s390x: improve error handling for SSCH and RSCH

Simplify the error handling of the SSCH and RSCH handler avoiding
arbitrary and cryptic error codes being used to tell how the instruction
is supposed to end.  Let the code detecting the condition tell how it's
to be handled in a less ambiguous way.  It's best to handle SSCH and RSCH
in one go as the emulation of the two shares a lot of code.

For passthrough this change isn't pure refactoring, but changes the way
kernel reported EFAULT is handled. After clarifying the kernel interface
we decided that EFAULT shall be mapped to unit exception.  Same goes for
unexpected error codes and absence of required ORB flags.

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Message-Id: <20171017140453.51099-4-pasic@linux.vnet.ibm.com>
Tested-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
[CH: cosmetic changes]
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

2 files changed, 18 insertions, 7 deletions

diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
index 08ad1a14cf..666ce1174b 100644
--- a/include/hw/s390x/css.h
+++ b/include/hw/s390x/css.h
@@ -136,11 +136,22 @@ struct SubchDev {
     /* transport-provided data: */
     int (*ccw_cb) (SubchDev *, CCW1);
     void (*disable_cb)(SubchDev *);
-    int (*do_subchannel_work) (SubchDev *);
+    IOInstEnding (*do_subchannel_work) (SubchDev *);
     SenseId id;
     void *driver_data;
 };
 
+static inline void sch_gen_unit_exception(SubchDev *sch)
+{
+    sch->curr_status.scsw.ctrl &= ~SCSW_ACTL_START_PEND;
+    sch->curr_status.scsw.ctrl |= SCSW_STCTL_PRIMARY |
+                                  SCSW_STCTL_SECONDARY |
+                                  SCSW_STCTL_ALERT |
+                                  SCSW_STCTL_STATUS_PEND;
+    sch->curr_status.scsw.cpa = sch->channel_prog + 8;
+    sch->curr_status.scsw.dstat =  SCSW_DSTAT_UNIT_EXCEP;
+}
+
 extern const VMStateDescription vmstate_subch_dev;
 
 /*
@@ -199,9 +210,9 @@ void css_generate_sch_crws(uint8_t cssid, uint8_t ssid, uint16_t schid,
 void css_generate_chp_crws(uint8_t cssid, uint8_t chpid);
 void css_generate_css_crws(uint8_t cssid);
 void css_clear_sei_pending(void);
-int s390_ccw_cmd_request(ORB *orb, SCSW *scsw, void *data);
-int do_subchannel_work_virtual(SubchDev *sub);
-int do_subchannel_work_passthrough(SubchDev *sub);
+IOInstEnding s390_ccw_cmd_request(SubchDev *sch);
+IOInstEnding do_subchannel_work_virtual(SubchDev *sub);
+IOInstEnding do_subchannel_work_passthrough(SubchDev *sub);
 
 typedef enum {
     CSS_IO_ADAPTER_VIRTIO = 0,
@@ -232,7 +243,7 @@ int css_do_msch(SubchDev *sch, const SCHIB *schib);
 int css_do_xsch(SubchDev *sch);
 int css_do_csch(SubchDev *sch);
 int css_do_hsch(SubchDev *sch);
-int css_do_ssch(SubchDev *sch, ORB *orb);
+IOInstEnding css_do_ssch(SubchDev *sch, ORB *orb);
 int css_do_tsch_get_irb(SubchDev *sch, IRB *irb, int *irb_len);
 void css_do_tsch_update_subch(SubchDev *sch);
 int css_do_stcrw(CRW *crw);
@@ -243,7 +254,7 @@ int css_collect_chp_desc(int m, uint8_t cssid, uint8_t f_chpid, uint8_t l_chpid,
 void css_do_schm(uint8_t mbk, int update, int dct, uint64_t mbo);
 int css_enable_mcsse(void);
 int css_enable_mss(void);
-int css_do_rsch(SubchDev *sch);
+IOInstEnding css_do_rsch(SubchDev *sch);
 int css_do_rchp(uint8_t cssid, uint8_t chpid);
 bool css_present(uint8_t cssid);
 #endif
diff --git a/include/hw/s390x/s390-ccw.h b/include/hw/s390x/s390-ccw.h
index 9f45cf1347..7d15a1a5d4 100644
--- a/include/hw/s390x/s390-ccw.h
+++ b/include/hw/s390x/s390-ccw.h
@@ -33,7 +33,7 @@ typedef struct S390CCWDeviceClass {
     CCWDeviceClass parent_class;
     void (*realize)(S390CCWDevice *dev, char *sysfsdev, Error **errp);
     void (*unrealize)(S390CCWDevice *dev, Error **errp);
-    int (*handle_request) (ORB *, SCSW *, void *);
+    IOInstEnding (*handle_request) (SubchDev *sch);
 } S390CCWDeviceClass;
 
 #endif