_nmi_add(ghes);
> @@ -1206,7 +1238,8 @@ static int ghes_remove(struct platform_device *ghes_dev)
>  		break;
>  
>  	case ACPI_HEST_NOTIFY_SEA:
> -		ghes_sea_remove(ghes);
> +	case ACPI_HEST_NOTIFY_SEI:
> +		ghes_abort_remove(ghes);
>  		break;
>  	case ACPI_HEST_NOTIFY_NMI:
>  		ghes_nmi_remove(ghes);
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
> index 9061c5c..ec6f4ba 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -118,6 +118,6 @@ static inline void *acpi_hest_get_next(struct acpi_hest_generic_data *gdata)
>  	     (void *)section - (void *)(estatus + 1) < estatus->data_length; \
>  	     section = acpi_hest_get_next(section))
>  
> -int ghes_notify_sea(void);
> +int ghes_notify_abort(u8 type);
>  
>  #endif /* GHES_H */
>