From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: kvm@vger.kernel.org, maorg@nvidia.com,
virtualization@lists.linux-foundation.org, jiri@nvidia.com,
leonro@nvidia.com
Subject: Re: [PATCH vfio 11/11] vfio/virtio: Introduce a vfio driver over virtio devices
Date: Thu, 21 Sep 2023 13:01:12 -0400 [thread overview]
Message-ID: <20230921125348-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20230921165224.GR13733@nvidia.com>
On Thu, Sep 21, 2023 at 01:52:24PM -0300, Jason Gunthorpe wrote:
> On Thu, Sep 21, 2023 at 10:43:50AM -0600, Alex Williamson wrote:
>
> > > With that code in place a legacy driver in the guest has the look and
> > > feel as if having a transitional device with legacy support for both its
> > > control and data path flows.
> >
> > Why do we need to enable a "legacy" driver in the guest? The very name
> > suggests there's an alternative driver that perhaps doesn't require
> > this I/O BAR. Why don't we just require the non-legacy driver in the
> > guest rather than increase our maintenance burden? Thanks,
>
> It was my reaction also.
>
> Apparently there is a big deployed base of people using old guest VMs
> with old drivers and they do not want to update their VMs. It is the
> same basic reason why qemu supports all those weird old machine types
> and HW emulations. The desire is to support these old devices so that
> old VMs can work unchanged.
>
> Jason
And you are saying all these very old VMs use such a large number of
legacy devices that over-counting of locked memory due to vdpa not
correctly using iommufd is a problem that urgently needs to be solved
otherwise the solution has no value?
Another question I'm interested in is whether there's actually a
performance benefit to using this as compared to just software
vhost. I note there's a VM exit on each IO access, so ... perhaps?
Would be nice to see some numbers.
--
MST
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next prev parent reply other threads:[~2023-09-21 17:01 UTC|newest]
Thread overview: 140+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-21 12:40 [PATCH vfio 00/11] Introduce a vfio driver over virtio devices Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 01/11] virtio-pci: Use virtio pci device layer vq info instead of generic one Yishai Hadas via Virtualization
2023-09-21 13:46 ` Michael S. Tsirkin
2023-09-26 19:13 ` Feng Liu via Virtualization
2023-09-27 18:09 ` Feng Liu via Virtualization
2023-09-27 21:24 ` Michael S. Tsirkin
2023-09-21 12:40 ` [PATCH vfio 02/11] virtio: Define feature bit for administration virtqueue Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 03/11] virtio-pci: Introduce admin virtqueue Yishai Hadas via Virtualization
2023-09-21 13:57 ` Michael S. Tsirkin
2023-09-26 19:23 ` Feng Liu via Virtualization
2023-09-27 18:12 ` Feng Liu via Virtualization
2023-09-27 21:27 ` Michael S. Tsirkin
2023-10-02 18:07 ` Feng Liu via Virtualization
2023-09-21 12:40 ` [PATCH vfio 04/11] virtio: Expose the synchronous command helper function Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 05/11] virtio-pci: Introduce admin command sending function Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 06/11] virtio-pci: Introduce API to get PF virtio device from VF PCI device Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 07/11] virtio-pci: Introduce admin commands Yishai Hadas via Virtualization
2023-09-24 5:18 ` kernel test robot
2023-09-25 3:18 ` kernel test robot
