From: Alex Williamson <alex.williamson@redhat.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>,
Don Dutile <ddutile@redhat.com>,
Will Deacon <will.deacon@arm.com>,
Eric Auger <eric.auger@redhat.com>,
eric.auger.pro@gmail.com, marc.zyngier@arm.com,
robin.murphy@arm.com, tglx@linutronix.de, jason@lakedaemon.net,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
drjones@redhat.com, linux-kernel@vger.kernel.org,
pranav.sawargaonkar@gmail.com, iommu@lists.linux-foundation.org,
punit.agrawal@arm.com, diana.craciun@nxp.com,
benh@kernel.crashing.org, arnd@arndb.de, jcm@redhat.com,
dwmw@amazon.co.uk
Subject: Re: Summary of LPC guest MSI discussion in Santa Fe
Date: Thu, 10 Nov 2016 10:07:04 -0700 [thread overview]
Message-ID: <20161110100704.7dd16e2f@t450s.home> (raw)
In-Reply-To: <20161110144007.GC2078@8bytes.org>
On Thu, 10 Nov 2016 15:40:07 +0100
Joerg Roedel <joro@8bytes.org> wrote:
> On Wed, Nov 09, 2016 at 01:01:14PM -0700, Alex Williamson wrote:
> > Well, it's not like QEMU or libvirt stumbling through sysfs to figure
> > out where holes could be in order to instantiate a VM with matching
> > holes, just in case someone might decide to hot-add a device into the
> > VM, at some point, and hopefully they don't migrate the VM to another
> > host with a different layout first, is all that much less disgusting or
> > foolproof. It's just that in order to dynamically remove a page as a
> > possible DMA target we require a paravirt channel, such as a balloon
> > driver that's able to pluck a specific page. In some ways it's
> > actually less disgusting, but it puts some prerequisites on
> > enlightening the guest OS. Thanks,
>
> I think it is much simpler if libvirt/qemu just go through all
> potentially assignable devices on a system and pre-exclude any addresses
> from guest RAM beforehand, rather than doing something like this with
> paravirt/ballooning when a device is hot-added. There is no guarantee
> that you can take a page away from a linux-guest.
Right, I'm not advocating a paravirt ballooning approach, just pointing
out that they're both terrible, just in different ways. Thanks,
Alex
next prev parent reply other threads:[~2016-11-10 17:07 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 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 4/8] iommu: Add a list of iommu_reserved_region in iommu_domain 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 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
2016-11-03 21:39 ` [RFC 8/8] iommu/arm-smmu: implement " 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
2016-11-08 17:54 ` Will Deacon
2016-11-08 19:02 ` Don Dutile
2016-11-08 19:10 ` Will Deacon
2016-11-09 7:43 ` Auger Eric
2016-11-08 16:02 ` Don Dutile
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
2016-11-09 2:52 ` Summary of LPC guest MSI discussion in Santa Fe Don Dutile
2016-11-09 17:03 ` Will Deacon
2016-11-09 18:59 ` Don Dutile
2016-11-09 19:23 ` Christoffer Dall
2016-11-09 20:01 ` Alex Williamson
2016-11-10 14:40 ` Joerg Roedel
2016-11-10 17:07 ` Alex Williamson [this message]
2016-11-09 20:31 ` Will Deacon
2016-11-09 22:17 ` Alex Williamson
2016-11-09 22:25 ` Will Deacon
2016-11-09 23:24 ` Alex Williamson
2016-11-09 23:38 ` Will Deacon
2016-11-09 23:59 ` Alex Williamson
2016-11-10 0:14 ` Auger Eric
2016-11-10 0:55 ` Alex Williamson
2016-11-10 2:01 ` Will Deacon
2016-11-10 11:14 ` Auger Eric
2016-11-10 17:46 ` Alex Williamson
2016-11-11 11:19 ` Joerg Roedel
2016-11-11 15:50 ` Alex Williamson
2016-11-11 16:05 ` Alex Williamson
2016-11-14 15:19 ` Joerg Roedel
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
2016-11-10 15:18 ` Joerg Roedel
2016-11-21 5:13 ` Jon Masters
2016-11-23 20:12 ` Don Dutile
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