KVM: s390: Change virtual to physical address access in diag 0x258 handler

KVM: s390: Change virtual to physical address access in diag 0x258 handler

The parameters for the diag 0x258 are real addresses, not virtual, but
KVM was using them as virtual addresses. This only happened to work, since
the Linux kernel as a guest used to have a 1:1 mapping for physical vs
virtual addresses.

Fix KVM so that it correctly uses the addresses as real addresses.

Cc: stable@vger.kernel.org
Fixes: 8ae04b8f500b ("KVM: s390: Guest's memory access functions get access registers")
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20240917151904.74314-3-nrb@linux.ibm.com
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>