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From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	"Williams, Dan J" <dan.j.williams@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"Dey, Megha" <megha.dey@intel.com>,
	"maz@kernel.org" <maz@kernel.org>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.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>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"parav@mellanox.com" <parav@mellanox.com>,
	"rafael@kernel.org" <rafael@kernel.org>,
	"netanelg@mellanox.com" <netanelg@mellanox.com>,
	"shahafs@mellanox.com" <shahafs@mellanox.com>,
	"yan.y.zhao@linux.intel.com" <yan.y.zhao@linux.intel.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"Ortiz, Samuel" <samuel.ortiz@intel.com>,
	"Hossain, Mona" <mona.hossain@intel.com>,
	"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection
Date: Mon, 9 Nov 2020 12:46:08 -0400	[thread overview]
Message-ID: <20201109164608.GF2620339@nvidia.com> (raw)
In-Reply-To: <MWHPR11MB164578A1CC38EB28F6EA8F918CEA0@MWHPR11MB1645.namprd11.prod.outlook.com>

On Mon, Nov 09, 2020 at 07:37:03AM +0000, Tian, Kevin wrote:
> >  3) SIOV sub device assigned to the guest.
> > 
> >     The difference between SIOV and SRIOV is the device must attach a
> >     PASID to every TLP triggered by the guest. Logically we'd expect
> >     when IMS is used in this situation the interrupt MemWr is tagged
> >     with bus/device/function/PASID to uniquly ID the guest and the same
> >     security protection scheme from #2 applies.
> 
> Unfortunately no. Intel VT-d only treats MemWr w/o PASID to 0xFEExxxxx
> as interrupt request. MemWr w/ PASID, even to 0xFEE, is translated
> normally through DMA remapping page table. 

I've heard that current IOMMUs are limited as well, but IMHO, as I
describe, if you want full symmetry then you want to route interrupts
via PASID for SIOV. Otherwise the architecture is incomplete.

At least from a Linux and VMM perspective this should be planned
for. It is the only generic way to have a sub device assigned to a
guest and still have access to IMS.

> Does your device already implement such capability? We can bring this 
> request back to the hardware team. 

In some cases we can generate PASID tagged TLPs for interrupt
messages, if there was a reason to do that.

> Yes, this is the main worry here. While all agree that using hypercall is 
> the proper way to virtualize IMS, how to disable it when hypercall is
> not available is a more urgent demand at current stage.

Hopefully Thomas's note about checking for virtualization will help..

> btw in reality such ACPI extension doesn't exist yet, which likely will
> take some time. In the meantime we already have pending usages 
> like IDXD. Do you suggest holding these patches until we get ASWG 
> to accept the extension, or accept using Intel IMS cap as a vendor
> specific mitigation to move forward while the platform flag is being 
> worked on? Anyway the IMS cap is already defined and can help fix 
> some broken cases.

I think you need to sort something generic out, these half baked
architectures just make it some other teams problem.

Thomas's suggestion to check cpuid seems reasonably workable

Jason

  reply	other threads:[~2020-11-09 16:46 UTC|newest]

