linux-pci.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jason Gunthorpe <jgg@mellanox.com>, "Jiang, Dave" <dave.jiang@intel.com>
Cc: "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>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
	"Raj, Ashok" <ashok.raj@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: Wed, 22 Apr 2020 00:53:25 +0000	[thread overview]
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19D86EE26@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20200421235442.GO11945@mellanox.com>

> From: Jason Gunthorpe
> Sent: Wednesday, April 22, 2020 7:55 AM
> 
> On Tue, Apr 21, 2020 at 04:33:46PM -0700, Dave Jiang wrote:
> > The actual code is independent of the stage 2 driver code submission that
> adds
> > support for SVM, ENQCMD(S), PASID, and shared workqueues. This code
> series will
> > support dedicated workqueue on a guest with no vIOMMU.
> >
> > A new device type "mdev" is introduced for the idxd driver. This allows the
> wq
> > to be dedicated to the usage of a VFIO mediated device (mdev). Once the
> work
> > queue (wq) is enabled, an uuid generated by the user can be added to the
> wq
> > through the uuid sysfs attribute for the wq.  After the association, a mdev
> can
> > be created using this UUID. The mdev driver code will associate the uuid
> and
> > setup the mdev on the driver side. When the create operation is successful,
> the
> > uuid can be passed to qemu. When the guest boots up, it should discover a
> DSA
> > device when doing PCI discovery.
> 
> I'm feeling really skeptical that adding all this PCI config space and
> MMIO BAR emulation to the kernel just to cram this into a VFIO
> interface is a good idea, that kind of stuff is much safer in
> userspace.
> 
> Particularly since vfio is not really needed once a driver is using
> the PASID stuff. We already have general code for drivers to use to
> attach a PASID to a mm_struct - and using vfio while disabling all the
> DMA/iommu config really seems like an abuse.

Well, this series is for virtualizing idxd device to VMs, instead of supporting
SVA for bare metal processes. idxd implements a hardware-assisted 
mediated device technique called Intel Scalable I/O Virtualization, which
allows each Assignable Device Interface (ADI, e.g. a work queue) tagged 
with an unique PASID to ensure fine-grained DMA isolation when those 
ADIs are assigned to different VMs. For this purpose idxd utilizes the VFIO 
mdev framework and IOMMU aux-domain extension. Bare metal SVA will
be enabled for idxd later by using the general SVA code that you mentioned.
Both paths will co-exist in the end so there is no such case of disabling
DMA/iommu config.

Thanks
Kevin

> 
> A /dev/idxd char dev that mmaps a bar page and links it to a PASID
> seems a lot simpler and saner kernel wise.
> 
> > The mdev utilizes Interrupt Message Store or IMS[3] instead of MSIX for
> > interrupts for the guest. This preserves MSIX for host usages and also
> allows a
> > significantly larger number of interrupt vectors for guest usage.
> 
> I never did get a reply to my earlier remarks on the IMS patches.
> 
> The concept of a device specific addr/data table format for MSI is not
> Intel specific. This should be general code. We have a device that can
> use this kind of kernel capability today.
> 
> Jason

  reply	other threads:[~2020-04-22  0:53 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 23:33 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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=AADFC41AFE54684AB9EE6CBC0274A5D19D86EE26@SHSMSX104.ccr.corp.intel.com \
    --to=kevin.tian@intel.com \
    --cc=alex.williamson@redhat.com \
    --cc=ashok.raj@intel.com \
    --cc=baolu.lu@intel.com \
    --cc=bhelgaas@google.com \
    --cc=dan.j.williams@intel.com \
    --cc=dave.jiang@intel.com \
    --cc=dmaengine@vger.kernel.org \
    --cc=eric.auger@redhat.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hpa@zytor.com \
    --cc=jacob.jun.pan@intel.com \
    --cc=jgg@mellanox.com \
    --cc=jing.lin@intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=kwankhede@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=maz@kernel.org \
    --cc=megha.dey@linux.intel.com \
    --cc=parav@mellanox.com \
    --cc=rafael@kernel.org \
    --cc=sanjay.k.kumar@intel.com \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=vkoul@kernel.org \
    --cc=x86@kernel.org \
    --cc=yi.l.liu@intel.com \
    --subject='RE: [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver.' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).