All of lore.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: "Raj\, Ashok" <ashok.raj@intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Dave Jiang <dave.jiang@intel.com>,
	vkoul@kernel.org, megha.dey@intel.com, maz@kernel.org,
	bhelgaas@google.com, alex.williamson@redhat.com,
	jacob.jun.pan@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, rafael@kernel.org,
	netanelg@mellanox.com, shahafs@mellanox.com,
	yan.y.zhao@linux.intel.com, pbonzini@redhat.com,
	samuel.ortiz@intel.com, mona.hossain@intel.com,
	dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
	x86@kernel.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org,
	Ashok Raj <ashok.raj@intel.com>
Subject: Re: [PATCH v3 05/18] dmaengine: idxd: add IMS support in base driver
Date: Thu, 01 Oct 2020 10:44:58 +0200	[thread overview]
Message-ID: <87y2kqfi7p.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201001010706.GD26492@otc-nc-03>

On Wed, Sep 30 2020 at 18:07, Ashok Raj wrote:
> On Wed, Sep 30, 2020 at 11:57:22PM +0200, Thomas Gleixner wrote:
>
> Devices exposed to guest need host OS support for programming interrupt
> entries in the IOMMU interrupt remapping table. VFIO provides those 
> services for standard interrupt schemes like MSI/MSIx for instance. 
> Since IMS is device specific VFIO can't provide an intercept when 
> IMS entries are programmed by the guest OS.

Why is IMS exposed to the guest in the first place? You expose a
subdevice to a guest, right? And that subdevice should not even know
that IMS exists simply because IMS is strictly host specific.

The obvious emulation here is to make the subdevice look like a PCI
device and expose emulated MSIX (not MSI) which is intercepted when
accessing the MSIX table and then redirected to the proper place along
with IRTE and PASID and whatever.

>> Also this stuff is host side and not guest side. I seriously doubt that
>> you want to hand in the whole PCI device which contains the IMS
>
> You are right, but nothing prevents a user from simply taking a full PCI
> device and assign to guest. 

You surely can and should prevent that because it makes no sense and
cannot work.

That's why you want a generic check for 'this device is magic SIOV or
whatever' and not something burried deep into a driver..

Thanks,

        tglx

  reply	other threads:[~2020-10-01  8:45 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <160021207013.67751.8220471499908137671.stgit@djiang5-desk3.ch.intel.com>
2020-09-15 23:27 ` [PATCH v3 01/18] irqchip: Add IMS (Interrupt Message Storage) driver Dave Jiang
2020-09-30 18:23   ` Thomas Gleixner
2020-10-01 22:59     ` Dey, Megha
2020-09-15 23:27 ` [PATCH v3 02/18] iommu/vt-d: Add DEV-MSI support Dave Jiang
2020-09-30 18:32   ` Thomas Gleixner
2020-10-01 23:26     ` Dey, Megha
2020-10-02 11:13       ` Thomas Gleixner
2020-10-08  7:54     ` David Woodhouse
2020-10-20 21:42       ` Dey, Megha
2020-09-15 23:28 ` [PATCH v3 05/18] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-09-30 18:47   ` Thomas Gleixner
2020-09-30 18:51     ` Jason Gunthorpe
2020-09-30 21:48       ` Thomas Gleixner
2020-09-30 21:49       ` Raj, Ashok
2020-09-30 21:57         ` Thomas Gleixner
2020-10-01  1:07           ` Raj, Ashok
2020-10-01  8:44             ` Thomas Gleixner [this message]
2020-09-30 22:38         ` Jason Gunthorpe
2020-10-01 20:48     ` Dave Jiang
2020-09-15 23:28 ` [PATCH v3 07/18] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-09-15 23:28 ` [PATCH v3 10/18] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-09-15 23:28 ` [PATCH v3 12/18] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-09-15 23:29 ` [PATCH v3 13/18] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-09-15 23:29 ` [PATCH v3 14/18] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-09-15 23:29 ` [PATCH v3 15/18] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-09-15 23:29 ` [PATCH v3 16/18] dmaengine: idxd: add ABI documentation for mediated device support Dave Jiang
2020-09-17 15:06 ` [PATCH v3 00/18] Add VFIO mediated device support and DEV-MSI support for the idxd driver Jason Gunthorpe
2020-09-17 17:15   ` Dave Jiang
2020-09-17 17:27     ` Jason Gunthorpe
2020-09-17 17:30     ` Alex Williamson
2020-09-17 17:37       ` Jason Gunthorpe
     [not found] ` <160021248280.67751.12525558281536923518.stgit@djiang5-desk3.ch.intel.com>
2020-09-30 18:36   ` [PATCH v3 04/18] dmaengine: idxd: add interrupt handle request support Thomas Gleixner
2020-10-01 20:16     ` Dave Jiang
     [not found] ` <160021253189.67751.12686144284999931703.stgit@djiang5-desk3.ch.intel.com>
2020-09-30 19:57   ` [PATCH v3 11/18] dmaengine: idxd: ims setup for the vdcm Thomas Gleixner
2020-10-07 21:54     ` Dave Jiang
2020-10-08  7:39       ` Thomas Gleixner
2020-10-08 16:51         ` Dave Jiang
2020-10-08 23:17           ` Thomas Gleixner
2020-10-08 23:32             ` Jason Gunthorpe
2020-10-09  0:27               ` Dave Jiang
2020-10-09  1:22               ` Raj, Ashok
2020-10-09 11:57                 ` Jason Gunthorpe
2020-10-09 12:43                   ` Raj, Ashok
2020-10-09 12:49                     ` Jason Gunthorpe
2020-10-09 13:02                       ` Raj, Ashok
2020-10-09 13:12                         ` Jason Gunthorpe
2020-10-09 13:40                           ` Raj, Ashok
2020-10-09 14:44               ` Thomas Gleixner
2020-10-09 14:52                 ` Jason Gunthorpe
2020-10-09 16:02                   ` Thomas Gleixner

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=87y2kqfi7p.fsf@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --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=jacob.jun.pan@intel.com \
    --cc=jgg@nvidia.com \
    --cc=jing.lin@intel.com \
    --cc=kevin.tian@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@intel.com \
    --cc=mona.hossain@intel.com \
    --cc=netanelg@mellanox.com \
    --cc=parav@mellanox.com \
    --cc=pbonzini@redhat.com \
    --cc=rafael@kernel.org \
    --cc=samuel.ortiz@intel.com \
    --cc=sanjay.k.kumar@intel.com \
    --cc=shahafs@mellanox.com \
    --cc=tony.luck@intel.com \
    --cc=vkoul@kernel.org \
    --cc=x86@kernel.org \
    --cc=yan.y.zhao@linux.intel.com \
    --cc=yi.l.liu@intel.com \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.