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From: Alex Williamson <alex.williamson@redhat.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: <will@kernel.org>, <robin.murphy@arm.com>, <joro@8bytes.org>,
	<cohuck@redhat.com>, <corbet@lwn.net>, <nicoleotsuka@gmail.com>,
	<vdumpa@nvidia.com>, <thierry.reding@gmail.com>,
	<linux-tegra@vger.kernel.org>, <nwatterson@nvidia.com>,
	<Jonathan.Cameron@huawei.com>, <jean-philippe@linaro.org>,
	<song.bao.hua@hisilicon.com>, <eric.auger@redhat.com>,
	<thunder.leizhen@huawei.com>, <yuzenghui@huawei.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<iommu@lists.linux-foundation.org>, <kvm@vger.kernel.org>,
	<linux-doc@vger.kernel.org>, "Tian, Kevin" <kevin.tian@intel.com>,
	Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [RFC][PATCH v2 00/13] iommu/arm-smmu-v3: Add NVIDIA implementation
Date: Tue, 31 Aug 2021 10:15:49 -0600	[thread overview]
Message-ID: <20210831101549.237151fa.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210831025923.15812-1-nicolinc@nvidia.com>

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.

We're expecting to talk more about the /dev/iommu approach at Plumbers
in few weeks.  Thanks,

Alex

[1]https://lore.kernel.org/kvm/BN9PR11MB5433B1E4AE5B0480369F97178C189@BN9PR11MB5433.namprd11.prod.outlook.com/

 
> * PATCH-9 and PATCH-10 are to accommodate the NVIDIA implementation with
>   the existing arm-smmu-v3 driver.
> 
> * PATCH-11 borrows the "implementation infrastructure" from the arm-smmu
>   driver so later change can build upon it.
> 
> * PATCH-12 adds an initial NVIDIA implementation related to host feature,
>   and also adds implementation specific ->device_reset() and ->get_cmdq()
>   callback functions.
> 
> * PATCH-13 adds virtualization features using VFIO mdev interface, which
>   allows user space hypervisor to map and get access to one of the VCMDQ
>   interfaces of CMDQV module.
> 
> ( Thinking that reviewers can get a better view of this implementation,
>   I am attaching QEMU changes here for reference purpose:
>       https://github.com/nicolinc/qemu/commits/dev/cmdqv_v6.0.0-rc2
>   The branch has all preparational changes, while I'm still integrating
>   device model and ARM-VIRT changes, and will push them these two days,
>   although they might not be in a good shape of being sent to review yet )
> 
> Above all, I marked RFC for this series, as I feel that we may come up
> some better solution. So please kindly share your reviews and insights.
> 
> Thank you!
> 
> Changelog
> v1->v2:
>  * Added mdev interface support for hypervisor and VMs.
>  * Added preparational changes for mdev interface implementation.
>  * PATCH-12 Changed ->issue_cmdlist() to ->get_cmdq() for a better
>    integration with recently merged ECMDQ-related changes.
> 
> Nate Watterson (3):
>   iommu/arm-smmu-v3: Add implementation infrastructure
>   iommu/arm-smmu-v3: Add support for NVIDIA CMDQ-Virtualization hw
>   iommu/nvidia-smmu-v3: Add mdev interface support
> 
> Nicolin Chen (10):
>   iommu: Add set_nesting_vmid/get_nesting_vmid functions
>   vfio: add VFIO_IOMMU_GET_VMID and VFIO_IOMMU_SET_VMID
>   vfio: Document VMID control for IOMMU Virtualization
>   vfio: add set_vmid and get_vmid for vfio_iommu_type1
>   vfio/type1: Implement set_vmid and get_vmid
>   vfio/type1: Set/get VMID to/from iommu driver
>   iommu/arm-smmu-v3: Add shared VMID support for NESTING
>   iommu/arm-smmu-v3: Add VMID alloc/free helpers
>   iommu/arm-smmu-v3: Pass dev pointer to arm_smmu_detach_dev
>   iommu/arm-smmu-v3: Pass cmdq pointer in arm_smmu_cmdq_issue_cmdlist()
> 
>  Documentation/driver-api/vfio.rst             |   34 +
>  MAINTAINERS                                   |    2 +
>  drivers/iommu/arm/arm-smmu-v3/Makefile        |    2 +-
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c  |   15 +
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  121 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |   18 +
>  .../iommu/arm/arm-smmu-v3/nvidia-smmu-v3.c    | 1249 +++++++++++++++++
>  drivers/iommu/iommu.c                         |   20 +
>  drivers/vfio/vfio.c                           |   25 +
>  drivers/vfio/vfio_iommu_type1.c               |   37 +
>  include/linux/iommu.h                         |    5 +
>  include/linux/vfio.h                          |    2 +
>  include/uapi/linux/vfio.h                     |   26 +
>  13 files changed, 1537 insertions(+), 19 deletions(-)
>  create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-impl.c
>  create mode 100644 drivers/iommu/arm/arm-smmu-v3/nvidia-smmu-v3.c
> 


  parent reply	other threads:[~2021-08-31 16:15 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 ` Alex Williamson [this message]
2021-09-01  6:55   ` [RFC][PATCH v2 00/13] iommu/arm-smmu-v3: Add NVIDIA implementation Tian, Kevin
2021-09-02 14:45     ` Jason Gunthorpe
2021-09-02 22:27       ` Tian, Kevin
2021-09-16 18:21         ` Nicolin Chen

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