From: Dave Jiang <dave.jiang@intel.com>
To: Jason Gunthorpe <jgg@mellanox.com>, "Raj, Ashok" <ashok.raj@intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
"vkoul@kernel.org" <vkoul@kernel.org>,
"megha.dey@linux.intel.com" <megha.dey@linux.intel.com>,
"maz@kernel.org" <maz@kernel.org>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"rafael@kernel.org" <rafael@kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"hpa@zytor.com" <hpa@zytor.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"Lu, Baolu" <baolu.lu@intel.com>,
"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
"Luck, Tony" <tony.luck@intel.com>,
"Lin, Jing" <jing.lin@intel.com>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
"eric.auger@redhat.com" <eric.auger@redhat.com>,
"parav@mellanox.com" <parav@mellanox.com>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver.
Date: Fri, 8 May 2020 16:52:57 -0700 [thread overview]
Message-ID: <57296ad1-20fe-caf2-b83f-46d823ca0b5f@intel.com> (raw)
In-Reply-To: <20200508231610.GO19158@mellanox.com>
On 5/8/2020 4:16 PM, Jason Gunthorpe wrote:
> On Fri, May 08, 2020 at 01:47:10PM -0700, Raj, Ashok wrote:
>
>> Even when uaccel was under development, one of the options
>> was to use VFIO as the transport, goal was the same i.e to keep
>> the user space have one interface.
>
> I feel a bit out of the loop here, uaccel isn't in today's kernel is
> it? I've heard about it for a while, it sounds very similar to RDMA,
> so I hope they took some of my advice...
It went into 5.7 kernel. drivers/misc/uacce. It looks char device exported with
SVM support.
>
>> But the needs of generic user space application is significantly
>> different from exporting a more functional device model to guest,
>> which isn't full emulated device. which is why VFIO didn't make
>> sense for native use.
>
> I'm not sure this is true. We've done these kinds of emulated SIOV
> like things already and there is a huge overlap between what a generic
> user application needs and what the VMM neds. Actually almost a
> perfect subset except for interrupt remapping (which is quite
> trivial).
>
> The things vfio focuses on, like groups and managing a real config
> space just don't apply here.
>
>> And when we move things from VFIO which is already established
>> as a general device model and accepted by multiple VMM's it gives
>> instant footing without a whole redesign.
>
> Yes, I understand, but I think you need to get more people to support
> this idea. From my standpoint this is taking secure lean VMMs and
> putting emulation code back into them, except in a more dangerous
> kernel location. This does not seem like a net win to me.
>
> You'd be much better to have some userspace library scheme instead of
> being completely tied to a kernel interface for modularity.
>
>> When we move things from VFIO to uaccel to bolt on the functionality
>> like VFIO, I suspect we would be moving code/functionality from VFIO
>> to Uaccel. I don't know what the net gain would be.
>
> Most of VFIO functionality is already decomposed inside the kernel,
> and you need most of it to do secure user access anyhow.
>
>> For mdev, would you agree we can keep the current architecture,
>> and investigate moving some emulation code to user space (say even for
>> standard vfio_pci) and then expand scope later.
>
> I won't hard NAK this, but I think you need more people to support
> this general idea of more emulation code in the kernel to go ahead -
> particularly since this is one of many future drivers along this
> design.
>
> It would be good to hear from the VMM teams that this is what they
> want (and why), for instance.
