diff options
| author | Farhan Ali <alifm@linux.ibm.com> | 2020-05-05 14:27:43 +0200 |
|---|---|---|
| committer | Cornelia Huck <cohuck@redhat.com> | 2020-06-03 11:27:43 +0200 |
| commit | d8cac29b1d52204e6632d2887eff766acd02b9aa (patch) | |
| tree | cef969d5a9b5e23684a582d11218b23ac5512896 /Documentation | |
| parent | 4296151d231eeee78514bf7f495c46683785255d (diff) | |
vfio-ccw: Introduce a new CRW region
This region provides a mechanism to pass a Channel Report Word
that affect vfio-ccw devices, and needs to be passed to the guest
for its awareness and/or processing.
The base driver (see crw_collect_info()) provides space for two
CRWs, as a subchannel event may have two CRWs chained together
(one for the ssid, one for the subchannel). As vfio-ccw will
deal with everything at the subchannel level, provide space
for a single CRW to be transferred in one shot.
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200505122745.53208-7-farman@linux.ibm.com>
[CH: added padding to ccw_crw_region]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/s390/vfio-ccw.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst index 32310df525ba..8aad08a8b8a5 100644 --- a/Documentation/s390/vfio-ccw.rst +++ b/Documentation/s390/vfio-ccw.rst @@ -298,6 +298,26 @@ This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_SCHIB. Reading this region triggers a STORE SUBCHANNEL to be issued to the associated hardware. +vfio-ccw crw region +--------------------- + +The vfio-ccw crw region is used to return Channel Report Word (CRW) +data to userspace:: + + struct ccw_crw_region { + __u32 crw; + __u32 pad; + } __packed; + +This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_CRW. + +Reading this region returns a CRW if one that is relevant for this +subchannel (e.g. one reporting changes in channel path state) is +pending, or all zeroes if not. If multiple CRWs are pending (including +possibly chained CRWs), reading this region again will return the next +one, until no more CRWs are pending and zeroes are returned. This is +similar to how STORE CHANNEL REPORT WORD works. + vfio-ccw operation details -------------------------- |