On Thu, Jul 04, 2024 at 08:51:05AM +0200, Paolo Bonzini wrote: > On Thu, Jul 4, 2024 at 2:01 AM Michael Roth <michael.roth@xxxxxxx> wrote: > > Currently if the 'legacy-vm-type' property of the sev-guest object is > > left unset, QEMU will attempt to use the newer KVM_SEV_INIT2 kernel > > interface in conjunction with the newer KVM_X86_SEV_VM and > > KVM_X86_SEV_ES_VM KVM VM types. > > > > This can lead to measurement changes if, for instance, an SEV guest was > > created on a host that originally had an older kernel that didn't > > support KVM_SEV_INIT2, but is booted on the same host later on after the > > host kernel was upgraded. > > I think this is the right thing to do for SEV-ES. I agree that it's > bad to require a very new kernel (6.10 will be released only a month > before QEMU 9.1), on the other hand the KVM_SEV_ES_INIT API is broken > in several ways. As long as there is a way to go back to it, and it's > not changed by old machine types, not using it for SEV-ES is the > better choice for upstream. Broken how ? I know there was the regression with the 'debug_swap' parameter, but was something that should just be fixed in the kernel, rather than breaking userspace. What else is a problem ? I don't think its reasonable for QEMU to require a brand new kernel for new machine types, given SEV & SEV-ES have been deployed for many years already. With 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 :|
