Draft: arm/kvm: report registers we failed to set

JIRA: RHEL-119369

If we fail migration because of a mismatch of some registers between source and destination, the error message is not very informative:

qemu-system-aarch64: error while loading state for instance 0x0 ofdevice 'cpu' qemu-system-aarch64: Failed to put registers after init: Invalid argument

At least try to give the user a hint which registers had a problem, even if they cannot really do anything about it right now.

Sample output:

Could not set register op0:3 op1:0 crn:0 crm:0 op2:0 to c00fac31 (is 413fd0c1)

We could be even more helpful once we support writable ID registers, at which point the user might actually be able to configure something that is migratable.

Suggested-by: Eric Auger eric.auger@redhat.com Reviewed-by: Sebastian Ott sebott@redhat.com Signed-off-by: Cornelia Huck cohuck@redhat.com Message-id: 20250911154159.158046-1-cohuck@redhat.com Signed-off-by: Peter Maydell peter.maydell@linaro.org (cherry picked from commit 19f6dcfe6b8b2a3523362812fc696ab83050d316) Signed-off-by: Eric Auger eric.auger@redhat.com