Merge tag 'kvm-x86-xen-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM Xen change for 6.8:

To workaround Xen guests that don't expect Xen PV clocks to be marked as being
based on a stable TSC, add a Xen config knob to allow userspace to opt out of
KVM setting the "TSC stable" bit in Xen PV clocks.  Note, the "TSC stable" bit
was added to the PVCLOCK ABI by KVM without an ack from Xen, i.e. KVM isn't
entirely blameless for the buggy guest behavior.