Thread overview: 125+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 18:50 [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Dave Jiang
2020-10-30 18:50 ` [PATCH v4 01/17] irqchip: Add IMS (Interrupt Message Store) driver Dave Jiang
2020-10-30 22:01   ` Thomas Gleixner
2020-10-30 18:51 ` [PATCH v4 02/17] iommu/vt-d: Add DEV-MSI support Dave Jiang
2020-10-30 20:31   ` Thomas Gleixner
2020-10-30 20:52     ` Dave Jiang
2020-10-30 18:51 ` [PATCH v4 03/17] dmaengine: idxd: add theory of operation documentation for idxd mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 04/17] dmaengine: idxd: add support for readonly config devices Dave Jiang
2020-10-30 18:51 ` [PATCH v4 05/17] dmaengine: idxd: add interrupt handle request support Dave Jiang
2020-10-30 18:51 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Dave Jiang
2020-10-30 19:51   ` Bjorn Helgaas
2020-10-30 21:20     ` Dave Jiang
2020-10-30 21:50       ` Bjorn Helgaas
2020-10-30 22:45       ` Jason Gunthorpe
2020-10-30 22:49         ` Dave Jiang
2020-11-02 13:21           ` Jason Gunthorpe
2020-11-03  2:49             ` Tian, Kevin
2020-11-03 12:43               ` Jason Gunthorpe
2020-11-04  3:41                 ` Tian, Kevin
2020-11-04 12:40                   ` Jason Gunthorpe
2020-11-04 13:34                     ` Tian, Kevin
2020-11-04 13:54                       ` Jason Gunthorpe
2020-11-06  9:48                         ` Tian, Kevin
2020-11-06 13:14                           ` Jason Gunthorpe
2020-11-06 16:48                             ` Raj, Ashok
2020-11-06 17:51                               ` Jason Gunthorpe
2020-11-06 23:47                                 ` Dan Williams
2020-11-07  0:12                                   ` Jason Gunthorpe
2020-11-07  1:42                                     ` Dan Williams
2020-11-08 18:11                                     ` Raj, Ashok
2020-11-08 18:34                                       ` David Woodhouse
2020-11-08 23:25                                         ` Raj, Ashok
2020-11-10 14:19                                           ` Raj, Ashok
2020-11-10 14:41                                             ` David Woodhouse
2020-11-08 23:41                                       ` Jason Gunthorpe
2020-11-09  0:05                                         ` Raj, Ashok
2020-11-08 18:47                                     ` Thomas Gleixner
2020-11-08 19:36                                       ` David Woodhouse
2020-11-08 22:47                                         ` Thomas Gleixner
2020-11-08 23:29                                           ` Jason Gunthorpe
2020-11-11 15:41                                         ` Christoph Hellwig
2020-11-11 16:09                                           ` Raj, Ashok
2020-11-11 22:27                                             ` Thomas Gleixner
2020-11-11 23:03                                               ` Raj, Ashok
2020-11-12  1:13                                                 ` Thomas Gleixner
2020-11-12 13:10                                                 ` Jason Gunthorpe
2020-11-08 23:23                                       ` Jason Gunthorpe
2020-11-08 23:36                                         ` Raj, Ashok
2020-11-09  7:37                                         ` Tian, Kevin
2020-11-09 16:46                                           ` Jason Gunthorpe [this message]
2020-11-08 23:58                                       ` Raj, Ashok
2020-11-09  7:59                                         ` Tian, Kevin
2020-11-09 11:21                                         ` Thomas Gleixner
2020-11-09 17:30                                           ` Jason Gunthorpe
2020-11-09 22:40                                             ` Raj, Ashok
2020-11-09 22:42                                             ` Thomas Gleixner
2020-11-10  5:14                                               ` Raj, Ashok
2020-11-10 10:27                                                 ` Thomas Gleixner
2020-11-10 14:13                                                   ` Raj, Ashok
2020-11-10 14:23                                                     ` Jason Gunthorpe
2020-11-11  2:17                                                       ` Tian, Kevin
2020-11-12 13:46                                                         ` Jason Gunthorpe
2020-11-11  7:14                                                     ` Tian, Kevin
2020-11-12 19:32                                                       ` Konrad Rzeszutek Wilk
2020-11-12 22:42                                                         ` Thomas Gleixner
2020-11-13  2:42                                                           ` Tian, Kevin
2020-11-13 12:57                                                             ` Jason Gunthorpe
2020-11-13 13:32                                                             ` Thomas Gleixner
2020-11-13 16:12                                                               ` Luck, Tony
2020-11-13 17:38                                                                 ` Raj, Ashok
2020-11-14 10:34                                                           ` Christoph Hellwig
2020-11-14 21:18                                                             ` Raj, Ashok
2020-11-15 11:26                                                               ` Thomas Gleixner
2020-11-15 19:31                                                                 ` Raj, Ashok
2020-11-15 22:11                                                                   ` Thomas Gleixner
2020-11-16  0:22                                                                     ` Raj, Ashok
2020-11-16  7:31                                                                       ` Tian, Kevin
2020-11-16 15:46                                                                         ` Jason Gunthorpe
2020-11-16 17:56                                                                           ` Thomas Gleixner
2020-11-16 18:02                                                                             ` Jason Gunthorpe
2020-11-16 20:37                                                                               ` Thomas Gleixner
2020-11-16 23:51                                                                               ` Tian, Kevin
2020-11-17  9:21                                                                                 ` Thomas Gleixner
2020-11-16  8:25                                                               ` Christoph Hellwig
2020-11-10 14:19                                                 ` Jason Gunthorpe
2020-11-11  2:35                                                   ` Tian, Kevin
2020-11-08 21:18                             ` Thomas Gleixner
2020-11-08 22:09                               ` David Woodhouse
2020-11-08 22:52                                 ` Thomas Gleixner
2020-11-07  0:32                           ` Thomas Gleixner
2020-11-09  5:25                             ` Tian, Kevin
2020-10-30 18:51 ` [PATCH v4 07/17] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-10-30 18:51 ` [PATCH v4 08/17] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 09/17] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-10-30 18:51 ` [PATCH v4 10/17] dmaengine: idxd: add emulation rw routines Dave Jiang
2020-10-30 18:52 ` [PATCH v4 11/17] dmaengine: idxd: prep for virtual device commands Dave Jiang
2020-10-30 18:52 ` [PATCH v4 12/17] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-10-30 18:52 ` [PATCH v4 13/17] dmaengine: idxd: ims setup for the vdcm Dave Jiang
2020-10-30 21:26   ` Thomas Gleixner
2020-10-30 18:52 ` [PATCH v4 14/17] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 15/17] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 16/17] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-10-30 18:52 ` [PATCH v4 17/17] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-10-30 18:58 ` [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Jason Gunthorpe
2020-10-30 19:13   ` Dave Jiang
2020-10-30 19:17     ` Jason Gunthorpe
2020-10-30 19:23       ` Raj, Ashok
2020-10-30 19:30         ` Jason Gunthorpe
2020-10-30 20:43           ` Raj, Ashok
2020-10-30 22:54             ` Jason Gunthorpe
2020-10-31  2:50             ` Thomas Gleixner
2020-10-31 23:53               ` Raj, Ashok
2020-11-02 13:20                 ` Jason Gunthorpe
2020-11-02 16:20                   ` Raj, Ashok
2020-11-02 17:19                     ` Jason Gunthorpe
2020-11-02 18:18                       ` Dave Jiang
2020-11-02 18:26                         ` Jason Gunthorpe
2020-11-02 18:38                           ` Dan Williams
2020-11-02 18:51                             ` Jason Gunthorpe
2020-11-02 19:26                               ` Dan Williams
2020-10-30 20:48 ` Thomas Gleixner
2020-10-30 20:59   ` Dave Jiang
2020-10-30 22:10     ` Thomas Gleixner
     [not found] <draft-875z6ekcj5.fsf@nanos.tec.linutronix.de>
2020-11-09 14:08 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Thomas Gleixner
2020-11-09 18:10   ` Raj, Ashok

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