vfio/ccw: identify CCW data addresses as physical

The CCW data address created by vfio-ccw is that of an IDAL
built by this code. Since this address is used by real hardware,
it should be a physical address rather than a virtual one.
Let's clarify it as such in the ORB.

Similarly, once the I/O has completed the memory for that IDAL
needs to be released, so convert the CCW data address back to
a virtual address so that kfree() can process it.

Note: this currently doesn't fix a real bug, since virtual
addresses are identical to physical ones.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20221121165836.283781-3-farman@linux.ibm.com

Author: efarman

drivers/s390/cio/vfio_ccw_cp.c

@@ -394,7 +394,7 @@ static void ccwchain_cda_free(struct ccwchain *chain, int idx)
 	if (ccw_is_tic(ccw))
 		return;
 
-	kfree((void *)(u64)ccw->cda);
+	kfree(phys_to_virt(ccw->cda));
 }
 
 /**
@@ -845,7 +845,7 @@ union orb *cp_get_orb(struct channel_program *cp, u32 intparm, u8 lpm)
 
 	chain = list_first_entry(&cp->ccwchain_list, struct ccwchain, next);
 	cpa = chain->ch_ccw;
-	orb->cmd.cpa = (__u32) __pa(cpa);
+	orb->cmd.cpa = (__u32)virt_to_phys(cpa);
 
 	return orb;
 }