Re: [RFC PATCH 00/10] QEMU Support for KVM Planes

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Jun 08, 2026 at 05:20:59PM +0200, Jörg Rödel wrote:
> From: Joerg Roedel <joerg.roedel@amd.com>
> 
> Hi,
> 
> here are the required QEMU changes to make use of the KVM Planes
> interface posted here[1].
> 
> The patches are based on QEMU v11.0.0 and can be used to launch an AMD
> SEV-SNP VM with COCONUT-SVSM + a Linux guest.
> 
> To make this work a change to the QEMU command line is required to
> tell QEMU which plane to target external IRQs to. this is done with
> the new device-plane property to the machine specification, e.g:
> 
> $ qemu-system-x86_64 \
>   -enable-kvm \
>   -cpu EPYC-v4 \
>   -machine q35,confidential-guest-support=sev0,memory-backend=ram1,igvm-cfg=igvm0,kernel-irqchip=split,device-plane=2 \
>   -object memory-backend-memfd,id=ram1,size=32G,share=true \
>   -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1 \
>   -object igvm-cfg,id=igvm0,file=$IGVM_FILE \
>   ...

How are device-plane values intended to be chosen by the user ?

Is "2" a value that can/should always be used, or is there a dependency
on the igvm file, or somethihng else ?


With regards,
Daniel
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