From: Alex Williamson <alex.williamson@hp.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org
Subject: Re: [PATCH 4/5] intel-iommu: Reinstate RMRRs if a device is removed from passthrough domain
Date: Tue, 27 Oct 2009 09:50:32 -0600 [thread overview]
Message-ID: <1256658632.5937.7.camel@bling> (raw)
In-Reply-To: <1256631324.9814.14.camel@macbook.infradead.org>
On Tue, 2009-10-27 at 08:15 +0000, David Woodhouse wrote:
> On Mon, 2009-10-26 at 17:25 -0600, Alex Williamson wrote:
> > When a device is setup for passthrough it has full access to memory
> > so processing the RMRRs is unnecessary. However, if we remove the device
> > from the si_domain, we need to reinstate the associated RMRRs.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@hp.com>
>
> If your device is doing DMA to host memory autonomously, you may still
> have problems with this patch -- you take it out of the si_domain and
> then there's a period of time before you reapply the RMRRs, during which
> its DMA may be prevented.
>
> You want to set up the new domain first, then switch the device over to
> it atomically.
Yes, good point. I'm not seeing any convenient ways to setup a new
domain for a device while it's still a member of the si_domain. It
looks like I'd need to extract parts of the get_valid_domain_for_dev()
path and ignore any bits about using the already existing domain. Is
there an easier way? Thanks,
Alex
next prev parent reply other threads:[~2009-10-27 15:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-26 23:24 [PATCH 0/5] intel-iommu fixes Alex Williamson
2009-10-26 23:24 ` [PATCH 1/5] dma: create dma_generic_alloc/free_coherent() Alex Williamson
2009-10-27 0:57 ` Paul Mundt
2009-10-27 2:26 ` Alex Williamson
2009-10-27 1:47 ` FUJITA Tomonori
2009-10-26 23:25 ` [PATCH 2/5] intel-iommu: Use dma_generic_alloc_coherent() for passthrough mappings Alex Williamson
2009-10-27 3:24 ` [PATCH v2 2/5] intel-iommu: Obey coherent_dma_mask for alloc_coherent on passthrough Alex Williamson
2009-10-26 23:25 ` [PATCH 3/5] intel-iommu: Use max_pfn to determine whether a device can passthrough Alex Williamson
2009-10-26 23:25 ` [PATCH 4/5] intel-iommu: Reinstate RMRRs if a device is removed from passthrough domain Alex Williamson
2009-10-27 8:15 ` David Woodhouse
2009-10-27 15:50 ` Alex Williamson [this message]
2009-10-28 14:36 ` David Woodhouse
2009-10-28 16:06 ` Alex Williamson
2009-10-28 20:35 ` Alex Williamson
2009-10-26 23:25 ` [PATCH 5/5] intel-iommu: Quiet unnecessary output Alex Williamson
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