From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Christoph Hellwig <hch@lst.de>, Lei Rao <lei.rao@intel.com>,
kbusch@kernel.org, axboe@fb.com, kch@nvidia.com,
sagi@grimberg.me, alex.williamson@redhat.com, cohuck@redhat.com,
yishaih@nvidia.com, shameerali.kolothum.thodi@huawei.com,
kevin.tian@intel.com, mjrosato@linux.ibm.com,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
kvm@vger.kernel.org, eddie.dong@intel.com, yadong.li@intel.com,
yi.l.liu@intel.com, Konrad.wilk@oracle.com,
stephen@eideticom.com, hang.yuan@intel.com
Subject: Re: [RFC PATCH 1/5] nvme-pci: add function nvme_submit_vf_cmd to issue admin commands for VF driver.
Date: Wed, 7 Dec 2022 14:52:03 +0100 [thread overview]
Message-ID: <20221207135203.GA22803@lst.de> (raw)
In-Reply-To: <Y5CWVu08abcOuEQH@ziepe.ca>
On Wed, Dec 07, 2022 at 09:34:14AM -0400, Jason Gunthorpe wrote:
> The VFIO design assumes that the "vfio migration driver" will talk to
> both functions under the hood, and I don't see a fundamental problem
> with this beyond it being awkward with the driver core.
And while that is a fine concept per see, the current incarnation of
that is fundamentally broken is it centered around the controlled
VM. Which really can't work.
> Even the basic assumption that there would be a controlling/controlled
> relationship is not universally true. The mdev type drivers, and
> SIOV-like devices are unlikely to have that. Once you can use PASID
> the reasons to split things at the HW level go away, and a VF could
> certainly self-migrate.
Even then you need a controlling and a controlled entity. The
controlling entity even in SIOV remains a PCIe function. The
controlled entity might just be a bunch of hardware resoures and
a PASID. Making it important again that all migration is driven
by the controlling entity.
Also the whole concept that only VFIO can do live migration is
a little bogus. With checkpoint and restart it absolutely
does make sense to live migrate a container, and with that
the hardware interface (e.g. nvme controller) assigned to it.
> So, when you see both Intel and Pensando proposing this kind of
> layered model for NVMe where migration is subsystem-local to VFIO, I
> think this is where the inspiration is coming from. Their native DPU
> drivers already work this way.
Maybe they should have talked to someone not high on their own
supply before designing this.
next prev parent reply other threads:[~2022-12-07 13:52 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-06 5:58 [RFC PATCH 0/5] Add new VFIO PCI driver for NVMe devices Lei Rao
2022-12-06 5:58 ` [RFC PATCH 1/5] nvme-pci: add function nvme_submit_vf_cmd to issue admin commands for VF driver Lei Rao
2022-12-06 6:19 ` Christoph Hellwig
2022-12-06 13:44 ` Jason Gunthorpe
2022-12-06 13:51 ` Keith Busch
2022-12-06 14:27 ` Jason Gunthorpe
2022-12-06 13:58 ` Christoph Hellwig
2022-12-06 15:22 ` Jason Gunthorpe
2022-12-06 15:38 ` Christoph Hellwig
2022-12-06 15:51 ` Jason Gunthorpe
2022-12-06 16:55 ` Christoph Hellwig
2022-12-06 19:15 ` Jason Gunthorpe
2022-12-07 2:30 ` Max Gurtovoy
2022-12-07 7:58 ` Christoph Hellwig
2022-12-09 2:11 ` Tian, Kevin
2022-12-12 7:41 ` Christoph Hellwig
2022-12-07 7:54 ` Christoph Hellwig
2022-12-07 10:59 ` Max Gurtovoy
2022-12-07 13:46 ` Christoph Hellwig
2022-12-07 14:50 ` Max Gurtovoy
2022-12-07 16:35 ` Christoph Hellwig
2022-12-07 13:34 ` Jason Gunthorpe
2022-12-07 13:52 ` Christoph Hellwig [this message]
2022-12-07 15:07 ` Jason Gunthorpe
2022-12-07 16:38 ` Christoph Hellwig
2022-12-07 17:31 ` Jason Gunthorpe
2022-12-07 18:33 ` Christoph Hellwig
2022-12-07 20:08 ` Jason Gunthorpe
2022-12-09 2:50 ` Tian, Kevin
2022-12-09 18:56 ` Dong, Eddie
2022-12-11 11:39 ` Max Gurtovoy
2022-12-12 7:55 ` Christoph Hellwig
2022-12-12 14:49 ` Max Gurtovoy
2022-12-12 7:50 ` Christoph Hellwig
2022-12-13 14:01 ` Jason Gunthorpe
2022-12-13 16:08 ` Christoph Hellwig
2022-12-13 17:49 ` Jason Gunthorpe
2022-12-06 5:58 ` [RFC PATCH 2/5] nvme-vfio: add new vfio-pci driver for NVMe device Lei Rao
2022-12-06 5:58 ` [RFC PATCH 3/5] nvme-vfio: enable the function of VFIO live migration Lei Rao
2023-01-19 10:21 ` Max Gurtovoy
2023-02-09 9:09 ` Rao, Lei
2022-12-06 5:58 ` [RFC PATCH 4/5] nvme-vfio: check if the hardware supports " Lei Rao
2022-12-06 13:47 ` Keith Busch
2022-12-06 5:58 ` [RFC PATCH 5/5] nvme-vfio: Add a document for the NVMe device Lei Rao
2022-12-06 6:26 ` Christoph Hellwig
2022-12-06 13:05 ` Jason Gunthorpe
2022-12-06 13:09 ` Christoph Hellwig
2022-12-06 13:52 ` Jason Gunthorpe
2022-12-06 14:00 ` Christoph Hellwig
2022-12-06 14:20 ` Jason Gunthorpe
2022-12-06 14:31 ` Christoph Hellwig
2022-12-06 14:48 ` Jason Gunthorpe
2022-12-06 15:01 ` Christoph Hellwig
2022-12-06 15:28 ` Jason Gunthorpe
2022-12-06 15:35 ` Christoph Hellwig
2022-12-06 18:00 ` Dong, Eddie
2022-12-12 7:57 ` Christoph Hellwig
2022-12-11 12:05 ` Max Gurtovoy
2022-12-11 13:21 ` Rao, Lei
2022-12-11 14:51 ` Max Gurtovoy
2022-12-12 1:20 ` Rao, Lei
2022-12-12 8:09 ` Christoph Hellwig
2022-12-09 2:05 ` Tian, Kevin
2022-12-09 16:53 ` Li, Yadong
2022-12-12 8:11 ` Christoph Hellwig
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