Re: [RFC PATCH 0/5] hw/arm/virt: Add support for user-creatable nested SMMUv3

[Daniel P . Berrangé]

On Fri, Nov 08, 2024 at 12:52:37PM +0000, Shameer Kolothum via wrote:
> How to use it(Eg:):
> 
> On a HiSilicon platform that has multiple physical SMMUv3s, the ACC ZIP VF
> devices and HNS VF devices are behind different SMMUv3s. So for a Guest,
> specify two smmuv3-nested devices each behind a pxb-pcie as below,
> 
> ./qemu-system-aarch64 -machine virt,gic-version=3,default-bus-bypass-iommu=on 
> \
> -enable-kvm -cpu host -m 4G -smp cpus=8,maxcpus=8 \
> -object iommufd,id=iommufd0 \
> -bios QEMU_EFI.fd \
> -kernel Image \
> -device virtio-blk-device,drive=fs \
> -drive if=none,file=rootfs.qcow2,id=fs \
> -device pxb-pcie,id=pcie.1,bus_nr=8,bus=pcie.0 \
> -device pcie-root-port,id=pcie.port1,bus=pcie.1,chassis=1 \
> -device arm-smmuv3-nested,id=smmuv1,pci-bus=pcie.1 \
> -device vfio-pci,host=0000:7d:02.1,bus=pcie.port1,iommufd=iommufd0 \
> -device pxb-pcie,id=pcie.2,bus_nr=16,bus=pcie.0 \
> -device pcie-root-port,id=pcie.port2,bus=pcie.2,chassis=2 \
> -device arm-smmuv3-nested,id=smmuv2,pci-bus=pcie.2 \
> -device vfio-pci,host=0000:75:00.1,bus=pcie.port2,iommufd=iommufd0 \
> -append "rdinit=init console=ttyAMA0 root=/dev/vda2 rw 
> earlycon=pl011,0x9000000" \
> -device virtio-9p-pci,fsdev=p9fs2,mount_tag=p9,bus=pcie.0 \
> -fsdev local,id=p9fs2,path=p9root,security_model=mapped \
> -net none \
> -nographic

Above you say the host has 2 SMMUv3 devices, and you've created 2 SMMUv3
guest devices to match.

The various emails in this thread & libvirt thread, indicate that each
guest SMMUv3 is associated with a host SMMUv3, but I don't see any
property on the command line for 'arm-ssmv3-nested' that tells it which
host eSMMUv3 it is to be associated with.

How does this association work ?


With regards,
Daniel
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