Subject: Re: [PATCH V4 0/8] KVM: PPC: Implement passthrough of emulated devices for nested guests

From: Paul Mackerras <[email-masked]>
Date: Tue, 18 Dec 2018 12:02:53 +1100

On Fri, Dec 14, 2018 at 04:29:02PM +1100, Suraj Jitindar Singh wrote:
> This patch series allows for emulated devices to be passed through to nested
> guests, irrespective of at which level the device is being emulated.
> 
> Note that the emulated device must be using dma, not virtio.
> 
> For example, passing through an emulated e1000:
> 
> 1. Emulate the device at L(n) for L(n+1)
> 
> qemu-system-ppc64 -netdev type=user,id=net0 -device e1000,netdev=net0
> 
> 2. Assign the VFIO-PCI driver at L(n+1)
> 
> echo vfio-pci > /sys/bus/pci/devices/0000:00:00.0/driver_override
> echo 0000:00:00.0 > /sys/bus/pci/drivers/e1000/unbind
> echo 0000:00:00.0 > /sys/bus/pci/drivers/vfio-pci/bind
> chmod 666 /dev/vfio/0
> 
> 3. Pass the device through from L(n+1) to L(n+2)
> 
> qemu-system-ppc64 -device vfio-pci,host=0000:00:00.0
> 
> 4. L(n+2) can now access the device which will be emulated at L(n)
> 
> V2 -> V3:
> 1/8: None
> 2/8: None
> 3/8: None
> 4/8: None
> 5/8: None
> 6/8: Add if def to fix compilation for some platforms
> 7/8: None
> 8/8: None
> 
> Suraj Jitindar Singh (8):
>   KVM: PPC: Only report KVM_CAP_SPAPR_TCE_VFIO on powernv machines
>   KVM: PPC: Book3S HV: Add function kvmhv_vcpu_is_radix()
>   KVM: PPC: Book3S HV: Implement functions to access quadrants 1 & 2
>   KVM: PPC: Add load_from_eaddr and store_to_eaddr to the kvmppc_ops
>     struct
>   KVM: PPC: Update kvmppc_st and kvmppc_ld to use quadrants
>   KVM: PPC: Book3S HV: Allow passthrough of an emulated device to an L2
>     guest
>   KVM: PPC: Introduce new hcall H_COPY_TOFROM_GUEST to access quadrants
>     1 & 2
>   KVM: PPC: Book3S HV: Allow passthrough of an emulated device to an L3
>     guest

Thanks, series applied to my kvm-ppc-next branch.

Paul.