On Wed, Nov 24, 2021 at 03:31:13PM +0800, Xiaoyao Li wrote: > On 8/26/2021 6:22 PM, Gerd Hoffmann wrote: > > On Wed, Jul 07, 2021 at 05:54:36PM -0700, isaku.yamahata@xxxxxxxxx wrote: > > > From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> > > > > > > Introduce a machine property, kvm-type, to allow the user to create a > > > Trusted Domain eXtensions (TDX) VM, a.k.a. a Trusted Domain (TD), e.g.: > > > > > > # $QEMU \ > > > -machine ...,kvm-type=tdx \ > > > ... > > Sorry for the very late reply. > > > Can we align sev and tdx better than that? > > > > SEV is enabled this way: > > > > qemu -machine ...,confidential-guest-support=sev0 \ > > -object sev-guest,id=sev0,... > > > > (see docs/amd-memory-encryption.txt for details). > > > > tdx could likewise use a tdx-guest object (and both sev-guest and > > tdx-guest should probably have a common parent object type) to enable > > and configure tdx support. > > yes, sev only introduced a new object and passed it to > confidential-guest-support. This is because SEV doesn't require the new type > of VM. > However, TDX does require a new type of VM. > > If we read KVM code, there is a parameter of CREATE_VM to pass the vm_type, > though x86 doesn't use this field so far. On QEMU side, it also has the > codes to pass/configure vm-type in command line. Of cousre, x86 arch doesn't > implement it. With upcoming TDX, it will implement and use vm type for TDX. > That's the reason we wrote this patch to implement kvm-type for x86, similar > to other arches. > > yes, of course we can infer the vm_type from "-object tdx-guest". But I > prefer to just use vm_type. Let's see others opinion. It isn't just SEV that is using the confidential-guest-support approach. This was done for PPC64 and S390x too. This gives QEMU a standard internal interface to declare that a confidential guest is being used / configured. IMHO, TDX needs to use this too, unless there's a compelling technical reason why it is a bad approach & needs to diverge from every other confidential guest impl in QEMU. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