2023-09-21 12:40 ` [PATCH vfio 08/11] vfio/pci: Expose vfio_pci_core_setup_barmap() Yishai Hadas via Virtualization
2023-09-21 16:35 ` Alex Williamson
2023-09-26 9:45 ` Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 09/11] vfio/pci: Expose vfio_pci_iowrite/read##size() Yishai Hadas via Virtualization
2023-09-21 12:40 ` [PATCH vfio 10/11] vfio/virtio: Expose admin commands over virtio device Yishai Hadas via Virtualization
2023-09-21 13:08 ` Michael S. Tsirkin
2023-09-21 20:34 ` Michael S. Tsirkin
2023-09-26 10:51 ` Yishai Hadas via Virtualization
2023-09-26 11:25 ` Michael S. Tsirkin
2023-09-22 9:54 ` Michael S. Tsirkin
2023-09-26 11:14 ` Yishai Hadas via Virtualization
2023-09-26 11:41 ` Michael S. Tsirkin
[not found] ` <20230927131817.GA338226@nvidia.com>
2023-09-27 21:30 ` Michael S. Tsirkin
[not found] ` <20230927231600.GD339126@nvidia.com>
2023-09-28 5:26 ` Michael S. Tsirkin
2023-10-02 6:28 ` Christoph Hellwig
[not found] ` <20231002151320.GA650762@nvidia.com>
2023-10-05 8:49 ` Christoph Hellwig
[not found] ` <20231005111004.GK682044@nvidia.com>
2023-10-06 13:09 ` Christoph Hellwig
[not found] ` <20231010131031.GJ3952@nvidia.com>
2023-10-10 13:56 ` Michael S. Tsirkin
[not found] ` <20231010140849.GL3952@nvidia.com>
2023-10-10 14:54 ` Michael S. Tsirkin
2023-10-10 15:09 ` Yishai Hadas via Virtualization
2023-10-10 15:14 ` Michael S. Tsirkin
2023-10-10 15:43 ` Yishai Hadas via Virtualization
2023-10-10 15:58 ` Parav Pandit via Virtualization
2023-10-10 15:58 ` Michael S. Tsirkin
2023-10-10 16:09 ` Yishai Hadas via Virtualization
2023-10-10 20:42 ` Michael S. Tsirkin
2023-10-11 7:44 ` Yishai Hadas via Virtualization
2023-10-11 8:02 ` Michael S. Tsirkin
2023-10-11 8:58 ` Yishai Hadas via Virtualization
2023-10-11 9:03 ` Michael S. Tsirkin
2023-10-11 11:25 ` Yishai Hadas via Virtualization
2023-10-11 6:12 ` Christoph Hellwig
[not found] ` <20231010155937.GN3952@nvidia.com>
2023-10-10 16:03 ` Michael S. Tsirkin
[not found] ` <20231010160712.GO3952@nvidia.com>
2023-10-10 16:21 ` Parav Pandit via Virtualization
2023-10-10 20:38 ` Michael S. Tsirkin
2023-10-11 6:13 ` Christoph Hellwig
2023-10-11 6:43 ` Michael S. Tsirkin
2023-10-11 6:59 ` Christoph Hellwig
2023-10-11 8:00 ` Parav Pandit via Virtualization
2023-10-11 8:10 ` Michael S. Tsirkin
[not found] ` <20231011121849.GV3952@nvidia.com>
2023-10-11 17:03 ` Michael S. Tsirkin
2023-10-11 17:05 ` Michael S. Tsirkin
2023-10-12 10:29 ` Zhu, Lingshan
[not found] ` <20231012132749.GK3952@nvidia.com>
2023-10-13 10:28 ` Zhu, Lingshan
2023-10-13 13:50 ` Michael S. Tsirkin
2023-10-16 8:33 ` Zhu, Lingshan
2023-10-16 8:52 ` Michael S. Tsirkin
2023-10-16 9:53 ` Zhu, Lingshan
2023-10-11 8:12 ` Michael S. Tsirkin
2023-10-12 10:30 ` Zhu, Lingshan
2023-10-11 6:26 ` Christoph Hellwig
[not found] ` <20231011135709.GW3952@nvidia.com>
2023-10-11 14:17 ` Christoph Hellwig
[not found] ` <20231011145810.GZ3952@nvidia.com>
2023-10-11 16:59 ` Michael S. Tsirkin
[not found] ` <20231011171944.GA3952@nvidia.com>
2023-10-11 20:20 ` Michael S. Tsirkin
2023-09-21 12:40 ` [PATCH vfio 11/11] vfio/virtio: Introduce a vfio driver over virtio devices Yishai Hadas via Virtualization
2023-09-21 13:16 ` Michael S. Tsirkin
[not found] ` <20230921141125.GM13733@nvidia.com>
2023-09-21 14:16 ` Michael S. Tsirkin
[not found] ` <20230921164139.GP13733@nvidia.com>
2023-09-21 16:53 ` Michael S. Tsirkin
[not found] ` <20230921183926.GV13733@nvidia.com>
2023-09-21 19:13 ` Michael S. Tsirkin
[not found] ` <20230921194946.GX13733@nvidia.com>
2023-09-21 20:45 ` Michael S. Tsirkin
