On 26/11/2018 10:58, Cornelia Huck wrote:
On Fri, 23 Nov 2018 15:13:12 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
On 22/11/2018 17:54, Cornelia Huck wrote:
A vfio-ccw device may provide an async command subregion for
issuing halt/clear subchannel requests. If it is present, use
it for sending halt/clear request to the device; if not, fall
back to emulation (as done today).
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
hw/s390x/css.c | 27 +++++++--
hw/vfio/ccw.c | 109 +++++++++++++++++++++++++++++++++++-
include/hw/s390x/s390-ccw.h | 3 +
3 files changed, 133 insertions(+), 6 deletions(-)
@@ -114,6 +120,87 @@ again:
}
}
+int vfio_ccw_handle_clear(SubchDev *sch)
+{
+ S390CCWDevice *cdev = sch->driver_data;
+ VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
+ struct ccw_cmd_region *region = vcdev->async_cmd_region;
+ int ret;
+
+ if (!vcdev->async_cmd_region) {
+ /* Async command region not available, fall back to emulation */
+ return -ENOSYS;
+ }
+
+ memset(region, 0, sizeof(*region));
+ region->command = VFIO_CCW_ASYNC_CMD_CSCH;
+
+again:
+ ret = pwrite(vcdev->vdev.fd, region,
+ vcdev->async_cmd_region_size, vcdev->async_cmd_region_offset);
+ if (ret != vcdev->async_cmd_region_size) {
+ if (errno == EAGAIN) {
Where do the EAGAIN come from?
It might be set by pwrite.
I saw that the man indicate this, and so we are legitimate to handle the
fail case, but I did not find EAGAIN in the path of the write for
accessing devices and I did not find it in the access to the CSS.
If we do not set it explicitly from the driver, the concern I have is:
isn't it dangerous to try again and shouldn't we better abort?
+ goto again;
+ }
+ error_report("vfio-ccw: wirte I/O region failed with errno=%d", errno);
I should also fix up this message here and for hsch as well :)
+ ret = -errno;
+ } else {
+ ret = region->ret_code;
+ }
+ switch (ret) {
+ case 0:
+ case -ENODEV:
+ case -EACCES:
should never happen?
It should not happen; but it can nevertheless be returned, so...
I understand: nothing to clear :)
+ return 0;
+ case -EFAULT:
+ default:
+ sch_gen_unit_exception(sch);
+ css_inject_io_interrupt(sch);
+ return 0;
+ }
+}
+
otherwise LGTM
Thanks!
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
