From: David Woodhouse <dwmw2@infradead.org>
To: Chris Wright <chrisw@sous-sol.org>
Cc: Alex Williamson <alex.williamson@redhat.com>,
linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] intel-iommu: Default to non-coherent for domains unattached to iommus
Date: Sat, 12 Nov 2011 00:51:48 +0000 [thread overview]
Message-ID: <1321059108.2006.24.camel@shinybook.infradead.org> (raw)
In-Reply-To: <20111112004513.GP14486@sequoia.sous-sol.org>
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On Fri, 2011-11-11 at 16:45 -0800, Chris Wright wrote:
> > So if you were to ditch the whole idea of a per-domain runtime update,
> > and instead calculate a global value for 'iommu_coherency' at boot time,
> > by iterating over for_each_active_iommu()¹, I think that would be a
> > better way to deal with the issue. And you *could* really call that a
> > 'fix'.
> >
> > Make sense?
>
> Ideally, yes. Not sure we can practically do it though. Would have to
> be sure we force incoherent access mode for the busted hw.
Why's it not practical? You do the *same* loop we currently have in
domain_update_iommu_coherency(), except that you do it just *once*, over
all active IOMMUs, at boot time. And then you just use that result
forever more.
So if *any* IOMMU in the system is non-coherent, you run them all that
way.
--
dwmw2
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next prev parent reply other threads:[~2011-11-12 0:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-11 22:49 Alex Williamson
2011-11-12 0:17 ` Chris Wright
2011-11-12 0:37 ` David Woodhouse
2011-11-12 0:45 ` Chris Wright
2011-11-12 0:47 ` Chris Wright
2011-11-12 0:51 ` David Woodhouse [this message]
2011-11-12 0:58 ` Chris Wright
2011-11-12 1:03 ` David Woodhouse
2011-11-12 0:46 ` Roland Dreier
2011-11-12 0:51 ` Chris Wright
2011-11-12 0:55 ` David Woodhouse
2011-11-12 1:08 ` Chris Wright
2011-11-12 1:20 ` David Woodhouse
2011-11-15 7:12 ` cody
2011-11-15 4:54 ` Chris Wright
2011-11-15 5:55 ` Kai Huang
2011-11-12 1:30 ` Roland Dreier
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