From: Jason Gunthorpe <jgg@mellanox.com>
To: Dave Jiang <dave.jiang@intel.com>
Cc: vkoul@kernel.org, megha.dey@linux.intel.com, maz@kernel.org,
bhelgaas@google.com, rafael@kernel.org,
gregkh@linuxfoundation.org, tglx@linutronix.de, hpa@zytor.com,
alex.williamson@redhat.com, jacob.jun.pan@intel.com,
ashok.raj@intel.com, yi.l.liu@intel.com, baolu.lu@intel.com,
kevin.tian@intel.com, sanjay.k.kumar@intel.com,
tony.luck@intel.com, jing.lin@intel.com,
dan.j.williams@intel.com, kwankhede@nvidia.com,
eric.auger@redhat.com, parav@mellanox.com,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, linux-pci@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: Tue, 21 Apr 2020 20:54:42 -0300 [thread overview]
Message-ID: <20200421235442.GO11945@mellanox.com> (raw)
In-Reply-To: <158751095889.36773.6009825070990637468.stgit@djiang5-desk3.ch.intel.com>
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.
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
next prev parent reply other threads:[~2020-04-21 23:54 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 ` Jason Gunthorpe [this message]
2020-04-22 0:53 ` [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver 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
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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