s390/hmcdrv: fix interrupt registration
authorHeiko Carstens <heiko.carstens@de.ibm.com>
Mon, 17 Aug 2015 05:56:20 +0000 (07:56 +0200)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Wed, 19 Aug 2015 08:40:17 +0000 (10:40 +0200)
commite619cd3d618672bea8602d682ea63b42a1faf1bc
treeeb14d81bb7c0e8fdc8a550334c61860c73c0ddf4
parent89b1145e93771d727645c96e323539c029b63f1c
s390/hmcdrv: fix interrupt registration

The z/VM driver sets bit "63-22" in control register zero to one in order
to enable the CP Service interrupt (0x2603). However the irq subclass mask
that normally corresponds to the CP Service interrupt is
"63-54" (== "63-22-32").

So it looks like the author read the documentation with the 32 bit sized
cr0 register bit positions (== 22), but didn't realize that bit numbers
change, if applied to a 64 bit register (== 54) due to the numbering
scheme.

Also use irq_subclass_register() instead if ctl_set_bit() since multiple
services depend on the service signal subclass mask, which is the correct
bit. This also explains why nobody noticed the bug, since the bit is always
enabled anyway (e.g. pfault).

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
drivers/s390/char/diag_ftp.c