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

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Date:   Tue, 25 Apr 2017 19:21:54 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tyler Baicar <tbaicar@...eaurora.org>
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 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.

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