From: Joerg Roedel <joro@8bytes.org>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org, drjones@redhat.com,
jason@lakedaemon.net, kvm@vger.kernel.org, marc.zyngier@arm.com,
benh@kernel.crashing.org, punit.agrawal@arm.com,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
pranav.sawargaonkar@gmail.com, arnd@arndb.de, dwmw@amazon.co.uk,
jcm@redhat.com, tglx@linutronix.de,
Christoffer Dall <christoffer.dall@linaro.org>,
eric.auger.pro@gmail.com
Subject: Re: Summary of LPC guest MSI discussion in Santa Fe
Date: Mon, 14 Nov 2016 16:19:24 +0100 [thread overview]
Message-ID: <20161114151923.GX2078@8bytes.org> (raw)
In-Reply-To: <20161111090543.57623f2d@t450s.home>
On Fri, Nov 11, 2016 at 09:05:43AM -0700, Alex Williamson wrote:
> On Fri, 11 Nov 2016 08:50:56 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
> >
> > It's really just a happenstance that we don't map RAM over the x86 MSI
> > range though. That property really can't be guaranteed once we mix
> > architectures, such as running an aarch64 VM on x86 host via TCG.
> > AIUI, the MSI range is actually handled differently than other DMA
> > ranges, so a iommu_map() overlapping a range that the iommu cannot map
> > should fail just like an attempt to map beyond the address width of the
> > iommu.
>
> (clarification, this is x86 specific, the MSI controller - interrupt
> remapper - is embedded in the iommu AIUI, so the iommu is actually not
> able to provide DMA translation for this range.
Right, on x86 the MSI range can be covered by page-tables, but those are
ignored by the IOMMU hardware. But what I am trying to say is, that
checking for these ranges happens already on a higher level (in the
dma-api implementations by marking these regions as allocted) so that
there is no need to check for them again in the iommu_map/unmap path.
Joerg
next prev parent reply other threads:[~2016-11-14 15:19 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-03 21:39 [RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II) Eric Auger
2016-11-03 21:39 ` [RFC 4/8] iommu: Add a list of iommu_reserved_region in iommu_domain Eric Auger
2016-11-03 21:39 ` [RFC 6/8] iommu: Handle the list of reserved regions Eric Auger
2016-11-03 21:39 ` [RFC 7/8] iommu/vt-d: Implement add_reserved_regions callback Eric Auger
[not found] ` <1478209178-3009-1-git-send-email-eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-03 21:39 ` [RFC 1/8] vfio: fix vfio_info_cap_add/shift Eric Auger
2016-11-03 21:39 ` [RFC 2/8] iommu/iova: fix __alloc_and_insert_iova_range Eric Auger
2016-11-03 21:39 ` [RFC 3/8] iommu/dma: Allow MSI-only cookies Eric Auger
2016-11-03 21:39 ` [RFC 5/8] vfio/type1: Introduce RESV_IOVA_RANGE capability Eric Auger
2016-11-03 21:39 ` [RFC 8/8] iommu/arm-smmu: implement add_reserved_regions callback Eric Auger
2016-11-04 4:02 ` [RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II) Alex Williamson
2016-11-08 2:45 ` Summary of LPC guest MSI discussion in Santa Fe (was: Re: [RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II)) Will Deacon
2016-11-08 14:27 ` Summary of LPC guest MSI discussion in Santa Fe Auger Eric
[not found] ` <dae12190-1eb6-20a9-5740-9e5be8bb65fc-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-08 17:54 ` Will Deacon
[not found] ` <20161108175457.GK20591-5wv7dgnIgG8@public.gmane.org>
