linux-kernel - Re: [PATCH] iommu/vt-d: Ratelimit fault handler

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Message-ID: <1458071276.78634.124.camel@infradead.org>
Date:	Tue, 15 Mar 2016 19:47:56 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	Alex Williamson <alex.williamson@...hat.com>,
	iommu@...ts.linux-foundation.org
Cc:	joro@...tes.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/vt-d: Ratelimit fault handler

On Tue, 2016-03-15 at 10:35 -0600, Alex Williamson wrote:
> Fault rates can easily overwhelm the console and make the system
> unresponsive.  Ratelimit to allow an opportunity for maintenance.
> 
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>

Rather than just rate-limiting the printk, I'd prefer to handle this
explicitly. There's a bit in the context-entry which can tell the IOMMU
not to bother raising an interrupt at all. And then we can re-enable it
if/when the driver recovers the device. (Or perhaps just when it next
does a mapping).

We really ought to be reporting faults to drivers too, FWIW. I keep
meaning to take a look at that.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation

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