From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v7 10/25] ACPI / APEI: Tell firmware the estatus queue
 consumed the records
Date: Fri, 11 Jan 2019 20:58:00 +0100
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To: James Morse <james.morse@arm.com>
Cc: Rafael Wysocki <rjw@rjwysocki.net>, Tony Luck <tony.luck@intel.com>, Fan Wu <wufan@codeaurora.org>, Linux ACPI <linux-acpi@vger.kernel.org>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Tyler Baicar <baicar.tyler@gmail.com>, Will Deacon <will.deacon@arm.com>, Dongjiu Geng <gengdongjiu@huawei.com>, linux-mm@kvack.org, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, kvmarm@lists.cs.columbia.edu, arm-mail-list <linux-arm-kernel@lists.infradead.org>, Len Brown <lenb@kernel.org>
List-Id: linux-acpi@vger.kernel.org

On Fri, Jan 11, 2019 at 06:25:21PM +0000, James Morse wrote:
> We ack it in the corrupt-record case too, because we are done with the
> memory.

Ok, so the only thing that we need to do unconditionally is ACK in order
to free the memory. Or is there an exception to that set of steps in
error handling?

> I think it is. 18.3.2.8 of ACPI v6.2 (search for Generic Hardware Error Source
> version 2", then below the table):
> * OSPM detects error (via interrupt/exception or polling the block status)
> * OSPM copies the error status block
> * OSPM clears the block status field of the error status block
> * OSPM acknowledges the error via Read Ack register
> 
> The ENOENT case is excluded by 'polling the block status'.

Ok, so we signal the absence of an error record with ENOENT.

        if (!buf_paddr)
                return -ENOENT;

Can that even happen?

Also, in that case, what would happen if we ACK the error anyway? We'd
confuse the firmware?

I sure hope firmware is prepared for spurious ACKs :)

> Unsurprisingly the spec doesn't consider the case that firmware generates
> corrupt records!

You mean the EIO case?

Not surprised at all. But we do not report that record so all good.

Thx.

-- 
Regards/Gruss,
    Boris.

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