From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: cohuck@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, peterx@redhat.com
Subject: Re: [PATCH v1 07/14] vfio: Add a device notifier interface
Date: Tue, 9 Mar 2021 12:47:43 -0400 [thread overview]
Message-ID: <20210309164743.GK2356281@nvidia.com> (raw)
In-Reply-To: <20210309084513.51fd2a97@x1.home.shazbot.org>
On Tue, Mar 09, 2021 at 08:45:13AM -0700, Alex Williamson wrote:
> > I'm having trouble guessing why we need to refcount the group to add a
> > notifier to the device's notifier chain?
> >
> > I suppose it actually has to do with the MMIO mapping? But I don't
> > know what the relation is between MMIO mappings in the IOMMU and the
> > container? This could deserve a comment?
>
> Sure, I can add a comment. We want to make sure the device remains
> within an IOMMU context so long as we have a DMA mapping to the device
> MMIO, which could potentially manipulate the device. IOMMU context is
> managed a the group level.
I find refcounting is easier to understand if the refcount inc/dec is
near the thing that is actually using the object - so I'd suggest to
move this to the iommu code.
A comment sounds like a good idea since this is security sensitive
Jason
next prev parent reply other threads:[~2021-03-09 16:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 21:47 [PATCH v1 00/14] vfio: Device memory DMA mapping improvements Alex Williamson
2021-03-08 21:47 ` [PATCH v1 01/14] vfio: Create vfio_fs_type with inode per device Alex Williamson
2021-03-09 8:36 ` Christoph Hellwig
2021-04-09 4:54 ` 答复: " Zengtao (B)
2021-04-09 14:24 ` Alex Williamson
2021-04-09 17:32 ` Jason Gunthorpe
2021-04-12 4:03 ` 答复: " Zengtao (B)
2021-04-12 4:09 ` Zengtao (B)
2021-03-08 21:47 ` [PATCH v1 02/14] vfio: Update vfio_add_group_dev() API Alex Williamson
2021-03-10 7:48 ` Christoph Hellwig
2021-03-10 12:19 ` Jason Gunthorpe
2021-03-10 15:28 ` Alex Williamson
2021-03-11 11:23 ` Christoph Hellwig
2021-03-08 21:47 ` [PATCH v1 03/14] vfio: Export unmap_mapping_range() wrapper Alex Williamson
2021-03-08 21:48 ` [PATCH v1 04/14] vfio/pci: Use vfio_device_unmap_mapping_range() Alex Williamson
2021-03-08 21:48 ` [PATCH v1 05/14] vfio: Create a vfio_device from vma lookup Alex Williamson
2021-03-08 21:48 ` [PATCH v1 06/14] vfio: Add vma to pfn callback Alex Williamson
2021-03-09 0:33 ` Jason Gunthorpe
2021-03-08 21:48 ` [PATCH v1 07/14] vfio: Add a device notifier interface Alex Williamson
2021-03-09 0:46 ` Jason Gunthorpe
2021-03-09 15:45 ` Alex Williamson
2021-03-09 16:47 ` Jason Gunthorpe [this message]
2021-03-10 7:56 ` Christoph Hellwig
2021-03-19 22:25 ` Alex Williamson
2021-03-22 15:16 ` Christoph Hellwig
2021-03-08 21:48 ` [PATCH v1 08/14] vfio/pci: Notify on device release Alex Williamson
2021-03-08 21:48 ` [PATCH v1 09/14] vfio/type1: Refactor pfn_list clearing Alex Williamson
2021-03-10 8:01 ` Christoph Hellwig
2021-03-08 21:49 ` [PATCH v1 10/14] vfio/type1: Pass iommu and dma objects through to vaddr_get_pfn Alex Williamson
2021-03-08 21:49 ` [PATCH v1 11/14] vfio/type1: Register device notifier Alex Williamson
2021-03-10 8:03 ` Christoph Hellwig
2021-03-08 21:49 ` [PATCH v1 12/14] vfio/type1: Support batching of device mappings Alex Williamson
2021-03-09 1:04 ` Jason Gunthorpe
2021-03-08 21:49 ` [PATCH v1 13/14] vfio: Remove extern from declarations across vfio Alex Williamson
2021-03-09 0:21 ` Halil Pasic
2021-03-09 1:07 ` Jason Gunthorpe
2021-03-08 21:49 ` [PATCH v1 14/14] vfio: Cleanup use of bare unsigned Alex Williamson
2021-03-09 1:07 ` Jason Gunthorpe
2021-03-09 8:31 ` Christoph Hellwig
2021-03-09 1:06 ` [PATCH v1 00/14] vfio: Device memory DMA mapping improvements Jason Gunthorpe
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