From: Alex Duyck <aduyck@mirantis.com>
To: Zhou Jie <zhoujie2011@cn.fujitsu.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Lan Tianyu <tianyu.lan@intel.com>,
Yang Zhang <yang.zhang.wz@gmail.com>,
Alex Williamson <alex.williamson@redhat.com>,
kvm@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
x86@kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: Re: [Qemu-devel] [RFC PATCH 0/3] x86: Add support for guest DMA dirty page tracking
Date: Mon, 6 Jun 2016 09:04:27 -0700 [thread overview]
Message-ID: <CAMt9YRpzAKt1KQW17VBzx0PT5BxiL_1+U1-AEK2A_Ao9KQjmGg@mail.gmail.com> (raw)
In-Reply-To: <df81dd53-dc03-667e-4d53-3c67f90aab8f@cn.fujitsu.com>
On Mon, Jun 6, 2016 at 2:18 AM, Zhou Jie <zhoujie2011@cn.fujitsu.com> wrote:
> Hi Alex,
>
>
> On 2016/1/6 0:18, Alexander Duyck wrote:
>>
>> On Tue, Jan 5, 2016 at 1:40 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
>>>
>>> On Mon, Jan 04, 2016 at 07:11:25PM -0800, Alexander Duyck wrote:
>>>>>>
>>>>>> The two mechanisms referenced above would likely require coordination
>>>>>> with
>>>>>> QEMU and as such are open to discussion. I haven't attempted to
>>>>>> address
>>>>>> them as I am not sure there is a consensus as of yet. My personal
>>>>>> preference would be to add a vendor-specific configuration block to
>>>>>> the
>>>>>> emulated pci-bridge interfaces created by QEMU that would allow us to
>>>>>> essentially extend shpc to support guest live migration with
>>>>>> pass-through
>>>>>> devices.
>>>>>
>>>>>
>>>>> shpc?
>>>>
>>>>
>>>> That is kind of what I was thinking. We basically need some mechanism
>>>> to allow for the host to ask the device to quiesce. It has been
>>>> proposed to possibly even look at something like an ACPI interface
>>>> since I know ACPI is used by QEMU to manage hot-plug in the standard
>>>> case.
>>>>
>>>> - Alex
>>>
>>>
>>>
>>> Start by using hot-unplug for this!
>>>
>>> Really use your patch guest side, and write host side
>>> to allow starting migration with the device, but
>>> defer completing it.
>>
>>
>> Yeah, I'm fully on board with this idea, though I'm not really working
>> on this right now since last I knew the folks on this thread from
>> Intel were working on it. My patches were mostly meant to be a nudge
>> in this direction so that we could get away from the driver specific
>> code.
>
>
> I have seen your email about live migration.
>
> I conclude the idea you proposed as following.
> 1. Extend swiotlb to allow for a page dirtying functionality.
> 2. Use pci express capability to implement of a PCI bridge to act
> as a bridge between direct assigned devices and the host bridge.
> 3. Using APCI event or extend shpc driver to support device pause.
> Is it right?
>
> Will you implement the patchs for live migration?
That is pretty much the heart of the proposal I had. I submitted an
RFC as a proof-of-concept for item 1 in the hopes that someone else
might try tackling items 2 and 3 but I haven't seen any updates since
then. The trick is to find a way to make it so that item 1 doesn't
slow down standard SWIOTLB when you are not migrating a VM. If nothing
else we would probably just need to add a static key that we could
default to false unless there is a PCI bridge indicating we are
starting a migration.
I haven't had time to really work on this though. In addition I am not
that familiar with QEMU and the internals of live migration so pieces
2 and 3 would take me some additional time to work on.
- Alex
next prev parent reply other threads:[~2016-06-06 16:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-13 21:28 [RFC PATCH 0/3] x86: Add support for guest DMA dirty page tracking Alexander Duyck
2015-12-13 21:28 ` [RFC PATCH 1/3] swiotlb: Fold static unmap and sync calls into calling functions Alexander Duyck
2015-12-13 21:28 ` [RFC PATCH 2/3] xen/swiotlb: " Alexander Duyck
2015-12-13 21:28 ` [RFC PATCH 3/3] x86: Create dma_mark_dirty to dirty pages used for DMA by VM guest Alexander Duyck
2015-12-14 14:00 ` Michael S. Tsirkin
2015-12-14 16:34 ` Alexander Duyck
2015-12-14 17:20 ` Michael S. Tsirkin
2015-12-14 17:59 ` Alexander Duyck
2015-12-14 20:52 ` Michael S. Tsirkin
2015-12-14 22:32 ` Alexander Duyck
2015-12-14 2:27 ` [RFC PATCH 0/3] x86: Add support for guest DMA dirty page tracking Yang Zhang
2015-12-14 4:54 ` Alexander Duyck
2015-12-14 5:22 ` Yang Zhang
2015-12-14 5:46 ` Alexander Duyck
2015-12-14 7:20 ` Yang Zhang
2015-12-14 14:02 ` Michael S. Tsirkin
[not found] ` <20160104204104.GB17427@char.us.oracle.com>
2016-01-05 3:11 ` Alexander Duyck
2016-01-05 9:40 ` Michael S. Tsirkin
2016-01-05 10:01 ` Dr. David Alan Gilbert
2016-01-05 10:35 ` Michael S. Tsirkin
2016-01-05 10:45 ` Dr. David Alan Gilbert
2016-01-05 10:59 ` Michael S. Tsirkin
2016-01-05 11:03 ` Dr. David Alan Gilbert
2016-01-05 11:11 ` Michael S. Tsirkin
2016-01-05 11:06 ` Michael S. Tsirkin
2016-01-05 11:05 ` Michael S. Tsirkin
2016-01-05 12:43 ` Dr. David Alan Gilbert
2016-01-05 13:16 ` Michael S. Tsirkin
2016-01-05 16:18 ` Alexander Duyck
2016-06-06 9:18 ` Re: [Qemu-devel] " Zhou Jie
2016-06-06 16:04 ` Alex Duyck [this message]
2016-06-09 10:14 ` Zhou Jie
2016-06-09 15:39 ` Alexander Duyck
2016-06-12 3:03 ` Zhou Jie
2016-06-13 1:28 ` Alexander Duyck
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