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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	"will@kernel.org" <will@kernel.org>,
	"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
	"corbet@lwn.net" <corbet@lwn.net>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>
Subject: RE: [RFC][PATCH v2 00/13] iommu/arm-smmu-v3: Add NVIDIA implementation
Date: Thu, 2 Sep 2021 22:27:06 +0000	[thread overview]
Message-ID: <BN9PR11MB54337332A83176241C984EC58CCE9@BN9PR11MB5433.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20210902144524.GU1721383@nvidia.com>

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Thursday, September 2, 2021 10:45 PM
> 
> On Wed, Sep 01, 2021 at 06:55:55AM +0000, Tian, Kevin wrote:
> > > From: Alex Williamson
> > > Sent: Wednesday, September 1, 2021 12:16 AM
> > >
> > > On Mon, 30 Aug 2021 19:59:10 -0700
> > > Nicolin Chen <nicolinc@nvidia.com> wrote:
> > >
> > > > The SMMUv3 devices implemented in the Grace SoC support NVIDIA's
> > > custom
> > > > CMDQ-Virtualization (CMDQV) hardware. Like the new ECMDQ feature
> first
> > > > introduced in the ARM SMMUv3.3 specification, CMDQV adds multiple
> > > VCMDQ
> > > > interfaces to supplement the single architected SMMU_CMDQ in an
> effort
> > > > to reduce contention.
> > > >
> > > > This series of patches add CMDQV support with its preparational
> changes:
> > > >
> > > > * PATCH-1 to PATCH-8 are related to shared VMID feature: they are
> used
> > > >   first to improve TLB utilization, second to bind a shared VMID with a
> > > >   VCMDQ interface for hardware configuring requirement.
> > >
> > > The vfio changes would need to be implemented in alignment with the
> > > /dev/iommu proposals[1].  AIUI, the VMID is essentially binding
> > > multiple containers together for TLB invalidation, which I expect in
> > > the proposal below is largely already taken care of in that a single
> > > iommu-fd can support multiple I/O address spaces and it's largely
> > > expected that a hypervisor would use a single iommu-fd so this explicit
> > > connection by userspace across containers wouldn't be necessary.
> >
> > Agree. VMID is equivalent to DID (domain id) in other vendor iommus.
> > with /dev/iommu multiple I/O address spaces can share the same VMID
> > via nesting. No need of exposing VMID to userspace to build the
> > connection.
> 
> Indeed, this looks like a flavour of the accelerated invalidation
> stuff we've talked about already.
> 
> I would see it probably exposed as some HW specific IOCTL on the iommu
> fd to get access to the accelerated invalidation for IOASID's in the
> FD.
> 
> Indeed, this seems like a further example of why /dev/iommu is looking
> like a good idea as this RFC is very complicated to do something
> fairly simple.
> 
> Where are thing on the /dev/iommu work these days?
> 

We are actively working on the basic skeleton. Our original plan is to send
out the 1st draft before LPC, with support of vfio type1 semantics and
and pci dev only (single-device group). But later we realized that adding
multi-devices group support is also necessary even in the 1st draft to avoid
some dirty hacks and build the complete picture. This will add some time
though. If things go well, we'll still try hit the original plan. If not, it will be
soon after LPC.

Thanks
Kevin

  reply	other threads:[~2021-09-02 22:27 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31  2:59 Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 01/13] iommu: Add set_nesting_vmid/get_nesting_vmid functions Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 02/13] vfio: add VFIO_IOMMU_GET_VMID and VFIO_IOMMU_SET_VMID Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 03/13] vfio: Document VMID control for IOMMU Virtualization Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 04/13] vfio: add set_vmid and get_vmid for vfio_iommu_type1 Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 05/13] vfio/type1: Implement set_vmid and get_vmid Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 06/13] vfio/type1: Set/get VMID to/from iommu driver Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 07/13] iommu/arm-smmu-v3: Add shared VMID support for NESTING Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 08/13] iommu/arm-smmu-v3: Add VMID alloc/free helpers Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 09/13] iommu/arm-smmu-v3: Pass dev pointer to arm_smmu_detach_dev Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 10/13] iommu/arm-smmu-v3: Pass cmdq pointer in arm_smmu_cmdq_issue_cmdlist() Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 11/13] iommu/arm-smmu-v3: Add implementation infrastructure Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 12/13] iommu/arm-smmu-v3: Add support for NVIDIA CMDQ-Virtualization hw Nicolin Chen
2021-08-31  2:59 ` [RFC][PATCH v2 13/13] iommu/nvidia-smmu-v3: Add mdev interface support Nicolin Chen
2021-08-31 16:15 ` [RFC][PATCH v2 00/13] iommu/arm-smmu-v3: Add NVIDIA implementation Alex Williamson
2021-09-01  6:55   ` Tian, Kevin
2021-09-02 14:45     ` Jason Gunthorpe
2021-09-02 22:27       ` Tian, Kevin [this message]
2021-09-16 18:21         ` Nicolin Chen

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