2016-11-08 19:02 ` Don Dutile
2016-11-08 19:10 ` Will Deacon
[not found] ` <5822214F.2070500-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-09 7:43 ` Auger Eric
2016-11-08 16:02 ` Don Dutile
[not found] ` <20161108024559.GA20591-5wv7dgnIgG8@public.gmane.org>
2016-11-08 20:29 ` Summary of LPC guest MSI discussion in Santa Fe (was: Re: [RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II)) Christoffer Dall
2016-11-08 23:35 ` Alex Williamson
[not found] ` <20161108163508.1bcae0c2-1yVPhWWZRC1BDLzU/O5InQ@public.gmane.org>
2016-11-09 2:52 ` Summary of LPC guest MSI discussion in Santa Fe Don Dutile
[not found] ` <58228F71.6020108-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-09 17:03 ` Will Deacon
2016-11-09 18:59 ` Don Dutile
[not found] ` <582371FB.2040808-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-09 19:23 ` Christoffer Dall
2016-11-09 20:01 ` Alex Williamson
2016-11-10 14:40 ` Joerg Roedel
[not found] ` <20161110144007.GC2078-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2016-11-10 17:07 ` Alex Williamson
2016-11-09 20:31 ` Will Deacon
[not found] ` <20161109203145.GO17771-5wv7dgnIgG8@public.gmane.org>
2016-11-09 22:17 ` Alex Williamson
[not found] ` <20161109151709.74927f83-1yVPhWWZRC1BDLzU/O5InQ@public.gmane.org>
2016-11-09 22:25 ` Will Deacon
[not found] ` <20161109222522.GS17771-5wv7dgnIgG8@public.gmane.org>
2016-11-09 23:24 ` Alex Williamson
2016-11-09 23:38 ` Will Deacon
[not found] ` <20161109233847.GT17771-5wv7dgnIgG8@public.gmane.org>
2016-11-09 23:59 ` Alex Williamson
2016-11-10 0:14 ` Auger Eric
[not found] ` <83b6440a-31eb-c1b4-642c-a4c311f37ef2-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-10 0:55 ` Alex Williamson
2016-11-10 2:01 ` Will Deacon
[not found] ` <20161110020130.GA19108-5wv7dgnIgG8@public.gmane.org>
2016-11-10 11:14 ` Auger Eric
[not found] ` <ddd8af9d-ad8f-78d8-3048-3d640b74470e-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-11-10 17:46 ` Alex Williamson
2016-11-11 11:19 ` Joerg Roedel
[not found] ` <20161111111944.GO2078-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2016-11-11 15:50 ` Alex Williamson
[not found] ` <20161111085056.4cf8989d-1yVPhWWZRC1BDLzU/O5InQ@public.gmane.org>
2016-11-11 16:05 ` Alex Williamson
2016-11-14 15:19 ` Joerg Roedel [this message]
2016-11-11 16:25 ` Don Dutile
2016-11-11 16:00 ` Don Dutile
2016-11-10 14:52 ` Joerg Roedel
2016-11-09 20:11 ` Robin Murphy
[not found] ` <e59e9a17-e943-a227-5ea4-d028232155a8-5wv7dgnIgG8@public.gmane.org>
2016-11-10 15:18 ` Joerg Roedel
2016-11-21 5:13 ` Jon Masters
[not found] ` <83d7bf8e-1aa9-b61b-4e83-ba9da1926d19-Zp4isUonpHBD60Wz+7aTrA@public.gmane.org>
2016-11-23 20:12 ` Don Dutile
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161114151923.GX2078@8bytes.org \
--to=joro@8bytes.org \
--cc=alex.williamson@redhat.com \
--cc=arnd@arndb.de \
--cc=benh@kernel.crashing.org \
--cc=christoffer.dall@linaro.org \
--cc=drjones@redhat.com \
--cc=dwmw@amazon.co.uk \
--cc=eric.auger.pro@gmail.com \
--cc=iommu@lists.linux-foundation.org \
--cc=jason@lakedaemon.net \
--cc=jcm@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=pranav.sawargaonkar@gmail.com \
--cc=punit.agrawal@arm.com \
--cc=tglx@linutronix.de \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).