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From: Peter Xu <peterx@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: qemu-devel@nongnu.org, tianyu.lan@intel.com,
	kevin.tian@intel.com, mst@redhat.com, jan.kiszka@siemens.com,
	alex.williamson@redhat.com, bd.aviv@gmail.com
Subject: Re: [Qemu-devel] [PATCH RFC v4 19/20] intel_iommu: unmap existing pages before replay
Date: Sun, 22 Jan 2017 17:09:58 +0800	[thread overview]
Message-ID: <20170122090958.GC26526@pxdev.xzpeter.org> (raw)
In-Reply-To: <e1b09efe-0201-a746-9aa9-62f798a222f9@redhat.com>

On Sun, Jan 22, 2017 at 04:13:32PM +0800, Jason Wang wrote:
> 
> 
> On 2017年01月20日 21:08, Peter Xu wrote:
> >Previous replay works for domain switch only if the original domain does
> >not have mapped pages. For example, if we switch domain from A to B, it
> >will only work if A has no existing mapping. If there is, then there's
> >problem - current replay didn't make sure the old mappings are cleared
> >before replaying the new one.
> 
> I'm not quite sure this is needed. I thought the only thing we need to do is
> stop DMA of device during the moving? Or is there an example that will cause
> trouble?

I think this patch is essential.

Example:

- device D1 moved to domain A, domain A has no mapping
- map page P1 in domain A, so D1 will have a mapping of page P1
- create domain B with mapping P2
- move D1 from domain A to domain B

Here if we don't unmap existing pages in domain A (P1), after the
switch, we'll have D1 with both P1/P2 mapped, while domain B actually
only has P2. That's unaligned mapping, and it should be wrong.

If you (or anyone) think this is a bug as well for patch 18, I can
just squash both 19/20 into patch 18.

Thanks,

-- peterx

  reply	other threads:[~2017-01-22  9:10 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-20 13:08 [Qemu-devel] [PATCH RFC v4 00/20] VT-d: vfio enablement and misc enhances Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 01/20] vfio: trace map/unmap for notify as well Peter Xu
2017-01-23 18:20   ` Alex Williamson
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 02/20] vfio: introduce vfio_get_vaddr() Peter Xu
2017-01-23 18:49   ` Alex Williamson
2017-01-24  3:28     ` Peter Xu
2017-01-24  4:30       ` Alex Williamson
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 03/20] vfio: allow to notify unmap for very large region Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 04/20] IOMMU: add option to enable VTD_CAP_CM to vIOMMU capility exposoed to guest Peter Xu
2017-01-22  2:51   ` [Qemu-devel] [PATCH RFC v4.1 04/20] intel_iommu: add "caching-mode" option Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 05/20] intel_iommu: simplify irq region translation Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 06/20] intel_iommu: renaming gpa to iova where proper Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 07/20] intel_iommu: fix trace for inv desc handling Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 08/20] intel_iommu: fix trace for addr translation Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 09/20] intel_iommu: vtd_slpt_level_shift check level Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 10/20] memory: add section range info for IOMMU notifier Peter Xu
2017-01-23 19:12   ` Alex Williamson
2017-01-24  7:48     ` Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 11/20] memory: provide IOMMU_NOTIFIER_FOREACH macro Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 12/20] memory: provide iommu_replay_all() Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 13/20] memory: introduce memory_region_notify_one() Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 14/20] memory: add MemoryRegionIOMMUOps.replay() callback Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 15/20] intel_iommu: provide its own replay() callback Peter Xu
2017-01-22  7:56   ` Jason Wang
2017-01-22  8:51     ` Peter Xu
2017-01-22  9:36       ` Peter Xu
2017-01-23  1:50         ` Jason Wang
2017-01-23  1:48       ` Jason Wang
2017-01-23  2:54         ` Peter Xu
2017-01-23  3:12           ` Jason Wang
2017-01-23  3:35             ` Peter Xu
2017-01-23 19:34           ` Alex Williamson
2017-01-24  4:04             ` Peter Xu
2017-01-23 19:33       ` Alex Williamson
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 16/20] intel_iommu: do replay when context invalidate Peter Xu
2017-01-23 10:36   ` Jason Wang
2017-01-24  4:52     ` Peter Xu
2017-01-25  3:09       ` Jason Wang
2017-01-25  3:46         ` Peter Xu
2017-01-25  6:37           ` Tian, Kevin
2017-01-25  6:44             ` Peter Xu
2017-01-25  7:45               ` Jason Wang
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 17/20] intel_iommu: allow dynamic switch of IOMMU region Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 18/20] intel_iommu: enable vfio devices Peter Xu
2017-01-22  8:08   ` Jason Wang
2017-01-22  9:04     ` Peter Xu
2017-01-23  1:55       ` Jason Wang
2017-01-23  3:34         ` Peter Xu
2017-01-23 10:23           ` Jason Wang
2017-01-23 19:40             ` Alex Williamson
2017-01-25  1:19               ` Jason Wang
2017-01-25  1:31                 ` Alex Williamson
2017-01-25  7:41                   ` Jason Wang
2017-01-24  4:42             ` Peter Xu
2017-01-23 18:03           ` Alex Williamson
2017-01-24  7:22             ` Peter Xu
2017-01-24 16:24               ` Alex Williamson
2017-01-25  4:04                 ` Peter Xu
2017-01-23  2:01   ` Jason Wang
2017-01-23  2:17     ` Jason Wang
2017-01-23  3:40     ` Peter Xu
2017-01-23 10:27       ` Jason Wang
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 19/20] intel_iommu: unmap existing pages before replay Peter Xu
2017-01-22  8:13   ` Jason Wang
2017-01-22  9:09     ` Peter Xu [this message]
2017-01-23  1:57       ` Jason Wang
2017-01-23  7:30         ` Peter Xu
2017-01-23 10:29           ` Jason Wang
2017-01-23 10:40   ` Jason Wang
2017-01-24  7:31     ` Peter Xu
2017-01-25  3:11       ` Jason Wang
2017-01-25  4:15         ` Peter Xu
2017-01-20 13:08 ` [Qemu-devel] [PATCH RFC v4 20/20] intel_iommu: replay even with DSI/GLOBAL inv desc Peter Xu
2017-01-23 15:55 ` [Qemu-devel] [PATCH RFC v4 00/20] VT-d: vfio enablement and misc enhances Michael S. Tsirkin
2017-01-24  7:40   ` Peter Xu

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