On 09/19/2017 11:06 AM, Cornelia Huck wrote: > On Tue, 19 Sep 2017 11:37:30 +0800 > Dong Jia Shi <bjsdj...@linux.vnet.ibm.com> wrote: > >> * Halil Pasic <pa...@linux.vnet.ibm.com> [2017-09-13 13:50:28 +0200]: >> >>> Replace direct access which implicitly assumes no IDA >>> or MIDA with the new ccw data stream interface which should >>> cope with these transparently in the future. >>> >>> Signed-off-by: Halil Pasic <pa...@linux.vnet.ibm.com> >>> >>> --- >>> >>> v1 --> v2: >>> Removed todo comments on possible errno change as with >>> https://lists.nongnu.org/archive/html/qemu-devel/2017-09/msg02441.html >>> applied it does not matter any more. >>> >>> Error handling: At the moment we ignore errors reported >>> by stream ops to keep the change minimal. An add-on >>> patch improving on this is to be expected later. >> Add a TODO somewhere around the code as a reminder? > > I expect Halil to have it on his TODO list and send a patch later ;) > >> >>> --- >>> hw/s390x/virtio-ccw.c | 156 >>> +++++++++++++++----------------------------------- >>> 1 file changed, 46 insertions(+), 110 deletions(-) >>> >>> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c >>> index b1976fdd19..a9baf6f7ab 100644 >>> --- a/hw/s390x/virtio-ccw.c >>> +++ b/hw/s390x/virtio-ccw.c >> [...] >> >>> @@ -394,11 +362,8 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) >>> } else { >>> VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev); >>> >>> - features.index = address_space_ldub(&address_space_memory, >>> - ccw.cda >>> - + >>> sizeof(features.features), >>> - MEMTXATTRS_UNSPECIFIED, >>> - NULL); >>> + ccw_dstream_advance(&sch->cds, sizeof(features.features)); >> How about: >> ccw_dstream_advance(&sch->cds, offsetof(VirtioFeatDesc, index)); > > I think keeping sizeof(features.features) is better: It matches the old > code, and we really do jump over the features flag and revisit it > later... > >> >>> + ccw_dstream_read(&sch->cds, features.index); >>> if (features.index == 0) { >>> if (dev->revision >= 1) { >>> /* Don't offer legacy features for modern devices. */ >>> @@ -417,9 +382,9 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) >>> /* Return zeroes if the guest supports more feature bits. >>> */ >>> features.features = 0; >>> } >>> - address_space_stl_le(&address_space_memory, ccw.cda, >>> - features.features, MEMTXATTRS_UNSPECIFIED, >>> - NULL); >>> + ccw_dstream_rewind(&sch->cds); >>> + cpu_to_le32s(&features.features); >>> + ccw_dstream_write(&sch->cds, features.features); >>> sch->curr_status.scsw.count = ccw.count - sizeof(features); >> How about: >> sch->curr_status.scsw.count = ccw_dstream_residual_count(&sch->cds); > > Hm, I thought I had commented on this, but I seem to have missed > these... > > I'd prefer to do it as a follow-up patch. > >> >> This also applies to other places. >> >>> ret = 0; >>> } >> [...] >> >>> @@ -501,21 +459,13 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) >>> } >>> } >>> len = MIN(ccw.count, vdev->config_len); >>> - hw_len = len; >>> if (!ccw.cda) { >>> ret = -EFAULT; >>> } else { >>> - config = cpu_physical_memory_map(ccw.cda, &hw_len, 0); >>> - if (!config) { >>> - ret = -EFAULT; >>> - } else { >>> - len = hw_len; >>> - /* XXX config space endianness */ >>> - memcpy(vdev->config, config, len); >>> - cpu_physical_memory_unmap(config, hw_len, 0, hw_len); >>> + ret = ccw_dstream_read_buf(&sch->cds, vdev->config, len); >>> + if (!ret) { >> Add a TODO here, and: >> >> if (ccw_dstream_read_buf(&sch->cds, vdev->config, len)) { >> ret = -EFAULT; >> } else { >> .... >> } > > I don't think that would be correct: The function will (at least > currently) return 0 or -EINVAL, and you are now mapping any error to > -EFAULT? (Not that it has an effect in the end: We map both to a > channel program check as of "s390x/css: drop data-check in > interpretation".) > >> >>> virtio_bus_set_vdev_config(&dev->bus, vdev->config); >>> sch->curr_status.scsw.count = ccw.count - len; >>> - ret = 0; >>> } >>> } >>> break; >> [...] >> >>> @@ -714,13 +654,9 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) >>> ret = -EFAULT; >>> break; >>> } >>> - revinfo.revision = >>> - address_space_lduw_be(&address_space_memory, ccw.cda, >>> - MEMTXATTRS_UNSPECIFIED, NULL); >>> - revinfo.length = >>> - address_space_lduw_be(&address_space_memory, >>> - ccw.cda + sizeof(revinfo.revision), >>> - MEMTXATTRS_UNSPECIFIED, NULL); >>> + ccw_dstream_read_buf(&sch->cds, &revinfo, 4); >> ^ >> A magic number? O:) > > Hah :) > > We can't use sizeof(revinfo), and sizeof(revinfo.revision) + > sizeof(revinfo.length) is a bit unwieldy. Let's keep some magic in our > code :) > >> >>> + be16_to_cpus(&revinfo.revision); >>> + be16_to_cpus(&revinfo.length); >>> if (ccw.count < len + revinfo.length || >>> (check_len && ccw.count > len + revinfo.length)) { >>> ret = -EINVAL; >>> -- >>> 2.13.5 >>> >> >> Otherwise, looks good. >> > > Can I get an ack? >
I agree that further cleanups are possible (e.g. using ccw_dstream_residual_count() and tightening error handling) but I also prefer to see these as on-top, and prefer sticking to change as little as possible in the transformation patch and stay as close as possible to what we had before in terms of behavior). Regards, Halil
