From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Thomas Gleixner <tglx@linutronix.de>
Cc: "Raj, Ashok" <ashok.raj@intel.com>,
Christoph Hellwig <hch@infradead.org>,
"Wilk, Konrad" <konrad.wilk@oracle.com>,
"Williams, Dan J" <dan.j.williams@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, 16 Nov 2020 23:51:35 +0000 [thread overview]
Message-ID: <MWHPR11MB1645E87DBEFFCC017C4849CC8CE30@MWHPR11MB1645.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20201116180241.GP917484@nvidia.com>
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, November 17, 2020 2:03 AM
>
> On Mon, Nov 16, 2020 at 06:56:33PM +0100, Thomas Gleixner wrote:
> > On Mon, Nov 16 2020 at 11:46, Jason Gunthorpe wrote:
> >
> > > On Mon, Nov 16, 2020 at 07:31:49AM +0000, Tian, Kevin wrote:
> > >
> > >> > The subdevices require PASID & IOMMU in native, but inside the guest
> there
> > >> > is no
> > >> > need for IOMMU unless you want to build SVM on top. subdevices
> work
> > >> > without
> > >> > any vIOMMU or hypercall in the guest. Only because they look like
> normal
> > >> > PCI devices we could map interrupts to legacy MSIx.
> > >>
> > >> Guest managed subdevices on PF/VF requires vIOMMU.
> > >
> > > Why? I've never heard we need vIOMMU for our existing SRIOV flows in
> > > VMs??
> >
> > Handing PF/VF into the guest does not require it.
> >
> > But if the PF/VF driver in the guest wants to create and manage the
> > magic mdev subdevices which require PASID support then you surely need
> > it.
>
> 'magic mdevs' are only one reason to use IMS in a guest. On mlx5 we
> might want to use IMS for VPDA devices. mlx5 can spawn a VDPA device
> in a guest, against a 'ADI', without ever requiring an IOMMU to do it.
>
> We don't even need IOMMU in the hypervisor to create the ADI, mlx5 has
> an internal secure IOMMU that can be used instead of the platform
> IOMMU.
>
> Not saying this is a major use case, or a reason not to link things to
> IOMMU detection, but lets be clear that a hard need for IOMMU is a
> another IDXD thing, not general.
>
I should use "may require" in original post. and one thing that I obviously
mixed is the requirement of PASID-granular interrupt isolation in the
physical IOMMU instead of virtual IOMMU. But anyway, I didn't attempt
to use above to build hard need for IOMMU, just the opposite when looking
at all three cases together.
btw Jason/Thomas, how do you think about the proposal down in this
thread (ims=[auto|on|off])? Does it sound a good tradeoff to move forward?
Thanks
Kevin
next prev parent reply other threads:[~2020-11-16 23:51 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
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 [this message]
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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