>
> Jason
>
next prev parent reply other threads:[~2020-05-08 23:53 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 23:33 [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver Dave Jiang
2020-04-21 23:33 ` [PATCH RFC 01/15] drivers/base: Introduce platform_msi_ops Dave Jiang
2020-04-26 7:01 ` Greg KH
2020-04-27 21:38 ` Dave Jiang
2020-04-28 7:34 ` Greg KH
2020-04-21 23:33 ` [PATCH RFC 02/15] drivers/base: Introduce a new platform-msi list Dave Jiang
2020-04-25 21:13 ` Thomas Gleixner
2020-05-04 0:08 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 03/15] drivers/base: Allocate/free platform-msi interrupts by group Dave Jiang
2020-04-25 21:23 ` Thomas Gleixner
2020-05-04 0:08 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 04/15] drivers/base: Add support for a new IMS irq domain Dave Jiang
2020-04-23 20:11 ` Jason Gunthorpe
2020-05-01 22:30 ` Dey, Megha
2020-05-03 22:25 ` Jason Gunthorpe
2020-05-03 22:40 ` Dey, Megha
2020-05-03 22:46 ` Jason Gunthorpe
2020-05-04 0:25 ` Dey, Megha
2020-05-04 12:14 ` Jason Gunthorpe
2020-05-06 10:27 ` Tian, Kevin
2020-04-25 21:38 ` Thomas Gleixner
2020-05-04 0:11 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 05/15] ims-msi: Add mask/unmask routines Dave Jiang
2020-04-25 21:49 ` Thomas Gleixner
2020-05-04 0:16 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 06/15] ims-msi: Enable IMS interrupts Dave Jiang
2020-04-25 22:13 ` Thomas Gleixner
2020-05-04 0:17 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 07/15] Documentation: Interrupt Message store Dave Jiang
2020-04-23 20:04 ` Jason Gunthorpe
2020-05-01 22:32 ` Dey, Megha
2020-05-03 22:28 ` Jason Gunthorpe
2020-05-03 22:41 ` Dey, Megha
2020-04-21 23:34 ` [PATCH RFC 08/15] vfio/mdev: Add a member for iommu domain in mdev_device Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 09/15] vfio/type1: Save domain when attach domain to mdev Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 10/15] dmaengine: idxd: add config support for readonly devices Dave Jiang
2020-04-21 23:34 ` [PATCH RFC 11/15] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 12/15] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 13/15] dmaengine: idxd: add support for VFIO mediated device Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 14/15] dmaengine: idxd: add error notification from host driver to " Dave Jiang
2020-04-21 23:35 ` [PATCH RFC 15/15] dmaengine: idxd: add ABI documentation for mediated device support Dave Jiang
2020-04-21 23:54 ` [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver Jason Gunthorpe
2020-04-22 0:53 ` Tian, Kevin
2020-04-22 11:50 ` Jason Gunthorpe
2020-04-22 21:14 ` Raj, Ashok
2020-04-23 19:12 ` Jason Gunthorpe
2020-04-24 3:27 ` Tian, Kevin
2020-04-24 12:44 ` Jason Gunthorpe
2020-04-24 16:25 ` Tian, Kevin
2020-04-24 18:12 ` Jason Gunthorpe
2020-04-26 5:18 ` Tian, Kevin
2020-04-26 19:13 ` Jason Gunthorpe
2020-04-27 3:43 ` Alex Williamson
2020-04-27 11:58 ` Jason Gunthorpe
2020-04-27 13:19 ` Alex Williamson
2020-04-27 13:22 ` Jason Gunthorpe
2020-04-27 14:18 ` Alex Williamson
2020-04-27 14:25 ` Jason Gunthorpe
2020-04-27 15:41 ` Alex Williamson
2020-04-27 16:16 ` Jason Gunthorpe
2020-04-27 16:25 ` Dave Jiang
2020-04-27 21:56 ` Jason Gunthorpe
2020-04-29 9:42 ` Tian, Kevin
2020-05-08 20:47 ` Raj, Ashok
2020-05-08 23:16 ` Jason Gunthorpe
2020-05-08 23:52 ` Dave Jiang [this message]
2020-05-09 0:09 ` Raj, Ashok
2020-05-09 12:21 ` Jason Gunthorpe
2020-05-13 2:29 ` Jason Wang
2020-05-13 8:30 ` Tian, Kevin
2020-05-13 12:40 ` Jason Gunthorpe
2020-04-27 12:13 ` Tian, Kevin
2020-04-27 12:55 ` Jason Gunthorpe
2020-04-22 21:24 ` Dan Williams
2020-04-23 19:17 ` Dan Williams
2020-04-23 19:49 ` Jason Gunthorpe
2020-05-01 22:31 ` Dey, Megha
2020-05-03 22:21 ` Jason Gunthorpe
2020-05-03 22:32 ` Dey, Megha
2020-04-23 19:18 ` Jason Gunthorpe
2020-05-01 22:31 ` Dey, Megha
2020-05-03 22:22 ` Jason Gunthorpe
2020-05-03 22:31 ` Dey, Megha
2020-05-03 22:36 ` Jason Gunthorpe
2020-05-04 0:20 ` Dey, Megha
2020-04-22 23:04 ` Dey, Megha
2020-04-23 19:44 ` Jason Gunthorpe
2020-05-01 22:32 ` Dey, Megha
2020-04-24 6:31 ` Jason Wang
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