KVM: s390: Add CPU dump functionality

KVM: s390: Add CPU dump functionality

The previous patch introduced the per-VM dump functions now let's
focus on dumping the VCPU state via the newly introduced
KVM_S390_PV_CPU_COMMAND ioctl which mirrors the VM UV ioctl and can be
extended with new commands later.

Signed-off-by: Janosch Frank <[email protected]>
Reviewed-by: Claudio Imbrenda <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Message-Id: <20220517163629[email protected]>
Signed-off-by: Christian Borntraeger <[email protected]>