Re: [RFC v16 0/9] SMMUv3 Nested Stage Setup (IOMMU part)

[Zhangfei Gao]

On 2021/12/7 下午6:27, Eric Auger wrote:
> Hi Zhangfei,
>
> On 12/3/21 1:27 PM, Zhangfei Gao wrote:
> > Hi, Eric
> >
> > On 2021/10/27 下午6:44, Eric Auger wrote:
> > > This series brings the IOMMU part of HW nested paging support
> > > in the SMMUv3.
> > >
> > > The SMMUv3 driver is adapted to support 2 nested stages.
> > >
> > > The IOMMU API is extended to convey the guest stage 1
> > > configuration and the hook is implemented in the SMMUv3 driver.
> > >
> > > This allows the guest to own the stage 1 tables and context
> > > descriptors (so-called PASID table) while the host owns the
> > > stage 2 tables and main configuration structures (STE).
> > >
> > > This work mainly is provided for test purpose as the upper
> > > layer integration is under rework and bound to be based on
> > > /dev/iommu instead of VFIO tunneling. In this version we also get
> > > rid of the MSI BINDING ioctl, assuming the guest enforces
> > > flat mapping of host IOVAs used to bind physical MSI doorbells.
> > > In the current QEMU integration this is achieved by exposing
> > > RMRs to the guest, using Shameer's series [1]. This approach
> > > is RFC as the IORT spec is not really meant to do that
> > > (single mapping flag limitation).
> > >
> > > Best Regards
> > >
> > > Eric
> > >
> > > This series (Host) can be found at:
> > > https://github.com/eauger/linux/tree/v5.15-rc7-nested-v16
> > > This includes a rebased VFIO integration (although not meant
> > > to be upstreamed)
> > >
> > > Guest kernel branch can be found at:
> > > https://github.com/eauger/linux/tree/shameer_rmrr_v7
> > > featuring [1]
> > >
> > > QEMU integration (still based on VFIO and exposing RMRs)
> > > can be found at:
> > > https://github.com/eauger/qemu/tree/v6.1.0-rmr-v2-nested_smmuv3_v10
> > > (use iommu=nested-smmuv3 ARM virt option)
> > >
> > > Guest dependency:
> > > [1] [PATCH v7 0/9] ACPI/IORT: Support for IORT RMR node
> > Thanks a lot for upgrading these patches.
> >
> > I have basically verified these patches on HiSilicon Kunpeng920.
> > And integrated them to these branches.
> > https://github.com/Linaro/linux-kernel-uadk/tree/uacce-devel-5.16
> > https://github.com/Linaro/qemu/tree/v6.1.0-rmr-v2-nested_smmuv3_v10
> >
> > Though they are provided for test purpose,
> >
> > Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
> Thank you very much. As you mentioned, until we do not have the
> /dev/iommu integration this is maintained for testing purpose. The SMMU
> changes shouldn't be much impacted though.
> The added value of this respin was to propose an MSI binding solution
> based on RMRRs which simplify things at kernel level.

Current RMRR solution requires uefi enabled,
and QEMU_EFI.fd  has to be provided to start qemu.

Any plan to support dtb as well, which will be simpler since no need 
QEMU_EFI.fd anymore.

Thanks