RE: [PATCH v2 0/8] Initial support for SMMUv3 nested translation

[Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>]

> -----Original Message-----
> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Wednesday, August 28, 2024 7:13 PM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: Jason Gunthorpe <jgg@nvidia.com>; acpica-devel@lists.linux.dev;
> Guohanjun (Hanjun Guo) <guohanjun@huawei.com>;
> iommu@lists.linux.dev; Joerg Roedel <joro@8bytes.org>; Kevin Tian
> <kevin.tian@intel.com>; kvm@vger.kernel.org; Len Brown
> <lenb@kernel.org>; linux-acpi@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; Lorenzo Pieralisi <lpieralisi@kernel.org>; Rafael J.
> Wysocki <rafael@kernel.org>; Robert Moore <robert.moore@intel.com>;
> Robin Murphy <robin.murphy@arm.com>; Sudeep Holla
> <sudeep.holla@arm.com>; Will Deacon <will@kernel.org>; Alex Williamson
> <alex.williamson@redhat.com>; Eric Auger <eric.auger@redhat.com>; Jean-
> Philippe Brucker <jean-philippe@linaro.org>; Moritz Fischer
> <mdf@kernel.org>; Michael Shavit <mshavit@google.com>;
> patches@lists.linux.dev; Mostafa Saleh <smostafa@google.com>
> Subject: Re: [PATCH v2 0/8] Initial support for SMMUv3 nested translation
> 
> On Wed, Aug 28, 2024 at 06:06:36PM +0000, Shameerali Kolothum Thodi
> wrote:
> > > > > As mentioned above, the VIOMMU series would be required to test
> the
> > > > > entire nesting feature, which now has a v2 rebasing on this series.
> > > > > I tested it with a paring QEMU branch. Please refer to:
> > > > > https://lore.kernel.org/linux-
> > > > > iommu/cover.1724776335.git.nicolinc@nvidia.com/
> > > >
> > > > Thanks for this. I haven't gone through the viommu and its Qemu
> branch
> > > > yet.  The way we present nested-smmuv3/iommufd to the Qemu seems
> to
> > > > have changed  with the above Qemu branch(multiple nested SMMUs).
> > > > The old Qemu command line for nested setup doesn't work anymore.
> > > >
> > > > Could you please share an example Qemu command line  to verify this
> > > > series(Sorry, if I missed it in the links/git).
> > >
> > > My bad. I updated those two "for_iommufd_" QEMU branches with a
> > > README commit on top of each for the reference command.
> >
> > Thanks. I did give it a go and this is my command line based on above,
> 
> > But it fails to boot very early:
> >
> > root@ubuntu:/home/shameer/qemu-test# ./qemu_run-simple-iommufd-
> nicolin-2
> > qemu-system-aarch64-nicolin-viommu: Illegal numa node 2
> >
> > Any idea what am I missing? Do you any special config enabled while
> building Qemu?
> 
> Looks like you are running on a multi-SMMU platform :)
> 
> Would you please try syncing your local branch? That should work,
> as the update also had a small change to the virt code:
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 161a28a311..a782909016 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1640,7 +1640,7 @@ static PCIBus
> *create_pcie_expander_bridge(VirtMachineState *vms, uint8_t idx)
>      }
> 
>      qdev_prop_set_uint8(dev, "bus_nr", bus_nr);
> -    qdev_prop_set_uint16(dev, "numa_node", idx);
> +    qdev_prop_set_uint16(dev, "numa_node", 0);
>      qdev_realize_and_unref(dev, BUS(bus), &error_fatal);

That makes some progress. But still I am not seeing the assigned
dev  in Guest.

-device vfio-pci-nohotplug,host=0000:75:00.1,iommufd=iommufd0

root@ubuntu:/# lspci -tv#

root@ubuntu:/# lspci -tv
-+-[0000:ca]---00.0-[cb]--
 \-[0000:00]-+-00.0  Red Hat, Inc. QEMU PCIe Host bridge
             +-01.0  Red Hat, Inc Virtio network device
             +-02.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-03.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-04.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-05.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-06.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-07.0  Red Hat, Inc. QEMU PCIe Expander bridge
             +-08.0  Red Hat, Inc. QEMU PCIe Expander bridge
             \-09.0  Red Hat, Inc. QEMU PCIe Expander bridge

The new root port is created, but no device attached.

But without iommufd,
-device vfio-pci-nohotplug,host=0000:75:00.1

root@ubuntu:/# lspci -tv
-[0000:00]-+-00.0  Red Hat, Inc. QEMU PCIe Host bridge
           +-01.0  Red Hat, Inc Virtio network device
           +-02.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-03.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-04.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-05.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-06.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-07.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-08.0  Red Hat, Inc. QEMU PCIe Expander bridge
           +-09.0  Red Hat, Inc. QEMU PCIe Expander bridge
           \-0a.0  Huawei Technologies Co., Ltd. Device a251

We can see dev a251.

And yes the setup has multiple SMMUs(8).

Thanks,
Shameer