From: Jason Gunthorpe <jgg@nvidia.com>
To: Peter Xu <peterx@redhat.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>,
"Burra, Phani R" <phani.r.burra@intel.com>
Subject: Re: [Intel-wired-lan] [PATCH iwl-next V2 10/15] ice: save and restore TX queue head
Date: Mon, 10 Jul 2023 12:54:03 -0300 [thread overview]
Message-ID: <ZKwpm1k+1hjN7oyE@nvidia.com> (raw)
In-Reply-To: <ZKReFWNJSVcfhL6y@x1n>
On Tue, Jul 04, 2023 at 01:59:49PM -0400, Peter Xu wrote:
> > This sounds counter-intuitive even for emulated devices. vIOMMU is
> > involved only when the device wants to access guest memory. But
> > by definition the RESUMING path should just restore the device to
> > the point where it is stopped. Why would such restore create a
> > dependency on vIOMMU state?
>
> For why QEMU migrates vIOMMU earlier than PCI generic devices, I can try to
> repeat here: IIRC it's because some device needs dma translations during
> post_load(), I forgot which device and why, but it can make some sense to
> me if recovering states of the pci device may need help from a translation.
Well, it has nothing to do with VFIO given the timeframe, and if
internal qemu devices are doing weird things like this it also
suggests they have problems with P2P as well.
The VFIO definition we have is that a device may not do any DMA while in
resuming/resuming_p2p, it is only allowed to initiate DMA once it
fully reaches running.
Obviously we have to setup the vIOMMU before going to running.
The internal qemu devices must follow this definition as well or they
are not P2P compatible.
About the only exception I could think is if some internal devices was
caching translations for some purpose, but it really should setup that
caching at entry to running..
Jason
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next prev parent reply other threads:[~2023-07-10 15:54 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 9:10 [Intel-wired-lan] [PATCH iwl-next V2 00/15] Add E800 live migration driver Lingyu Liu
2023-06-21 9:10 ` [Intel-wired-lan] [PATCH iwl-next V2 01/15] ice: Fix missing legacy 32byte RXDID in the supported bitmap Lingyu Liu
2023-06-21 9:10 ` [Intel-wired-lan] [PATCH iwl-next V2 02/15] ice: add function to get rxq context Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 03/15] ice: check VF migration status before sending messages to VF Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 04/15] ice: add migration init field and helper functions Lingyu Liu
2023-06-21 13:35 ` Jason Gunthorpe
2023-06-27 7:50 ` Cao, Yahui
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 05/15] ice: save VF messages as device state Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 06/15] ice: save and restore " Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 07/15] ice: do not notify VF link state during migration Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 08/15] ice: change VSI id in virtual channel message after migration Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 09/15] ice: save and restore RX queue head Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 10/15] ice: save and restore TX " Lingyu Liu
2023-06-21 14:37 ` Jason Gunthorpe
2023-06-27 6:55 ` Tian, Kevin
2023-07-03 5:27 ` Cao, Yahui
2023-07-03 21:03 ` Jason Gunthorpe
2023-07-04 7:35 ` Tian, Kevin
2023-06-28 8:11 ` Liu, Yi L
2023-06-28 12:39 ` Jason Gunthorpe
2023-07-03 12:54 ` Liu, Yi L
2023-07-04 7:38 ` Tian, Kevin
2023-07-04 17:59 ` Peter Xu
2023-07-10 15:54 ` Jason Gunthorpe [this message]
2023-07-17 21:43 ` Peter Xu
2023-07-18 15:38 ` Jason Gunthorpe
2023-07-18 17:36 ` Peter Xu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 11/15] ice: stop device before saving device states Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 12/15] ice: mask VF advanced capabilities if live migration is activated Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 13/15] vfio/ice: implement vfio_pci driver for E800 devices Lingyu Liu
2023-06-21 14:23 ` Jason Gunthorpe
2023-06-27 9:00 ` Liu, Lingyu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 14/15] vfio: Expose vfio_device_has_container() Lingyu Liu
2023-06-21 9:11 ` [Intel-wired-lan] [PATCH iwl-next V2 15/15] vfio/ice: support iommufd vfio compat mode Lingyu Liu
2023-06-21 14:40 ` Jason Gunthorpe
2023-06-27 8:09 ` Cao, Yahui
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