3 files changed, 95 insertions, 2 deletions

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 5d8e086..a44faa3 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -1335,11 +1335,20 @@ static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src)
     }
 }
 
-int css_do_stsch(SubchDev *sch, SCHIB *schib)
+IOInstEnding css_do_stsch(SubchDev *sch, SCHIB *schib)
 {
+    int ret;
+
+    /*
+     * For some subchannels, we may want to update parts of
+     * the schib (e.g., update path masks from the host device
+     * for passthrough subchannels).
+     */
+    ret = s390_ccw_store(sch);
+
     /* Use current status. */
     copy_schib_to_guest(schib, &sch->curr_status);
-    return 0;
+    return ret;
 }
 
 static void copy_pmcw_from_guest(PMCW *dest, const PMCW *src)
diff --git a/hw/s390x/s390-ccw.c b/hw/s390x/s390-ccw.c
index c48510f..b497571 100644
--- a/hw/s390x/s390-ccw.c
+++ b/hw/s390x/s390-ccw.c
@@ -51,6 +51,27 @@ int s390_ccw_clear(SubchDev *sch)
     return cdc->handle_clear(sch);
 }
 
+IOInstEnding s390_ccw_store(SubchDev *sch)
+{
+    S390CCWDeviceClass *cdc = NULL;
+    int ret = IOINST_CC_EXPECTED;
+
+    /*
+     * This code is called for both virtual and passthrough devices,
+     * but only applies to to the latter.  This ugly check makes that
+     * distinction for us.
+     */
+    if (object_dynamic_cast(OBJECT(sch->driver_data), TYPE_S390_CCW)) {
+        cdc = S390_CCW_DEVICE_GET_CLASS(sch->driver_data);
+    }
+
+    if (cdc && cdc->handle_store) {
+        ret = cdc->handle_store(sch);
+    }
+
+    return ret;
+}
+
 static void s390_ccw_get_dev_info(S390CCWDevice *cdev,
                                   char *sysfsdev,
                                   Error **errp)
diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index ca06213..f5a5e03 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -41,6 +41,9 @@ struct VFIOCCWDevice {
     uint64_t async_cmd_region_size;
     uint64_t async_cmd_region_offset;
     struct ccw_cmd_region *async_cmd_region;
+    uint64_t schib_region_size;
+    uint64_t schib_region_offset;
+    struct ccw_schib_region *schib_region;
     EventNotifier io_notifier;
     bool force_orb_pfch;
     bool warned_orb_pfch;
@@ -116,6 +119,51 @@ again:
     }
 }
 
+static IOInstEnding vfio_ccw_handle_store(SubchDev *sch)
+{
+    S390CCWDevice *cdev = sch->driver_data;
+    VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
+    SCHIB *schib = &sch->curr_status;
+    struct ccw_schib_region *region = vcdev->schib_region;
+    SCHIB *s;
+    int ret;
+
+    /* schib region not available so nothing else to do */
+    if (!region) {
+        return IOINST_CC_EXPECTED;
+    }
+
+    memset(region, 0, sizeof(*region));
+    ret = pread(vcdev->vdev.fd, region, vcdev->schib_region_size,
+                vcdev->schib_region_offset);
+
+    if (ret == -1) {
+        /*
+         * Device is probably damaged, but store subchannel does not
+         * have a nonzero cc defined for this scenario.  Log an error,
+         * and presume things are otherwise fine.
+         */
+        error_report("vfio-ccw: store region read failed with errno=%d", errno);
+        return IOINST_CC_EXPECTED;
+    }
+
+    /*
+     * Selectively copy path-related bits of the SCHIB,
+     * rather than copying the entire struct.
+     */
+    s = (SCHIB *)region->schib_area;
+    schib->pmcw.pnom = s->pmcw.pnom;
+    schib->pmcw.lpum = s->pmcw.lpum;
+    schib->pmcw.pam = s->pmcw.pam;
+    schib->pmcw.pom = s->pmcw.pom;
+
+    if (s->scsw.flags & SCSW_FLAGS_MASK_PNO) {
+        schib->scsw.flags |= SCSW_FLAGS_MASK_PNO;
+    }
+
+    return IOINST_CC_EXPECTED;
+}
+
 static int vfio_ccw_handle_clear(SubchDev *sch)
 {
     S390CCWDevice *cdev = sch->driver_data;
@@ -382,10 +430,23 @@ static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
         vcdev->async_cmd_region = g_malloc0(info->size);
     }
 
+    ret = vfio_get_dev_region_info(vdev, VFIO_REGION_TYPE_CCW,
+                                   VFIO_REGION_SUBTYPE_CCW_SCHIB, &info);
+    if (!ret) {
+        vcdev->schib_region_size = info->size;
+        if (sizeof(*vcdev->schib_region) != vcdev->schib_region_size) {
+            error_setg(errp, "vfio: Unexpected size of the schib region");
+            goto out_err;
+        }
+        vcdev->schib_region_offset = info->offset;
+        vcdev->schib_region = g_malloc(info->size);
+    }
+
     g_free(info);
     return;
 
 out_err:
+    g_free(vcdev->schib_region);
     g_free(vcdev->async_cmd_region);
     g_free(vcdev->io_region);
     g_free(info);
@@ -394,6 +455,7 @@ out_err:
 
 static void vfio_ccw_put_region(VFIOCCWDevice *vcdev)
 {
+    g_free(vcdev->schib_region);
     g_free(vcdev->async_cmd_region);
     g_free(vcdev->io_region);
 }
@@ -569,6 +631,7 @@ static void vfio_ccw_class_init(ObjectClass *klass, void *data)
     cdc->handle_request = vfio_ccw_handle_request;
     cdc->handle_halt = vfio_ccw_handle_halt;
     cdc->handle_clear = vfio_ccw_handle_clear;
+    cdc->handle_store = vfio_ccw_handle_store;
 }
 
 static const TypeInfo vfio_ccw_info = {