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Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for ARMv8

Started byBorislav Petkov <bp@alien8.de>
First post2017-04-25 19:30 +0200
Last post2017-04-25 19:50 +0200
Articles 3 — 2 participants

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  Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for  ARMv8 Borislav Petkov <bp@alien8.de> - 2017-04-25 19:30 +0200
    Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for  ARMv8 Borislav Petkov <bp@alien8.de> - 2017-04-25 19:50 +0200
    Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for  ARMv8 "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-04-25 19:50 +0200

#1630816 — Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for ARMv8

FromBorislav Petkov <bp@alien8.de>
Date2017-04-25 19:30 +0200
SubjectRe: [PATCH V15 06/11] acpi: apei: handle SEA notification type for ARMv8
Message-ID<tAcrL-7Dc-1@gated-at.bofh.it>
On Tue, Apr 18, 2017 at 05:05:18PM -0600, Tyler Baicar wrote:
> ARM APEI extension proposal added SEA (Synchronous External Abort)
> notification type for ARMv8.
> Add a new GHES error source handling function for SEA. If an error
> source's notification type is SEA, then this function can be registered
> into the SEA exception handler. That way GHES will parse and report
> SEA exceptions when they occur.
> An SEA can interrupt code that had interrupts masked and is treated as
> an NMI. To aid this the page of address space for mapping APEI buffers
> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
> changed to use the helper methods to find the prot_t to map with in
> the same way as ghes_ioremap_pfn_irq().

...

> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>  	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>  		inf->name, esr, addr);
>  
> +	/*
> +	 * Synchronous aborts may interrupt code which had interrupts masked.
> +	 * Before calling out into the wider kernel tell the interested
> +	 * subsystems.
> +	 */
> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
> +		nmi_enter();
> +		ghes_notify_sea();
> +		nmi_exit();
> +	}

Well, the other GHES notification methods use a notifier:
ghes_notify_sci, ghes_notify_nmi. You probably should do that too
instead of calling straight into a driver from arch code.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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#1630828

FromBorislav Petkov <bp@alien8.de>
Date2017-04-25 19:50 +0200
Message-ID<tAcL7-7Ju-3@gated-at.bofh.it>
In reply to#1630816
On Tue, Apr 25, 2017 at 11:41:39AM -0600, Baicar, Tyler wrote:
> I originally had this as a notifier, but Will requested to remove the
> notifier. That conversation is here: https://lkml.org/lkml/2017/1/18/1018

Yeah, he mentioned on IRC. I just think notifiers would be the cleaner
thing but whatever you guys say.

Just we had a nasty hack on x86 which I got rid of recently:

https://lkml.kernel.org/r/20170406090634.30950-1-bp@alien8.de

and I wouldn't want you guys to have the same "fun". :)

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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#1630829

From"Baicar, Tyler" <tbaicar@codeaurora.org>
Date2017-04-25 19:50 +0200
Message-ID<tAcL7-7Ju-5@gated-at.bofh.it>
In reply to#1630816
On 4/25/2017 11:21 AM, Borislav Petkov wrote:
> On Tue, Apr 18, 2017 at 05:05:18PM -0600, Tyler Baicar wrote:
>> ARM APEI extension proposal added SEA (Synchronous External Abort)
>> notification type for ARMv8.
>> Add a new GHES error source handling function for SEA. If an error
>> source's notification type is SEA, then this function can be registered
>> into the SEA exception handler. That way GHES will parse and report
>> SEA exceptions when they occur.
>> An SEA can interrupt code that had interrupts masked and is treated as
>> an NMI. To aid this the page of address space for mapping APEI buffers
>> while in_nmi() is always reserved, and ghes_ioremap_pfn_nmi() is
>> changed to use the helper methods to find the prot_t to map with in
>> the same way as ghes_ioremap_pfn_irq().
> ...
>
>> @@ -518,6 +520,17 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>>   	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>>   		inf->name, esr, addr);
>>   
>> +	/*
>> +	 * Synchronous aborts may interrupt code which had interrupts masked.
>> +	 * Before calling out into the wider kernel tell the interested
>> +	 * subsystems.
>> +	 */
>> +	if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
>> +		nmi_enter();
>> +		ghes_notify_sea();
>> +		nmi_exit();
>> +	}
> Well, the other GHES notification methods use a notifier:
> ghes_notify_sci, ghes_notify_nmi. You probably should do that too
> instead of calling straight into a driver from arch code.
I originally had this as a notifier, but Will requested to remove the 
notifier. That conversation is here: https://lkml.org/lkml/2017/1/18/1018

Thanks,
Tyler

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.

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