From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Yishai Hadas <yishaih@nvidia.com>,
saeedm@nvidia.com, kvm@vger.kernel.org, netdev@vger.kernel.org,
kuba@kernel.org, kevin.tian@intel.com, joao.m.martins@oracle.com,
leonro@nvidia.com, maorg@nvidia.com, cohuck@redhat.com,
Kirti Wankhede <kwankhede@nvidia.com>
Subject: Re: [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs
Date: Tue, 19 Jul 2022 17:18:03 -0300 [thread overview]
Message-ID: <20220719201803.GL4609@nvidia.com> (raw)
In-Reply-To: <20220719135714.330297ed.alex.williamson@redhat.com>
On Tue, Jul 19, 2022 at 01:57:14PM -0600, Alex Williamson wrote:
> If userspace needs to consider the bitmap undefined for any errno,
> that's a pretty serious usage restriction that may negate the
> practical utility of atomically OR'ing in dirty bits.
If any report fails it means qemu has lost the ability to dirty track,
so it doesn't really matter if one chunk has gotten lost - we can't
move forward with incomplete dirty data.
Error recovery is to consider all memory dirty and try to restart the
dirty tracking, or to abort/restart the whole migration.
Worrying about the integrity of a single bitmap chunk doesn't seem
worthwhile given that outcome.
Yes, there are cases where things are more deterministic, but it is
not useful information that userspace can do anything with. It can't
just call report again and expect it will work the 2nd time, for
instance.
We do not expect failures here, lets not overdesign things.
> reserve -EIO for such a case. The driver itself can also gratuitously
> mark ranges dirty itself if it loses sync with the device, and can
> probably do so at a much more accurate granularity than userspace.
A driver that implements such a handling shouldn't return an error
code in the first place.
Jason
next prev parent reply other threads:[~2022-07-19 20:18 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-14 8:12 [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 01/11] net/mlx5: Introduce ifc bits for page tracker Yishai Hadas
2022-07-21 8:28 ` Tian, Kevin
2022-07-21 8:43 ` Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 02/11] net/mlx5: Query ADV_VIRTUALIZATION capabilities Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs Yishai Hadas
2022-07-18 22:29 ` Alex Williamson
2022-07-19 1:39 ` Tian, Kevin
2022-07-19 5:40 ` Kirti Wankhede
2022-07-19 7:49 ` Yishai Hadas
2022-07-19 19:57 ` Alex Williamson
2022-07-19 20:18 ` Jason Gunthorpe [this message]
2022-07-21 8:45 ` Tian, Kevin
2022-07-21 12:05 ` Jason Gunthorpe
2022-07-25 7:20 ` Tian, Kevin
2022-07-25 14:33 ` Jason Gunthorpe
2022-07-26 7:07 ` Tian, Kevin
[not found] ` <56bd06d3-944c-18da-86ed-ae14ce5940b7@nvidia.com>
2022-07-25 7:30 ` Tian, Kevin
2022-07-26 8:37 ` Yishai Hadas
2022-07-26 14:03 ` Alex Williamson
2022-07-26 15:04 ` Jason Gunthorpe
2022-07-28 4:05 ` Tian, Kevin
2022-07-28 12:06 ` Jason Gunthorpe
2022-07-29 3:01 ` Tian, Kevin
2022-07-29 14:11 ` Jason Gunthorpe
2022-07-14 8:12 ` [PATCH V2 vfio 04/11] vfio: Move vfio.c to vfio_main.c Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 05/11] vfio: Add an IOVA bitmap support Yishai Hadas
2022-07-18 22:30 ` Alex Williamson
2022-07-18 22:46 ` Jason Gunthorpe
2022-07-19 19:01 ` Alex Williamson
2022-07-20 1:57 ` Joao Martins
2022-07-20 16:47 ` Alex Williamson
2022-07-20 17:27 ` Jason Gunthorpe
2022-07-20 18:16 ` Joao Martins
2022-07-14 8:12 ` [PATCH V2 vfio 06/11] vfio: Introduce the DMA logging feature support Yishai Hadas
2022-07-18 22:30 ` Alex Williamson
2022-07-19 9:19 ` Yishai Hadas
2022-07-19 19:25 ` Alex Williamson
2022-07-19 20:08 ` Jason Gunthorpe
2022-07-21 8:54 ` Tian, Kevin
2022-07-21 11:50 ` Jason Gunthorpe
2022-07-25 7:38 ` Tian, Kevin
2022-07-25 14:37 ` Jason Gunthorpe
2022-07-26 7:34 ` Tian, Kevin
2022-07-26 15:12 ` Jason Gunthorpe
2022-07-14 8:12 ` [PATCH V2 vfio 07/11] vfio/mlx5: Init QP based resources for dirty tracking Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 08/11] vfio/mlx5: Create and destroy page tracker object Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 09/11] vfio/mlx5: Report dirty pages from tracker Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 10/11] vfio/mlx5: Manage error scenarios on tracker Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 11/11] vfio/mlx5: Set the driver DMA logging callbacks Yishai Hadas
2022-07-21 8:26 ` [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Tian, Kevin
2022-07-21 8:55 ` Yishai Hadas
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