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

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Date:   Tue, 25 Apr 2017 11:41:39 -0600
From:   "Baicar, Tyler" <tbaicar@...eaurora.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     christoffer.dall@...aro.org, marc.zyngier@....com,
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Subject: Re: [PATCH V15 06/11] acpi: apei: handle SEA notification type for
 ARMv8

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

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