[not found] ` <20230921225526.GE13733@nvidia.com>
2023-09-22 3:02 ` Jason Wang
2023-09-22 11:23 ` Michael S. Tsirkin
2023-09-22 3:01 ` Jason Wang
[not found] ` <20230922121132.GK13733@nvidia.com>
2023-09-25 2:34 ` Jason Wang
[not found] ` <20230925122607.GW13733@nvidia.com>
2023-09-25 19:44 ` Michael S. Tsirkin
[not found] ` <20230926004059.GM13733@nvidia.com>
2023-09-26 5:34 ` Michael S. Tsirkin
2023-09-26 5:42 ` Michael S. Tsirkin
[not found] ` <20230926135057.GO13733@nvidia.com>
2023-09-27 21:38 ` Michael S. Tsirkin
[not found] ` <20230927232005.GE339126@nvidia.com>
2023-09-28 5:31 ` Michael S. Tsirkin
2023-09-26 4:37 ` Jason Wang
2023-09-26 5:33 ` Parav Pandit via Virtualization
2023-09-21 19:17 ` Michael S. Tsirkin
[not found] ` <20230921195115.GY13733@nvidia.com>
2023-09-21 20:55 ` Michael S. Tsirkin
2023-09-25 4:44 ` Zhu, Lingshan
2023-09-22 3:45 ` Zhu, Lingshan
2023-09-21 13:33 ` Michael S. Tsirkin
2023-09-21 16:43 ` Alex Williamson
[not found] ` <20230921165224.GR13733@nvidia.com>
2023-09-21 17:01 ` Michael S. Tsirkin [this message]
2023-09-21 17:09 ` Parav Pandit via Virtualization
2023-09-21 17:24 ` Michael S. Tsirkin
[not found] ` <20230921170709.GS13733@nvidia.com>
2023-09-21 17:21 ` Michael S. Tsirkin
[not found] ` <20230921174450.GT13733@nvidia.com>
2023-09-21 17:55 ` Michael S. Tsirkin
[not found] ` <20230921181637.GU13733@nvidia.com>
2023-09-21 19:34 ` Michael S. Tsirkin
[not found] ` <20230921195345.GZ13733@nvidia.com>
2023-09-21 20:16 ` Michael S. Tsirkin
2023-09-22 3:02 ` Jason Wang
[not found] ` <20230922122246.GN13733@nvidia.com>
2023-09-22 12:25 ` Parav Pandit via Virtualization
2023-09-22 15:13 ` Michael S. Tsirkin
[not found] ` <20230922151534.GR13733@nvidia.com>
2023-09-22 15:40 ` Michael S. Tsirkin
[not found] ` <20230922162233.GT13733@nvidia.com>
2023-09-25 17:36 ` Michael S. Tsirkin
2023-09-25 2:30 ` Jason Wang
2023-09-25 8:26 ` Parav Pandit via Virtualization
2023-09-25 18:36 ` Michael S. Tsirkin
2023-09-26 2:34 ` Zhu, Lingshan
2023-09-26 3:45 ` Parav Pandit via Virtualization
2023-09-26 4:37 ` Jason Wang
2023-10-12 10:52 ` Michael S. Tsirkin
2023-10-12 11:11 ` Parav Pandit via Virtualization
2023-10-12 11:30 ` Michael S. Tsirkin
2023-10-12 11:40 ` Parav Pandit via Virtualization
2023-09-26 2:32 ` Jason Wang
2023-09-26 4:01 ` Parav Pandit via Virtualization
2023-09-26 4:37 ` Jason Wang
2023-09-26 5:27 ` Parav Pandit via Virtualization
2023-09-26 11:49 ` Michael S. Tsirkin
2023-10-08 4:28 ` Jason Wang
[not found] ` <20230921224836.GD13733@nvidia.com>
2023-09-22 9:47 ` Michael S. Tsirkin
[not found] ` <20230922122328.GO13733@nvidia.com>
2023-09-22 15:45 ` Michael S. Tsirkin
2023-09-22 3:02 ` Jason Wang
[not found] ` <20230922122501.GP13733@nvidia.com>
2023-09-22 15:39 ` Michael S. Tsirkin
[not found] ` <20230922161928.GS13733@nvidia.com>
2023-09-25 18:16 ` Michael S. Tsirkin
[not found] ` <20230925185318.GK13733@nvidia.com>
2023-09-25 19:52 ` Michael S. Tsirkin
2023-09-21 19:58 ` Alex Williamson
[not found] ` <20230921200121.GA13733@nvidia.com>
2023-09-21 20:20 ` Michael S. Tsirkin
2023-09-21 20:59 ` Alex Williamson
[not found] ` <20230922123708.GA130749@nvidia.com>
2023-09-22 12:59 ` Parav Pandit via Virtualization
2023-09-26 15:20 ` Yishai Hadas via Virtualization
2023-09-26 17:00 ` Michael S. Tsirkin
2023-10-02 4:38 ` Parav Pandit via Virtualization
2023-09-22 10:10 ` Michael S. Tsirkin
2023-09-22 15:53 ` Michael S. Tsirkin
2023-10-02 11:23 ` Parav Pandit via Virtualization
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